A Special Compilation of Formwork Articles a Special Compilation of Formwork Articles from the Masterbuilder from the Masterbuilder

SNAP THE MASTERBUILDER A Pioneering Initiative from SALES, NETWORKING AND PROMOTIONS The Masterbuilder FORMWORK FV1: No:O 1 RMWORK digest A Special Compilation of Formwork Articles A Special Compilation of Formwork Articles from The Masterbuilder from The Masterbuilder

What you will find in this edition of formwork digest

MB's ‘Formwork Digest’ is a special compilation of articles, case studies, communication features on formwork contributed by industry experts. This special compilation is meant to disseminate critical information on a broad range of topics with the objective of improving quality, safety and economy in all types of formwork and a must read for any- For more information on this edition one working with concrete. please contact:

‘Formwork Digest’ is also meant to be a one stop source for those who would like to Call: +91 9343833191 or alternatively gather information on leading formwork and scaffolding products that are available in Email: [email protected] the country at a simple click of a button.

If you need information on any or all of the below featured companies, write to: [email protected]

This special compilation is brought to you by:

Doka India Pvt. Ltd. GCI Wall Forms Private Ltd. Hi-Lite Systems Indigo Multitrade Pvt. Ltd. Kumkang Kind India The Formwork Experts Mass Customizer of Concrete India Private Limited Composite Fiberglass The Total Formwork Solutions Forming Systems Experince the Advantage Formwork System Provider for Gang-Formwork, Only Mantra of Construction Aluminum Formwork, System Formwork “Speed-speed & Speed”

Build with Confidence MFE Formwork Technology Nav Nirman Beam Technics Nova Plasmold P. Limited Paschal Formwork Peri (india) Pvt. Ltd. (I) Pvt. Ltd. Formwork H-Beam for Column India's First Modular Plastic India Pvt. Ltd. Formwork Scafffolding Engineering JUST GOT BETTER We lead… Formwork, Circular Formwork, Wall Formwork System Paschal - The German Formwork for The light weight Panel formwork Others follow Formwork, Slab Formwork Modular Panel System for Vertical for crane independent Forming Structures, Paschal Deck System and e-deck System for Horizontal Structures

PRANAV Pranav Construction Sharp Formwork & Sparkonix (India) Tac System Formwork Ulma Formwork Systems Systems Pvt. Ltd. Consulting Engineers Pvt. Ltd. Pvt. Ltd. The Aluminium Formwork India Pvt. Ltd. “END TO END SOLUTION” Formwork Systems for Construction Largest ABS Plastic Formwork Manufacturer for Complete Self Climbing and Crane for Formwork, Staging, Launching, Industry, Aluminium, Plywood, Manufacturer Building System Formwork Climbing System Formwork Tunneling & Formliner Systems for Polyurethane Every Civil Project

Need information on a specific product ? If you would like to receive more information on the solutions and services offered by the above mentioned formwork manufacturers write to us at [email protected] NOBODY COVERS FORMWORK BETTER

Established for over 17 years, 'The Masterbuilder' India's premier construction magazine has been serving the Indian civil engineering and infrastructure community through its in-depth analysis and reporting of emerging trends, methods and practices in concrete formwork since 1996. Our high editorial standards together with its most comprehensive and topical coverage by industry specialists has made the Masterbuilder as the most referred and circulated construction magazine in the country. No other publication for this sector comes close to The Masterbuilder either by volume and depth of quality editorial or through Masterbuilder's circulation of wholly industry-specific requested readership, which is why The Masterbuilder is the professions must read magazine and the most influential product in the community.

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A Special Compilation of Formwork Articles from The Masterbuilder Ÿ Modern Formwork Systems: A Ringside View of the Variety of Formwork Systems Available Today Ÿ Formwork: Future Approach in India Ÿ Formwork: Custom-Made Solutions Takes Center Stage Ÿ Certain Safety Considerations for Formwork Ÿ Formwork, Insulation, Wall thickness and Fly Ash: Do They Affect Concrete Maturity? Ÿ Effect of Concrete Temperature and Formwork Width on Variation Pressure Formwork of Self-compacting Concrete Ÿ Formwork Failure: Cases & Causes t Ÿ Formwork for Precast - An Overview Ÿ Formwork Equipment: Policy Initiatives Hold the Key for Continued Growth of Formwork Industry Ÿ Fabric Formwork: Sky's the Limit This Special Compilation is brought to you by:

If you would like to receive more information on the solutions and services offered by any or all of the below mentioned formwork manufacturers write to: [email protected]

Doka India Pvt. Ltd. GCI Wall Forms Private Ltd. Hi-Lite Systems India Private Limited The Formwork Experts Mass Customizer of Concrete Forming Systems Experince the Advantage Only Mantra of Construction “Speed-speed & Speed”

Indigo Multitrade Pvt. Ltd. Kumkang Kind India MFE Formwork Technology (I) Pvt. Ltd. Composite Fiberglass Formwork System The Total Formwork Solutions Provider for Gang- JUST GOT BETTER We lead… Others follow Formwork, Aluminum Formwork, System Formwork

Build with Confidence Nav Nirman Beam Technics Nova Plasmold P. Limited Paschal Formwork India Pvt. Ltd. Formwork H-Beam for Column Formwork, Circular India's First Modular Plastic Formwork System Paschal - The German Formwork for Modular Panel Formwork, Wall Formwork, Slab Formwork System for Vertical Structures, Paschal Deck System and e-deck System for Horizontal Structures

PRANAV Peri (india) Pvt. Ltd. Pranav Construction Systems Pvt. Ltd. Sharp Formwork & Consulting Formwork Scafffolding Engineering The light “END TO END SOLUTION” for Formwork, Staging, Engineers Pvt. Ltd. weight Panel formwork for crane independent Launching, Tunneling & Formliner Systems for Formwork Systems for Construction Industry, Forming Every Civil Project Aluminium, Plywood, Polyurethane

Sparkonix (India) Pvt. Ltd. Tac System Formwork Ulma Formwork Systems India Pvt. Ltd. Largest ABS Plastic Formwork Manufacturer The Aluminium Formwork Manufacturer for Self Climbing and Crane Climbing System Complete Building System Formwork Formwork Message

Special Compilation on Formwork

It gives us immense pleasure to present the first edition of MB’s Formwork Digest ‘A special compilation of articles on concrete formwork’ that aims to disseminate critical information on a broad range of topics with the objective of improving quality, safety and economy in all types of formwork. Destined to be a must read for anyone working with concrete.

We welcome your valuable suggestions on improving the scope of this publication. Please feel free to e-mail us with inquiries or to propose content.

Your feedbacks are welcome and should be sent to: The Editor, The Masterbuilder Formwork Digest, 102/11 (New No. 46/11), Tripti Apartments, Marshalls Road, Egmore, Chennai, India. Phone: +91 44 28555248 Telefax: +91 44 28586703

Editor-in-Chief Contributors Production Manager Karnataka K.P. Pradeep Bhavani Balakrishna, Priya, Caroline D'sylva No.40, 2nd Floor, 7th "C" Cross, [email protected] Chaitanya Raj Goyal Digital Production Assistant Ashwini Layout, Koramangala, Editor-in-Charge Vice President Marketing R. Anand, Sudhir Kumar Singh Bangalore - 560047. Phone: 080 - 25701079 / 25705888 Ravi Damodaran H. Usha Devi Circulation Team Mobile: 09343833191 Editor Head-New Media Initiative Sateesh Kuniyil, S. Sasi Nigel Narayan Pradeep Nair Corporate Office Owned and Published by MB Publishers Pvt. Limited K.P. Pradeep Associate Editors Manager Digital Production 102/11 (New No. 46/11), 102/11 (New No. 46/11), Tripti M.J. Krishna, M.K. Prabhakar, K. Sravanthi Kiran Tripti Apartments, Marshalls Road, Apartments, Marshalls Road, Egmore, Sonjay Deb Manager Digital Media Egmore, Chennai - 600 008. Chennai - 600 008. Head - Content Development CE, Lakshmi Ph: 044-28555248 Telefax: 28586703 Infrastructure & Environment Creative Head Website Sadagopan Seshadri S. Nithiyanandam www.masterbuilder.co.in

DISCLAIMER All rights reserved. Reproduction, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, in whole or part without prior written permission is prohibited. All views expressed in this magazine are those of the authors and do not necessarily reflect those of the publisher.

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V1 N1 · May 2013 FORMWORK 1 digest 11 Content

3 Modern Formwork Systems: A Ringside View of the Variety of Formwork Systems Available Today M.K. Prabhakar, Associate Editor

8 Formwork: Future Approach in India A.L.Sekar, B.Murugesan and C.N.V.S. Rao, Larsen & Toubro Ltd 36 11 Formwork: Custom-Made Solutions Takes Center Stage MB Bureau Report

17 Certain Safety Considerations for Formwork N. Krishnamurthy, Safety and Structures Consultant, Singapore

22 Formwork, Insulation, Wall thickness and Fly Ash: Do They Affect Concrete Maturity? Rishi Gupta1 and Katie Kuder2 1Faculty & Program Coordinator, Department of Civil Engineering, British Columbia Institute of Technology 2Assistant Professor, Dept. of Civil and Environmental Engineering, Seattle University

30 Effect of Concrete Temperature and Formwork Width on 41 Variation Pressure Formwork of Self-compacting Concrete 1Amir Hosein Bakhtiarain, 2Morteza Askari 1The Bsc. Student of Islamic Azad University, Iran 2The Faculty Member of Islamic Azad University, Iran

36 Formwork Failure: Cases & Causes Special Correspondent

41 Formwork for Precast - An Overview Mangesh Kumar Hardas, Director, Precision Precast Solutions Pvt. Ltd.

45 Formwork Equipment: Policy Initiatives Hold the Key for Continued Growth of Formwork Industry M.K. Prabhakar, Associate Editor

49 Fabric Formwork: Sky's the Limit 45 Special Correspondent

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2 FORMWORK V1 N1 · May 2013 digest Modern Formwork An Overview

Modern Formwork Systems: A Ringside View of the Variety of Formwork Systems Available Today M.K. Prabhakar, Associate Editor

Picture Source: Doka International, www.Doka.com

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V1 N1 · May 2013 FORMWORK 3 digest Modern Formwork An Overview

t won't be a misnomer to say that in concrete as a material has led to a perhaps no other industry has been revolutionary change where safer, Iimpacted by advancements in quicker , sustainable and more efficient technology as the construction construction is possible these days. industry in the last three decades or so. While during the early 1990s factors In fact, with the economic boom that such as cost, speed and efficiency was witnessed in several parts of Asia were the driving force behind the (still continuing in many, despite growth of the global formwork industry, economic slowdown) during the 1990s the last decade has seen increasing and South America, it could be stated emphasis on sustainability add to their that the 1990s and the following 2000s demand. Table formwork systems are typically used in large have been decades of construction. The modern formwork systems are floor layouts Several countries were and are even a far cry from the bespoke timber now vying for the title of 'construction formwork that used to be the staple of per elevator or using cranes from one site 'of the world. Gone are the days the construction industry earlier. Intense story to another. 'Fillers' are used to fill when mega projects were the domain competition has meant that suppliers gaps between the tables and walls. of only the superpowers. Today, even are always on their toes and coming The mobility factor, along with the small countries have given vent to their out with product innovations to garner relatively easy installation means that ambitions and coming out with out- their share of the market. Let us take a these system are widely used in standing civil engineering achieve- look at various types of formwork construction projects where repetitive ments. No longer are skyscrapers the systems that are being used, their key structures, where flat slab and slab fiefdom of US. Even a tiny country application areas, their advantages layouts are involved. Some of the like Taiwan or South Korea boasts of and their sustainability quotient. application areas include residential apartment units and commercial gleaming towers. Better quality Table or Flying Form Systems buildings are being at a faster speed buildings. and importantly in a cost effective and Let us begin with the 'Table' or Typically in cases where large floor environment friendly manner, all 'Flying' form systems. These systems layouts are the need, then this type of thanks to advancements in one area - consist of slab formwork “tables” that formwork system holds the best bet. Formwork systems. are reused on multiple stories of a Since the assembled units can be The rapid advancements in the field building without being dismantled. The moved easily, it ensures speedy of formwork, along with the innovations assembled sections are either lifted construction, apart from the high

An assembled Table section formwork being lifted by a crane

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4 FORMWORK V1 N1 · May 2013 digest Modern Formwork An Overview

construction operations. This automatically means reduction in wastage, time and labour costs. Moreover, adding to their sustainability factor is the fact that quite often disposable forms can be recycled and used again. Horizontal Panel Systems Advancements in the field of formwork have seen several new types of materials being experimented with making an entry into the market. Smaller, lightweight modular systems have nowadays become the norm. These systems are being made from a variety of materials such as fiber glass, aluminum and steel, apart from other customized options. These easy-to- handle systems enable quicker erection, saving precious time and The highly engineered nature of a system column formwork ensures greater construction efficiency money. Suppliers have also been quality surface finish. The system also then stripped and moved to the next concentrating on reducing the number scores high on the sustainability front position. In certain cases the formwork of different components in formwork since it can be reused. Moreover, the systems may be left for a longer period systems, which in turn allows for a wastage generated is negligible as of time for added curing. quicker installation process. Horizontal compared to the traditional formwork One of the major advantages with panel systems usually consist of a systems that were earlier used. column formwork systems is the highly series of interconnected falsework Another key factor that should be noted engineered nature of the formwork. bays and pre-formed decking panels is that with the table formwork system What this in turn means is that they and are typically used for slab time is also saved, which in turn leads ensure greater control over the construction. to cost savings , particularly in the case with structures with flat slabs. Moreover, the engineered nature of the formwork and the repetitive process ensures that there is almost negligible wastage, making it a favorite with contractors. System Column Formwork System column formwork has gained in popularity due to the acute shortage of labour in recent times. Modular in nature and allowing for quick installation on site, column formwork systems are now available in a variety of materials. Depending on the concrete finish that is required, contractors can now choose from aluminum or steel column formwork systems these days. R & D has led to several product innovations. Today different formwork systems for different column sizes can be easily assembled on site. Their entire working process is also simple. Once the concrete is poured and hardened, the formwork is Lightweight formwork systems are in demand

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V1 N1 · May 2013 FORMWORK 5 digest Modern Formwork An Overview

The lightweight nature of the along with the fact that their assembly components is perhaps the biggest is less labour intensive and simple has advantage with horizontal panel been behind the popularity of vertical systems. They can be moved around panel systems. The easier erection the site with relative ease, as compared process aids in expediting the to traditional formwork. Adding to it is construction process, apart from the the engineered nature of the formwork fact that the engineered nature allows which ensures reduced wastage. for precision and superior control of Another major advantage with operations for the on-site team. Adding lightweight formwork systems is safety, to the sustainability factor is the fact since working from height is not they can be used repeatedly, after an necessary, as erection work can be easy cleaning process. carried out from below. Jump Form Vertical Panel Systems Jump form systems are increasingly Vertical panel systems, because of becoming popular globally, thanks to their flexible nature can either be the spurt in high-rise construction. smaller modular components or larger Jump form, also referred to as climbing crane-lifted systems that are used in form, comprises of formwork systems the construction of standard columns, complete with working platforms that concrete walls or perimeter basement supports itself on the concrete that has walls. They are used for forming vertical been cast earlier. It therefore does not elements and are usually modular in rely on support from the building. They Spurt in high-rise construction has driven demand for climbing formwork systems nature. Consisting of a steel frame, are typically used in construction of they are easier to assemble, in turn multi-stored vertical concrete elements. labour costs, while increasing con- leads to reduced labour costs, making Some of the concrete elements that are struction efficiency. The jump form them a more cost effective option than constructed using jump form systems modules can be joined together to suit traditional formwork systems. include, core walls, shear walls, bridge different construction geometries. Their adaptability to varying wall pylons and lift shafts. The use of jump Latest advancement in the field has heights and structural geometries, form systems helps in cutting down on been the advent of self-climbing formwork systems, that do not require the help of a crane to be relocated to the next construction level and climbs on rails by means of hydraulic mechanism. Climbing formwork is usually used in the construction of buildings over five storeys. Self-climbing, automated systems are generally used in the construction of buildings with more than 20-25 floors. Based on the site conditions, there are also instances when a combination of self-climbing and crane-handled jump form systems is used. The engineered nature of the formwork means that jump form systems allows for better control of the lb construction process. Repetitive use is possible adding to the cost-effective- ness of the construction process. Apart from offering enhanced safety, the use of jump form systems also ensures minimal concrete wastage and helps contractors to stick to tight project Vertical panel systems are adaptable to various structural geometries deadlines.

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6 FORMWORK V1 N1 · May 2013 digest Modern Formwork An Overview

allow the form to 'slip' to the next level above, apart from supporting the freshly poured concrete above it. Typically slipform systems rise at a rate of about 300 mm per hour and with prudent planning, high rates of production are possible. Fine tuning of operations in the site is facilitated by the repetitive and continuous nature of work. This also leads to reduced concrete wastage. The integration of work platforms in the formwork systems is another advantage that apart from ensuring safety also makes optimum utilization of work space available in a construction site. Given the slew of advantages it is not surprising that slip form systems are a preferred choice of contractors nowadays.

