ENGINEER - Vol. LII, No. 02, pp. [45-56], 2019 © The Institution of Engineers, Sri Lanka DOI: http://doi.org/10.4038/engineer.v52i2.7353 Mechanization and Performance Analysis of Vertical Slip Form Wall Construction Technology
H.P. Hemantha Kumara and G.K.K.A. De Silva
Abstract: Building construction industries in Sri Lanka are currently facing burning issues due to lack of construction materials, transportation and high labour cost. Masonry wall construction and plastering is one of the most important jobs of small and large building construction.
The slip form technology is an alternative wall construction method, introduced to the Sri Lankan construction industry in 1980, instead of burnt clay brick walls or cement sand block walls. The conventional slip form wall construction technology was commenced by the National Engineering Research & Development Centre (NERDC) with a fully manually operated system consisting of steel shutters, yokes, hydraulic jacks, and manually operated compaction hammers. An amount of 10% cement with quarry dust mix volume is sufficient to get required strength (cement quarry dust ratio is 1: 10) and it can be used as a load bearing wall between columns. The system has identified main drawbacks while construction of a wall such as uneven compaction due to manual compaction, high operational and shutter lifting time etc.
NERDC has been studying and developing a mechanized slip form wall construction machine in order to promote this technology in the society. The machine consists of a single phase 230 V hydraulic power unit, two slip form shutters, two lifting hydraulic cylinders and a movable vibrator compaction unit. Cement quarry dust mixer compact between columns by vibrating and applying a maximum of 140 kg static load by a hydraulic cylinder. Shutter lifting total vertical force measured is 620 kg with overcoming friction between metal shutter and newly bonded wall. Compaction ratio obtained was 40% to 45% varying with moister content of a mixer. Average wall construction rate is around 75 to 80 min/m. A standard 140 mm diameter cylindrical core was tested with the test results for 150 mm thick and 2900 mm span wall showing an average strength of 4.9 N/mm2 after 28 day completion of wall .The average shutter lifting speed was measured as 24 mm/second. The machine was tested up to 10 feet wall height continuously. The tactile controlled basic hydraulic system was employed to improve better man machine interface with the entire operation. High initial setting time and heavy weight are the main drawbacks identified while operating the system with three operators. It is likely that four operators are required to achieve a better performance from the system.
Key words: Slip Form, Vibration, Compaction, Tactile controller
1. Introduction assurance of masonry engineering wall The wall is a main component of any building strength. Further, masonry brick walls cannot and carries out important functions such as be constructed and plastered continuously due bearing loads, provide fire protection, heat and to lack of adequate strength to steady the wall. sound insulation, and provide protection Generally, the construction is carried out in against environmental and weather conditions. stages with construction discontinuing after a Wall is also used as a partition of interior spaces particular period once built-up to 1.5 m height [1]. Different kinds of masonry materials have to allow strength gain. At least 4 days are been used for the construction of building walls required to complete the wall with plastering in Sri Lanka. Burnt clay bricks and sand cement [1]. [email protected], [email protected] blocks are typically used. The main drawbacks of using conventional clay bricks are lack of Eng. H.P. Hemantha Kumara, MSc, CEI I&II, AMIE (SL) clay, low strength, and high production cost Senior Research Engineer, National Engineering Research and and time. Development Centre of Sri Lanka, Ekala, Ja-Ela. Email:[email protected]
ORCID ID: http://orcid.org/0000-0003-0311-6458 Low quality bricks affect the strength of the Eng. G.K.K.A. De Silva, BSc Eng(Civil), MSc, C.Eng, building walls. Low strength and high MIE(SL), Deputy Director General (R&D), National variability are the reasons why it is difficult to Engineering Research and Development Centre of Sri Lanka , select clay bricks for load bearing wall Ekala, Ja-Ela. Email:[email protected] construction. In that case, hence, walls are being ORCID ID: http://orcid.org/0000-0001-7051-0012 constructed in a concrete frame due to non-
