130R-19: Report on the Role of Materials in Sustainable Concrete Construction

Report on the Role of Materials in Sustainable Concrete Construction Reported by ACI Committee 130 --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- ACI 130R-19 ACI

Report on the Role of Materials in Sustainable Concrete Construction

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Report on the Role of Materials in Sustainable Concrete Construction

Reported by ACI Committee 130

Julie K. Buffenbarger, Chair John T. Kevern, Secretary Kevin A. MacDonald, Vice Chair

Thomas H. Adams Barry A. Descheneaux Tracy D. Marcotte Tonatiuh Rodriguez-Nikl James M. Aldred David W. Fowler Christian Meyer Larry Rowland Khaled Walid Awad Dean A. Frank Theodore L. Neff Koji Sakai Nemkumar Banthia James K. Hicks Charles K. Nmai Arezki Tagnit-Hamou Laurent Barcelo R. Doug Hooton* Lawrence C. Novak Peter C. Taylor Florian G. Barth Lionel A. Lemay Matthew A. Offenberg Jeffrey S. Volz Mark F. Chrzanowski Emily B. Lorenz John P. Ries Jeffrey S. West Larry D. Church Zoubir Lounis John W. Roberts Peter T. Yen

Subcommittee Members Eckart R. Buhler Per A. Jahren James Don Powell James R. Van Acker Yogini S. Deshpande Sam R. Johnson Farshad Rajabipour Thomas J. Van Dam* Ashish Dubey Maria G. Juenger Kare Reknes Olafur H. Wallevik Moetaz Maher El-Hawary Tyler Ley Andres Salas David Wan Alfred Gardiner Darmawan Ludirdja Andrea J. Schokker Vicky Zajakowski William Gaspar Sean Monkman Tim James Smith Daniel J. Huffman Charles E. Pierce Michael D. A. Thomas *Subcommittee Co-chair

Consulting Members Cesar A. Constantino John D. Hull Martha G. VanGeem

Concrete has general properties, including versatility, resilience, rials includes efficient use of materials (conservation, substitution, durability, and relatively low cost, that make it the most widely used reuse, repurposing, and recycling), materials life-cycle assessment, building material in the world. Architects, engineers, researchers, replacement materials (scarcity, resource availability, and mate- and concrete practitioners have immeasurable opportunities to rials economics), energy (materials to support alternative energy incorporate sustainable development into their selection of mate- technologies, to mitigate problems with fossil-fuel technologies, rials for the manufacture of concrete. The immediate and direct and to increase energy efficiency), mitigation of undesirable envi- connection between sustainable development and concrete mate- ronmental impacts from technology and economic growth (corrosion, pollution, and toxic waste), and water purification. Informa- tion is presented to assist in the development of practical knowledge ACI Committee Reports, Guides, and Commentaries are and selection of materials used in concrete manufacture. intended for guidance in planning, designing, executing, and inspecting construction. This document is intended for the use Keywords: admixtures; aggregates; blended cement; non-portland binders; of individuals who are competent to evaluate the significance portland cement; recycled aggregates; reinforcing steel; supplementary and limitations of its content and recommendations and who cementitious materials; waste reduction; water. will accept responsibility for the application of the material it contains. The American Concrete Institute disclaims any and all responsibility for the stated principles. The Institute shall not be liable for any loss or damage arising therefrom. Reference to this document shall not be made in contract ACI 130R-19 was adopted and published January 2019. documents. If items found in this document are desired by Copyright © 2019, American Concrete Institute. All rights reserved including rights of reproduction and use in any form or by the Architect/Engineer to be a part of the contract documents, any means, including the making of copies by any photo process, or by electronic they shall be restated in mandatory language for incorporation or mechanical device, printed, written, or oral, or recording for sound or visual by the Architect/Engineer. reproduction or for use in any knowledge or retrieval system or device, unless --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- permission in writing is obtained from the copyright proprietors. Copyright American Concrete Institute Provided by IHS Markit under license with ACI Licensee=http://www.GigaPaper.ir1 No reproduction or networking permitted without license from IHS Not for Resale, 04/01/2019 08:49:59 MDT 2 REPORT ON THE ROLE OF MATERIALS IN SUSTAINABLE CONCRETE CONSTRUCTION (ACI 130R-19)

CONTENTS materials, typically between 7 and 12 percent by mass. The balance is made up of water and small amounts of other CHAPTER 1—INTRODUCTION AND SCOPE, p. 2 additives and chemical admixtures. The environmental foot- 1.1—Introduction, p. 2 prints of these ingredients are different and are discussed in 1.2—Scope, p. 3 detail in Chapter 3. Recall that the beneficial performance of concrete is fully realized by the satisfactory design and CHAPTER 2—DEFINITIONS, p. 3 detailing of a structure; appropriate mixture proportions; proper production, placement, and curing of concrete; and CHAPTER 3—CEMENTITIOUS MATERIALS, p. 3 timely maintenance and repair. 3.1—Portland cement, p. 3 Concrete is used throughout the world in many applica- 3.2—Blended hydraulic cement, p. 6 tions in construction. Historically, many civilizations used 3.3—Supplementary cementitious materials, p. 9 concrete and masonry in their structures. One often-cited 3.4—Non-portland cement binders, p. 11 example is the Roman Pantheon, which has been standing for nearly two millennia. Today, concrete is a versatile mate- CHAPTER 4—AGGREGATES AND FILLERS, p. 14 rial, allowing a large range of shapes, textures, and structural 4.1—Introduction, p. 14 applications. Concrete is a durable and economical material 4.2—Natural sand and gravel, p. 14 when proportioned, manufactured, and installed properly. 4.3—Crushed stone, p. 15 Its use in designing long-life structures enables the 4.4—Lightweight aggregates, p. 16 construction of housing and infrastructure that contrib- 4.5—Recycled/reused aggregates, p. 16 utes to environmental protection and the assurance of 4.6—Mineral filler, p. 19 public safety, health, security, serviceability, and life-cycle cost-effectiveness. CHAPTER 5—CHEMICAL ADMIXTURES AND For nearly two centuries, portland cement has been used ADDITIVES, p. 19 to produce concrete. Modern cement production began with 5.1—Overview, p. 19 the patent for portland cement manufacturing issued to 5.2—Materials used in admixture formulations, p. 20 Joseph Aspdin in England in 1824. From small batches of 5.3—Environmental impact, p. 20 cement in beehive kilns to today’s more efficient rotary kilns 5.4—Sustainable benefits of chemical admixtures, p. 21 with worldwide output of over 4.5 billion tons (4.1 billion 5.5—Reducing concrete waste, p. 23 metric tons) of cement (USGS 2018), the impact of cement production on natural resources and energy use is signifi- CHAPTER 6—WATER, p. 23 cant. With increasing societal demands placed on resource 6.1—Overview, p. 23 and energy conservation, sustainable concrete production 6.2—Standards for water in concrete mixtures, p. 23 and diligent use of materials are required for construction of 6.3—Strategies for reducing consumption of potable the built environment. water in production of concrete, p. 24 Improvements in cement production, such as development 6.4—Summary, p. 25 of efficient kiln technology and the use of both alternative raw materials and alternative fuels, have resulted in signifi- CHAPTER 7—REINFORCEMENT, p. 25 cant advancements in concrete sustainability. These changes 7.1—Introduction, p. 25 have also reduced the consumption of virgin raw materials 7.2—Steel reinforcement, p. 26 and fossil fuels. Further, concrete production has embraced 7.3—Steel reinforcing bars, p. 26 as common practice the use of reclaimed water, such as wash 7.4—Welded-wire reinforcement, p. 26 water, and the use of reclaimed materials, such as cementi- 7.5—Fiber reinforcement, p. 27 tious materials or aggregates. Additionally, new technolo- 7.6—Nonferrous reinforcement, p. 27 gies containing little or no portland cement are also being adopted. Aggregates are the largest portion of concrete by CHAPTER 8—CONCLUSION, p. 28 mass and volume, and the use of reclaimed aggregate materials have a significant impact on resource conservation. CHAPTER 9—REFERENCES, p. 28 Other materials in concrete construction, such as reinforcing Authored documents, p. 29 steel and fibers, also include a significant portion of recycled content or reclaimed material that can lower their environ- CHAPTER 1—INTRODUCTION AND SCOPE mental impact. This document provides an overview of the materials 1.1—Introduction commonly used in sustainable concrete construction, the Concrete is defined as a mixture of hydraulic cement, benefits of their use, and how efforts to reduce the environ- aggregates, and water, with or without admixtures, fibers, mental impact of their production and use are evolving. or other cementitious materials. The main ingredients of This document presents aspects of the material choices concrete by mass are aggregates, constituting up to 80 percent used in mixture proportioning and their impact on the

of the total, followed by the cement and other cementitious--`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- sustainable nature of concrete.