Slip form systems enable high production rates Tunnel Form Tunnel form systems are among the Slip Form rely on the quick setting properties of latest innovations to have hit the Similar to jump form systems, this concrete and require balance between formwork industry. The use of repetitive type of formwork rises continuously, quick setting capacity and workability cellular structures to construct both supporting itself on the core. Slip form of the concrete. While the concrete horizontal and vertical elements systems are typically used for the needs to be workable enough to be together is something that has got the construction of core walls in skyscraper placed into the form and packed, it potential to revolutionize the construction projects. Since very little crane time is should also be quick setting so that it industry in countries like India. The fact required, they are used for the con- emerges from the form with strength. that they enable construction of walls struction of stair shafts and lift shafts in Moreover, the freshly set concrete and floors together make the process high-rise structures. Slip form systems should, apart from its strength, also ideally suited for both high and low raise housing. In fact, the technology can play a key role in the promotion of affordable housing projects in a country like India. Longer tunnel lengths can be achieved joining individual tunnel units together. Easy to clean and reuse, the use of tunnel form systems also enables high quality surface finishes. Engineers are also assured of high dimensional accuracy of structures. The repetitive nature of the construction work is another plus point with this type of formwork system, adding to its other advantage of requirement of a very small team on site. Picture Source www.kildownet.co.uk, www.alibaba.com www.uni-span.com.au, www.doka.com www.tfl-gr.com, www.nb-luowen.com www.water-technology.net Construction cycles can be as low as 24 hours with tunnel form systems www.made-in-china.com

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V1 N1 · May 2013 FORMWORK 7 digest Focus Formwork Systems

Formwork - Future Approach in India

A.L.Sekar, B.Murugesan and C.N.V.S. Rao Larsen & Toubro Ltd

“It is not the strongest of the species that survives, or the the other two links being reinforcement and concrete. At most intelligent. It is the one that is the most adaptable to present, the Indian construction industry’s major concern change that does it.” - Charles Darwin. is the stringent timelines (duration) in the projects. With the clients’ demands increasing day by day, the construction Winds of change are blowing across every sphere of companies’ focus is mainly on the ‘floor to floor cycle’ time construction in India. Same is the case with the formwork to meet the timelines of the projects. But to achieve this, a and scaffolding systems in India. An approx. data on good engineered formwork system is alone not a solution. formwork derived from the cement consumption in India A good formwork system by itself might not give all the reveals that in India, formwork executed is around 750 desired results; it only enables to reduce the timelines in million Sqm. out of which formwork executed using system one of the vital links of the value chain. There should be or engineered formwork hardly constitutes around 10%. It a wholistic approach considering the other two links of is a known fact that formwork constitutes around 6%-8% of rebar and concrete. Also there should be emphasis on the the cost of concrete and 60% of the time of the structure. So development of the skill levels of the supervisors, labour it is the right time an emphasis is laid on the right approach and the approach of the engineers rather than just on the on formwork for the future of the Indian construction.

With the increased growth in high-rise construction, demanding infrastructure projects shaping up the metros and tier 2 cities in India, the questions that arise now are - “Are the formwork systems available in India today sufficient enough for executing such demanding projects? Are the major formwork suppliers across the world that have entered the Indian market able to give end to end solutions to the Indian construction industry? “ Though the utilisation of formwork has gone up by leaps and bounds over the years our approach is still old fashioned. Have we modernized our approach is still a question to be answered by all the stake-holders.

This paper deals with focal points which will shape up the Future Approach of Formwork for the Indian construction industry. They can be broadly defined as Value Chain Linkage, Safety Integration in Formwork, Comprehensiveness in Quality, Standardisation, Green concept and sustainability and finally the Costing of Formwork.

Value Chain Linkage

Formwork is one of the vital links in the total Value Chain,

V1 N1 May 2013 Focus Formwork Systems

selection of the right system. To put it in a simpler way, Quality our future approach while selecting a formwork system should be such that it should integrate the necessary Quality of the finished product is another aspect resulting features to support the other two links of the value chain from a good and efficient formwork system. For achieving a i.e. rebar and concrete which will enable us to carry out good concrete surface, the right kind of sheathing member these two activities also in a fast track manner. Only such should be used in any formwork system, depending on the a comprehensive approach would yield the desired results type of finish demanded by the client. Invariably, plywood and help us to meet the demands of the customers. has been the most commonly used sheathing member world-wide and has yielded the best results till date with Safety regards to form finish. Nevertheless considering other factors in choosing the right kind of formwork system Safety in formwork is another major concern today for the right job, today aluminium formwork has started especially in high-rise construction and large infrastructure penetrating and off late captured the market rapidly with a projects like metros, flyovers, airports etc. It is a known share of about 15% of the overall formwork value in India. fact that in India, Safety levels are yet to catch up to the Due to its easier handling, good quality surface finish, International Standards. There is a lot of pressure on repeatability and durability, and best suited for high-rise the Indian construction companies today to improve the residential buildings which are the trend today, aluminium same by the Govt. of India, Foreign Investors and also the in future might be a strong contender as far as sheathing increased number of PMC’s (which are basically reputed is concerned in formwork. Apart from this, to achieve a MNC’s). Safety cannot be treated as a separate entity, good quality product, the formwork system should deal rather it should be an integral part of the formwork system. with critical issues such as Grout tightness, Deformation, Formwork & scaffolding being the major contributors to the Facilitating Concrete Compaction, Provision of Clean-out safety in construction sites as they are also used for the doors and Box-outs etc. Only when all these issues are rebar and concreting works, it is time we pay proper heed addressed along with the selection of the right sheathing to how these have to be integrated with safety so as to member, a good quality product can be delivered. Looking ensure the overall safety at sites. The various areas of safety into the future, our approach in selection of the system that we need to focus and integrate with formwork are: should keep all these aspects in view to deliver quality - Access (both Vertical & Horizontal) products. - Working platforms Standardisation - Lifelines and Safety Catch Nets - Erection & Dismantling of Formwork Standardisation of the various formwork systems is also an - Storage & Maintenance of Formwork aspect to introspect because we cannot afford to have too - Simple Tools & Tackles many systems at sites which leads to lot of complications - Design and Engineering in terms of usage as well as accountability. The formwork systems should be standardized such that a single system So our future approach when choosing a formwork system is adaptable to various structural elements and also across should address the above aspects and how they are various projects. Though it has its own limitations, still integrated into the formwork system. Only then, in our way standardization can be done to an extent which reduces forward, we will be able to live upto the expectations of the number of components involved in a system, increase the customers and also reach to the level of International efficiency of the components involved and the flexibility Standards. in usage of these (in terms of sizing and detailing). This automatically reduces the pain for the engineers / supervisors and also the labour who are the end-users of the system and gives better results as they can easily account for the materials and use them efficiently. In this particular aspect, our future approach should be “Using less for more output through Innovative Solutions”.

Green Formwork

Rapid industrialization, growth in population and urbanization in the two previous millennia and in the current century have not only taken a heavy toll on non-renewable natural resources of the planet but also caused unprecedented

V1 N1 May 2013 Focus Formwork Systems

rise in global warming. Most leading business houses and industries across the world have adopted Corporate Social Responsibility (CSR) as the roadmap of their current and future business ethics and principles. Whether this principle is adhered to while manufacturing of formwork systems? A confident ‘YES’ may not be forthcoming. Currently no importance is being given to this aspect of Green Concept and Sustainability. Stepping into the future, our approach should be “Greener Formwork Systems” to do our part for the betterment of environment. The focus here can be on some of the important parameters like Energy Consumption, Wastage, Recycling and Depletion of Natural Resources. If these aspects are dealt with in the sourcing of raw materials, manufacturing of the products involved in the formwork systems as well as utilisation of the system as a whole, it helps in delivering “Greener Formwork Systems”.

Description Hire charges or WDV method Cost per (5% per month) use method Investment Cost 9960 4800 Apportioned Fixing and Removing 3000 3000 Cost Upkeep and 1000 1000 (Mobilisation delay, work front delay, delay due to shortage Maintenance Cost of other resources & demobilization) Total Cost 13960 8000 Also the associated costs like the upkeep and maintenance Costing of formwork can be dealt with a central approach by building it up in the investment cost or with a localized approach to create a With the rapid growth in the construction industry, sense of ownership for the sites using the formwork systems. introduction of modern formwork systems is essential to meet the delivery requirements of the customers and at the The above example clearly indicates that the ‘life of same time be competitive. However the modern formwork formwork’ plays a major role in the Costing of Formwork. systems come with a high-price tag. Hence costing of Formwork cannot be a scapegoat for inefficiency within formwork for a particular project is very critical for the and across sites which revolve around these time-bound engineers. However different costing methods are used methods of costing. However if the realistic costing is done by different contractors. Considering the factors like the as per the cost incurred per use, it can help construction efficiency of formwork being linked to the succeeding & companies in India to take a positive call on purchase preceding activities, idling at sites and poor planning; the or hire of modern formwork systems and change their time-bound costing method (Written Down Value or Hire- approach in future. charges) ends up with higher formwork costs especially on materials for no fault of formwork. A small example Conclusion below gives a clear picture of how the time-bound costing Finally to conclude, Formwork Systems cannot be decided methods can be compared: just by suppliers alone as they might not think of all the Sample Calculations of Formwork Costing for Aluminium related elements in the value chain, instead it has to be Formwork decided by the end-users and engineers who are the future change-managers. And the guiding principle should be - - Cost of formwork - Rs. 16000 / Sqm. (say) Formwork must be approached not in isolation, but in a - Duration of the project - 10 Months (Only for Structure) comprehensive manner to include the entire Value Chain, - No. of possible re-uses - 100 (say) Safety, Quality and Sustainability. Also the thrust should be - No. of re-uses expected / month - 3 on realistic costing of formwork to enable viable usage of - Actual duration considering all delays - 20 Months (say) Modern Formwork Systems.

10 V1 N1 May 2013 Formwork Industry Analysis

FORMWORK: Custom-Made Solutions Takes Center Stage MB Bureau Report

f there is one market segment among construction equipment that has maintained a steady pace of growth, despite the Icrests and troughs of the uneconomic uncertainties that have been affecting the market over the last few years, it has to formwork equipment. While in the case of most other types of construction equipment, the major driver for demand was the infrastructure development process, for manufacturers of formwork and scaffolding equipment, it has not limited to the infrastructure development activities. Since they also have the real estate sector to cater to, they have had a far smoother ride than some other types of equipment. The formwork industry has been perhaps the biggest beneficiary of the impressive growth of the Indian construction industry over the last two decades.

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V1 N1 · May 2013 FORMWORK 11 digest Formwork Industry Analysis

Adding to the good news for manu- ”Quality assurance on the job growth. Speaking about the sectors facturers is the fact that even though site is sometimes an issue in that are driving demand for formwork modern formwork and scaffolding sys- India. As of now, there is no systems in the country, Mr.Bharat Patel, tems made their way into the Indian specific certified body to give Head- Sales & Marketing, Nav Nirman market in the mid to late 1990s, the quality assurance on site. To Beam Technics , pointed out that pres- extent of the market tapped till now is avoid any quality issues we ently, “The residential sector and among just a minute percentage of the total have our in-house QA-QC the infrastructure sector, metro pro- potential. In fact, according to industry department which monitors jects are among the key market seg- estimates, modern formwork systems quality at every stage, ments that are propelling demand for form only about 15 percent of the mar- beginning from procurement of formwork systems.” With the realty focus ket share presently, a figure that is raw materials to dispatch. We shifting to tier II and III cities, formwork expected to more than double by the encourage our clients to have suppliers are now catering to an end of the 12th Five Year Plan period the quality inspection done” increasingly diversified market with dif- (2012-17), with the continued impetus ferent application demands. Contrac- being provided to infrastructure devel- tors around the country have realized opment and the growth of the real estate that in order to meet these two criteria sector. the use of formwork and scaffolding systems has become imperative. The Getting organized increase in the size of projects, espe- The formwork industry in the coun- cially with respect to infrastructure and try is gradually getting organized due to high-rise projects has also been a fac- the entry of big ticket players in the fray. tor that has been pushing the demand Globally reputable names such as Doka, for formwork equipment. Meva, Ulma, Paschal, Pranav, Peri, GCI High rise and Infrastructure Projects Composite, Desi etc have established Sushil Sahani their presence in the Indian market over Managing Director, The consistent growth of the form- the recent past. There have been two Pranav Construction Systems Pvt. Ltd. work industry in the country has been key factors that have been driving for- enabled by the thrust given to infra- ward the markets momentum- short- While the recent economic slowdown structure development over the last age of labour and increasing pressure has slightly impacted the industry, decade. Infrastructure project includ- on contractors to adhere to stricter qual- there is no denying the fact that the ing for those of bridges, metro stations, ity standards and project deadlines. industry is poised for a period of tunnels, airport projects, flyovers, etc

Doka India's formwork will be used in the Continued impetus to infrastructure development projects bodes well for the formwork industry Lokhandwala Minerva skyscraper project

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12 FORMWORK V1 N1 · May 2013 digest Formwork Industry Analysis

climbing formworks is available in the form of Doka India's SKE50 and SKE 100 systems. The company will be report- edly using these automatic climbing formwork systems in the construction of 'Lokhandwala Minerva' a skyscraper in Mumbai that will top out at 300 m and feature 82 storeys in two separate towers. The luxury residential project is being designed by Hafeez Contractor and in use will be the SKE 50 and SKE 100 automatic climbing formwork systems that help in providing an efficient solution for achieving weather-independent construction workflow and maximum crew safety. The building is scheduled to be finished in 2014 according to the company.

“A change is always a struggle. Meva India's formwork during the construction of Palais Royale building in Mumbai Mindset of influential decision makers , inadequate/ have been behind the rising demand iliary systems like placing booms, apart inappropriate quality codes, for formwork systems. Adding to the from offering adaptability to complex cost factors everything plays a demand factor is the 'vertical' growth of wall geometries. Almost every player in the country. High-rise construction is the field such as, Doka, Meva, Ulma, role in the growth". an area where specialized formwork Paschal, Nav Nirman, Pranav, GCI Wall plays a key role. Automated self-climbing forms., Peri, Design Desire Construc- formwork systems that can be lifted up tion Systems to mention only a few are hydraulically come with a host of fea- offering specific products catering to tures including, wide and protective this growing market segment. platforms, apart from provisions for aux- A good example for automated

Eldo Varghese General Manager, Paschal Formwork (India) Pvt. Ltd.

Speaking about high-rise construction and the use of specialized formwork systems, Meva India is another company that has been associated with a landmark project- Palais Royale in Mumbai. The company had used its MAC (MEVA Automatic Climbing) system, which provides complete protec- tion for workers with full cladding sur- rounding the external hanging platforms in the project. No external sec- ondary platforms are required on the MAC. The hydraulic system of the automatic climbing system has a capacity of 20 tons per ram and a non-return Paschal formwork systems being used in different types of construction projects rachet that locks on each cylinder. The

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design of the climbing system is such that the load is carried by concrete that is already set and this helps in safer and faster construction. Ulma India is another leading name that offers self-climbing formwork systems for fast, safe, and cost-effective construction of high rise buildings. Accor- ding to the company these systems can be lifted in extreme weather condi- tion up to maximum wind speed of 72 kmph. They come with wide and protective working platforms. The formwork system features provisions for attachment of auxiliary systems like placing booms along with the formwork panels.

“The residential sector and among the infrastructure sector, metro projects are among the key market segments that are Ulma India's formwork in action propelling demand for formwork systems” structures' according to the company have been used in projects including, and is used in footings, retaining walls, Salarpuria Hotel project, Hyderabad, columns, beams, internal and external Golden Jubilee project, Hyderabad, walls, track hoppers, canal drains, box Panduranga power project, Rajamundry, culverts, water treatment plants, reser- Branddix Apparel City, Vishakhapatnam, voirs, crude oil refinery storage pits, TCS Building project, Bhubaneswar, cooling towers, etc. Paschal is also the Defence project , Bellary and Prestige name behind the popular 'e-deck' sys- Forum Mall in Mangalore, to mention tem. The company's formwork systems but a few.