This article is published under the Creative Commons CC-BY-ND License (http://creativecommons.org/licenses/by-nd/4.0/). This license permits use, distribution and reproduction, commercial and non-commercial, provided that the original work is properly cited and is not changed in anyway. 1 45 ENGINEER However, findings have been made to steel angle frames and yokes to maintain the Thus, vertical slip forming is an extrusion of yoke assembly is shown in Figure 4. Note introduce new bricks, such as cement blocks, spread and shape of the forms, while a lifting process where the material is stationary and the that there are no supports to keep wall compressed soil blocks and cement-ash mixed force was applied to the forms by hand- form moves upward. thickness at mid span. If, in the case, bricks, for building wall construction. operated locomotive screw jacks located on top deformation occurs at mid span of the wall, of previously harden wall [3]. Figure 1 provides The actual median form speed however, wall strength will reduce. Soil blocks are better to construct well finishing a sketch of the Peavey system. depends on such factors as admixtures used, both interior and boundary walls. Availability Yoke type of the cement, water cement ratio and of soil and cost of production are main Screw cement quarry dust content, symmetry of the drawbacks for soil block production. The Jack Hair Pin structure being constructed, required variations cement stabilized block is widely used in Lifting Hook in wall thickness, amount and complexity of building construction industries in Sri Lanka. Angle placement, jack spacing, number of blackouts Moving Frame required, and the depth of the forms. In early 80’s, Kulasinghe [2] first introduced Frame slip form technology as an alternative wall 3. NERDC Slip Form Technology Slip Form construction method to burnt clay brick walls or cement sand block walls. Wall The conventional NERDC slip form wall Figure 1 - Peavey Slip Form Wall Construction construction system consists of yokes, frame The conventional slip form wall construction System and shuttering assembly. method is fully manually operated, and system Figure 4 - NERDC Conventional Slip Form has identified several drawbacks while The first true slip form system was developed Yokes provide two primary functions: to keep Wall Construction Technology constructing a wall, such as uneven compaction in 1903, when contractors began supplying the forms from spreading; and to transfer the due to manual compaction, high compaction lifting power to the forms by screw jacks load of the forms to the jack [2] [4] [5]. Yokes The wall strength is analysed by 140 mm and shutter lifting time etc. positioned outside the form through the use of are inverted U shape, consisting of two legs and diameter core testing according to BS1881
wooden jacking legs. Such a system is shown in a cross beam. The legs are attached to the frame standard. Figure 5 shows the compressive As a solution to this problem, NERDC has Figure 2. and carry the vertical loads in tension, and the strength variation of the whole wall span. developed a mechanized slip form wall Yoke Working Deck lateral loads as cantilever beams. The cross arm According to the test results, wall strength construction machine to promote this of the yoke must be designed as a simple beam obtained is low at mid span of each sample. technology in the construction industry. The supported at the centre by the jack and subject Compressive strength Variation of Wall Span 4.00 mechanized machine operates well with to the moments from both the vertical and 3.90
) 3.90 minimizing operational time. Greater initial sample1 lateral leg loads. Yoke spacing depends on 2 setting time and the heavy weight are the main Moving Form 3.80 sample2 Jacking Leg several factors, including the design loads of 3.80 sample3 drawbacks that were identified while operating 3.70 3.71 the yoke and wales, and the lifting capacity of 3.70 3.65 the system with three operators. Most likely, Slip Form the jacks attached to the yokes. Conventional 3.60 3.57 3.57 four operators are required to achieve a better Wall Screw Jack slip-forming systems employ 2 ton capacity performance from the system. 3.50 3.45 hydraulic jacks. The frame provides support 3.44 and holds the shuttering in position, suspended 3.40
Figure 2 - First True Slip Form System ( N/mm Compressive Strength 3.30 2. Slip Form History and Types scaffolding and transmit the lifting forces from Several additional lifting systems were devised, the yokes to the form system. 3.20 Slip form techniques consist of forming panels, 300 mm from 1left side colunm Mid 2Span 300 mm from3 right side colunm and by 1910, the most commonly used system Sample Position yokes and jacks. There are two types of slip consisted of a hand-operated hollow screw jack, The shutters make up the sides/walls of the form constructions [6], viz., horizontal and which climbed a steel rod or a hollow pipe, that forms and are the portion of the formwork Figure 5 - Compressive Strength Variation vertical. was subsequently left in place in the completed which actually contains and shapes the wall. Across the Wall Span concrete wall. Figure 3 illustrates such a system. Since slip-forms are subjected to the hydrostatic Horizontal Construction pressure of the plastic masonry mix, the Uneven compaction It is a process which is used to consolidate form shutters must support this lateral pressure with into a geometric shape appropriate for larger Yoke Hollow beam action between the wales, and as a While compaction of mortar between shutters, jobs that require high production