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1.2—Scope ical reactions take place and form the mineral phases of port- This report deals with the sustainability aspects of mate- land cement clinker. After cooling, clinker is then ground rials selection in concrete production. Chapters 3 to 7 with a small amount of gypsum to regulate setting time. In address each of the major material components of a concrete the United States, cement manufactured according to ASTM mixture: cementitious materials, aggregates, chemical C150/C150M may also contain ground limestone and admixtures, mixture water, and reinforcement. The sustain- processing additions to produce portland cement. Regional ability impacts of a concrete mixture depend not only on specifications such as BS EN 197-1:2011 include a wide the materials selected, but on their proportioning. Mate- range of cement types and allowable constituents. rials selection can improve concrete sustainability through In portland cement production, the primary environmental a range of metrics, including but not limited to reduced impact is typically considered to be carbon dioxide (CO2) carbon impacts, enhanced material efficiency, improved emissions. CO2 is classified as a greenhouse gas (GHG), is construction practices, and extended service life. Informa- naturally found in the atmosphere, and is an end-result of tion providing an overview of each category is presented fuel combustion. In addition, during the pyroprocessing of with observed effects reported for each group of materials. cement raw ingredients, calcination of limestone occurs. The wide scope of concrete materials, the continued devel- Calcination is the process of converting calcium carbonate opment and introduction of new or modified materials, and (CaCO3) to calcium oxide (CaO), releasing CO2 in the the variations of effects with different concreting materials process. Approximately 40 percent of the CO2 emitted during and conditions preclude a complete listing of all concrete pyroprocess is due to fuel combustion, with the remaining materials and their sustainability impacts on concrete. 60 percent driven off of the limestone during calcination (Marceau et al. 2007). CHAPTER 2—DEFINITIONS In 2016, the Portland Cement Association published an ACI provides a comprehensive list of definitions through Environmental Product Declaration (EPD) that estimated an online resource, ACI Concrete Terminology. the cradle-to-gate carbon intensity of cement in the United States to be 1.040 units of CO2 per unit of cement (PCA CHAPTER 3—CEMENTITIOUS MATERIALS 2016). The percentage of total annual CO2 from cement production can fluctuate based on total CO2 emitted and 3.1—Portland cement cement production levels. In 2010, the U.S. Environmental The term ‘cement’ is usually associated with portland Protection Agency (EPA) (2012) data showed the portion of cement, the most common hydraulic cement. Although the total CO2 from cement production in the United States to use of lime and pozzolans to produce concrete and masonry be approximately 1 percent, as shown in Fig. 3.1.1. A 2016 dates back to the Roman Empire, the invention of portland study of the global carbon budget estimated that cement cement is relatively recent. It is credited to Joseph Aspdin, production accounts for 5.6 percent of anthropogenic CO2 a builder from Leeds, England. In 1824, he was awarded released globally (Le Quéré et al. 2016). a patent for his process of grinding limestone, mixing it Although CO2 makes up a significant portion in GHG with finely divided clay, burning the mixture in a kiln, and emissions, other compounds such as methane (CH4) and finely grinding the resulting clinker. He gave his invention nitrous oxide (N2O) are also considered in assessing envi- the name portland cement because of its resemblance to the ronmental impacts of a material. The combined impact of natural building stone near Portland, England. This was the GHG emissions is commonly referred to as CO2 equivalents, beginning of the modern cement industry, which in 2017 had or CO2e. CO2e is a measurement used to normalize the emis- an estimated world-wide production of 4.5 billion tons (4.1 sions from various greenhouse gases based on their global billion metric tons), including both portland and blended warming potential (GWP). CO2e are commonly expressed cements (USGS 2018). as terragrams of carbon dioxide equivalents (a terragram 3.1.1 Cement manufacture and environmental impact— is 1 million metric tons). The CO2e for a gas is derived by Concrete is expected to be strong, durable, safe, versatile, multiplying the tons of the gas by its associated GWP, thus: and economical in all forms of construction, supporting TgCO2Eq = (Gg of gas) × (GWP) × (Tg/1000Gg). (Environ- communities and infrastructure. Hydraulic cement is the mental Protection Agency 2012). For example, the GWP of most important ingredient that gives concrete these qualities. CH4 is 24; that is, the impact of unit mass of CH4 may have a Concrete has demonstrated its longevity, which is one factor similar impact on global warming over 100 years as 24 units that contributes to sustainability, retaining its engineering mass of CO2. properties for decades. With present technology, concrete 3.1.2 Improving cement manufacturing energy and envi- is being used in 100-year-service-life structures in severe ronmental efficiency—The manufacturing of any construc- exposure conditions. tion material results in environmental impacts. Conse- As with all manufacturing processes, cement manufacture quently, manufacturers and researchers of cement have has environmental impacts that in turn affect the environ- invested time and funding to reduce the impact of cement mental impact of concrete. The manufacture of cement is production while maintaining the expected performance of an energy-intensive process. Raw ingredients are mined and concrete. Impact reductions are found in several catego- then ground, blended, and heated to approximately 2640°F ries, including pyroprocessing and mechanical processing (1450°C). As a result of heating to this temperature,--`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- chem- (grinding/blending) cement formulations, and the inclu-

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Fig. 3.1.1—Quantifying greenhouse gas emissions from key industrial sectors in the United States (Environmental Protection Agency 2008). (Note: Contribution to CO2e by manufacturing process segment per sector.) --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`---

Fig. 3.1.2—Energy consumption data for U.S. cement industry from 1988 to 2010 (Port- land Cement Association 2011).

sion of alternative energy and raw material sources. Each of Figure 3.1.2 shows the energy required to produce 1 ton these options provides positive benefits, with potential side (0.907 metric tons) of clinker in the United States. Process effects in reducing environmental impacts for a given level improvements have resulted in a 40.1 percent reduction in of concrete performance: energy consumption since 1972 (Portland Cement Associa- (a) Shifts from wet kilns to dry kilns tion 2011). (b) Capturing what was considered waste heat through Europe, for example, has a long tradition of producing preheater/precalciner technology blended hydraulic cements. Up to 85 percent slag has been (c) More efficient grinding processes used for many years, and over the last three decades, the (d) Use of alternative fuels ordinarily considered as use of fly ash blends and limestone as cement constitu- by-products from consumers and other industries; over 65 ents has become common. Pozzolanic additions, such as percent of U.S. cement plants integrate alternative fuel into perlite, have been common in Mediterranean countries for their energy consumption strategy according to the Portland quite some time. Presently, most cements (19 of 27 types in Cement Association (2011) BS EN 197-1:2011) in Europe are blended, and efforts are (e) Bio-fuel use based on recent energy research and pilot continuously being made to reduce the GHG contribution of projects and carbon sequestration (Business World Magazine hydraulic cement. 2012), as well as harvesting wind energy (Shafer 2009) 3.1.2.1 Use of alternative fuels and materials in cement manufacturing—Cement manufacturing uses some

Fig. 3.1.2.1a—Portland cement plants that used blast-furnace or iron slag as a raw material in 2010 (Portland Cement Association 2011).