Bharat Patel Head- Sales & Marketing, Nav Nirman Beam Technics

A wide range of climbing formwork systems is also offered by Peri India, another trendsetter in the industry. The company's range includes the FB 180 Platform System, CB Climbing System, ACS Self Climbing System, RCS Rail Climbing System, KG 240- KG180 Climbing Systems, and SKS Single Sided climbing system, to mention only some. Product Innovations Manufacturers are banking on specific product design to cater to different types of application. The 'Modular Panel System' from Paschal, a leading name in the industry is a good example. The modular panel system from the company is a 'one system for all vertical Repetition in operational use up to 90-100 times is possible with systems from Nav Nirman Beam Technics

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14 FORMWORK V1 N1 · May 2013 digest Formwork Industry Analysis

Metro projects have emerged as a key demand driver for formwork systems

Pranav Construction Systems Pvt perfect form finish, free from bulging country. It is in fact one of the reasons Ltd, is one more player which offers a and distortion. Repetition in opera- why even bigger developers are opting range of innovative formwork systems. tional use up to 90-100 times is possi- for rental solutions since they need not The company has this year introduced ble with the H-Beams which are used in worry about storing formwork equip- a range of new generation systems , the construction of residential and com- ment. Even in the case of the rental mar- which are not only light weight but have mercial projects, industrial projects, water ket, according to industry analysts, the optimum life of up to even 1000 repeti- resources engineering, roads and market potential realized is just the tip tions. The range includes, 'Alvert'- alu- bridges, and stadiums, among others. of the iceberg and there is a huge mar- minum light weight panel system for ket that is lying untapped. Industry ana- Rental Push walls, columns and lift cores, 'Modvert/ lysts feel that the gradual rise in the Steelvert'- alloy steel light weight panel The Indian formwork industry has number of rental companies would system for retaining walls, rafts, col- evolved the years and one of the signs automatically streamline several other umns, abutments with ply/steel facing of maturity is available in the form of a processes including improvement in and 'Aludek'- aluminum light weight developing rental market. Rental solu- logistics and setting up of formwork modular system with drop head for tions have come in handy, especially systems at work sites in the near future. faster cycle time. The company has been for smaller contractors for whom out- Challenges ahead involved with several key projects includ- right purchase of the equipment is ing Palm Jebel Ali, Dubai, Doha Inter- often a difficult proposition. In fact, While there is no denying the growth national Airport, Bandra-Worli Sea Link, rental solutions have also been instru- of the Indian formwork and scaffolding Nivedita Setu (second Vivekananda mental in formwork equipment now industry, there are still a set of chal- Setu) bridge in Kolkata; the Dubai, entering the hitherto unexplored areas lenges that the industry needs to sur- Delhi, Mumbai, Bangalore, Chennai, of the country. With the realty market mount, as the country enters into a sec- Kolkata, Hyderabad and Navi Mumbai passing through a phase of difficulty in ond phase of infrastructure develop- metro projects, to mention only a few. metros, due to a variety of factors includ- ment. Fluctuating cost of steel, sales In fact the company has the distinction ing rising property prices and interest tax and excise duty are some factors of supplying formwork materials to rates, the scene has now shifted to that have been said to be inhibiting the every metro being consructed in India. smaller tier II and III cities and towns. growth of the industry. The movement Another good example for product Formwork systems have come as a boon of the sector towards light weight and innovation is available in the of the to contractors in these smaller locations. stronger materials such as aluminium 'H-Beams' from Nav Nirman Beam Another key reason for the develop- has meant that higher levies are Technics, which are easy to handle, ment of the rental market is storage another inhibiting factor these days. light in weight, ready to use and give space, often a neglected factor in our Manufacturers are looking up to the

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tries and the pace will definitely improve as the number goes up. Formwork is still in the inception stage in India and change is inevitable towards better growth rate. It is directly connected to time. Lack of adequate codes and the cost factors are also the reasons for the growth rate. Both are directly linked to the volume of formwork in usage. As the volume and usage of modern formwork goes up as both these factors will be tackled,” a thought with which almost all leading manufacturers will agree. Another important challenge that suppliers need to take care of is quality assurance at the job site. Giving an insight into how they tackle the issue, Mr. Sushil Sahani, Managing Director of Pranav Construction Systems said,” Quality assurance on the job site is Alvert System, Industrial Project ,Gujarat from Pranav System sometimes an issue in India. As of now, there is no specific certified body to government to help them procure raw Varghese, General Manager, Paschal give quality assurance on site. To avoid materials at a reasonable price in order Formwork (India) Pvt Ltd, said, “A 'change' any quality issues we have our in- to give the much needed fillip to an is always a struggle. Mindset of influen- house QA-QC department which moni- industry. The government needs to tial decision makers (engineering / con- tors quality at every stage, beginning remember that India has the potential struction fraternity), inadequate / inap- from procurement of raw materials to to emerge as a key exporter of formwork propriate quality codes, cost factors dispatch. We encourage our clients to and scaffolding equipment. The encour- everything plays a role in the growth. have the quality inspection done,” a aging news has come in the form of an Engineering community is not reluctant strategy which is well worth emulation. evolving customer. Different stakeholders to change but updating themselves Many industry analysts believe that in the construction industry including, towards an overall change in the pro- the formwork industry needs specific contractors and engineers, are now cedure or system, so that the transition certification bodies for inspecting and accepting formwork systems as an inte- is easier. More and more engineers are then certifying formwork systems, as gral part of the construction process. getting involved in this drastic change otherwise the largely unorganized Dwelling on this key point, Mr. Eldo though their experience in other coun- nature of the construction industry could mean that quality sometimes could take a backseat. This apart, an evolving market also presents another challenge in the form of a maturing customer. The customer of today wants equipment that is easier to handle, adds to the sustainability quotient of the building process, is reusable and importantly, is also competitively priced. With policy initiatives expected to increase inflow of funds into infrastructure development, the formwork industry is entering a crucial growth and consolidation phase. Photo Courtesy:

GCI Wall Form Systems www.meva.de, www.archiproducts.com www.doka.com, www.skyscrapercity.com

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16 FORMWORK V1 N1 · May 2013 digest Formwork Safety

Certain Safety Considerations for Formwork

N. Krishnamurthy Safety and Structures Consultant, Singapore

ormwork, the temporary mould and support for fresh employer, as far as is reasonably practicable, to protect every concrete until the concrete is strong enough to support employee from injury and ill-health at the workplace. Fits own weight and other construction loads, itself requires a support called ‘falsework’. In many codes, formwork and This aim of providing a ‘safe place to work’ is achieved by falsework together are called ‘formwork structure’ or just adopting guidelines provided by the Ministry of Manpower ‘formwork’ - which last will be the terminology used in this paper. and Workplace Safety and Health Council, including the following: The problem with formwork is that it is ‘temporary’. In many under-developed and even some developing countries, the word - Risk assessment and control, before work starts [Ref.1]. ‘temporary’ is automatically associated with lack of need for - Safe Work Procedure for every activity at the workplace planning, design and care, and with neglect of appearance, which may involve risk. strength, and safety. As the owner pays only for the finished - Permit to Work for all hazardous activities such as work at permanent structure and not the temporary structure, least cost height. (including cheapest labour and materials, and in the worst - Construction Reg. 2007, Sec. 22(2) reads: “In a worksite, case scenario, low compensation for accident and fatality every open side or opening into or through which a person claims) are often the easiest way to cut costs on this ‘non- is liable to fall more than 2m, shall be covered or guarded essential’ item. by effective guard-rails, barriers or other equally effective means to prevent fall.” In advanced countries however, it is recognised that most - Construction Reg. 2007, Sec. 63(2) reads: “Any formwork accidents and in fact most fatalities and property damage structure that (a) exceeds 9m in height; (b) consists of any occur during the brief construction stage and not during the formwork which is supported by shores constructed in 2 long usage phase of a structure. The business case for safety or more tiers; or (c) consists of any formwork where the in these countries also has amply demonstrated the wisdom thickness of the slab or beam to be cast in the formwork of preventing or mitigating the effects of accidents as against exceeds 300mm, shall be designed by a P.E.” paying for large compensation and work disruption costs due to accidents. This is exactly why hazards present in formwork Figure 1 depicts formwork for a condominium block in must be identified, and the risks arising from them must be Singapore. assessed and controlled. Hazards in Formwork In this paper, not being sufficiently familiar with Indian practices in regard to formwork safety - except as a lay observer during ‘Hazards’ are potential dangers. Hazardous activities in his visits to India - author will focus on his experience with formwork design, erection, use and dismantling are as follows: Singapore practices, in the hope that Indian professionals may - Incorrect or incomplete formwork design make their own comparisons and draw their own lessons for - Erecting frames and bracing local application. - Erecting bearers and joists Basic Safety Requirements - Placing deck and beam formwork - Moving around on formwork during rebar placement, The basic safety requirement is set in the Singapore Workplace concreting, and curing Safety and Health Act of 2006 as the responsibility of every - Dismantling formwork

V1 N1 May 2013 17 Formwork Safety

2. Working safely at height, and, 3. Manual handling of heavy loads.

Some Design Considerations

Factor of safety

India has its own design norms, and they are likely to be world class. Problems may arise during implementation, and in the safety culture that may be prevalent in various enterprises.

Author has seen some excellent formwork in big projects in cities. (Fig. 2.)

But more commonly, especially with formwork for residential and office building floors, a common sight that greets one is a forest of supposedly vertical and straight but actually twisted, bent, de-barked tree branches leaning at all angles some as much as 20 degrees to the vertical, supporting the beam and slab formwork. (Fig. 3.)

Other Asian countries also use natural timber for falsework. In the Far East, bamboo is common, with the advantage that bamboo is straight and nearly uniform in size along its length, In India we use all kinds of timber which are twisted, bent, and non-uniform along their length.

Having just finished an assignment on the formwork code

Fig. 1. Author with site engineers in front of extensive formwork for a committee in Singapore, author is very conversant with the condominium construction in Singapore. need for strict and conservative design for formwork and other temporary structures, as already mentioned in the Introduction. In erection, use and dismantling phases, most activities involve following common hazards:

- Climbing up to or down from formwork, usually by ladders - Working at height with unprotected edges on platforms - Tripping and falling at level - Falling through gaps and holes in formwork - Falling from incomplete or badly designed formwork - Hit by formwork components - Carrying heavy loads - Struggling with awkward shapes - Fitting damaged connections and components - Handling sharp objects and corrosive materials - Working in harsh (sunny, cold, wet, windy, dusty, noisy etc.) environments - Uneven, sloping and cramped work surfaces - Overloading of formwork Fig. 2. A recent picture taken by author in India. In addition to these, dangers may also arise from inadequate In the past, load factors of 1.5 were commonly used for supervision, material flaws etc. To cover all these in a paper falsework design. Often wear and tear in use, and poor field would be an onerous task. The author will therefore focus only conditions of connections and erection encroached into this on the following factors in this paper: factor, and in certain cases resulted in accidents involving 1. Some design considerations, injuries including fatalities and property damage.

18 V1 N1 May 2013 Formwork Safety

Fig. 4. Forces on an inclined prop. Fig.5. Props sloping opposite ways.

to some boards, and at bottom the friction and random projections will usually prevent sliding.

If in a particular case everything is fine when erected, but when wet the friction coefficient vanishes, and/or when the load increases the slide resistance is inadequate, disaster may strike.

Smart people may think that they can cancel out the slope effects by arranging adjacent members AB and A’B’ sloping in opposite directions. But there will still be the same horizontal separating force H at the top and bottom, and if the resistance to opening up at top and bottom is not enough, woe be unto Fig. 3. A common sight? the formwork! (Fig. 5.) Of course, someone who knows what is happening can easily take care of this problem by two Current Singapore Formwork Code [Ref. 2] stipulates a simple ties at or near AA’ and BB’ - but this is not much in minimum “Load safety factor” of 2.0 to be applied to all evidence. designs by whatever method, and for all testing, so that the Sloping shores may be the fast and cost-effective way to use designed or tested capacity is at least twice the maximum available poles without cutting them down to required size. It requirement under the worst combination of loadings. may also be true that they have worked well for decades, and What is the corresponding design requirement for Indian the permanent structures that emerge from these temporary construction with such timbers? structures of whatever shape, have been finished beautifully.

Inclined shores The point author is making here is that any structural resistance to failure is not by design, but by chance. Contractors have There is another aspect of such ad-hoc arrangement of shores just been lucky, and professionals have not even considered, that raises the question: If formwork has to be approved to let alone provided for the horizontal component. That they satisfy design criteria, how are sloping shores handled? survive is because of modifications by trial and error. Potential for failure continues to exist. An inclined member AB at an angle  to the vertical subjected to a vertical compressive force V will develop a horizontal Author shows special concern about this sloping shore, component H, which would be 18% and 36% of V for angles because in a court case in which he was involved, he of 10° and 20°. This horizontal component will tend to increase demonstrated that it was exactly such an undesigned inclined the angle . (Fig. 4.) strut - although it happened to be a straight steel rod - that might have contributed to the formwork failure. Then, how come we have not had all inclined members slide and fall down? That is because the horizontal components In this day and age, when India is contributing globally to the cyber have been successfully resisted, as at top they may be nailed era and space effort, engineers should be a little more scientific,

V1 N1 May 2013 19 Formwork Safety

contractors a little more professional, and the owners who In terms of hierarchy of safety then, A or D is the best, and F is pay for all this a little more considerate of essential expenses the worst. The full-body harness (E) also comes with a number in what they do, at least in the interests of ultimate structural of other auxiliary requirements for effective deployment, safety, if not for the sake of appearance. including proper fit, sufficient fall distance, strong anchorage, and prompt rescue. [Ref. 4] Working Safely at Height All these requirements are mandatory according to the Working at height has been the most hazardous activity all Singapore Code of Practice for Working Safely at Height. [Ref. 5] over the world from time immemorial, and continues to attract the maximum number of accidents and the maximum number of Manual Handling of Heavy Loads fatalities. There are many ways in which safety may be ensured while working at height [ Ref. 3], as follows: In formwork - in common with most construction and factory activities - regularly carrying loads larger than about 25kg is A. Guardrail and toeboard (Fig.6A) an insidious risk, not sudden and dramatic like falling from B. Work restraint, attachment to lifeline (Fig. 6B) height, but slowly causing musculoskeletal disorder (MSD) and escalating to permanent damage of the spine over a period C. Retractable lifeline (Fig. 6C) of about an year. D. Auxiliary scaffolding (Fig. 6D) E. Safety net below (Fig. 6E) Musculoskeletal disorders (MSD) are among the most common worker complaints in the West. In Asia and other under- F. Safety harness (Fig. 6F) developed countries however, it is not reported as much or taken In providing risk control against falling from height, collective as seriously, possibly because natives of these countries control for all workers (A, D, or E) is better than individual are more pain tolerant than citizens of the more developed control (B, C, or F); fall prevention (A, B, C, or D) is better countries, or because management will not do anything about than ‘fall arrest’ (meaning termination of a fall before hitting it, or both. It may also be that both management and workforce the base) to reduce the effects of fall impact after one has do not realise that what starts as a little persistent discomfort fallen (E or F). can escalate into a permanent painful problem. In any case,

Fig. 6. Safeguards for working at height.

20 V1 N1 May 2013 Formwork Safety

most do not recognise it as a problem, and even workers who Australia, where the average person would be larger in size experience it resign themselves to it as their lot in life, enduring and stronger than Asians, legislated a few years ago that no lifelong discomfort if not suffering as a consequence. worker should carry more than 20kg routinely. UK had done likewise a few years earlier when their workers complained So workers regularly carry heavy loads over long distances about 40kg hollow concrete blocks. or keep doing repetitive physical activity; supervisors and bosses let them, expect it from them, and even order them to Singapore recommends a limit of 25kg for worker loads. do so. The reason is simple: Labourers (by very name) have always been doing it. If they don’t, who will? They are paid for Author is not sure about any limitations mandated in India, but it, aren’t they? We are not forcing them against their will! purely on humanitarian grounds he appeals to employers not to burden their workers with more than 25kg in their normal This topic comes under ‘Ergonomics’ the science of work work. posture. Author’s recent paper [Ref.6] covers many aspects of construction ergonomics. If any activity requires lifting and movement of larger loads, mechanical aids like trolleys may be provided for moving Why is this important? What do we do about it? The answers the heavier weights around; two or more workers may be are not simple. It becomes a matter of safety culture in a society, deployed to lift them on to trolleys, or carry them for short the concern of the more powerful groups of people for the distances. Even the simple expedient of rotating the task weaker and less fortunate sections of society. Author hopes between different workers would reduce exposure to risk to that once he explains his stand, professionals will rethink about more tolerable levels. Proper procedure to lift heavy loads by how we are using or abusing our fellow human beings. squatting and getting up with the load is also easily learnt.

Many do not know that each kilogram of weight we bend and Needless to say, this analysis and recommendations for pick up and carry in front of our body develops a force of this particular hazard, apply to white collar non-construction about 12kg on our low back muscle and bone. (Fig. 7.) workers too, such as office and lab assistants.

So a 50kg cement bag will put a load of 600kg on the back Conclusion of a worker. An average Asian’s back is designed by nature to carry a maximum force of about half that (after allowing for Author has highlighted a few of the hazards in formwork the force imposed by our own torso weight), which means design, erection, use and dismantling with which he has that nobody should be carrying more than 25kg on a regular personal experience in Singapore. Not all the hazards may be basis. perceived as equally critical in India. But in a nation committed to democracy and concern for all citizens, the risks described and the solutions proffered by the author may serve to trigger improvement of overall safety culture.

References

1. Krishnamurthy, N., Introduction to Risk Management, (Self-Published), Singapore, May 2007, 86p, ISBN: 978 -981-05-7924-1. 2. SS580:2012 (ICS 91.080.99), Code of Practice for Formwork (Formerly CP23), SPRING, Singapore, Nov. 2012, 40p. 3. Figures 5A to 5E sourced from “Falls from height during the floor slab formwork of buildings: Current situation in Spain”, by Jose M. Adam, Francisco J. Pallarés, and Pedro A. Calderón, Copyright 2009 National Safety Council and Elsevier Ltd. 4. Krishnamurthy, N., “Full Body Harness - Blessing or Bane?”, The Singapore Engineer, Magazine of the Institution of Engineers, ‘Health and Safety Engineering’ issue, August 2012, p. 18-22. 5. WSH Council, Code of Practice for Working Safely at Height, Workplace Safety and health Council, Singapore, October 2009, 50p. 6. Krishnamurthy, N., “Ergonomics at the Construction Sites”, The Singapore Engineer, Magazine of the Institution of Engineers, Fig. 7. Forces on vertebrae ‘Health and Safety Engineering’ issue, February 2013, p. 20-27.

V1 N1 May 2013 21 Formwork Research

Formwork, Insulation, Wall thickness and Fly Ash: Do They Affect Concrete Maturity?