rates. Screw Jack cantilever at the bottom of the form. The uneven compaction could occur due to Working friction or drag force on the forms during the manually operation of impact hammer. The Vertical Construction Deck 1” Jack Rod sliding action is significant. This loading is impact hammer consists of a force applied by In vertical slip forms, mixture is continuously Lift Completed highly variable and depends not only on the foot and sliding mass component. It is placed, compacted and form work is pulled up. Wall type and depth of shutter used, but also on the practically difficult to maintain the hammering Rate of slipping of formwork depends on the temperature, moisture content, workability, unit in a vertical position during compaction of feeding speed of cement quarry dust mixer, and rate of concrete set. Steel forms are more mortar. It causes variation of wall strength moisture content and rate of compaction. This rugged, smoother, and easier to clean, but they across the total span. Random observations indicate the manually compaction rate to vary method is suitable for uniform shaped rapid Moving Form do not lend themselves to easy alteration or Slip form Wall from 35% to 45%. construction. Various methods of moving and repair during the slip operation. lifting sectional forms were tried. The method Figure 3 - Hand-operated Hollow Screw Jack A conventional NERDC slip form shutter used by Peavey in 1899 employed a system of Operated Slip Form System assembly fixed between two columns by means
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2 3 Thus, vertical slip forming is an extrusion of yoke assembly is shown in Figure 4. Note process where the material is stationary and the that there are no supports to keep wall form moves upward. thickness at mid span. If, in the case, deformation occurs at mid span of the wall, The actual median form speed however, wall strength will reduce. depends on such factors as admixtures used, type of the cement, water cement ratio and cement quarry dust content, symmetry of the structure being constructed, required variations in wall thickness, amount and complexity of placement, jack spacing, number of blackouts required, and the depth of the forms.
3. NERDC Slip Form Technology
The conventional NERDC slip form wall construction system consists of yokes, frame and shuttering assembly. Figure 4 - NERDC Conventional Slip Form Yokes provide two primary functions: to keep Wall Construction Technology the forms from spreading; and to transfer the load of the forms to the jack [2] [4] [5]. Yokes The wall strength is analysed by 140 mm are inverted U shape, consisting of two legs and diameter core testing according to BS1881 a cross beam. The legs are attached to the frame standard. Figure 5 shows the compressive and carry the vertical loads in tension, and the strength variation of the whole wall span. lateral loads as cantilever beams. The cross arm According to the test results, wall strength of the yoke must be designed as a simple beam obtained is low at mid span of each sample. supported at the centre by the jack and subject Compressive strength Variation of Wall Span 4.00 to the moments from both the vertical and 3.90
) 3.90 sample1 lateral leg loads. Yoke spacing depends on 2 3.80 sample2 several factors, including the design loads of 3.80 sample3 3.70 3.71 the yoke and wales, and the lifting capacity of 3.70 3.65 the jacks attached to the yokes. Conventional 3.60 3.57 3.57 slip-forming systems employ 2 ton capacity 3.50 hydraulic jacks. The frame provides support 3.44 3.45 and holds the shuttering in position, suspended 3.40 scaffolding and transmit the lifting forces from ( N/mm Compressive Strength 3.30 the yokes to the form system. 3.20 300 mm from 1left side colunm Mid 2Span 300 mm from3 right side colunm Sample Position The shutters make up the sides/walls of the forms and are the portion of the formwork Figure 5 - Compressive Strength Variation which actually contains and shapes the wall. Across the Wall Span Since slip-forms are subjected to the hydrostatic pressure of the plastic masonry mix, the Uneven compaction shutters must support this lateral pressure with beam action between the wales, and as a While compaction of mortar between shutters, cantilever at the bottom of the form. The uneven compaction could occur due to friction or drag force on the forms during the manually operation of impact hammer. The sliding action is significant. This loading is impact hammer consists of a force applied by highly variable and depends not only on the foot and sliding mass component. It is type and depth of shutter used, but also on the practically difficult to maintain the hammering temperature, moisture content, workability, unit in a vertical position during compaction of and rate of concrete set. Steel forms are more mortar. It causes variation of wall strength rugged, smoother, and easier to clean, but they across the total span. Random observations do not lend themselves to easy alteration or indicate the manually compaction rate to vary repair during the slip operation. from 35% to 45%.