Fig. 3.1.2.1b—Portland cement plants that used fly ash and/or bottom ash as a raw material in 2010 (Portland Cement Association 2011).

by-product and recovered materials from other industries. bottom ash from electric power plants (Portland Cement Waste oils and scrap tires are commonly used as fuels in Association 2011) (Fig. 3.1.2.1a and 3.1.2.1b). cement manufacture. Identified as an EPA Best Practice, the Other materials used in cement manufacturing include cement industry consumed 805,910 tons (731,109 metric copper slag, foundry sand, mill scale, sandblasting grit, and tons) of scrap tires as fuel in 2017, according to the Rubber synthetic gypsum. The high volumes of raw materials used Manufacturers Association (2018). Forty-one of the 111 to make cement and the detailed chemical analysis of raw operating cement plants reporting in the United States in materials allow for chemically-efficient and beneficial use 2006 used blast-furnace or iron slag as a raw material (Port- of large volumes of these waste materials. These materials land Cement Association 2011); 50 plants used fly ash or would otherwise be disposed of in landfills and, thus, their beneficial use in cement manufacturing reduces the volume

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of these waste streams in addition to reducing the use of able development and the transfer of knowledge, experi- virgin materials. ences, and best practices. WBCSD focuses on four areas: 3.1.2.2 Cement manufacturing and future planned (1) Energy and climate actions—The U.S. cement industry committed to four major (2) Development goals to improve its environmental impact (Portland Cement (3) The business role Association 2011). The first major goal with a voluntary (4) Ecosystems target date of 2006 relates to environmental management The Cement Sustainability Initiative of the WBCSD is systems (EMS): a subgroup of cement companies dedicated to addressing (1) Environmental management systems—A target by the sustainable development of cement. Approximately 70 2010 that at least 75 percent of U.S. cement plants would percent of the U.S. clinker-producing cement plants partici- have implemented an auditable and verifiable EMS rising to pate in the WBCSD. 90 percent by the end of 2020. PCA reported that by the end 3.1.2.4.1 Energy Star Cement Manufacturing Focus—The of 2010, 68 percent of the plants had implemented a program U.S. Department of Energy and the EPA sponsor the Energy (Portland Cement Association 2011) Star Industrial Focus Program. One aspect of this program The three remaining industry goals adopted a voluntary is to assist businesses in overcoming barriers to energy target date of 2020 from a 1990 baseline to: efficiency by developing industry-specific energy manage- (2) Reduce CO2 emissions by 10 percent per ton of ment tools and resources. The Cement Manufacturing Focus cementitious product produced or sold began in 2003 and now includes over 65 percent of the (3) Reduce by 60 percent the amount of cement kiln dust clinker-producing cement plants. disposed in landfills per ton of clinker produced 3.1.2.5 White portland cement—White cement clinker (4) Improve energy efficiency by 20 percent as measured is manufactured to limit the formation of compounds or by total Btu-equivalent per unit of cementitious product minerals that darken the concrete. It can play an integral role 3.1.2.3 Specification revisions and potential reduction of in innovative sustainability strategies in numerous ways. environmental impacts—Changes in cement specifications Because the properties of white cement are essentially the have enabled further reductions in the environmental impact same as gray cement, with the exception of its color, concrete of portland cement in addition to those already achieved in made with white cement retains all the properties and dura- the process area. In ASTM C150/C150M and AASHTO M bility of standard gray portland-cement concrete. Concrete 85, two changes have had a significant impact: 1) permitting made using white cement can deliver architectural benefits the use of up to 5 percent by mass of limestone to be used in that eliminate the need for less durable or volatile organic cement; and 2) permitting use of up to 5 percent inorganic compound-emitting surface-applied coatings or covering processing additions. In ASTM C595/C595M and AASHTO materials. White cement used in concrete facilitates a broad M 240M/M 240, Type IL cement is permitted to use up to pallet of architectural colors and finishes, some of which 15 percent limestone by mass. ASTM C595/C595M and would otherwise be unachievable with typical gray cements.

AASHTO--`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- M240 ternary blended cement, Type IT, provides In addition, slag cement or other light colored supplemen- additional opportunities. tary cementitious materials (SCMs) can maintain white Similarly, in Canada, CAN/CSA A3001 also allows up appearance while improving sustainability by reducing port- to 15 percent interground limestone in portland-limestone land cement use. Concrete produced with white hydraulic cements. These changes permit reduced amounts of clinker cement has significantly higher reflectance than gray cement in finished cement, which reduces both the embodied energy concrete. For interior concrete applications, this can reduce and the GHG emissions related to cement manufacture lighting needs, potentially saving electrical power and (Nisbet 1996). Research on the characteristics and perfor- reducing the cooling load of a building (Portland Cement mance of cement with limestone demonstrated that equiva- Association 2002). In exterior applications, white cement lent performance in terms of strength, mechanical proper- concrete’s higher reflectivity reduces solar heat gain and ties, plastic properties, and durability was achievable with urban heat island effects. Marceau and VanGeem (2007) these changes. A review of much of the existing work can tested a wide range of concrete mixture designs and found be found in Hawkins et al. (2005) and Tennis et al. (2011). all of them were effective in reflecting solar energy and could 3.1.2.4 Additional cement industry initiatives related to contribute to the reduction of urban heat islands when used sustainability—The cement industry partners with multiple in pavement, roofing, or cladding. White cement mixtures organizations devoted to improving the sustainability showed the highest reflectivity. of cement manufacturing, including the World Business Council for Sustainable Development (WBCSD) Cement 3.2—Blended hydraulic cement Sustainability Initiative (CSI) (3.1.2.4.1) and the Energy Blended hydraulic cement is a combination of portland Star Cement Manufacturing Focus (Energy Star 2014). cement and other cementitious or mineral constituents, 3.1.2.4.1 World Business Council for Sustainable Devel- sometimes referred to as composite cements. In the United opment—WBCSD is an association of companies dealing States, blended cements are manufactured in accordance exclusively with business and sustainable development. with ASTM C595/C595M and C1157/C1157M as well as WBCSD supports companies in the exploration of sustain- AASHTO M240, whereas in Canada they are covered in CAN/CSA-A3001. As previously mentioned, other stan-