Rishi Gupta1 and Katie Kuder2 1Faculty & Program Coordinator, Department of Civil Engineering, British Columbia Institute of Technology 2Assistant Professor, Dept. of Civil and Environmental Engineering, Seattle University

Use of different forming material, insulation, and stripping time can significantly affect the maturity and hence the strength gain of concrete within such forming systems. This information can be vital in determining the stripping time of scaffolding and formwork. In this project, maturity and compression tests were performed on specimens (simulating scaled-down walls) formed using a PVC stay-in-place (SIP) forming system with and without insulation. These findings were then compared to data obtained from walls formed by wood formwork, which is the material typically used in the field. The various parameters studied in this project were wall thickness, type of forming material, insulation, and addition of fly ash. Results indicate that with an increase in wall thickness, the peak temperature and the temperature development index (TDI) increase proportionally. TDI is defined as the area under the temperature versus time curve measured from the dormant temperature to the peak temperature. The data show that the proposed TDI is a good indicator of the extent of the hydration reaction, and with further research the relationship between temperature development and strength gain of concrete could be clearly identified. Both wood forming when compared to the SIP system, and insulated systems when compared to un-insulated systems, increase the peak temperature and TDI. Use of fly ash in concrete results in a lower temperature peak and TDI and a delay in reaching peak temperature. However, use of concrete containing fly ash in insulated SIP systems has a higher TDI than a conventional concrete mix formed in wood forms, indicating better concrete maturity at the same age.

oncrete is the most widely used construction material provide structural strength and ductility (Kuder, Gupta et al. and its formability is one very important property. 2009), some provide higher R value and some just provide CSeveral different types of formwork are available in a finished surface. Some forming systems such as Insulated the market. One way of classifying them is based on whether Concrete Forms (ICF) increase the insulative properties and they are stripped or not: (1) conventional formwork and (2) R value of the concrete walls and some SIP systems also stay-in-place (SIP) formwork made using different materials integrate insulation in the forming system. However, the effect such as steel, PVC (poly vinyl chloride), FRP (fiber-reinforced of such highly insulated walls on concrete hydration at early- polymers), EPS (expanded polystyrene), etc. Typically, wood ages is not fully understood. One such category of SIP forms formwork is used to form concrete. However, the amount of are the plastic forming systems that are also more versatile wood that can be harvested has been reduced, increasing than wood and metal because various shapes can be easily the cost and reducing the availability of wood. In addition, it manufactured given its flexibility. is environmentally advantageous to decrease the amount of wood needed in construction. Since the SIP forms are not stripped, hence never exposing the surface of concrete, it is very important to ascertain New concrete forming technologies designed to reduce that concrete in the forms has met or exceeded the project wood consumption include reusable and SIP formwork. specifications. One such type of forming system is a SIP After being used, reusable metal and wood forms must system that utilizes PVC panels and connectors as formwork be removed, cleaned, transported and then stored. These (Octaform Systems Inc, 2009). This forming system can be systems limit design versatility since they generally come used with and without insulation and its effect on the maturity in large, flat panels. Unlike traditional formwork that are of concrete is not fully understood. stripped after concrete has gained enough maturity, the SIP forms remain an integral part of the structure; some even On the material side, fly ash is a commonly used Supplementary

22 V1 N1 May 2013 Formwork Research

Cementing Material (SCM) which enhances the fresh A concrete mix design typical of what is used in field properties of concrete including increased workability construction with the PVC SIP system was used. The control (Mindess, Young et al. 2003; Malhotra 2006; Mehta 2009). concrete mix had a water-cement ratio of 0.49 with 350 kg/ High volume fly ash contents are now replacing cement m3 of cement, 1160 kg/m3 coarse aggregate, 700 kg/m3 of because (1) this results in lower consumption of cement, sand, dosage of 600 ml/m3 of superplasticizer and 200 ml/ hence reducing the energy required to produce cement and m3 air entrainer. Another mix was prepared by replacing 40% also reducing the associated green house gas emissions, of the cement with fly ash by weight. (2) production of many self consolidating mixes require high contents of fly ash, and (3) this results in cost-savings and is PVC SIP Forming System a more sustainable process since an industrial by-product (fly The SIP forming system used in this study is briefly described ash) is now being utilized which otherwise would end-up in a below. This forming system is composed of PVC panels, landfill. However, addition of fly ash can decrease the rate of connectors, and braces that form cells. The panels are the hydration reaction, negatively impacting the construction typically 150 mm wide and come in variable heights. The process as the stripping of forms may be delayed. The effect connectors, which are available in various widths, are placed of using fly ash in concrete on the maturity of concrete was perpendicular to the panels and have openings that are studied in this project. During the hydration reaction, heat is provided for placement of rebar and to allow the concrete generated and released to the surroundings; the rate of the to flow through the wall. Figure 1 (a) shows one such cell reaction is proportional to the heat generated. The dissipation of the forming system braced with standard connectors, T- of this heat of hydration to the environment will depend on connectors, and the 45° braces to the panels. Insulation is the type of forming material used, thickness of the concrete also available (Figure 1 (b)) for an increased thermal mass, mass, and use of insulation (Khan, Cook et al. 1998; Wang, leading to higher energy efficiency. Zhi et al. 2006). The effect of using insulation, wood or a PVC SIP system on the maturity of concrete was studied in this The panels that make up the interior and exterior of the project. The maturity of concrete was evaluated by calculating formwork and can be curved to conform to the shape needed a Temperature Development Index (TDI), which is described for the specific application, such as an aquaculture tank later. shown in Figure 2 (a). Once the vertical formwork has been assembled and raised, wood bracing is used, as shown in The TDI is a close function of the hydration process and hence Figure 2 (b). This bracing is similar to the bracing required it is important to note the different stages of the hydration when the wood formwork is used and is removed once process. The first stage is the rapid heat evolution, which concrete within the forms has gained sufficient strength. occurs very quickly, the concrete then moves into the dormant stage where the concrete is workable. The dormant stage ends with the initial set and moves into the acceleration stage as the reaction begins to accelerate. The concrete remains workable until the final set where the greatest temperature is achieved. During the deceleration stage, the reaction slows down and temperature is reduced, bringing the concrete to a steady state. A practical and effective way to evaluate this hydration process is to monitor the temperature released by the hydration reaction over time. The temperature data also serves as an indicator of the rate of reaction, as temperature Figure 1. Components of SIP formwork cell (a) Top vies of cell containing all increase is proportional to the heat generated. components, (b) Schematic of cell with insulation (Octaform 2009)

Materials and Forming Systems Specimen Preparation Concrete was prepared in a rotary drum mixer using Type I To compare the influence of PVC SIP formwork on the heat of cement (manufacturer- Lafarge), river sand, coarse aggregate hydration (maturity/temperature release), the results from PVC with maximum size 10 mm, Class F fly ash (Plant- Centralia), SIP system were compared to wood formwork. The SIP test and admixtures including superplasticizer (product- Glenium wall configuration, shown in Figures 3 and 4, was designed to 3000 NS) and air entrainer (product- MB VR Standard). For have three rectangular cells. This configuration was chosen constructing the wood forms, lumber meeting the following so that the two extra cells on either side of the middle cell specifications was used: 23/32 inch DF-DF plywood, 48/24 would eliminate the temperature effects of closeness to the span rated. The forms were oiled using a release agent (WD- end of the wall (boundary effects). The sides of the end cells 40) before pouring concrete. were filled with wood pieces to prevent concrete from flowing

V1 N1 May 2013 23 Formwork Research

out of the wall. The final interior dimensions of the wall were: Specimen width Concrete type Formwork type 460 mm (18”) length, 300 mm height, and variable width (mm) (ranging from 100 to 300 mm). For the wood formed walls, 100 200 300 plywood was assembled to match the interior dimensions of SIP system’s dimensions. SIP Normal (NC) Wood

SIP Fly Ash (FA) Wood

SIP with 50 mm insulation - - Normal (NC) Wood with 50 mm insulation - - (a) (b) SIP with 50 mm insulation - - Figure 1. Components of SIP formwork cell (a) Top vies of cell containing all Fly Ash (FA) components, (b) Schematic of cell with insulation (Octaform 2009) Wood with 50 mm insulation - -

To evaluate the effect of the PVC formwork on the hydration Table 1: Test matrix for the variables investigated of concrete, concrete was cast inside the PVC formwork standards (C192) and poured into small wall-shaped formwork and was compared with concrete cast inside traditional 300 mm in height supported by a bracing system (previously wood formwork. It was initially hypothesized that the PVC described). A tamping rod was used to ensure the concrete SIP formwork would contain heat and moisture during the was well compacted within the formwork. hydration process, therefore increasing the rate of the reaction and the ultimate strength. Three variables were introduced Thermocouples (Type K) were embedded into the central to simulate the varying field conditions to which concrete is cell at five locations, which are shown in Figure 5. One typically exposed: concrete composition, wall thickness and thermocouple was placed in the center of the test specimen insulation. The matrix of variables tested is shown in Table 1 to evaluate temperatures in the middle. Four thermocouples below. were placed around the central thermocouple to provide a more accurate depiction of temperatures throughout the test specimen, particularly locations closer to the formwork. It was hypothesized that, if thermocouple location was critical, the thermocouples located closer to the faces of the wall would be more affected by the ambient temperature than those in the middle, and the centrally-located thermocouple would reach the highest peak temperature as it was surrounded by the largest thermal mass during curing. In addition, a sixth Figure 3. Schematic (plan view) showing dimensions of the formed specimens thermocouple measured the ambient temperature in the lab. The thermocouples were attached to a data acquisition system and the temperature was recorded for the duration of the test.

Figure 4. Bracing of specimen constructed using PVC SIP

Test set-up

During casting, the concrete was mixed according to ASTM Figure 5. Thermocouple locations in the middle SIP formwork cell

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Temperature measurements

Before the concrete was mixed and poured into the formwork, the data acquisition system was started to obtain the initial ambient temperature. The thermocouple wires were then placed in the concrete as described earlier. Temperature readings were collected at a rate of 3 readings per minute, each reading being an average of 100 scans. Once the test had run for an amount of time determined by previously conducted preliminary tests indicating complete hydration, the data acquisition system was stopped and the data was saved for analysis.

Compression testing

Cast cylinders Figure 6. Coring 100 mm diameter sections for compression testing from SIP To determine the compressive strength, cylinders (100 x 200 formed specimens mm) were cast according to ASTM C 31. Cylinders were de- molded after 24 hours and moist cured for 56 days. Testing Results and discussion was done using a Riehle hydraulic testing machine with a 300 Data averaging kip load cell. Specimens were loaded by displacement-control at a rate of 0.085 mm/min. The data acquisition system was The temperature data were recorded from all six set up to measure the applied load at a rate of 25 readings thermocouples over time. After analyzing the data, it was per second, each reading being an average of 1000 scans. noted that the temperature readings from the five embedded Four cylinders were tested for each mix type (NC and FA). thermocouples did not vary significantly with the location of the Neoprene caps were used in lieu of capping or grinding of thermocouples; therefore the average curves were deemed cylinders. suitable for analysis. This finding is illustrated in Figure 7. Note Cores that the bottom and the top thermocouples reach the second lowest and the highest temperatures, respectively, even To study the effect of the PVC SIP system and insulation though these were located approximately the same distance on the concrete compressive strength, drilled cores were from the center of the wall. extracted after monitoring the temperature for 36 hours. This was also done to determine if there was any correlation between temperature and strength development. Cores were taken from various 200 mm walls and subjected to compressive testing equipment as described above. The various configurations from which were extracted are shown in Table 2.

Formwork type Concrete type Insulation Normal Present SIP Fly Ash Absent Normal Present Wood Fly Ash Absent

Table 2: Various specimen types used for extracting core samples Figure 7. Typical plot: temperature versus time as a function of thermocouple location for a 200 mm thick wall formed with wood

Each wall was cored with a concrete coring machine as Temperature Development Index (TDI) shown in Figure 6, with a 100 mm diameter drill. Three cores were taken from each wall: one from the middle cell, and From the averaged data, the peak temperature (Tp) was one from each of the two side cells. Each 100 mm diameter determined along with the time at which the peak (tp) occurred. core was then cut down to a height of 200 mm and tested for Figure 8 presents a typical plot of average temperature versus compressive strength. time, indicating the Tp and tp. Throughout the testing program,

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the ambient temperature in the lab fluctuated, resulting in the 100 mm specimen with fly ash (Table 3). Refer to Figure 8 varying initial temperatures from specimen to specimen. This for identification of critical points for the temperature analysis situation would also be typical of a construction site where the and an illustration of the areas calculated. After analysis it ambient conditions will be different from day to day. Figure 8 was seen that the 100 mm FA specimen (shown in Figure 8) presents the average temperature versus time for two tests achieved a smaller A1 calculation in comparison to the larger, performed during primary testing. The ambient temperature 200 mm FA specimen. The area calculation was conducted recorded during each test is not presented in the plot for clarity. for each test and the areas were compared. These values The variation in ambient temperature was less than ±1°C in were used as an indication of temperature development each test and hence the effect was considered negligible. during hydration. The A1 value representing temperature rise Although it was expected that the 100 mm FA specimen and maturity immediately after the dormant stage was found would achieve a lower peak temperature than the 200 mm FA to be more relevant than that of A2 and is used extensively specimen because it contained a smaller volume of concrete, throughout this report. The authors have called this value the the results show just the opposite. As research has shown, “Temperature Development Index” (TDI or simply A1). The ambient temperatures affect the rate of the hydration process results from these comparisons are discussed later. (Wang, Zhi et al. 2006); warmer temperatures speed up the hydration process and contribute to higher peak temperatures, while colder temperatures slow down the hydration process and contribute to lower peak temperatures. Because of the effect of ambient temperatures on the hydration process, and that ambient temperatures were not controlled during testing, there was no linear relationship between hydration and ambient temperature. Therefore this experimental project cannot directly account for this effect.

Figure 9. Average temperature versus time for 100, 200 and 300 mm thick walls formed with SIP formwork with normal concrete (NC) and 40% fly ash replacement (FA)

Peak Time at A1 (TDI) A2 Wall Type Temp Peak (°C-hr) (°C-hr) (°C-hr) (hrs) 100 mm 24.08 11.9 13.91 22.36 Normal 200 mm 27.79 13.3 25.93 30.38 Concrete 300 mm 29.69 15.0 40.75 60.80 Figure 8. Average temperature versus time curve for 100 and 200 mm thick walls 100 mm 22.07 13.0 5.72 -0.19 Fly Ash 200 mm 25.81 15.5 24.04 28.95 To minimize the effect of the ambient temperature during the 300 mm 27.39 16.4 30.08 36.79 analysis, it was proposed that the area under the hydration Table 3: Temperature at peak and A1 (Temperature Development Index, TDI), curve be calculated and analyzed. This area was split into A2 for the SIP system two smaller areas: A1 being the region bound by the initial Peak Time at A1 (TDI) A2 minimum temperature (indicating the dormant period) and Wall Type Temp Peak (°C-hr) (°C-hr) the peak temperature and A2 being the region bound by (°C-hr) (hrs) the peak temperature and the final temperature at 30 hours. 100 mm 25.31 15.0 24.12 34.07 Normal Preliminary tests (not reported here for maintaining brevity) 200 mm 29.12 13.5 38.71 60.93 Concrete had indicated that the internal temperature in specimens 300 mm 29.85 15.7 53.71 76.99 more or less dropped to ambient temperature after 30 hours 100 mm 24.09 12.1 8.44 3.99 (Lowrie, Sommer et al. 2007). In certain specimens the peak Fly Ash 200 mm 24.02 16.7 22.65 29.67 temperature was very similar to the ambient temperature and 300 mm 26.11 18.1 32.47 37.85 sometimes lower than that recorded at 30 hours. In such Table 4: Temperature at peak and A1(Temperature Development Index, TDI), cases, the value of A2 would be negative as in the case of A2 for the Wood formwork

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when compared to thicker walls. Hence, there is a need to be closely monitor and consider the strength gain of such wall before stripping the forms especially when high volumes of fly ash are used.