A conventional NERDC slip form shutter assembly fixed between two columns by means 47 ENGINEER 3 Static load variation with Time e r ar as lle e een e s ers 0 an le elle r ar as a e s n e 0 ra r n y a ly n a s a l a 0
e a n e an a l e s a l a 00 ere n r lle y e a ne era r le 80 a n 00 e res ly lle r ar 0 Force (Kg) Force
(kg) Force 00 n s e all er a a n n e 0
re re a n, s ers ere l e e 0
Figure 6 - Uneven Compaction Pattern of ne layer ere re, n r er a n 0 ee 0 Manual Impact Hammering ll all e , as ne essary re ea e 0 0 0 0 r ess TIme(Seconds) 6. Vibratory Compaction Figure 9 - Quasi Static Load Variation with Time during Mortar Compaction – – –
– – – 6.1 Compaction e r r en ra n e an s 0 , 4. Mechanization of the System – – a n s e ne as e e 0 s s ally a r a n e en r e r – e an ally n reas n e ens y r ar s n s r n na n a – ra n r e an a l e e a n r ar e re re e ree s a rs el er a ra se en e l s a ery essen al as e n n s as nry 5. Slip Form Wall Construction a s e s r a e, ere y a e n e ns r n ren , s r a e n s n e layers as ell as ee er layers ra n all an ns r a l y a nly e en n e es r e a er al, se n ar les n ” x 6” precast column which e ree a n ere are r y es n an n e l ser e er r e a n e r n as nry ns r n es ens y ss le ase n e a er als s as ra n, a , nea n an e n a e , a er a n a n r e ress re e r n le y es s e se er e e es e na re a n r es ere en e as s a an ar lar ar les re 0 an a le ra ry a r e s s ly e ea e s s e ra al ens y ar a n r ar e a ne, a ly n n ar r e n e se ar s a n e n es B e r ar s r a e an ress n e r ar
H ar les e nly ay an e e e e e C a n r e s y n reas n r re n
e e e a ne a a n s
n ne er r ar layers an s l e any a re a le e D an al ra r e n r lla le s a l a e sys e , a e re a n a n a n
B a l e y ress e s r n l a e y ra l yl n er a le n r lle Figure 10 - Density Variation with Different an al al e, s s n n re 8 re K Compaction Methods s s e s a l a ar a n e r n r ar a n Table 1 - Density measurements due to G different compaction techniques Hydraulic Static Load
E Cylinder Control Spring a J A Vibrators s ran lar r ar es a n en P F T nes ar les 0,0 less an 0 an e a e y ra ry an a e s
I 6.2 Energy transfer from compaction foot In e las ne a e n er a e e een e r ar an e a n , e a Figure 8 - Vibratory Mortar Compaction Unit s ear s ress an a r a e y a n with Controllable Static Load Application v vZ C … Figure 7 - Mechanized Slip Form Wall Construction Machine and Components f max s max s
ENGINEER 48
4 5 Static load variation with Time e r ar as lle e een e s ers 0 an le elle r ar as a e s n e 0 ra r n y a ly n a s a l a 0
e a n e an a l e s a l a 00 ere n r lle y e a ne era r le 80 a n 00 e res ly lle r ar 0 Force (Kg) Force
(kg) Force 00 n s e all er a a n n e 0 re re a n, s ers ere l e e 0 ne layer ere re, n r er a n 0 ee 0 ll all e , as ne essary re ea e 0 0 0 0 r ess TIme(Seconds)
6. Vibratory Compaction Figure 9 - Quasi Static Load Variation with Time during Mortar Compaction
6.1 Compaction e r r en ra n e an s 0 , a n s e ne as e e 0 s s ally a r a n e en r e r e an ally n reas n e ens y r ar s n s r n na n a
ra n r e an a l e e a n r ar e re re e ree s a rs el er a ra se en e l s a ery essen al as e n n s as nry a s e s r a e, ere y a e n e ns r n ren , s r a e n s n e layers as ell as ee er layers ra n all an ns r a l y a nly e en n e es r e a er al, se n ar les n e ree a n ere are r y es n an n e l ser e er r e a n e r n as nry ns r n es ens y ss le ase n e a er als s as ra n, a , nea n an e n a e , a er a n a n r e ress re e r n le y es s e se er e e es e na re a n r es ere en e as s a an ar lar ar les re 0 an a le ra ry a r e s s ly e ea e s s e ra al ens y ar a n r ar e a ne, a ly n n ar r e n e se ar s a n e n es e r ar s r a e an ress n e r ar
ar les e nly ay an e e e e e a n r e s y n reas n r re n e e e a ne a a n s n ne er r ar layers an s l e any a re a le e an al ra r e n r lla le s a l a e sys e , a e re a n a n a n a l e y ress e s r n l a e y ra l yl n er a le n r lle Figure 10 - Density Variation with Different an al al e, s s n n re 8 re Compaction Methods s s e s a l a ar a n e r n r ar a n Table 1 - Density measurements due to Hydraulic different compaction techniques Static Load Cylinder Control Spring a Vibrators s ran lar r ar es a n en nes ar les 0,0 less an 0 an e a e y ra ry an a e s