dards such as BS EN 197-1:2011 also include a wide range of cement classifications that can include other cementitious materials and mineral constituents. In cement production, there are two distinct steps in the process: 1) pyroprocessing that occurs in the kiln; and 2) grinding and blending of clinker and other constituents after the kiln. The nonclinker components of blended cements are added to the clinker after the kiln, and so do not require pyroprocessing as do the clinker raw materials. Exceptions to this are some natural pozzolans that may require either heating or grinding to prepare them for use in cement. 3.2.1 Environmental impacts and blended cement— The cement industry has made advancements in reducing overall energy use and environmental impact in portland cement production. Further reductions in the environmental impacts of cement are possible. The use of ASTM C595/ C595M, ASTM C1157/C1157M, AASHTO M240, or CAN/ CSA-A3001 blended cements can also help to reduce the carbon footprint of concrete. In these cements, higher amounts of slag cement and pozzolans, collectively known as SCMs, are used. The amount of pyroprocessed materials in cement is therefore reduced, as is the amount of calcined limestone, both of which have the potential to reduce the carbon footprint of cement. Blended cements containing SCMs are delivered to the concrete production facility as a single product as opposed to separately supplied and batched SCMs. Although available in the U.S. market, many concrete producers prefer using different proportions of SCMs with portland cement at the concrete production facility. Blended cements are commonly believed to have slower strength gain and setting characteristics. In practice, the concrete containing them can be comparable in performance Fig. 3.2.1—(a) One-day; and (b) 28-day strengths of ASTM to ASTM C150/C150M Type II portland cement, as shown C150/C150M Type II, ASTM C595/C595M, and ASTM in Fig. 3.2.1. There are advantages to the use of blended C1157/C1157M cements from a 2004 survey (Bhatty and cements (as opposed to concretes with SCMs added sepa- Tennis 2008). Note that each column represents a single rately to the concrete mixer) with regard to chemical and cement sample of the type in the color key. physical properties that can be better controlled. However, some concrete producers feel that more flexibility in use and slag cement, or interground, as with portland cement of different replacement levels of SCMs is available than clinker and slag cement. The pozzolan or slag content of with fixed-proportion, blended cements. Ternary concrete blended cements can vary depending on the desired charac- mixtures may also be produced using an ASTM C595/ teristics of the final product. C595M Type IT blended cement, or by batching three sepa- Type IL cement contains uncalcined limestone that is rate cementitious materials, such as cement, fly ash, and ground to cement fineness. The amount of limestone is silica fume at the concrete batching facility. Ternary blends limited to 5 to 15 percent by mass of the cement. This will are another method of achieving environmentally efficient, be discussed in more detail in 3.2.5. yet practical, concrete mixtures. Ternary blended cement, Type IT, is a blended cement 3.2.2 ASTM C595/C595M cement types—ASTM C595/ made with two SCMs or ground limestone and an SCM. The C595M is a prescriptive specification that recognizes four specifications were also revised to provide transparency in main classifications of blended cements: 1) Type IP; 2) Type communication with regard to the amount and type of SCMs IS; 3) Type IL; and 4) Type IT. These cements can be produced and limestone in blended cements. by--`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- blending individual constituents or by intergrinding. 3.2.3 Performance-based cements—In the United States, Type IP incorporates portland cement or portland cement ASTM C1157/C1157M is a performance specification clinker and a pozzolan in amounts of up to 40 percent by for hydraulic cement and provides even greater flexibility mass. The pozzolans used can include fly ash, natural in producing cements with lesser environmental impact. pozzolan, or silica fume. Specification requirements are in place to ensure - perfor Type IS cement combines portland cement or portland mance of these cements based on testing, rather than indi- cement clinker with some form of slag cement. Type IS rect (prescriptive) limits. ASTM C1157/C1157M cements cement can be blended, as is the case with portland cement are classified based on their potential application. For

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example, GU is designated for general use and HE for high- Table 3.2.4a—Estimated kiln emissions savings early-strength requirements. Other designations include MS potential (lb of emissions per ton of cement (moderate sulfate resistance), HS (high sulfate resistance), production [kg per metric ton])* MH (moderate heat of hydration), and LH (low heat of 5 percent CR† 20 percent CR† 35 percent CR† hydration). SO2 0.30 (0.15) 1.16 (0.58) 2.04 (1.02) 3.2.4 Potential reduction of emissions—ASTM C595/ C595M and ASTM C1157/C1157M provide opportunities NOx 0.30 (0.15) 1.16 (0.58) 2.04 (1.02) for lessening the environmental impact of concrete. CO 0.06 (0.03) 0.20 (0.10) 0.36 (0.18)

Tables 3.2.4a and 3.2.4b give estimates of emission reduc- CO2 94.30 (47.15) 377.18 (188.59) 660.42 (330.21) tions based on the amounts of noncalcined limestone or THC (total 0.00 (0.00) 0.02 (0.01) 0.06 (0.03) SCMs used in cements, based on the approach of Nisbet hydrocarbons) (1996) and The Environmental Protection Agency (2014). *Following the approach of Nisbet (1996) and using The Environmental Protection 3.2.5 Portland-limestone cements (PLCs)—Globally, Agency (2014) emissions factors. † portland-limestone cements, or PLCs, have been used for Clinker reduction (CR)—clinker production is the primary source of CO2 release in many years (Hooton et al. 2007). Limestone is a partial cement manufacture; the ability to reduce the amount of clinker per ton in a finished cement may reduce its emissions. constituent to replace clinker in these cements. The limestone is processed by intergrinding with portland cement Table 3.2.4b—Estimated kiln emissions savings clinker or blending ground material. In some cases, it may potential, tons per year (metric tons per year)* be added to the concrete mixture (Hooton et. al. 2007). As 5 percent CR 20 percent CR 35 percent CR previously noted, ASTM C150/C150M now allows up to 5 percent limestone as a constituent in portland cement. SO2 13,358 (12,300) 54,344 (49,300) 95,240 (86,400)

ASTM C595/C595M Type IL PLCs are cements that use NOx 13,358 (12,300) 54,344 (49,300) 95,240 (86,400) percentages of 5 to 15 percent limestone replacement; these CO 2425 (2200) 9700 (8800) 16,976 (15,400) are not covered by ASTM C150/C150M. --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- 4,417,513 17,669,940 30,939,233 CO Limestone is easier to grind than clinker, requiring less 2 (4,007,500) (16,029,900) (28,067,600) energy to prepare the raw material (Cost 2008). Cement with limestone can also increase concrete strength and THC 331 (300) 1323 (1200) 2315 (2100) reduce porosity, thereby increasing durability (Matschei et *Using data in Table 3.2.4a and assuming 85 million metric tons (94 million tons) per year per year of portland cement production. al. 2007b). Calcination of the limestone is not necessary, thereby avoiding some CO emissions. The CSA A3000 2 and this blended cement, containing just 68 percent clinker, (Hooton et al. 2007) allows up to 15 percent limestone in provided equivalent performance in terms of concrete strength portland-limestone cements. In Canada, PLC use is governed and durability as portland cement produced with 91 percent of by CSA A23.1/A23.2 and NBC 2015. Prior to this in North the same clinker (Thomas et al. 2010b). America, PLC use had been minimal due to limited adoption Intergrinding clinker and limestone produces an improved of industry standards. ASTM C1157/C1157M cements with (broadened) particle size distribution compared to a clinker approximately 10 percent limestone have been produced at alone, with the softer limestone grinding finer than the several locations in the United States since the mid-2000s. harder clinker. In addition to improving particle packing, the An approach in Canada to the introduction of PLC has fine limestone particles also act as nucleation sites, thereby been to produce PLC with equivalent performance to port- increasing the rate of hydration of the calcium silicates at land cement manufactured from the same clinker relative early ages and, possibly, improving distribution of hydrates. to strength gain and setting characteristics. The equivalent Clinker particles can also be ground finer compared with performance is achieved by grinding the PLC to a higher portland cement, which will increase the degree of hydra- fineness, the increase typically being approximately 100 to tion of the PLC at any given age. Furthermore, it has been 120 m2/kg for PLC with 12 percent limestone. Laboratory demonstrated that CaCO will react chemically (although and field testing of full industrial trial grinds were conducted 3 to a small extent, depending on the tricalcium aluminate in Canada prior to the inclusion of PLC in the Canadian [C A] content of the clinker) with the aluminate phases to Standards (Thomas and Hooton 2010). The testing included 3 form carboaluminate phases (Bonavetti et al. 2001), which strength development and durability on a wide range of may contribute to reducing the porosity and increasing the concrete mixtures with and without SCMs and confirmed strength of the paste (Matschei et al. 2007a). Any additional that PLC with up to 15 percent interground limestone can be aluminates supplied by pozzolans and slag could increase produced with equivalent performance to portland cement. the formation of carboaluminate. In one paving trial, PLC was used with 50 percent SCM- The only significant concern with the use of PLC as the combined fly ash and slag; the cementitious materials compo- sole cementing material is increased potential for the thau- nent of this concrete consisted of just 41.5 percent portland masite form of sulfate attack, if poor-quality concrete is cement clinker (Thomas et al. 2010a). In another trial, a exposed to sulfates at temperatures of approximately 50°F blended PLC was produced by intergrinding 12 percent lime- (10°C) or lower. It has been found that, when used with stone and 15 percent slag together with clinker and gypsum, appropriate levels of pozzolans or slag cement, PLC does not