Figure 10. Average thermocouple temperature versus time for 100, 200 and 300 mm thick walls formed with wood with normal concrete (NC) and 40% fly ash replacement (FA)

Forming Systems Figure 11. TDI (A1) as a function of wall thickness for walls formed with PVC SIP and wood formwork for NC and FA A plot of temperature versus time for the SIP system for varying composition and wall thickness is summarized in Figure 9 and Effect of insulation Table 3. Overall temperature test results for concrete formed Figure 12 presents temperature versus time for walls formed using the wood forms are summarized in Figure 10 and Table with SIP formwork with and without insulation and with and 4. without fly ash. Incorporating a 50 mm thick insulation with Effect of fly ash the SIP system resulted in greater TDIs and higher peak temperatures (Figure 12). Use of insulation increased the For the walls formed using the SIP system, with the addition peak temperature and TDI by 10% and 52% respectively of fly ash, the peak temperature and TDI decreased for all wall for the normal concrete mix, and increased 13% and 83%, thicknesses, however, the time to peak when comparing the respectively with the use of fly ash. Figure 13 presents same wall thickness increased indicating that the extent of the average temperature versus time for wood formed specimens reaction is reduced with the addition of fly ash. Similar trends with and without insulation. Similar to the results of the SIP were observed for the specimens formed using wood. specimens, the data indicate that when insulation is used, the peak temperature is greater in comparison to walls without Effect of wall thickness insulation. The NC specimen with insulation also achieved a greater temperature development in comparison to the NC Figure 11 presents the average TDI for the two mixes specimen without insulation; however, this trend was not tested when wall thickness is varied for the SIP system. In visible in the FA specimens. When insulation was used with comparing the wall thickness among the SIP specimens the normal concrete mix, peak temperature and TDI increased (Figure 9), the data show an increase in temperature, time by 15% and 19%, respectively. When insulation was used with to peak temperature, and TDI as the thickness is increased the fly ash mix, the peak temperature increased by 9%, while for both mixes tested. The increase in wall thickness from the TDI decreased by 12%. The reasons for this decrease are 100 to 300 mm increased the TDI by more than 192% for NC not clear and warrant further investigation. SIP specimens and 210% for FA SIP specimens. The data shows that larger walls reach a higher peak temperature at Wood formed vs. SIP system: Comparison a later time and achieve a greater TDI than smaller walls. In general, an increase in wall thickness is correlated with an Figure 11 presented earlier is a plot of the average temperature increase in peak temperature, time to peak temperature, development for the SIP system and wood formed walls and total temperature development in the hydration reaction. of various wall thicknesses. For both the wood and SIP Similar results were observed for wood formed specimens system formed walls, there was an increase in temperature and the results are presented in Figure 11. For wood formed development with an increase in wall thickness due to the specimens the increase in wall thickness from 100 mm to increased thermal mass of the additional concrete from the 300 mm increased the TDI by 120% for NC specimens and larger walls. The results show that the wood formed specimens 280% for FA specimens. This result implies that the TDI and achieve greater temperature development in comparison to hence the strength gain in thin walls is significantly lower the SIP system, particularly when the normal concrete mix is

V1 N1 May 2013 27 Formwork Research

used. In general, the determined. The R-Value for the PVC SIP is reported as 0.60 (Octaform Systems Inc., 2009) while that for 20 mm (¾”) addition of fly ash appears to slow the hydration process, plywood is reported as 0.90 (TECO, 2010). The lower R-Value lowering the total amount of temperature developed, and of the SIP indicates that it is less resistant to thermal change cause the specimen to reach a lower peak temperature at a than wood, and hence may explain why it achieved lower later time for both the wood and SIP walls. In the case of the temperature development overall in non-insulated systems. 200 mm SIP fly ash specimen, a slightly higher temperature development was achieved in comparison to the wood Compression Testing formed specimen. When varying the composition, there is a greater difference in the TDI for the wood walls, an average Cast cylinders: When 40% cement was replaced with fly ash, of a 49% difference, than for the SIP walls, with an average of a 31% difference. This may indicate that the SIP system may contain more moisture and develop more cumulative temperature relative to wood formwork during the hydration process when fly ash is used.

In general, the inclusion of insulation for both wood and SIP systems increases the peak temperature during hydration, and contributes to greater temperature development. In general the peak temperatures for specimens containing insulation occur later in comparison to specimens without insulation. For the specimens tested, the inclusion of insulation with the SIP system appears to have a more significant effect on temperature development and peak temperatures achieved Figure 12. Average thermocouple temperature versus time for walls formed in comparison to the wood system. This finding may be a with SIP formwork with NC and FA with and without insulation (Insul) result of the wood system itself providing insulation and the additional insulation having little effect. It is interesting to note that the SIP system used with the fly ash mix and insulation achieved a greater temperature development than the wood forming system used with the normal concrete mix and no insulation. These results are an indication that the SIP system used in combination with fly ash and insulation more positively contributes to the hydration process in comparison to standard wood forms used with the normal concrete mix.

The compression test results for cored specimens along with the analyzed temperature data is presented in Table 5. In comparing the wood and SIP formed walls, the wood formed walls generally achieved a higher temperature development than the SIP formed walls for all size walls. To understand Figure 13. Average thermocouple temperature versus time for walls formed this correlation, the R-Value of each formwork material was with wood formwork with NC and FA with and without insulation (Insul)

Compressive Standard Avg. Peak Temp Avg.Time at Sample TDI / A1 (°Chr) Strength (f’c) (MPa) Deviation (MPa) (Tp) (oC) Peak (tp) (hrs) SIP 17.86 4.83 42.24 29.45 14.34 Normal Concrete Wood 20.13 7.38 43.50 31.00 11.84 SIP 12.07 2.69 24.31 25.42 17.87 Fly Ash Wood 12.41 1.72 34.53 26.57 17.99 SIP 15.05 0.92 64.01 32.54 16.00 NC Insulated Wood 12.51 7.52 44.52 28.80 17.33 SIP 20.40 0.35 51.68 35.50 12.80 FA Insulated Wood 5.85 0.24 30.25 28.89 14.87 Table 5: Compressive strength data from cored samples (36 hours after casting) and the corresponding temperature data

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the compressive strength decreased from an average of 32 + 4. Special attention is required to ensure strength gain before 3 MPa to 29 + 6 MPa at 56 days. stripping forms especially for thin wall cast using concrete containing high volume fly ash. Cores: Cores were taken from four 200 mm walls and four 250 mm walls with 50 mm insulation (and 200 mm concrete): Further Research two each from SIP NC, SIP FA, Wood NC, and Wood FA. These cores were tested and averaged for each wall. The In addition to wood and one type of SIP formwork, further compression testing data is summarized in Table 5. It should research should be done to compare the effect of other be noted that the compressive strengths reported in Table 5 forming systems used in the industry on maturity of concrete. are at an age of 36 hours and hence significantly lower than In particular, larger wall sizes should be tested to better that measured for cast specimens tested after 56 days. One simulate the conditions experienced in the field. Stripping of the other methods of comparison for these walls was the time variability should be incorporated into this testing. Validity TDI (A1 in Table 5), which has been explained already. of TDI should be examined by conducting tests at extreme ambient conditions to simulate colder winter climates and Treating the compressive strength for FA insulated wood warmer summer climates. Further research is suggested specimen as an anomaly, a reasonable correlation between to clearly establish the relationship between concrete f’c measured for cored samples and TDI was observed. compressive strength and TDI by having a larger sample size This correlation existed only when the same concrete type of cored specimens. and formwork configurations were considered. The general trend shows that when the TDI increases there is an increase Acknowledgements in compressive strength. However, when comparing the The authors would like to thank Octaform Systems Inc. for insulated walls to the non-insulated walls, similar compressive sponsoring this project and for providing the materials and strengths were measured for dissimilar TDIs. This may be technical expertise for this project. The authors would also attributed to limited number of cores and the high standard like to acknowledge the contributions of the Seattle University deviation observed in the compressive test results; as high senior design team that was comprised of Kristian Lowrie, as 60% for the NC insulated wood specimen). Establishing David Sommer, and Nikki Wheeler. a straightforward correlation between f’c and TDI was difficult also because TDI corresponded to thermal activity up to References peak (time to peak ranged between 11 and 18 hrs), whereas all coring occurred at 36 hours, hence making a direct - Khan, A. A., W. D. Cook, et al. (1998). “Thermal Properties and comparison more difficult. Further research is necessary to Transient Thermal Analysis of Structural Members During Hydration.” ACI Materials Journal 95(3), 293-303. clearly establish this correlation. - Kuder, K. G., R. Gupta, et al. (2009). “Effect of PVC Stay-in-Place Formwork on Mechanical Performance of Concrete.” Journal of Conclusions Materials in Civil Engineering 21(7), 309-315. 1. The proposed TDI was an effective method of analyzing - Lowrie, K., D. Sommer, et al. (2007). Effect of PVC Stay-In-Place Formwork on the Hydration of Concrete, Seattle University: 40. the temperature data. TDI could be effectively used to - Malhotra, M. (2006). “Reducing CO2 Emissions: The Role of Fly minimize the effect of different ambient conditions and to Ash and Other Supplementary Cementitious Materials.” Concrete capture the hydration that occurs immediately after the International, 42-45. dormant hydration stage. - Mehta, P. K. (2009). “Global Concrete Industry Sustainability: Tools for 2. The wood forming system contributes to higher peak Moving Forward to Cut Carbon Emissions.” Concrete International, 45-48. temperatures, which occur later when compared to the - Mindess, S., F. J. Young, et al. (2003). Concrete. Upper Saddle River, PVC SIP forming system. The extent of hydration process Prentice Hall. does appear to be greater in the wood system for a normal - Octaform Systems Inc., Technical Guide (accessed October, 2009), concrete mix. This corroborates well with the R value for both forming systems. - TECO, Panel R Values (accessed June 2010), 3. The SIP system used in combination with a high volume fly ash mix and insulation achieved greater temperature - Wang, K., G. Zhi, et al. (2006). Developing a Simple and Rapid Test for Monitoring the Heat Evolution of Concrete Mixtures for Both development in comparison to the non-insulated wood Laboratory and Field Applications. N. C. P. T. Center. forming system used with normal concrete. These results indicate that the insulated SIP system used with fly ash more positively contributes to the hydration process in Publishers Note: This paper was presented at the Proceedings of the One Day Seminar on Modern Formwork Systems for Building Construction Held in IIT comparison to the noninsulated wood formed system Madras, Chennai. The Masterbuilder was the official Media Partner for the above used with the normal concrete mix. event.

V1 N1 May 2013 29 Formwork Pressure

Effect of Concrete Temperature and Formwork Width on Variation Pressure Formwork of Self-compacting Concrete

1Amir Hosein Bakhtiarain, 2Morteza Askari 1The Bsc. Student of Islamic Azad University, Iran 2The Faculty Member of Islamic Azad University, Iran

In this article two complete programs about effect of concrete temperature, formwork width, on lateral pressure formwork of Self- Compacting Concrete are discussed. For considering effect of concrete temperature concrete mixtures which are built under 10- 30°c , are used and the result show that concrete temperature hasn't considerable effect on initial pressure (after casting finishing). But in time passing, pressure reduction is significant for surveying in formwork width effect, two columns with 200 and 920mm diameter, are applied

The design of formwork systems for vertically cast elements For walls: is controlled by the lateral pressure developed by the flesh concrete. It is well established that concrete consistency, method of placement, consolidation, type of cement, temperature of concrete, maximum aggregate size, head of concrete, pore water pressure, rate of placement, and size and shape of the formwork have all marked effect on the development of lateral pressure [3-6-9]. Where Pmax: maximum lateral pressure, KPa Maxton (from Rodin [9]) studied the coupled effect of the R: rate of casting, m/h casting rate and concrete temperature on the lateral ° pressure envelope for conventional concrete. Different T: concrete temperature, C series of low-slump concrete mixtures placed at casting H: head of concrete, m rates varying between 0.6 and 2 m/h were investigated. The concrete temperature varied from 4.5 to 27°C. Effect of concrete temperature on formwork pressure Maximum lateral pressure was found to increase with the For investigation of effect of concrete temperature on increase in the casting rate and/or decrease in concrete lateral formwork pressure, experimental research of Assad temperature. Irrespective of the tested parameters, the [7] and his colleagues was used and described those pressure envelope was reported to be hydrostatic from below: the free surface to a certain maximum value, and then remained constant until the bottom of the formwork. Materials The ternary cement contained 6% silica fume, 22% fly For formwork design purposes, ACI Committee 622 [2] ash, and 72% CSA Type 10 cement. The Type 30 cement, proposed the following design equations for column and Type 10 cement, and fly ash had blaine specific surface wall elements, both of which take into account the rate of values of 600, 325, and 410m2/kg, respectively. The silica casting and concrete temperature: For columns: fume had a B.E.T specific surface of 20,250m2/kg. Continuously graded crushed limestone aggregate with nominal size of 10mm and well-graded siliceous sand

30 V1 N1 • May 2013 Formwork Pressure

tempera- Mixture* Ternary Type 30 Water, Sand (0- Coarse VEA, mL/ Set- HRWRA L/ AEA, mL/ 100 ture, .C codification cement, cement, kg/m3 (w/ 5 mm), aggregate, 100 kg of accelerator, m3 kg of cement kg/m3 kg/m3 cm = 0.40) kg/m3 (5-10 mm), cement mL/100 kg kg/m3 of cement 10 TER-10 450 - 180 740 870 260 - 3.8 120 20 TER-20 450 - 180 740 870 260 - 3.8 120 30 TER-30 450 - 180 740 870 260 - 3.9 120 20 TER20-ACC 450 - 180 740 870 260 1000 3.7 135 20 T30-20 - 450 180 740 900 260 - 3.3 170

Table 1. Mixture proportions of evaluated SCC were employed. The coarse aggregate and sand had sensors similar to those employed in the former column fineness module of 6.4 and 2.5, bulk specific gravities of were mounted at 50, 250, and 450mm from the base. 2.71 and 2.69, and absorption values of 0.4% and 1.2%, Both experimental columns were made of PVC with a respectively. Polycarboxylate-based high-range water- smooth inner face to minimize friction with the concrete. reducing admixture (HRWRA) of 1.1 specific gravity and 27% solid content was used. A high molecular weight Fabrication and testing program cellulosic-based material was employed for the VEA to The slump flow, concrete temperature, unit weight, air enhance stability of mixtures proportioned with 0.40 w/cm. volume, L-box flow characteristics, surface settlement, and setting time were determined, and the results are Mixture proportion summarized in Table 2. As summarized in Table 1, the investigated mixtures were prepared with 450 kg/m3 of binder content and w/cm of TER-10 TER-20 TER-30 TER-20- T30-20 0.40.The effect of concrete temperature on lateral pressure ACC variations was evaluated by testing mixtures prepared at Slump flow, mm 655 655 645 645 640 10, 20, and 30 ± 2°C for the TER-10, TER-20, and TER-30 Air content, % 6.5 4.3 5.9 4.5 6.2 mixtures, respectively. Ambient temperatures during the Initial concrete 9.5 21.7 30.1 20.8 21.7 sampling and testing were 14, 20, and 27°C, respectively, temperature, .C to minimize heat loss of the tested concrete. The effect of Unit weight, kg/m3 2230 2265 2190 2315 2335 0.82 0.85 using Type 30 cement and set accelerating admixture on h2/h1 of L-box test 0.84 0.81 0.85 0.15 the variations in lateral pressure was investigated, as they Surface settlement, % 0.48 0.34 0.32 0.29 have marked effect on the rate of cement hydration. The Initial set time, min 690 610 585 440 425 dosage of the set accelerator was set at 1000 mL/100 kg Final set time, min 780 705 660 480 470 of binder. The T30-20 and TER-20-ACC mixtures prepared Table 2. Properties of evaluated SCC mixtures with Type30 cement and set accelerating admixture, respectively, were proportioned at 20 ± 2°C and tested Fresh concrete properties at 20°C ambient temperature. The VEA dosage was fixed All SCC mixtures had L-box blocking ratios (h2/h1) greater at 260 mL/100 kg of binder, and the sand-to-total than 0.80 indicating adequate passing ability, and aggregate ratio remained constant at 0.46 for all tested relatively low surface settlement (<0.5%). Surface mixtures. The HRWRA and AEA concentrations were settlement values are shown to decrease with the increase adjusted to secure initial slump flow of 650 ± 15mm and in the initial concrete temperature. The maximum surface air content of 6 ± 2%. settlement decreased from 0.48% to 0.34% and 0.32% for the TER-10, TER-20, and TER-30 mixtures cast at Instrumented column systems approximate temperatures of 10, 22, and 30°C, Two experimental columns were used to determine the respectively. The use of high early strength cement and lateral pressure exerted by plastic concrete. The first set-accelerator are also shown to enhance the static column measures 2800mm in height and 200mm in stability of the plastic concrete. The mixtures prepared diameter, and was used to evaluate pressure variations of with set-accelerating admixture and Type 30 cement the plastic concrete. The lateral pressure was determined exhibited settlement values of 0.29% and 0.15%, using five pressure sensors mounted at 50, 250, 450, 850, respectively. and 1550mm from the base. In order to enable the Lateral pressure envelope with respect to height evaluation of pressure variation up to the hardening of the concrete, a shorter column measuring 1100mm in A typical diagram showing the distribution of lateral height and 200mm in diameter was used. Three pressure Pressure along the 2800-mm high experimental column

V1 N1 • May 2013 31 Formwork Pressure for the TER-30 mixture is given in Fig.1. The slump flow values determined at the end of pressure monitoring are values noted at various times are also indicated. Right noted. Mixtures prepared with ternary cement at initial after casting, the concrete is shown to develop lateral temperatures of 10, 22, and 30°C develop similar relative pressure close to the theoretical hydrostatic pressure. The pressures of 91% at the end of casting. This indicates ρ hydrostatic pressure (Phyd) is calculated as: Phyd = × g × that concrete temperature has no significant effect on the H; where ρ, g, and H refer to the concrete unit weight, development of initial pressure. The maximum initial gravity constant, and head of concrete in the formwork, pressure is rather affected by the degree of internal friction respectively. The relative pressures compared to Phyd at that depends on the coarse aggregate volume and the base of the column determined at end of casting and mixture consistency. On the other hand, the rate of then after 1, 2, and 3 hours were 91%, 77%, 68%, and 61% pressure drop with time is significantly affected by respectively. concrete temperature. For example, the time to reduce the relative pressure by 25% decreased from 400 to 250 and 160 minutes for the TER-10, TER-20, and TER-30 mixtures, respectively. Alexandridis and Gardner [1] reported that concrete cast at higher initial temperature can exhibit higher cohesion through the formation of a gel structure. This can enable the plastic concrete to develop higher shear strength capable of carrying a greater fraction of the vertical load, thus resulting in increased rate of pressure drop with time. It is important to note that higher initial temperature can result in greater rate of loss in slump flow consistency, thus reducing the degree of lateral pressure. For example, slump values of 170 and 180mm were measured 5 and 3.5 hours after casting for the TER-10 and TER-30 mixtures, respectively.