6.2 Energy transfer from compaction foot In e las ne a e n er a e e een e r ar an e a n , e a Figure 8 - Vibratory Mortar Compaction Unit s ear s ress an a r a e y a n with Controllable Static Load Application … f v max s vZ max C s
49 ENGINEER 5 where vmax is the maximum particle i ration Table 2 - Load Analysis Test Data for Vertical elocit Zs is the mortar impe ance an ρ is the Slip Form Wall Construction ul ensit he mortar impe ance is the pro uct o the strain epen ent shear wa e i tin spee mm sec elocit Cs an the soil ensit ρ ccor in all thic ness mm to uation the maximum i ration elocit aterial ement uarr ust that can e transmitte to the mortar in the ixer ratio ust ust plastic one can e estimate he compaction ater cement ratio 6 unit can tra el hori ontall on the shutter orm wor material il steel assem l operatin the h raulic motor ea wei ht o shutters 6 with a spee o mm sec riction oa in – ax – 6 pper ter placin mortar alin a 7. Case Study ter i ration
ower ter placin mortar
7.1 Influence Factors alin ter i ration atterham 6 reporte on a series o tests which in esti ate the lateral an riction urin li tin orces actin on ertical slip orms he arious esultin slip orm pressure on in luence actors in ol e were i i e into on the orm pressure wor m the li tin rame two eneral roups roup ne actors were e ine as the controlla le aria les such as he orm shutter ertical li tin orce an eneral ormwor esi n wall thic ness sli e hori ontal rame loa were measure usin a spee t pe o ormwor acin mortar compressi e loa cell with lintec compaction i ration an wall consistenc ei ht n icator shown in i ures an slump he roup wo actors were the respecti el uncontrolla le in luence actors which inclu e li e loa s an i erences in tra el o the li tin ear here ore it was assume that the pressure hea on the orm was irectl relate to the rate o sli e o a er limite extent the thic ness o the complete wall was also relate to the rate o sli e orces transmitte to the wales were pre calculate to allow or correct separation o the ertical an hori ontal orces
7.2 Lifting of Shutters he o e an h raulic li tin c lin er unit consist o rame h raulic c lin er an pressin oot attache to the piston o h raulic Figure 11 - Vertical Lifting Force Measured by c lin er he purpose o this unit is to li t the Using Compressive Load Cell set o orm shutters a ter compaction o pre ious la er o the wall hen the h raulic c lin er is operate h raulic al e the pressin oot connecte to en o the piston ro exert a ownwar pressure on top o the wall an as a result rame an set o orm shutters sli e erticall up alon two columns o ensure the hori ontal ali nment o the orm shutters two units o this t pe ha e een installe in the s stem close to two columns
7.3 Test Results he ata resultin rom the series o tests con ucte is i en in a le
Figure 12 - Slip form Shutter Horizontal Force Measurement
ENGINEER 50
6 Vertical Lifting Force
g)
k
Horizontal Upper Waling Force (
Horizontal Lower Waling 0 10 20 30 40 50 60 70
Time (Second)
Figure 13 - Horizontal and Vertical Forces on the Slip Form During Lifting Shutters
HP HH Uoo … Po Ho Hu Zo Po .0 05 o .0 24HH U Zo HH … Uo
Figure 14 - Batterham Model of Lateral Pressure with Vertical Slip Form Depth
51
7 ENGINEER
Figure 15 - Maximum Pressure on Vertical Slip form
F1 = C2CIE2 = F2 = B1E2D2B2 = F … j(z) z PI (Z1 - Zo) = F a … j(z) pz P1 = P0
F = F1 = F2 = a FI F2 P1. P1 P0 2xP o Z1 … P F3, F4 F5 F4 + F5 = F3. P k D hq … q D h k 1 Sin … k 1 Sin k P2 = Po = Pl and Z2 = Z0
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8
Figure 17 - Compressive Strength Test of Specimen Core Samples
Table 3 - Compressive Strength Variation with Different Ages of Sample Wall
8. Performance Analysis
Table 4 - Compressive Strength Comparison of Different Wall Panel Types 4” 9” 4” 9” 4” 4” 4” 6” 6”
Figure 16 - Cylindrical Specimen Core
Samples Cut by Machine
53 ENGINEER 9 9. Analysis of Failure Mode 11. Conclusions Figure 21 - Stresses Formation of the Form shutters. Figure 19 - Lump Formation on the Bottom 9.1 Lifting Cracks Side of the Vibrator Foot 4 9