exhibit signs of thaumasite form of sulfate attack. (Hooton Table 3.3a—Embodied energy and embodied et al. 2010). carbon of various binder components (Circular 3.2.6 Grinding aids—Traditional grinding aids are Ecology Ltd. 2011) organic amino alcohols (such as triethanolamine [TEOA] Embodied energy, Embodied carbon, kg or triisopropanolamine [TIPA]) or glycol materials added Component MJ/kg CO2/kg at low dosages ranging from 0.02 to 0.05 percent to affect Cement 4.5 0.73 the process of dry grinding of most solid materials, reducing Fly ash 0.10 0.008 overall grinding energy. Examples include all types of portland cement, slag cement, clay cement, and chalk. Slag cement 1.60 0.083 Grinding aids adsorb onto the existing and newly created Ground limestone 0.62 0.032 cement particle surfaces, partially neutralizing the charges present on the surface particles that develop during milling. Table 3.3b—Embodied energy and embodied This reduces the surface-free energy of the material being carbon of various BS 8500-1:2015/40 MPa concrete ground and enhances separating capabilities that will lead (general structural) mixtures (Circular Ecology to increased production volume. Improved or higher cement Ltd. 2011) production rates lead to lower specific energy consumption Embodied energy, Embodied carbon, kg per unit of cement, reducing one of the most electricity- Binder MJ/kg CO2/kg consuming processes in cement production (60 to 70 percent 100 percent cement 1.03 0.163 of the total electricity consumed in a cement plant). Use of 85 percent cement, 15 grinding aids also helps improve the flowability of cement. 0.97 0.152 percent fly ash New performance-enhancing grinding aids such as polycar- 70 percent cement, 30 boxylate polymers, in addition to the traditional grinding aid 0.89 0.136 percent fly ash function, are used to modify setting or strength properties 75 percent cement, 25 of concrete. These grinding aids also have shown enhanced 0.91 0.133 particle dispersion and the ability to increase cement fine- percent slag cement 50 percent cement, 50 ness capabilities. Increasing fineness in blended cements 0.78 0.100 allows for higher clinker replacements with SCMs or lime- percent slag cement stone, reducing the CO2 emissions in concrete. and thus some of its environmental impact. Additionally, this 3.3—Supplementary cementitious materials may reduce both the rate of virgin resource use for cement Supplementary cementitious materials (SCMs) are a production and disposal of industrial by-products. class of materials that can be used to replace part of the The environmental footprint of concrete is sensitive to the portland cement in concrete. Their application varies and binder composition (3.4). The relative embodied energy and could depend on the type of SCM. In addition to replacing embodied carbon of different binder components can vary a portion of the portland cement in a particular mixture widely (Circular Ecology Ltd. 2011) (Table 3.3a). Their rela- proportion, they may be added to the total cementitious tive proportioning then impacts the embodied energy and content in some cases. When properly proportioned, the use embodied carbon of concrete (Table 3.3b). These tables are of SCMs can help achieve desired concrete properties for the provided for illustrative purposes only. Preference is given anticipated use and exposure of the concrete. Though SCMs to specific quantitative comparisons using appropriate data. can be incorporated in blended cements, they can also be Based on the included content, Tables 3.3a and 3.3b added separately by a concrete producer at their batch plant should appear after each of fly ash, slag, and limestone have or production facility. been mentioned. Many SCMs are by-products of industrial processes Cement, slag cement, and fly ash all have European-related and their use removes them from the waste stream. These organizations coordinating efforts to improve their respective include fly ash, slag cement, silica fume, and rice husk ash. organization’s contribution to further sustainable construction. Other SCMs, such as diatomaceous earth, volcanic ash, or In addition to the organizations for slag and fly ash, a silica expanded shale, are classified as natural pozzolans. Some fume organization was organized and formally announced in natural pozzolans require processing prior to use in concrete, early 2013. Similarly, in the United States there is the Slag which may affect the degree to which they may reduce the Cement Association (SCA), the American Coal Ash Associa- embodied environmental impact of the concrete. Depending tion (ACAA), and the Silica Fume Association (SFA). on the type of natural pozzolan, the processing may include 3.3.1 Coal fly ash—Coal fly ash is an important pozzolan grinding or, in some cases, thermal treatment. SCMs can because it is widely used in concrete. Fly ash is the mineral enhance the performance and durability of concrete. The residue from the combustion of coal, typically in the genera- particular SCM or the proportion of SCM used may be tion of electricity at a power plant. The physical and chem- varied to help provide enhanced performance over a range ical properties of this type of fly ash can vary considerably of exposures and applications of concrete. from power plant to power plant, due to the different sources The judicious inclusion of SCMs in concrete can reduce the of coal used, as well as different combustion and emission control systems. Coal fly ash performance can be influenced --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`---amount of portland cement used per unit volume of concrete,