Fig. 1: Variations of lateral pressure envelope with time for the TER-30 mixture The T30-20 and TER-20-ACC mixtures developed the lowest initial relative pressures of 78% and 83%, respectively, compared to 91% for those cast at 10 to 30°C initial temperatures and placed at similar casting rates of 10 m/h (Fig. 2). The incorporation of set- accelerating admixture in the TER-20-ACC mixture resulted in the highest rate of pressure drop with time; the elapsed period required to reduce the relative pressure by 25% was 88 minutes. The increased rate of cement hydration due to the incorporation of set- accelerating admixture can lead to greater cohesiveness, and hence sharper rate of drop in lateral pressure.[4]

Effect of section width on formwork pressure For investigation of effect of concrete temperature on lateral formwork pressure, experimental research of Khayat[8] and his colleagues was used and described those below:

Materials Fig. 2: Effect of concrete temperature, cement Type 30, and use of set- A ternary cement made with approximately 6% silica accelerating admixture on pressure variations determined at the bottom of the 2800-mm high column fume, 22% Class F fly ash, and 72% Type 10 cement was used. A continuously graded crushed limestone Effect of concrete temperature on variations in lateral aggregate with nominal size of 10 mm and well-graded pressure siliceous sand were employed. The sand had a fineness modulus of 2.5. The bulk specific gravities of the aggregate Variations of the P(maximum)/P(hydrostatic) values and sand were 2.72 and 2.69, and their absorptions were measured along the 2800-mm column of the five SCC 0.4% and 1.2%, respectively. A naphthalene-based high- mixtures placed at 10 m/h are plotted in Fig.2. Slump range water reducer (HRWR) with solid content of 41%

32 V1 N1 • May 2013 Formwork Pressure and specific gravity of 1.21 was used. A liquid-based truck into the formwork from the top at the desired pouring polysaccharide was used for the viscosity-modifying rate without stoppage or vibration. In the case of the 3600- admixture (VMA) to enhance stability of the plastic ram high column, the concrete was placed at a rate of concrete. A synthetic detergent-based air-entraining rise of 10m/hr. For the 2100-ram high column, the formwork admixture (AEA) and a carboxylic acid-based water- pressure was evaluated twice; once using a rate of reducing admixture were incorporated. placement of 10m/hr and then at 25 m/hr for a second column. The slump flow values determined upon the Mixture proportion arrival on site of the concrete and after 1 and 2 hours were For the SCC mixture used in this study, a proven mixture 650, 635, and 450 mm, respectively. After 3 and 3.5 hours, prepared using 490 kg/m3 of binder, 0.38 w/cm, and 0.44 slump consistencies of 180 and 65 mm were measured, sand to-coarse aggregate ratio was used. The VMA was respectively. incorporated at a dosage of 1325 mL/100 kg of water, The initial and final setting times were determined in the and the HRWR dosage was adjusted at 6 L/m3 to secure laboratory at 20°C in compliance with ASTM C403 and initial slump flow of 650 mm. A dosage of 150 mL/100 kg are given in Fig.3. The adiabatic temperature was also of cementitious materials of the AEA was used. The unit evaluated in an adiabatic calorimeter on mortar obtained weight and air content were 2280 kg/m 3 and 6.1%, by sieving fresh concrete through a 4.75-mm sieve. The respectively. heat evolved was determined by deriving the temperature Instrumented formworks rise as a function of time. The time between the initial contact of cement with water and that corresponding to As already mentioned, two experimental formworks were the beginning of the acceleration of temperature rise was used. The first measured 2100 mm in height and 200 mm 6 hours, as also shown in Fig.3. in diameter. The PVC tube had a wall thickness of 10 mm and a smooth inner face to minimize friction during and after concrete placement. The stress in the diaphragm caused by concrete lateral pressure was determined using five pressure sensors mounted at 850, 1250, 1650, 1850, and 2050 nun from the top. The monitoring of pressure distribution was stopped once the concrete had an approximate slump consistency of 100 mm. The second column consisted of a sonotube of 3600 mm in height and 920 mm in diameter. The column was adequately braced and reinforced. The lateral pressure was determined using two pressure sensors located at 2050 and 2880 mm from the top. The monitoring of pressure distribution was stopped once the concrete had an approximate slump consistency of Fig 3: Variations of hydration and stiffening kinetics with time 100 mm. The second column consisted of a sonotube of 3600 mm in height and 920 mm in diameter. The column Lateral pressure variations was adequately braced and reinforced. The lateral The variations of the lateral pressure envelope determined pressure was determined using two pressure sensors on the 2100-ram high column along with the consistency located at 2050 and 2880 mm from the top. In this case, are plotted in Fig.4. Immediately after filling the formwork, the lateral pressure was monitored until the hardening of the concrete is shown to act as a fluid exerting almost the concrete. hydrostatic head. However, a gradual decrease in lateral Fabrication and testing program pressure takes place with time. The relative pressures at the base of the column determined initially and after 1, 2 Ready-mixed concrete was delivered to the experimental and 3 hours were 98%, 89%, 83% and 76% of hydrostatic site. The ambient and concrete temperatures were 16 pressure respectively. and 19°C respectively. The slump flow, air content, JRing and Lbox flow characteristics, and surface settlement were Results of the section width Influence on formwork determined for the SCC. The measurement corresponds The effect of column diameter (200 vs. 920 mm) on to the mean diameter of the spread concrete at the end of changes in lateral pressure is illustrated in Fig.5 by plotting flow. The JRing spread values was 600 mm and for Lbox the variations of the P(measured)/P(hydrostatic) values test the measure was 0.81 and maximum surface calculated at 2050 mm from the top of the formworks as a settlement was 0.34%. function of time. It is important to mention that both The concrete was directly discharged from the mixing columns were cast on the job site at the same casting

V1 N1 • May 2013 33 Formwork Pressure rate of 10 m/hr. Initially, the mixture placed in the larger material is left standing at rest without any shearing action. column exhibited slightly greater pressure of 99% of In the case of the 200-mm diameter column, the arching hydrostatic pressure compared to 96% for the 200-mm effect can be relatively more pronounced than that diameter column. However, the rate of drop in pressure resulting from the 920-ram diameter column. was significantly different. In the case of the former concrete placed in the 920-mm diameter column, the Conclusions time required to reduce lateral pressure by 5% of the - Variations in fresh concrete temperature have limited hydrostatic value was 20 minutes, resulting in a slope of effect on the maximum lateral pressure developed by 5.3 kPa/hr. Conversely, for the 200-mm diameter column, SCC at the time of casting. However, the rate of this period was 38 minutes resulting in a slope of 3.3kPa/ pressure drop with time increases with the concrete hr. In general, the rate of drop in lateral pressure of plastic temperature that promotes faster development of concrete depends on the degree of thixotropy or shear cohesion. recovery [9]. This phenomenon causes a build-up of the structure and an increase in cohesiveness soon after the - The use of Type 30 cement or set-accelerating admixture can lead to 10% reduction in the initial pressure and accelerate the rate of pressure drop by two folds compared to similar concrete prepared with a ternary cement. - The scale effect had an influence on the rate of drop in lateral pressure of SCC with time; however, no appreciable difference in the maximum initial pressure was observed. - Immediately after casting, the SCC placed in the 200- ram diameter column was found to exert slightly less pressure than that cast in the 920-ram column. This can be due to an arching effect in the relatively restricted section.

References [1] ACI Committee 347 (2001) "Guide to formwork for concrete", Farmington Hills, 32. [2] ACI Committee 622 (1958)" Pressures on formwork", ACI Journal, Fig 4: Variations of hydration and stiffening kinetics with time Proceedings, and 55(2):173-190. [3] ACI Committee 622, "Pressures on formwork", ACI Journal,Proceedings, 55 (2) (1958) 173-190. [4] Assaad J, Khayat KH, Mesbah H (2003) "Variation of formwork pressure with thixotropy of self-consolidating concrete." ACI Materials Journal, 100(1):29-37. [5] Bartos, P.J.M., "An appraisal of the orimet test as a method for on-site assessment of fresh SCC concrete", Int. Workshop on Self-Compacting Concrete, Japan, (1998) 121-135. [6] Gardner, N.J. and Ho, P.T.-J., "Lateral pressure of fresh concrete", ACI Journal, Technical Paper, Title No. 76-35 (1979) 809-820. [7] Joseph J. Assaad · Kamal H. Khayat "Effect of casting rate and concrete temperature on formwork pressure of self-consolidating concrete",Rilem Materials and Structures (2006) 39:333-341 [8] K. Khayat, J. Assaad, H. Mesbah, and M. Lessard "Effect of section width and casting rate on variations of formwork pressure of self-consolidating concrete ", Rilem Materials and Structures 38 (January-February 2005) 73-78 [9] Rodin, S., "Pressure of concrete on formwork", Proceedings Institution of Civil Engineers (London) 1 Part 1 (6) (1952) 709- Fig. 5: Effect of the section width on lateral pressure 746.

34 V1 N1 • May 2013 This Special Compilation is brought to you by:

If you would like to receive more information on the solutions and services offered by any or all of the below mentioned formwork manufacturers write to: [email protected]

Pic source: http://www.ppconstructionsafety.com Formwork Failure: Cases & Causes

Special Correspondent

ollapse of concrete structures during construction 2003.The focus will be on what has been learned over time has been happening since concrete has been from these failures and what has been done to keep these Cplaced in formwork. Cases and causes of these type of tradgedies from occurring in the future. type of failures have been documented and recorded in Although there were many cases of concrete failures during many texts, articles and journals. This article will try and construction prior to the New York Coliseum collapse as focus on a few of them from the available reports, starting illustrated in (McKaig 13-27, 1962), only a few will be with The New York Coliseum on May 9, 1955, 2000 looked at after this point because of the changes and Commonwealth Ave. on January 5,1971, Skyline Plaza in progressions being made in the construction industry at Bailey's Crossroads on March 2, 1973, The Harbour Cay this time in history. Condominium in Cocoa Beach, Florida in March 1981 and ending with The Tropicana in Atlantic City on October 30, (A) New York Coliseum on May 9, 1955

36 V1 N1 • May 2013 Formwork Failure

The construction method was a flat plate waffle slab with solid slabs at the column caps. It was one of the first times the use of motorized buggies had been used in the pouring of this type of structure. The floor that collapsed was the first floor above grade supported on two tiers of shores at

Figure 2: Typical flatplate with uniform distributed loading

Figure 1: N.Y. Coliseum Collapse, National Archives a total of 22' high. It can be seen from Figure 1 how collapse happened. The buggies weighed about 3000 lb loaded, ran at about 12 mph, and there were eight of them at the time of the failure with about 500 cubic yards of concrete Figure 3: Punching shear failure diagram already placed. The investigation that followed put the blame solely on inadequate provisions in the formwork to resist lateral forces, it even went on to say that "if there had been sufficient diagonal, horizontal, and end bacing of the temporary supporting structure, the collapse could have been prevented entirely,...", (McKaig 15-16, 1962). After the collapse the district attorney called attention to the lack of inspections and made recommendations to revising the building code with respect to formwork because of the new advances.

(B) 2000 Commonwealth Avenue: January 5, 1971

This was a progressive collapse of a cast-in-place reinforced concrete flat-slab structure. Punching shear was Figure 4: Skyline Plaza at Bailey's Crossroads, National Archives determined to have been the triggering mechanism but the real problem was in the numerous errors and omissions - Improper placement of reinforcement by every party involved in the project (Delatte 133-143). - Little construction control on site The investigating committee determined that if the - Owner changed hands many times construction had had a proper building permit and had - Almost all jobs were sub contracted followed codes, then the failure could have been avoided - No architectural opr engineering inspection done (Delatte 142) (See Figure 2 and 3 how failure occurred). - Inadequate inspection by the city of Boston Some of the problems leading to the collapse are - The general contractors representative was not a - Not following the structural engineers specifications licensed builder for shoring and formwork - Construction was based on arrangements done by the - Lack of concrete design strength subcontractors - Lack of shoring or removed too soon - No direct supervision of subcontractors

V1 N1 • May 2013 37 Formwork Failure

(C) Skyline Plaza: March 2,1973 walls with the required reinforcing steel. Built without the necessary steel, it is no wonder it collapsed like a house of Skyline Plaza (See Figure 4) in Bailey's Crossroads is an cards." (pr newswire) The vertical columns left standing example of a catastrophic collapse of a 30 story cast-in- and the fact that the floors were not connected implies place reinforced concrete structure. This was also a flat- that this was another punching. Refer Figure 5 for the plate design structure that failed due to punching shear collapse picture. on the 23rd floor and resulted in a progressive collapse. Some of the reasons for this failure again were 1) premature Codes & Regulations removal of shores and reshores, 2) insufficient concrete stength, 3) no preconstruction plans of concrete casting, Codes in Place formwork plans, removal of formwork schedules, or ACI, The American Concrete Institute's origins started in reshoring program (Kaminetzky 66-67). 1905 with its first building code published in 1910 and (D) Harbour Cay Condominium: March 1981 changing its name to the current designation in 1913. ACI's first design handbook came out in1939 and the first Built just 10 years after 2000 Commonwealth Ave. and 8 building code titled ACI 318 came out in 1941. The years after Skyline Plaza, was another cast-in-place beginning volumes of ACI were less tha fifty pages with reinforced concrete structure that collapsed during the current code specification being nearly 470 pages of construction. It was determined that the most important design specifications and commentaries (ACI 318). This factor towards its failure was a design error coupled with a clearly shows the history of ACI is closely tied to the ever construction error of the wrong size rebar and chair height. changing demands of concrete construction and The designer never performed any calculations to check technology. The ACI sees itelf as an expanding, alert,and for punching shear, the most common form of failure in informed organization prepared to stimulate imaginative these type of structures (Feld & Carper 18). applications of concrete and better knowledge of its properties and uses, and will take an increasingly active part in solving problems affecting the public welfare (History of ACI).

Lessons Learned

(A) New York Coliseum on May 9, 1955

From this failure the construction industry learned that shoring systems should be well braced to resist lateral loads and to consider the effect of power or motorized buggies/carts on the formwork (Auburn University).

(B) 2000 Commonwealth Avenue: January 5, 1971

From 2000 Commonwealth Ave. the industry learned that this type of failure is a critical failure mechanism for flatplate-slab concrete construction. Structural safety

Figure 5: Tropicana Casino; Parking Garage Picture taken from depends on adequate slab thickness, proper placement www.CTLGroup.com of reinforcement, and adequate concrete strength (Delatte 144). (E) The Tropicana Casino parking garage in Atlantic City, N.J.: October 30,2003 (C) Skyline Plaza: March 2,1973

The structure collapsed during construction killing another Six lessons learned from the colloapse of Skyline Plaza at four construction workers and and leaving more than 30 Bailey's Crossroads are listed in (Kaminetzky 67) others injured. Larry Bendesky, Mongeluzzi's partner of the - the contractor should prepare formwork drawings Philadelphia law firm Saltz, Moongeluzzi, Barrett & showing details of the formwork, shores, and reshores. Bendesky, P.C, the lead counsel for the litigation with Paul D'Amato of the D'Amato Law Office and a member of the - The contractor should prepare a detailed concrete trial team, said that "the simple explanation of the cause of testing program, to include cylinder testing, before the collapse is that the floors were not connected to the stripping forms.

38 V1 N1 • May 2013 Formwork Failure

- The engineer of record should ascertain that the Contractor failed to tie rebar in the frames floor beams to contractor has all the pertinent design data (such as the columns and shear walls in several places was only live loads, superimposed dead loads, and any other one reason as listed in (ASQ Newswire 11-12). information which is unique to the project). Statistics - Inspectors and other quality control agencies should verify that items 1 and 2 above are being adhered to. Statistics released in 1984 by the National Safety council - Uncontrolled acceleration of formwork removal may reported over 2200 deaths were reported for the lead to serious consquences. 6) Top and bottom rebars construction industry for that year, and 220,000 disabling running continuously within the column periphery must injuries, the largest total for the eight major industries be incorporated in the design. surveyed (Carper 312).