10. Structural Analysis of Form Shutters
6
Figure 22 - Strain Variation throughout the Shutter Material Lifting Forces Figure 18 - Horizontal Cracks Propagate Loads from upper Wailing During Shutter Lifting Gravitational Forces Loads from Lower Wailing
Reaction from column Hydrostatic from
Figure 20 - Slip Form Shutters Subjected to Complex Combine Forces
Figure 23 - Total Deflection Pattern of the Slip 9 Form Shutter Assembly 9.2 Lump Formation 4 4 9
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10 11
11. Conclusions
Figure 21 - Stresses Formation of the Form shutters. 4 9
Figure 22 - Strain Variation throughout the Shutter Material
Figure 23 - Total Deflection Pattern of the Slip Form Shutter Assembly 4 4
55 ENGINEER 11 ENGINEER - Vol. LII, No. 02, pp. [page range], 2019 © The Institution of Engineers, Sri Lanka dust and cement. It is likely that four operators 11. Camellerie, J. F. (1959), "Slip-Form Details and are required to achieve a better performance Techniques", Journal of the American Concrete from the system. The mechanized system was Institute, Vol. 30, No. 10, April 1959, p. 1131. Cost Forecasting Analysis on Bored and Cast-In-situ designed as bulk for heavy operational (two- 12. Kulatilake, M. P. M. (2002), ”A Study on the tone) lifting forces. According to the test results, Piles in Sri Lanka: Case Study at Selected Pile Characteristics of Cement Block Manufacturing in Sri further developments are required to simplify Lanka, MSc Thesis, University of Peradeniya. Construction Sites in Colombo Metropolis Area the structure of the mechanized slip form system. S. Surenth, R.M.P.P.V. Rajapakshe, I.S. Muthumala and M.N.C. Samarawickrama
References Abstract: Installation of bored and cast-in-situ (CIB) piles is a complicated process and relates to
a large number of factors connected with subsurface uncertainties, contractor experience and site- 1. Manike, J. M. N. U. J. and Sooriyaarachchi, H. P. (2009), “Constructability and Performance of specific factors. Such factors make it difficult for the estimator to predict the cost of a CIB pile in the Continuous Masonry Wall Panels” ENGINEER - tendering stage. This study was carried out to identify most influential factors on cost of CIB pile Vol. XXXX11, No. 04, pp. [38-45], The Institution construction with relevance to local conditions and to develop a cost prediction criterion for CIB of Engineers, Sri Lanka. construction in Sri Lanka. It was initiated with a study on cost influential factors and estimation models developed in the international context. Then the study proceeded to identify additional 2. Kulasinghe A. N. S. (2000), “Kulasinghe Technology specific factors relevant to the local conditions using a questionnaire survey and analysis. Cost for the Low Cost Housing”. National Engineering prediction models were then developed for local context using regression analysis based on the Research & Development Centre, Colombo. identified most influential factors, and finally, developed models were validated using actual cost
data. It was revealed that the most critical cost affecting factors are pile size, pile drilling time, depth 3. Camellerie, J. F. (1959), "Slip-Form Details and Techniques," Journal of the American Concrete of pile, concrete pouring time, rock socket length, drilling type and weather conditions. Linear cost Institute, Vol. 30, No. 10, April 1959. models developed for each of these factors were amalgamated to one overall cost prediction model. This was found to be successful during the validation with actual costs of executed piling projects. 4. Dissanayake, T. A, Dissanayake U. I. and Moreover, it is recommended to be used along with the intuitive judgment of the decision maker and Ranaweera M. P.(2001), “Material Properties of the model should be timely readjusted with updated market rates at least in three-month periods. Slip-Form Load Bearing Wall Panel for Low Cost Medium Rise Buildings”, Fifty seventh Annual Keywords: Pile foundations; Bored piles construction; Cost of pile Sessions of Sri Lanka Association for the Advancement of Science, Colombo.