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by its chemical and physical makeup. Standards in some carbon and methods to address its impact on concrete has countries, such as CAN/CSA, classify the type of coal fly ash also been performed (Ley et al. 2008; Kulaots et al. 2003; by its calcium content, reported as CaO. In the United States, Freeman et al. 1997). fly ash is classified according toASTM C618 as either Class Fly ash, as a by-product of coal combustion, would require C (pozzolanic and cementitious) or Class F (pozzolanic) disposal if not used beneficially. This shortens the useful life based on the sum of the oxides of silica, alumina, and iron of landfills and wastes a valuable material. Although widely (SiO2, Al2O3, and Fe2O3). available, the use rates of generated fly ash vary widely The performance of a particular coal fly ash in concrete can within the United States and internationally. Usage rates depend on a number of factors, including the combination of range from as low as 3.5 percent in India to as high as 93.7 materials in the concrete mixture, the proportion of the ash, percent in Hong Kong (Malhotra 2000). Although beneficial and the characteristics of the ash. That said, properly propor- as an SCM, there are technical reasons that a particular fly tioned concrete mixtures containing fly ash can enhance the ash may fall outside of specification limits, making it unsuit- strength and durability of concrete, potentially extending the able for concrete use and, therefore, affecting use potential service life, and therefore the sustainability, of the structure. and rates. According to the American Coal Ash Associa- Coal fly ash can enhance the performance of concrete tion (2011), U.S. fly ash generation was 59.9 million tons when compared to concrete manufactured with portland (54.3 million metric tons), of which 11.7 million tons (10.6 cement only. Long-term compressive strength may improve, million metric tons) were used directly in concrete, concrete and some ashes are very effective in helping to reduce the products, or grout. Based on the previously stated carbon effects of alkali-silica reaction and sulfate attack (Thomas intensity factor of 0.88 units of CO2 per unit of cement and 2009). In mass concrete applications such as mat founda- assuming a 1-to-1 replacement rate (fly ash to cement), tions, heat generated during the concrete’s hydration can it could be estimated that the use of coal fly ash in those cause heat gradients in the concrete that can lead to unac- applications avoided approximately 10.3 million tons (9.3 ceptable thermal cracking due to internal or external million metric tons) of CO2 emissions in 2011. An additional restraint. Controlling the early heat of hydration is crit- 2 million tons (1.8 million metric tonnes) of fly ash was used ical, and properly designed and proportioned mixtures can as a component of blended cement, or as in raw feed for help to offset this. This may necessitate the use of higher- cement clinker production. volume fly ash mixtures. The development of high-volume The use of coal fly ash as an SCM provides benefits related fly ash concrete mixture proportions is typically attributed to sustainable concrete in enhancing concrete performance, to Malhotra (1999), who developed mixtures with over 60 reducing the amount of material in the waste stream, and percent cement replacement by fly ash. As with all mixtures helping lower the environmental footprint of concrete. with high volumes of SCMs, attention should be paid to the 3.3.2 Slag cement—Slag cement is a by-product of the concrete curing conditions to achieve the desired properties. steel industry, derived from granulated blast-furnace slag. Prolonged wet curing or higher curing temperatures may Granulated blast-furnace slag is the glassy granular material be required, depending on the mixture proportions. Further formed when molten blast-furnace slag is rapidly chilled, curing information can be found in ACI 232.3R. as by immersion in water. This material is then ground When used at high replacement levels, when placed at to produce slag cement. The first recorded production of cold temperatures, or both, the relatively slower rate of blended portland blast-furnace slag cement was in Germany strength development of fly ash concrete is a disadvantage in in 1892, and since the 1950s, use of slag cement as a sepa- applications where high early strength is required. In some rate cementitious material has become widespread in many applications, however, the concrete may not be loaded to its different countries ACI( 233R). design value until months after its placement, and it may be Molten slag is handled in various ways at a steel mill. If acceptable to specify 56- or 90-day strengths instead of the the molten slag is allowed to cool slowly, it crystallizes into conventional 28-day strengths, provided that the concrete a solid mass. This air-cooled slag may then be crushed and will receive sufficient curing. If normal strength develop- sized and sometimes used as an aggregate. In producing slag ment is critical, accelerators are available to speed up the cement, the molten slag is rapidly cooled after leaving the hydration rates of fly ash concrete mixtures (Shi and Day furnace in a process called granulation. This essentially stops 1995; Shi 1998). the crystallization process and produces the glassy slag gran- Coal fly ash may present some challenges for the concrete ules that can be ground into slag cement. It is only the rapidly producer. Color may vary due to fluctuations in chemistry. cooled granulated slag that has a high cementitious potential. Unburned carbon content can affect the ability to entrain Because the calcium-to-silicate ratio of the calcium- air in concrete. The amount of the unburned carbon and its silicate-hydrate (C-S-H) formed from slag cement is lower potential impact on the effectiveness of the air-entraining than that formed from portland cement, slag cement is able --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- admixture can be monitored by the concrete producer and to chemically bind a larger amount of alkali in the C-S-H. mixtures adjusted to attain the desired result. The optimum cement replacement level varies depending on The coal fly ash industry is working to improve quality application. Percentages from 20 to 50 percent have histori- control and has developed technologies to help reduce the cally been used in concrete and sometimes in mass concrete amount or offset the effects of the carbon content of fly ash. as high as 80 percent. As previously mentioned, the concrete Other research to assess the surface area and amount of industry has also seen an increase in the use of ternary

cementitious systems—that is, a blend of ordinary portland guidance on the evaluation of the performance characteris- cement, fly ash or other pozzolans, and slag cement.ASTM tics of these materials. C595/C595M recognizes such systems for blended cement 3.3.5.1 Photocatalytic materials—A relatively novel tool (Type IT), and concrete producers can also add the mate- in the effort to combat air pollution is the use of photocata- rials separately at the batch plant or production facility. Slag lytic materials (Van Hampton 2007). These chemicals, most cement may be a constituent of these cements or systems. notably titanium dioxide (TiO2) particles, can be mixed The use of slag cement as an SCM also provides benefits with cement or added as a separate ingredient in concrete related to sustainable concrete in enhancing concrete perfor- to give concrete an inherent ability to convert pollutants mance, reducing the amount of material in the waste stream, such as carbon monoxide to carbon dioxide, NOx to nitrate, and helping lower the carbon footprint of concrete. Like SOx to sulfate, and oxidizing some organics when exposed other SCMs, when properly proportioned and cured, slag to sunlight or other ultraviolet light sources. The process is cement improves many mechanical and durability properties somewhat analogous to photosynthesis. Because the photo- of concrete and can generate less heat of hydration. catalytic materials are catalysts, they are not consumed in 3.3.3 Silica fume—Condensed silica fume is a by-product the reactions and will continue to work at reducing pollution. of the silicon metal and ferrosilicon alloy industry and is These agents also help maintain the light-colored appear- another example of beneficial use of an industrial by-product. ance of concretes that are referred to as self-cleaning. The This siliceous material improves both strength and dura- breakdown of organic materials decreases staining of the bility of concrete to such an extent that high-performance concrete, which reduces maintenance, while maintaining its concrete mixture proportions often call for the addition of reflectance in supporting heat island mitigation. silica fume. Although it is typically used in modest amounts (approximately 5 to 8 percent by mass) and sometimes as an 3.4—Non-portland cement binders addition to the cementitious material rather than a replace- 3.4.1 Concrete without portland cement—This section ment, the potential to extend structural service life, optimize provides an overview of concretes in which the binder phase strength and element sizing, and the fact that it is a recovered contains no portland cement. The non-portland cement material, fits well in sustainable building. Silica fume acts binders discussed herein are alkali-activated slag cement, both as a reactant as well as improving packing of the binder alkali-activated fly ash, calcium aluminate cements, and particles. Its use is found in ACI 234R and ASTM C1240. calcium sulfoaluminate cements. Note that most of these 3.3.4 Other pozzolans—There are many different pozzo- binder systems have been used for specific applications lans, most notably those considered natural ones. Among across the world for several decades. Recent concerns these are metakaolin, expanded shale, expanded slate, about the environment, however, have created a renewed expanded clay, pumice, rice husk ash, volcanic ashes, and interest in these lower-energy and CO2-intensive binder materials such as diatomaceous earth. These materials may systems. Although the materials discussed in the following require some form of processing before use in concrete. This are considered the most industrially viable alternatives to may entail thermal processing as in the case of metakaolin, portland cement, this document does not claim to provide or physical grinding in the case of mined pozzolans such a comprehensive list of all possible non-portland-cement as diatomaceous earth. Such processing would add to, and binder materials. need to be accounted for when assessing, the environmental 3.4.2 Alkali-activated slag and alkali-activated fly ash impact of such materials. As with other SCMs, these pozzo- concretes—Slag cement is produced by finely grinding the lans can be used in concrete to replace part of the portland glassy granular material formed when molten blast-furnace cement, to enhance performance characteristics and poten- slag is rapidly chilled. As slag cement is a recovered material tially extend service life. More information on natural from the iron industry, its intrinsic embodied energy is low. pozzolans is found in ACI 232.1R. They are specified in An alkali-activated slag (AAS) concrete is one in which the