(D) Harbour Cay Condominium: March 1981 Over $1.6 billion is lost annually in the U.S. due to construction accidents (Carper 312). Forty-nine percent The Harbour Cay Condominiums presented the industry of falsework collapse happens during concrete placing with six more lessons learned in this type of construction (Hadipriono & Wang 115).Untimely removal of falsework is also listed in (Kaminetzky 77-78). This tradgedy happened the second most significant event related toconcrete failure only eight years after the Skyline Plaza tradgedy and yet (Hadipriono & Wang 116). Investigations prove that many some of the same lessons are listed again, they are accidents causing thousands of dollars worth of damage could have been prevented if only a few hundred dollars - A punching shear strength check s critical to the had been spent on diagonal bracing for the formwork success of a flat-slab, since punching shear is the most structure (University of Washington). common failure mode of concrete slabs. - Minimum depth of a flat-slab must be checked to Conclusions assure proper strength and acceptable deflections. OSHA, ASCE, and ACI have all responded to these as well - Reinforcing bars, both at the top and at the bottom of as many other accidents and issues with activities, the slab, should be placed directly within the column publications and codes aimed at improving construction periphery to avoid progressive collapse. This can easily safety and the welfare of our construction workforce; be accomplished routinely in all flat-slab jobs at no however, these organizations alone cannot be responsible additional cost at all. for all construction related activities and failures. - Proper construction control must be provided in the field, including design of formwork by professionals. The safety record in the construction industry can be and This must include shoring and reshoring plans, must be improved in all phases. As C. Roy Vince has stated, procedures, and schedules, with data on minimum many construction accidents are the result of ignorance, carelessness, and greed (Carper 133). The lessons learned allowable stripping strength of the concrete. from above being repeated over and over again can only - When there are failure warning signs of any type on a point to the fact that this statement is precisely true. "As construction site, work must stop. All aspects of the long as structures are constructed by humans, using project must be carefully evaluated by experienced imperfect materials and procedures, failures are likely to professional help. Immediate evacuation of the continue. Many of these failures will occur during the structure must be considered. process of construction, endangering the lives of - Special care must be taken during cold weather to construction workers." (Carper 143) There is no way to break evaluate the actual in place strength of the concrete. It everyone of their bad habits but awareness has to be raised is also a fact that the level of construction carelessness and the consequences have to be sharply increased. increases in the winter months. More focus has to be placed on required education of all (E) The Tropicana Casino parking garage in Atlantic City, construction personel beyond certain levels of N.J.: October 30,2003 responsibility, this is to include the workers themselves who are actually assembling these structures. Better The Tropicana lessons learned have not yet been licensure requirements, more stringent inspections, and published in any documented form, but from articles such increased factors of safety during construction (because as the one from ASQ Newsletter published in the summer it is at this time when the structure will be likely to see its of 2004, one can reasonably determine that all of the above most significant loading), should also be considered to lessons learned will be revisited. The article states that all help prevent these tragedies from reoccurring. From the of the errors were remarkably simple engineering error. initial design phase to maintenance of the structure after

V1 N1 • May 2013 39 Formwork Failure

completion everyone involved needs to pay strict attention newyork%20coliseum.htm> (2009), (Sept. 18, 2009) to all details and warning signs of impending failures. There - Charles D. Reese and James Vernon Eidson, (2006). "Handbook can be NO SHORTCUTS if we are to protect the safety and of OSHA Construction Safety and Health" pp. 181-183 lives of the individuals who provide us with all of the - Fabian C. Hadipriono,1 M. ASCE and Hana-Kwang Wang2, essential structures in our lives. (March/April 1986). "Analysis of Falsework Failures in Concrete Structures" J. Constr. Engrg. Mgmt. 112(1), pp. 112-121. Most often it is not their mistake that cost them their life and the misery of the families who lost them too soon. - Jacob Feld and Kenneth L. Carper, ((1997) "Construction Failure" pp. 242-274 Kaminetzky D. (1991). "Design and Construction References Failures" Lessons In Forensic Investigations pp. 67-78 - M. ASCE, (August 1987). "Structural Failures During Construction" - American Concrete Institute. "History of ACI" (October 10, 2009) - McKaig T. (1962). "Building Failures" Case Studies in Construction - ACI Committee 318, (2008). ACI 318-08 "Building Code and Design Norbert J. Delatte Jr., Ph.D., P.E. (2009). "Beyond Requirements for Structural Concrete and Commentary" Failure" Forensic Case Studies For Civil Engineers pp. 129-155 pp. 81-82 - PR Newswire. "$101 Million Settlement in Deadly 2003 Tropicana - ACI Committee 318, (1963). ACI 318-63 "Building Code Parking Garage Collapse That Killed Five Workers" < http:// Requirements for Structural Concrete and Commentary" pp. . www.prnewswire.com/news-releases/101-million-settlement-in- deadly-2003-tropicana-parking-garage-collapse-that-killed-five- - Arthur H. Nilson, David Darwin and Charles W. Dolan, (2004). workers-58264282.html> (October 10, 2009) "Design of Concrete Structures" pp. 12-17 - University of Washington. "CM 420 Course Lecture 1" Temporary - The ASQ Newsletter. "Extracts from Engineering News Record" Structures (Spring Quarter 2002), (Sept. 18, 2009) to Tie Rebar and Properly Shore (summer 2004), Placement" (July 2002), (Sept. 18, 2009) - Auburn University. "Lateral Stability of Structures" New York - http://failures.wikispaces.com/2000+Commonwealth+Avenue+- Coliseum

40 V1 N1 • May 2013 Precast Concrete Formwork

Formwork for Precast - An Overview

Mangesh Kumar Hardas Director, Precision Precast Solutions Pvt. Ltd.

The principles for formwork for precast concrete remain mostly the same as that for conventional in situ construction. However there are a few nuances arising due to the fact that concrete is cast away from the location where the element is supposed to be for its service life. The forms used for precast are of better quality in dimensions and straightness as no one expects to do any plastering (and thus hide the inconsistencies in formwork) at site. Beautiful shapes and architectural finishes can be achieved which otherwise are very difficult or even impossible to achieve in a conventional in situ construction. Formwork for precast can be used multiple times and at the same time the quality of concrete achieved is much better. This paper touches at the requirements of formwork for precast and overviews the systems generally used as in building construction.

recast concrete buildings are structures made up of road conditions. Setting up of long line prestressed beds is numerous small individual elements of concrete cast difficult on site and may not be economical, hence most of the Pat an off-site location. These precast elements such as site-cast precast is non-prestressed. beams, columns, slabs and walls are transported to the site for assemblage and erection. Wind and earthquake loads Wet concrete is poured in forms (moulds) and stripped out are resisted by coupling of beams to columns for moment when it attains certain minimum strength. It is stored in a frame resistance, and coupling of wall elements together for storage area and later transported to the site for erection. composite shear wall resistance. Thus generally in precast Forms are basically either stationary steel plate forms or concrete buildings the individual element on its own plays Tilting tables or battery moulds or moving Carrousel systems no role in gravity and lateral resistance. It is the assembly of with production pallets. Selection of a system depends upon all these elements by proper connections which gives the the volume of production of a particular element and flexibility building its stability against vertical and lateral resistance. desired in production. There are various patented systems for forms systems available in India. Precast concrete usually is either ordinary reinforced concrete or prestressed reinforced concrete. Prestressing gives Prestressed systems are usually long line systems wherein advantages of reduced cross-sections and steel requirements large number of elements are produced in a single bed. (reduced weights). However prestressing needs additional Typical elements produced in such a system are Hollowcore equipments, abutments etc.

Precast Concrete is either a factory-cast (off-site) precast or site-cast (on-site) depending on the volume of work and logistics. Factory cast is typically more popular. Factory cast precast gives more control to the producer and the designer with better options for prestressing, architectural finishes and grade of concrete. A better quality can be obtained as workers and supervisors are well trained and experienced. Work does not hamper due to bad weather.

Site-cast precast is adopted when the project volume is so large that setting up a plant at site is economical. It is also adopted when the transport of precast products becomes very expensive or difficult due to large distances and adverse

V1 N1 May 2013 41 Precast Concrete Formwork

planks, Double Tee floor elements, Spandrels and Inverted finishes such as brick, stone, ribbed finish sand blasted or acid Tee girders. A prestressed bed needs stressing abutments at itched exposed aggregates. the ends and a long form is in between. Generally the forms for prestressing elements are either self stressing forms which Steam curing and heating of the bed is possible in precast take the hydrostatic forces of concrete and compressive forces formwork which increases the rate of strength gain of concrete. from prestressing, or non-self-stressing or free forms which Design Considerations take only hydrostatic forces leaving the compressive forces coming from prestressing to the abutments. End abutments Maximum reuse of formwork is the key to economy. The for stressing is a good solution but sometimes one needs Architect must keep the number of different shapes to a setup for small quantity of elements where self stressing beds minimum and design shapes which can be stripped easily, can be used. Sometimes post tensioning is also done within preferably cast in single pour. Even so, it should achieve the the factory for small number of elements. desired edges, surfaces and textures.

The forms must be designed properly so that they do not Typically forms should be made for standard cross sections deform during any of the operations of production - pouring of columns, beams etc. The Architect should try to use these concrete, vibrating, stressing, distressing and stripping the standard sizes as much as possible so that new forms are not element out of form. The end product must comply with the required to be made. specified tolerances as specified in the BIS codes. The form side(s) of the precast are usually on exterior of the Material for Precast forms building. When a panel is cast horizontal, the bottom side may be exposed aggregate, rubber form lined (to give desired The forms for precast concrete are also called as Moulds texture) or just plain surface. The upper surface of the concrete (US: Molds). These moulds can be made up of Wood, Steel, in the mould which is not as smooth is on the interior of the Aluminium, Fiberglass, Plastic, Concrete or even EPS (Expanded building. Polystyrene) as long as it retains it shape against the hydrostatic pressure of concrete, provides product tolerances, and is In case of forms with fixed sides, the vertical faces should have able to withstand the vibrations, the impacts of placing the draft (slope) of about 1:5 to 1:12 depending upon the width of rebars and the forces of stripping. Generally good quality the section - this would make it easy to remove. fiberglass and wood forms can be reused about 50 times. Steel forms have a very large reuse capacity. For complex The interior edges of the form should be radiused or chamfered shapes of elements as used in architectural precast, forms at least 10mm to avoid edge damage during stripping. This made with wood fiberglass or concrete are used. EPS forms can be done using chamfer strips made up of wood or steel. have limited reuse and mostly used in Architectural precast where the shapes are complex. EPS is also used as sacrificial formwork.

Comparison with Conventional Formwork

Unlike cast in situ formwork, precast formwork can be vibrated in place using vibrating tables thereby giving excellent quality.

Cast in situ formwork needs extensive shoring/ propping which precast formwork does not.

In case of precast formwork it is very important to maintain shapes and dimensional accuracies (tolerances) or else the product may not fit at its place at the time of erection.

Precast formwork presents unlimited possibilities of architectural

Figure 1 - A long moving Prestressed bed showing blockouts

42 V1 N1 May 2013 Precast Concrete Formwork

In long line - prestressed method of casting during detensioning Long forms usually have slopes and drainage should be of strands concrete shortens, and so the inside forms need to provided. be removed before detensioning. The design should be such that these inside forms can be removed without disturbing the Formwork for precast wall panels strands. Wall panels are cast individually or on a long bed when The form surface against which concrete is cast should be prestresssed. Generally the bottom platform is a steel plate smooth. These are cleaned by wirebrush, scrapping, scrubbing of at least 5mm thick mounted on a concrete. The side forms and even chipping. The form sheet should be thick and strong are usually are fixed rail/channel or wooden. The blockouts enough to maintain its smooth surface. The plywood used is are also wooden. raisin coated. In a long line method, there is a long form of about 50 to 100m If steel bed is chosen, which normally is the case, magnetic with side fixed rail on one side which makes the common side systems can be used to fix side forms. Side forms are needed for all the panels. The second rail is usually movable and is for not only defining the boundaries of the panel but also for kept such that it is on the largest width in the pack. Others door and window openings. in between are wooden. Sometimes the bed is capable of vibrating. Formwork construction techniques vary, but generally heavier construction gives more dimensional stability and helps reduce transmission of vibration and results in longer life. Fabrication tolerances are typically half the product tolerances. The surface roughness of the steel used is about 0.15 micron. The steel forms have thickness of plates of about 5mm to 8mm and have gussets at every 200mm to 500mm depending upon the forces. Sometimes the Steel plates are made of Chrome Molybdenum Steel.

Sometimes accelerated curing is achieved by heating. To do so, elobrate piping is done under the form bed and hot water or steam is passed through it. To reduce heat loss, insulation Figure 3 - Battery Mould should be installed under the beds. The pipe for heating is above the insulation. Tilting tables are used to cast wall panels. These tables are equipped with heating and vibrating bed as well. Tilting tables are hydraulically operated and are horizontal at the time of casting. At the time of striping, tilting tables tilt to almost vertical – thus need lifting inserts only on the edges. They also reduce the steel required or can be stripped quickly.

Battery moulds are designed for the vertical fabrication wall panels. Each layer can have a variable area and reinforcement. They consist of bulkheads between which 5 to 10 panels can be simultaneously formed. Vibrators facilitate the effective compacting of concrete. Battery moulds offer to produce architectural wall panels with both inside and outside surfaces as smooth.

Another system is based on production pallets (a steel table) which pass through various workstations manually over a set off protruding wheels before concrete products are complete. Various transport systems (such as central shifter, side shifters, and rollers) transport the pallets from workstation to workstation. Each workstation has a role – preparing, concreting, curing and stripping. This system offers the flexibility of horizontal casting and economizes on Figure 2 - Tilting Table tilting table.

V1 N1 May 2013 43 Precast Concrete Formwork

Strong magnetic systems are available which help in fixing the side forms. The force is more that 500kgs and th

A fully automated system called carrousel system is also available. It is computer controlled and gives a very rate of production. Lattice Girder Slabs can be made with such a system.

Double wall formwork is essentially the same but it additionally needs a system to rotate one half of the already cast and set slab all around and keep it on the one which is recently concreted.

Formwork for Columns and beams

Usually precasters keep standard width and height forms. Column forms are usually non prestressed and can be made up of steel or wood. These can also be made in specially

Figure 6 – Steel Formwork for Rectangular Column

fabricated battery moulds. Rectangular beams can be cast in similar way but special forms are needed for Inverted Tee beams. The sides of these forms can be detached. Long line prestressed forms have arrangements for prestressing steel. They need permanent abutments and hence are fixed in place.

Formwork for Hollowcore slabs

Formwork for Hollowcore beds need steel plates firmly mounted on a foundation and abutments at both ends to take prestressing force. Manufacture of hollowcore is a propriety system and a hollowcore machine manufacturer normally provides the beds as well. No side forms are required as Figure 4 - Formwork for IT beams hollowcore production needs a very dry mix concrete and remains their on its own. Some machine manufacturers recommend concrete beds to cast the hollowcores on.

Conclusions

Formwork or precast is needed more in the plant and less at the construction site. The principles of structural design of formwork remain the same. Tolerances required for the finished product and the forces coming on it govern the design of formwork. Precast concrete products do not need any finishing (such as plastering) on site. By using coloured aggregates and formliners beautiful patters can be achieved. Companies can fabricate their own formwork or choose from the various systems available in the market based on the production needs.

Publishers Note: This paper was presented at the Proceedings of the One Day Seminar on Modern Formwork Systems for Building Construction Held in IIT Madras, Chennai. The Masterbuilder was the official Media Partner for the above Figure 5 - Steel Formwork for Round Column event.

44 V1 N1 May 2013 Formwork Industry Analysis

FormworkFormwork Equipment:Equipment: PolicyPolicy InitiativesInitiatives HoldHold thethe KeKeyy forfor ContinuedContinued GrowthGrowth ofof FormworkFormwork IndustryIndustry M.K. Prabhakar, Associate Editor

f there is one segment among various and steel based formwork and initiatives, vis-à-vis the envisaged US$ types of construction equipment, scaffolding systems began making an 1 trillion investment in infrastructure Iwhich has been maintaining a steady increasing appearance on the horizon. development during the 12th Five Year pace of growth, without hitting frequent While there was growth, it was Plan period (2012-17), holds the key to crests and troughs, it has to be that of dominated by the unorganized sector. the growth of the formwork industry. formwork and scaffolding equipment. However, the last decade has seen, The Union Finance Minister is also Steady, rather than spectacular growth aided by the entry of several leading expected to push for further reforms in has been the story of the formwork global players, the organized sector, the realty sector during the Union industry in India so far. With the which still only constitutes about 10 Budget 2012-13, which again holds the construction industry growing at a percent of the industry, gradually leading key to how fast the formwork industry CAGR of about 14 percent in the recent to improvement in quality standards and grows. The industry though, is currently past, before the economic slowdown enabling customers a wider choice of estimated to be growing at a rate of 10- impacted it, the growth story of the formwork and scaffolding equipment. 15 percent. While the growth may have formwork industry in the country makes The Indian formwork industry is been steady rather than spectacular, for fascinating reading. It is a story that entering perhaps its most crucial phase experts however agree that it is began in the 1990s when aluminum this year. The government's policy nevertheless evolving all the time. Today

THE MASTERBUILDER

V1 N1 · May 2013 FORMWORK 45 digest Formwork Industry Analysis

a typical customer in India, apart from quarter at its slowest pace in more “Interestingly, somehow this looking at the technical attributes of than two years, after maintaining an slowdown has increased the products, also expects value added aggressive growth trajectory. Factors proportion of the usage of services, something that global players such as increased lending rates by the in the fray have realized. Reserve Bank of India (RBI) and the system formwork compared Two key factors have been driving Euro Zone crisis have contributed to the to traditional formwork in forward the growth momentum of the economic slowdown. According to order to reduce the interest formwork and scaffolding market. These Mr.Anupam Sharma, CEO, Doka India, during construction time and include acute shortage of labour and consequently the construction industry several other factors“ rising construction costs, quite often faced a slump and many sectors such due to project delays. Contractors are as housing, power, high-rise, and now looking towards automated infrastructure are witnessing a sluggish formwork systems to address these growth rate. However, Mr. Sharma two issues. The increase in the size of observes that, “Interestingly, somehow the projects, especially with respect to this slowdown has increased the infrastructure and high-rise projects proportion of the usage of system has also been instrumental in pushing formwork compared to traditional the demand for formwork. With a formwork in order to reduce the interest Anupam Sharma majority of infrastructure projects being during construction time and several CEO, Doka India Pvt. Ltd. implemented on a PPP mode, it has other factors. “ Continuing further he become imperative for project owners said that Doka India had last year Giving his take on the slowdown, and investors to complete projects on launched “FramiXlife”, which is a panel Mr.Bharat Patel, Head-Sales & time in order to generate revenues. By formwork system, easy to handle and Marketing, Nav Nirman Beam Technics, opting for system/engineered formwork with a higher number of repetitions, to remarked, “Forecasting of demand contractors have realized that sub- which the company has received has now become difficult. Generally stantial savings are ensured, resulting tremendous response due to a variety speaking, formwork suppliers are coming in turn in faster return on investments. of factors, including, scarcity of skilled out with different product solutions to beat the slowdown.” Some in the Impact of Slowdown manpower, reduced cycle time, safety and also because it is an economic industry however feel that the economic The country's economy grew last option. slowdown has had negligible impact.