5. Mendis, D. L. O. (2001), “Innovation and Self- 1. Introduction construction economy and instead studies have Reliance” Kulasinghe Felicitation Volume, only been focused on pile design aspects. Institution of Engineers, Sri Lanka, Colombo. Pile construction is a comparatively Furthermore, even planners are reluctant in
complicated process, which initiates with applying such forecasting models due to lack of 6. Batterham, R. G. (1980), “Slipform Concrete” confidence on the applicability of such factors Construction Press Ltd., Lancaster, England, and geotechnical investigations, from which or cost prediction models to local context as Longman Inc., New York. insufficient or inaccurate data collection causes unforeseen delays and cost variations during these factors will need to be verified and 7. Appuhamy, J. M. R. S., Chandrasekara, H. K. C. the pile installation. Cast-in-situ bored piles are appreciate methodically before application. P., Ruhunage J. C., Dissanayake T. A. and preferred over other deep foundation options Dissanayake U. I. (2003), ”Strength Variation of due its inherent cost effectiveness in This study was carried out to reduce this gap to Slip Formed Load with Partial Replacement of Crusher construction (Mullins and Winters [1]). During some extent and to form a base for further Dust by River Sand“, Fifty Ninth Annual Sessions the pile boring, problems associated with pile studies for more accurate cost prediction of Sri Lanka Association for the Advancement of drilling and disposal of excavated material models for local context. Science. cause heavy influence on the site performance Eng. S. Surenth, AMIE(SL), MITP(SL), BSc. Plnr.Hons. 8. Fossa, K. T. (2001),”Slip forming of Vertical Concrete (Zayed [2]). In addition, rate of reinforcement (Moratuwa), BTec. Eng.Hons. (OUSL), Dip.in.PM (LBS), Structures, Friction between Concrete and Slip form gauge installation and concrete pouring also Construction Engineer, CHEC Port City Colombo (Pvt) Ltd., Sri Lanka. Email:[email protected] Panel”. Dr.Ing Thesis, Department of Structural affect the pile construction economy. To ORCID ID: https://orcid.org/0000-0001-9172-1273 Engineering. The Norwegian University of optimize the profit margins, while maintaining Science and Technology, Norway. R.M.P.P.V. Rajapakshe, NDES.Civil. (TTI), Technical the required quality standards, planners should officer, Western Province Engineering Organization, Sri
be able to forecast the level of influence of such Lanka. Email:[email protected] 9. Camellerie, J. F. (1978), "Vertical Slip forming as a factors on cost of piles at the tendering and Construction Tool", Concrete Construction, May I.S. Muthumala, BTec. Eng.Hons (OUSL), Civil planning stages. 1978. Superintendent, State Engineering Corporation, Sri Lanka. Email:[email protected]
10. Perkins, A. C.,(1977). “Slip form Concrete However, such forecasting is mostly based on Eng. M.N.C. Samarawickrama, CEng., MIE(SL), MGS Construction” Fegles-Power Service Corp. Booklet the previous experience of the team. Even (SL), BSc. Eng.Hons. (Moratuwa), MSc. (Peradeniya), MBA (Moratuwa), Senior Lecturer in Civil Engineering, though substantial amount of studies has been Department of Civil Engineering, The Open University of carried out in the international context, none Sri Lanka. Email:[email protected] has been reported in Sri Lanka about pile ORCID ID: https://orcid.org/0000-0002-5378-764X
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