ASTM--`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- C618 as Class N pozzolans. binder phase is made of slag cement, water, and an alkali 3.3.5 Other materials—Along with historically used activator that triggers the chemical reactions involving SCMs, there has been research on the potential use of other dissolution of slag and precipitation of calcium silicate and materials as SCMs. These materials fall outside the ASTM calcium aluminosilicate phases that serve as the binder phase definition of SCMs, such as slag cement, fly ash, or silica of concrete. These systems contain no portland cement. fume. Many materials may possess chemical or mineralog- Although slag is cementitious and can self-activate, the reac- ical properties that might be considered for use in concrete. tion is typically slow and requires external alkali activators Wood ash and various types of nonferrous slags are just a to enhance reaction rates and form stronger products. Suffi- few examples of these types of materials. Also, finely ground cient alkali content is also necessary for the development of glass powder derived from recycled glass has been shown significant strength. Because slag is deficient in alkalis, these to be an effective pozzolan Tagnit-Hamou( and Bengougam have to be supplied externally. These AAS also appear in the 2012; Jin 1998; Byars et al. 2004; Shao et al. 2000). Many literature with a variety of names such as alkali-activated of these materials deserve closer attention because their use cements (Palomo and López dela Fuente 2003) and alkali- as SCMs may be of benefit in concrete rather than being sent slag cements (Roy 1999). to disposal. Refer to ASTM C1709 and CSA A3004-E1 for Alkali-activated fly ash is another potential substitute for portland cement. Fly ash is a coal combustion by-product

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and is primarily composed of aluminosilicate glass, which is There will be embodied energy in the activator system. formed due to rapid cooling from the molten state within the For example, the energy to produce sodium hydroxide is flu gas of a coal power plant. The alumina (Al2O3) and silica 20.5 MJ/kg (Hardjito and Rangan 2005) compared with 5.35 (SiO2) phases originate from clay impurities that are inter- MJ/kg for portland cement (Goggins et al. 2010). As acti- mixed with coal during the natural process of coal formation. vators are used at approximately 10 percent mass of solid Similar to slag, fly ash ASTM( C618 Class C and Class F) binder, the reduction in embodied energy for the binder can be activated by an alkaline solution to promote dissolution system could be approximately 60 percent. of fly ash and formation of a binder phase. Additional heat When specifying non‐portland-cement binders, users need curing may be needed to ensure desirable early-age strength to consider and validate all performance characteristics, and property development in alkali-activated fly ash concrete. such as workability, durability, and fire resistance of these Some commonly used alkaline activating agents are portland cement substitutes to ensure they are suitable for sodium hydroxide (NaOH) and sodium silicate (Na2SiO3, the intended purpose (ASTM C1709). also known as water glass) or combinations of these (Shi 3.4.3 Calcium aluminate cements—Calcium aluminate and Day 1996; Krizan and Zivanovic 2002). A variety of cements (CACs) are a special class of cement containing industrial by-products containing alkalis and sulfates such primarily aluminates and calcium. Small amounts of ferrite as cement kiln dusts are also equally effective in activating and silica are also typically present. CACs were invented slag (Chaunsali and Peethamparan 2011). Among the acti- in the early 1900s to resist sulfate attack. CACs are inher- vators used, water glass is widely reported to give rise to ently rapid-hardening and can be rapid-setting and adjust- rapid hardening and high compressive strengths (Oh et al. able with appropriate chemical admixtures. These cements 2010). Note that some of these activators are very corrosive are often used in refractory applications; self-leveling floor alkaline liquids that require safety precautions during manu- compounds; as a component in grouts, mortars, bonding facture of the concrete. agents and other adhesives; highly-abrasion-resistant appli- The main hydration product in an AAS systems is C-S-H, cations; rapid repair; rehabilitation and construction of with a low Ca/Si ratio regardless of the type of activator concrete flatwork such as sidewalks and overlays; and full- used (Song et al. 2000; Wang et al. 1994; Richardson and depth pavement construction. The rapid-hardening prop- Cabrera 2000; Davidovits 2008). In addition, an Al-modified erties; resistance to sulfate attack, acid attack, and alkali- C-S-H is also present due to the alumina content of slag. aggregate reaction; and abrasion resistance make these The morphology of the hydration products changes with the cements desirable in a wide range of special applications activator and other hydration conditions (Wang and Scriv- (Scrivener and Capmas 1998). As there is no calcination of ener 1995; Richardson et al. 1994; Ravikumar et al. 2010). limestone, the manufacturing process of CACs generates In alkali-activated Class F fly ash, the primary binder phase significantly less CO2 than portland cement—roughly on the is an alkali-alumino-silicate-hydrate (N-A-S-H) phase, also order of 50 percent less (Gartner 2004; Juenger et al. 2011). known as geopolymer (Davidovits 1991). This geopolymer However, there is slightly more grinding energy required phase, which has compositional similarities with natural (than portland cement) due to the increased strength of the zeolites, serves as concrete binder. In addition to Class F fly clinker (Juenger et al. 2011; Scrivener and Capmas 1998). ash, geopolymers can be produced using metakaolin or other The most widely discussed and controversial aspect of aluminosilicate materials. Class C ash is compositionally in CACs is a process referred to as conversion. Conversion is between Class F ash and slag, as it contains significant quanti- a process where metastable hydrates (CAH10 and C2AH8) ties of lime, silica, and alumina (Duxson 2009). As a result of formed at low and moderate temperatures (41 to approxi- alkali activation, Class C fly ash primarily forms an Al-modi- mately 158°F [5 to approximately 70°C]) convert to stable fied C-S-H gel, which is also known as C-A-S-H gel. hydrates (C3AH6) formed at high temperatures (greater than Alkali-activated concretes exhibit useful strength (Atis et 158°F [70°C]). This process leads to an increase in porosity al. 2009), durability against chemical/acid attack, chloride and subsequent decrease in strength. Conversion is an inevi- penetration (Fernández-Jiménez and Puertas 2002; Puertas table process and must be accounted for when designing the et al. 2009), and a variety of other potentially valuable char- concrete mixture. The hydration process of CACs is thus acteristics such as fire and wastewater resistance. A wide highly temperature-dependent and the time spent during range of different alkali‐activated binder systems are avail- hydration within specific temperature ranges will dictate the

able and discussed in the literature. The performance with type and amount of metastable or stable hydrates, or both, that --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- respect to rheology, strength development, shrinkage, and are formed (Scrivener and Capmas 1998). Several building durability performance varies widely. The performance of collapses in the 1970s were attributed to CAC conversion, each product and the systems in place to ensure consistency and many structural codes subsequently banned its use. and safety need to be carefully assessed before use. Since then, research has provided a greater understanding of An advantage of alkali-activated concretes is that they CAC chemistry and behavior. Furthermore, a report by The have a low CO2 emission rate embodied energy compared to Concrete Society (1997) revisited these landmark collapses traditional portland cement concretes. This is because these and revealed that improper structural detailing, a lack of systems do not require calcination and the energy-intensive, understanding about CAC properties, and not following high-temperature clinkering processes involved during manufacturers’ guidance had led to most of the structural production of portland cement. failures. Improved guidance for predicting long-term prop-

erties and a better scientific understanding of the material CSA cements, aside from further knowledge of its material have seen resurgence in interest and use of this alternative properties, is the cost of raw materials. The high alumina cementitious binder (The Concrete Society 1997; Juenger content demands the use of bauxite as a raw material, which et al. 2011). There are several recommendations that have is not widely available and is expensive. Alternatively, the been employed to keep the strength lost during conversion high sulfur and iron contents, when C4AF is included, allow to a minimum. This includes keeping the water-cementitious for the use of many types of industrial by-products as raw material ratio (w/cm) below 0.40 and including a minimum materials, reducing the cost of the clinker, both in terms of cement content of 675 lb/yd3 (400 kg/m3). More information the economy and the environment (Palou and Majling 1995; on CACs can be found in Juenger et al. (2011), Scrivener Phair 2006). and Capmas (1998), The Concrete Society (1997), Fentiman 3.4.5 Recycled glass-based cements and concretes—One et al. (2008), and Gosselin et al. (2010). incentive behind using recycled soda-lime glass, such as 3.4.4 Calcium sulfoaluminate cements—Calcium bottles and windows in concrete, is the prohibitive costs of sulfoaluminate (CSA) cements are receiving increasing shipping recycled glass from collection points to remelting examination from the cement industry and researchers as facilities that manufacture new glass products. Another a lower-energy, lower-CO2 alternative to portland cement. incentive is use of glass powder as a pozzolanic material, Such cements are not new; they contain as a primary phase given that access to a quality pozzolan may be limited in Ye’elimite, Ca4Al6SO16 or C4A3S¯ in cement chemistry some locations. As of 2003 in the United States, approxi-