Picture Courtesy: www.doca.com

Infrastructure development push holds key to formwork industry's growth

THE MASTERBUILDER

46 FORMWORK V1 N1 · May 2013 digest Formwork Industry Analysis

The rapidly evolving Indian customer has realized that formwork systems are Continued spurt in high-rise projects bodes well for the formwork industry important for safer, faster and sustainable construction

Giving his views on the subject, Mr.Ajay could grow forward in the construction advantages of being, safer, efficient Maini, Director, Maini Construction industry by rapid technological and quality system.” These views are Equipments (P) Ltd, another leading advancements and we are expecting seconded by most of the industry name in the field, when quizzed about good progress, year on year.” Industry analysts who feel that factors such as the impact of the slowdown said, “ Not experts however believe that in order to fast and timely construction of projects, really, because of our versatile range of fully achieve the potential of system lesser dependency on manpower, and products in steel as well as aluminum formwork, India needs to provide a the concern for increased quality and formwork. MCE's aluminum formwork boost to the infrastructure sector. There safety have driven all construction was launched when the entire industry is unanimous opinion that a positive agencies to use modern System was going through a rough phase, environment needs to be created for Formwork for critical projects. however, we were able to sustain and the construction industry and immediate According to Mr.Eldo Varghese the managed a steady growth.” steps such as curbing lending rates, government is making several efforts Sharing similar views, Mr.Eldo which would in turn lead to a boost to such as bring down the lending rates Varghese, General Manager, Paschal power projects and the realty sector and giving boost to power projects in Formwork (India) Pvt Ltd, when asked should be taken. order to give fillip to growth of about the impact of the slowdown on infrastructure projects. Some of the Unique Paradox the company's order book, said,” While factors pointed by Mr.Varghese which the economic slowdown has slightly The story of the formwork and would be driving forward the market in effected growth, but not to an extent scaffolding industry in India is also the near future include, need for speedy that it could hit our order book. We interesting because of another reason. and quality construction, labour scarcity While the construction industry has and safety requirement at sites. One “Forecasting of demand has been maintaining a robust pace of key sector which could give further now become difficult. growth from the turn of 2000, the growth boost to the formwork market is power. Generally speaking, formwork rate of the formwork industry has not With the situation on coal linkages and suppliers are coming out with kept pace. According to Mr.Anupam funding expected to improve in the different product solutions to Sharma, due to lack of government second and third quarters of this fiscal, regulations , most developers are not beat the slowdown” this sector could be just the trigger that pressurized for safety, quality and time the formwork industry has been waiting bound construction, which in turn for in recent times. Thermal, hydro and allows them to use cheaper solutions. nuclear power projects constitute more Adds Mr. Sharma, “Moreover, the than 85 percent of the power sector. knowledge of system formwork is not These apart there are other structure widespread, and hence clients are not that the sector needs such as dams, aware of the advantages. While the power houses, water carrying tunnels , initial investment in these systems may channels, containment tanks, TG deck, be higher, but if you consider the and cooling towers, etc, all of which Bharat Patel number of reuses, it actually works out Head- Sales & Marketing, need the use of system formwork for Nav Nirman Beam Technics to be a cost effective blend with the faster and safer construction.

THE MASTERBUILDER

V1 N1 · May 2013 FORMWORK 47 digest Formwork Industry Analysis

“Not really (impacted sales), from provisions for auxiliary systems “In terms of market value, because of our versatile range like placing booms, while also offering formwork market in India is of products in steel as well as adaptability to complex wall geometries approximately ` 14 billion, out are one of the reasons behind the spurt aluminum formwork. MCE's in high-rise projects throughout the of which modern formwork aluminum formwork was country, a trend that is expected to has a 15 percent share” launched when the entire continue in the near future. It is not industry was going through a surprising that every major player in the rough phase, however, we field such as Peri, Doka, Meva, Ulma, were able to sustain and Pascahal, Navnirman, Technocraft, managed a steady growth” Maini, EPIC Indigo, to mention only some, offer specific products aimed at this fast growing market segment. Onus on Government Surajit Ray While certain factors are not within Managing Director & Country Head, the control of those in the formwork ULMA Formwork Systems India Pvt. Ltd. industry, such as investment in infrastructure or realty projects, there industry though. As rightly pointed out are certain aspects that suppliers feel by Mr.Surajit Ray ,Managing Director & Ajay Maini Country Head, Ulma India, who in an Director, Maini Construction Equipments (P) Ltd need to be done in order to give fillip to the industry. Increasing cost of steel, interaction with The Masterbuilder stated sales tax and excise duty are for that, “In terms of market value, formwork Vertical Growth instance, key factors that are inhibiting market in India is approximately ` 14 Another key area which has been the growth of the industry. billion, out of which modern formwork instrumental in aiding the growth of the With formwork systems being has a 15 percent share,” figures which formwork industry has that been of today made mostly out of light weight show the sheer magnitude of the high-rise projects. While getting and strong materials such as aluminium, untapped market. clearance for such projects remains an higher levies have become a stumbling The predominantly unorganized area of concern, there is no doubting block, since they add to the end cost of nature of the market is another challenge the fact that vertical growth is here to the product. According to industry that needs mention here. There have stay in India and therefore makes for analysts the least that the government been calls from industry experts for good news for the formwork industry. can do is to help suppliers procure raw setting up of specific certification bodies Automated self-climbing formwork materials at reasonable rates that for construction industry product systems that can be lifted up and would go a long way in helping segments such as formwork systems, coming with a host of features including, suppliers keep their prices competitive. since otherwise quality could take a wide and protective platforms, apart There is no doubting the potential of the severe beating. A rapidly evolving customer is perhaps the most important challenge that suppliers are facing today. Customers are demanding equipment that is easier to handle, reusable, helps them in adding to the efficiency and sustainability of the construction process and all this at a fair price. With market conditions expected to show signs of recovery as the economy enters a crucial phase as part of the 12th Five Year Plan period, it remains to be seen as to what direction the formwork industry takes in the next five years. Picture Source http://www.beton.org Rising cost of raw materials is an an area of concern for formwork suppliers http://www.rmdkwikformnews.co.uk

THE MASTERBUILDER

48 FORMWORK V1 N1 · May 2013 digest Focus Fabric Formwork

Picture Source: www.matsysdesign.com Fabric Formwork: Sky’s the Limit

Special Correspondent

abric formworks for reinforced concrete construction the first practical applications for fabric formwork were and architecture is an emerging technology with introduced in the mid-1960s for erosion control and to line Fthe capacity to transform concrete architecture and ponds, although there are several patents for 19th- and reinforced concrete structures. The natural tension early 20th-century fabric forms. In the 1970s, the Spanish geometries given by flexible fabric membranes provide architect Miguel Fisac used thin plastic sheets as formwork extraordinarily light and inexpensive formworks, some for textured wall panels. In the late 1980s and early 1990s, using hundreds of times less material than conventional three men, each on his own, invented a variety of formworks, and some providing zero-waste formwork techniques for fabric-forming aboveground structures. systems. The flexibility of a fabric formwork makes it Kenzo Unno, a Japanese architect in Tokyo, invented a possible to produce a multitude of architectural and fabric formwork system for in situ cast concrete walls. Rick structural designs from a single, reusable mold. The use of Fearn, a builder and businessman in Canada, invented a a permeable formwork fabric produces improved surface number of fabric formwork techniques. This led him to finishes and higher strength concrete as a result of a filtering develop a series of foundation footing and column action that allows air bubbles and excess mix water to products now manufactured and sold by Fab-Form bleed through the formwork membrane. Industries in Surrey, British Columbia, Canada. He is president of the company. Mark West - an artist, A brief history architectural educator and builder who is now the director According to the International Society of Fabric Forming, of the Centre for Architectural Structures and Technology

V1 N1 • May 2013 49 Focus Fabric Formwork

(CAST) at the University of anitoba's Faculty of Architecture formwork. Morover where space is a concern, stocking and in Winnipeg - invented a series of techniques for keeping of rigid formwork will be a major concern. Since constructing fabric-formed walls, beams, columns, slabs most of the fabric formworks are made for one time use and panels. CAST is the first research center dedicated to only, they can be kept after concreting which will facilitate fabric formwork technology and education. in curing of the concrete. If any kind of aesthetic treatment is required to be given in the structure fabric formwork is Visualizing the end result the only option as it is very tough with rigid formwok and in "Fabric is so much more efficient than plywood (for forms), some cases it is impossible also. but the industry is slow to change," says Rick Fearn. "It's End product using fabric formwork staggering how long it takes to get new ideas into the marketplace." He thinks the biggest stumbling block to A flexible fabric mold awakens concrete to its original wet, fabric formwork's acceptance is that many contractors plastic nature by naturally producing concrete members cannot picture the end result before they start. "(Unlike with complex sensual curvatures. The sculptural and rigid formwork), it's just a loose piece of fabric. What you architectural freedom offered by this method of get is not what you see." To help contractors visualize an construction is matched by new possibilities for efficiently end product, Fearn has a computer program that predicts curved structures. Research at CAST has produced simple the shapes fabric forms will produce. He's hoping that as methods for forming beautiful and efficient beams, trusses, more contractors accept computer-generated virtual- panels, vaults, slabs, and columns. reality scenarios, fabric formwork will grow in use. "Fabric is a tension membrane," Fearn says. "If you use a different The Centre for Architectural Structures and Technology fabric, it will give you a different texture, but the shape will (C.A.S.T.) is fundamentally interested in finding simple ways be the same." Also, some fabrics aren't coated, so they let to reduce the amount of material consumed in excess water bleed out, he notes. This can make fabric- construction, while at the same time, making these formed concrete products stronger than those made with constructions more beautiful. C.A.S.T. is also committed traditional lumber forms. In a world where resources are to making these methods accessible to as many people dwindling, he notes, fabric forms, like the ones he sells for as possible. columns, just make good sense. Fast-Tubes, made from The end product is divided here into two parts viz. (A) high-strength polyethylene, come in 120-foot rolls that Architectural application, (B) Strutural Application. easily fit behind the seat of a truck and can be cut to any length with minimal waste. Fabric formworks are such a (A)Architectural application green product and so efficient. They take up 1% of the space cardboard does and they are 1/10 the weight. Also Fabric formwork can be used to give tough architectural unlike cardboard, there is no waste to be hauled to the shapes to the structural member very easily. Figure 1 shows landfill after the column forms are trimmed to size or when typical surface of a fabric cast panel and Figure 2 shows a the forms are stripped. "Fast-Tubes can be put under a branched column made with fabric formwork. slab after they are stripped. They act as a moisture Fabric forms can be used to produce complex concrete protector." Besides allowing contractors to form sturdy columns of varying lengths - Lawton used Fast-Tubes to make 29-foot columns for a treehouse he built in Vermont - Fearn's fabric-formed columns can be easily decorated by simply tying ropes or putting bands around the forms while the concrete is still wet.

Flexible fabric vs. hardened forms

The primary differences between both the formwork is ease of errection.While rigid formwork needs more time to errect. Also lot of staging and design work is needed for rigid formwork which Is not required for flexible formwork. One more striking advantage with flexible formwork is that any shape can be designed and made using fabric formwork. The same fact is supported by the all the Figures in the entire storey. Use of fabric formwork saves lot of manpower Figure 1:Surface detail of a fabric-cast Figure 2:Branching column formed in cost and saves lot of energy for preparation of the rigid panel a geotextile form-liner

50 V1 N1 • May 2013 Focus Fabric Formwork

shapes that would be extremely costly or nearly impossible ties to make "buttonholes" to placing a brick under a fabric to create with traditional rigid formwork. Anne-Mette form to make a relief. Manelius, an architect and doctoral student in Copenhagen, Denmark, made this chair as part of her thesis Kenzo Unno, a Japanese architect in Tokyo, devised work on fabric formwork for concrete. She wanted the soft- methods to cast beautifully shaped walls with thin, flexible looking chair to fool sitters (Figure 3). textile sheets. These methods are collectively called "Unno Reinforced Concrete (Shown in Figure 4)."

Figure 3: Chair produced with fabric formwork

Green, clean, relatively inexpensive and incredibly Figure 4: Walls casted with Fabric formwork practical, fabric formwork can be used with concrete to produce structurally efficient and architecturally Figure 5 shows a thin GFRC stingray sink created by compelling components in all shapes and sizes, ranging students of Brandon Gore of Gore Design Co. from footings, columns and beams to walls, sinks, furniture and an array of accessories

"It's allowed us to create masonry architecture using very simple skills," says Sandy Lawton, owner of ArroDesign, a design/build construction company in Waitsfield. With a background in carpentry, Lawton says, he found rigid formwork complicated and labor intensive. "Fabric formwork has given us the freedom to do complicated structural work in a very different way that's not complicated at all. That's the bigger advantage. There's a lot more flexibility with this system." Fabric formwork also has benefits from a sustainable viewpoint, Lawton says. "Fabric formwork basically reduces the amount of everything required to construct something - placement, storage and even building the forms. There are huge savings every Figure 5: The 1-inch-thick GFRC Stingray Sink step of the way." (B) Strutural Application Also, he points out, depending on the type of fabric you use for the formwork, you can get a really nice finish. "You Here the use of fabric formworks in various structural don't have to go behind and refinish." Instead of using rigid members is shown. Figure 6 and Figure 7 shows casting of forms made from lumber, plywood, cardboard, steel or a isolated footing and slab footing using fabric formwork. aluminum, fabric forms use a flexible textile membrane to The fabric comes in rolls of certain widths and it is simply form concrete in place. Wet concrete is poured into a cut on site to suit the size needed. Apart from normal tools tensile membrane, which produces efficient structural for cutting and fixing the braces and perimeter frame, the curves and extraordinary surface finishes. The shape is only extra items are a Stanley knife and a staple gun. The determined by how the material is restricted. This can fabric is cut neatly with the knife and staple to the timber. happen in a number of ways, from creatively using form There is a very simple method of cutting the fabric at the

V1 N1 • May 2013 51 Focus Fabric Formwork

corners, and when it is simply stapled in position that it, in - The fabric tube is effect, holds the corners together just as strongly as normal simply cut to length methods. Before the pour, a sheet of standard plastic with a Stanley knife. vapour barrier is laid on top of the fabric to stop the footing - In the manufacture, absorbing moisture if it is required. tabs are made It can be noticed from Figure 6 and Figure 7, that no vertically along a movement at the top and a slight bulging at the bottom is center line. there in the freshly concreted isolated footing. - The loose sleeve of fabric is fitted over the rebar. - The tabs are then nailed to a straight length of 4" x 2" timber. - The 4" x 2" timber is Figure 6: Fabric formwork used for casting isolated footing in a construction site then positioned, and braced to hold it Figure 9: Fabric Formwork - Stripped column plumb.

- For the first foot or so a guy hold the base of the tube in the correction position with a boot on either side. - During the pour, it is possible for a guy to feel and guide Figure 7: Fabric formwork used for casting isolated slab footing in a construction the rebar cage, to make sure that it is in the correct site position. A system for forming round concrete columns using - Unlike conventional formwork, because this is a throw fabric formwork away, one off system there is never any reason for undue Figure 8 and Figure 9 shows round various stages of casting haste to strip the formwork. of round concrete column. It can be very easily seen the - Therefore the fabric can be left in position to act as a end product finish in Figure 9 and also the ease of casting perfect curing membrane from the other Figures ( from Figure 8 (a) to (c) ). However if there is a doubt that whether this system can work for higher columns, then Figure 10 shows the 20ft tall column ready to be poured in one hit. The project for a church in Nicaragua in Central America.

The concrete was mixed by hand on the site and lifted up by hand. In itself, this was probably a good thing as the slowness of the pour would mean that the concrete at the bottom would be stiffening up nicely as the height increased, reducing the theoretical hydrostatic pressure.

Conclusion

It is very essential to use fabric forms and rebar in an area where wood is scantily available. Fabric is a very forgiving Figure 8: (a) Column ready to be poured, (b) Column pouring in progess, (c) material.However one should remember that fabric column pouring completed formwork is not as uniform as standard formwork. Engineers had to create some structure to give the appearance of This method of casting column is beneficial because of following reasons what they wanted, but in the same breath it gives us a lot of design freedom. It is really an exciting medium. As for - The fabric come ready made up in tube sections to fabric formwork's limitations, "It's wide open. No one have form the desired diameter of the column. tested its limits yet.

52 V1 N1 • May 2013 Established for over 16 years, 'The Masterbuilder' India's premier NOBODY COVERS construction magazine has been serving the Indian civil engineering and infrastructure community through its in-depth analysis and reporting of emerging trends, methods and practices in concrete since 1996. Our high editorial standards together with its most CONCRETE comprehensive and topical coverage by industry specialists has made the Masterbuilder as the most referred and circulated construction magazine in the country. No other publication for this sector comes close to The Masterbuilder either by volume and depth of quality editorial or through Masterbuilder's circulation of wholly industry-specific requested readership, which is why The BETTER Masterbuilder is the professions must read magazine and the most influential product in the community.

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