notation, sometimes called Klein’s compound because it mately 600,000 tons/year (544,000 metric tons/year) of --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- was used by Alexander Klein in the 1960s as an expansive recycled glass is landfilled or stockpiled in hopes that future additive to portland cement (Klein 1966). China has been technologies would allow a profitable use of this material industrially producing these cements since the 1970s and (Reindl 2003). Pulverized glass can be used in concrete as their annual production may exceed 1 million tons (907,000 fine aggregates or as cement replacement. Aggregate appli- metric tons) (Glasser and Zhang 2001). CSA cements are cations are more developed and have been commercialized used for some structural applications, but they are especially in the United States, United Kingdom, and Australia. Desir- well-suited for the precast and cold-weather applications able strength and workability of concretes containing glass that take advantage of the rapid strength gain of these mate- sand have been achieved by proper mixture proportioning rials (Su et al. 1997). Their mechanical properties and dura- (Polley et al. 1998). The main challenge of the use of these bility are reported to rival portland cement (Quillin 2001), materials is the alkali-silica reaction (ASR) of glass parti- but much work is needed to fully understand the long-term cles leading to cracking and deterioration of concrete. ASR, material performance. however, has been successfully controlled by: CSA cements lack standardized composition or perfor- a) Use of fly ash or other suitable SCMs (Shafaatian et al. mance criteria. They are distinguished by the presence of 2013) C4A3S¯ as the primary cementing phase, belite (C2S) as b) Use of glass aggregates finer than No. 50 (0.3 mm) a secondary phase, and the absence of alite (C3S). Other sieve (Jin et al. 2000) phases that are commonly present include C4AF, C2AS, CA, c) Annealing crushed glass before use in concrete (Rajabi- and CS¯, and gypsum is added for hydration control as in pour et al. 2010; Maraghechi et al. 2012) portland cement. Because ettringite is the primary reaction Lithium admixtures and use of glass powder as a cement product of C4A3S¯ with gypsum and water, these cements supplement may also be effective in mitigating ASR in these can exhibit rapid setting, rapid strength gains, and expan- materials (Shayan and Xu 2006). sion. These properties, however, can be controlled through In comparison, the use of glass powder as a cementitious/ manipulating the composition of the cement and through pozzolanic material has not been sufficiently developed the addition of chemical retarders. Mechanical properties despite its promise as a pozzolan with reliable compositional and dimensional stability similar to portland cement can be consistency. Due to a high concentration of amorphous silica achieved (Juenger and Chen 2011). (approximately 70 percent wt.) soda-lime glass can react The reputation of CSA cements as environmentally friendly pozzolanically with portlandite in a glass-portland cement comes from reductions in energy use and CO2 emissions system and produce low Ca/Si C-S-H. At moderate (up during manufacturing. CSA clinkers can be made at lower to 30 percent wt.) replacement levels of ordinary portland kiln temperatures than portland cement clinkers (2280°F cement, glass powder has been found to improve compres- [1250°C] instead of 2460 to 2640°F [1350 to 1450°C]), and sive strength beyond 28 days; however, early strengths can be are more porous and friable, thereby requiring less energy reduced when using the same w/cm (Shao et al. 2000; Shi et for grinding (Mehta 1980; Glasser and Zhang 2001). The al. 2005). Fineness of glass powder has a significant impact lime (CaO) content of C4A3S¯ is low (36.7 wt. percent) on its reactivity; glass finer than 38 µm satisfies the strength compared to that of C3S (73.7 wt. percent); therefore, much activity index of ASTM C618 (greater than 75 percent at 7 less limestone is calcined in the production of CSA cements, days) (Shao et al. 2000). By further increasing glass fineness, leading to lower CO2 emissions. CSA cements may be able to heat curing, or both, concretes with 3-day strengths surpassing reduce limestone use by 40 percent and energy by 25 percent that of PC concrete can be prepared (Shi et al. 2005). compared to portland cement (Sharp et al. 1999). One of 3.4.6 Hydraulic fly ash cements (HFACs)—These cements the primary challenges facing the widespread adoption of use high-calcium fly ash (HCFA) along with a functional

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additive. This approach produces performance character- physical properties of the mixture, depending on the aggre- istics in concrete similar to portland and other hydraulic gate properties (Stark 2006; Thomas 2011). cements in terms of strength, durability, and rate of curing Most of the concrete aggregates are natural or crushed or of hydration (Hicks 2010). Depending on the mixture and can consist of many types of minerals (Barksdale 1991). proportion, HFAC materials will meet or exceed the perfor- Some aggregates come from natural deposits such as sand mance specifications contained in ASTM C1157/C1157M. and gravel and are used as-mined, after washing, or in some These cements can be used to produce concretes, grouts, cases, after crushing. With environmental concerns at the mortars, flowable fills, and other specialty mixture propor- forefront, it is becoming more difficult to obtain approval tions. The functional additive consists of some combination to mine natural aggregates near rivers and waterways where of activator and setting retardant (SR). The activator/retar- they are indigenous. Depletion of readily accessible sources dant enhances the hydraulic activity of the calcium alumi- of natural aggregates has also led to a reduction in their use. nosilicates contained in HCFA while the SR helps to control Most crushed aggregates come from stone that is quarried the rate of reaction. and then processed in mechanical crushers. Crushed and The activator/SR additive is near neutral pH while fresh nontraditional aggregates including synthetic, lightweight, activated HFAC mixture is slightly more basic (pH of 7 to recycled/reused aggregates, and mineral fillers will likely be 9). This is lower than in an OPC mixture. The main reaction used more frequently in the future due to the environmental products are calcium aluminosilicate hydrates. The set time concern of mining sand and gravel. There has been an and strength development of HCFA concrete can be adjusted increased use of nontraditional aggregates, some of which by changing the concentration of SR. By controlling setting are otherwise derived from diverted waste materials, and time, these cements can meet ASTM C1600/C1600M stan- their use strongly contributes to sustainability by reducing dards. These cements are commercialized and have been the embodied energy and CO2 emissions and eliminating used in numerous projects (Patel and Kinney 2013; Diaz waste materials as long as similar or improved concrete Loya et al. 2013). performance can be achieved. As shown in Fig. 4.1 (USGS 2011), it is predicted that CHAPTER 4—AGGREGATES AND FILLERS crushed aggregates will increase in use in relation to natural aggregates in the future of the U.S. concrete industry; this 4.1—Introduction trend will likely occur in many other parts of the world as Aggregates are a widely used construction material. well. The use of crushed aggregates poses some challenges. Concrete pavements, bridges, foundations, dams, utili- Due to their angular shape, workability is generally decreased ties, buildings, and other structures would not be possible (Graves 2006). The dust of fracture or microfines of those without aggregates. Aggregates are produced in most materials that pass the 75 μm sieve and are produced in the regions worldwide because transportation costs often exceed crushing operation often require the use of admixtures to yield the on-site cost of aggregate production. They are among the concrete with the desired workability (Graves 2006; Fowler least expensive building materials, and even when used in and Rached 2011). The use of nontraditional aggregates, concrete as 75 or 80 percent of the total mixture, aggregates which may be angular in shape, also can affect concrete prop- are usually still less expensive than the binder. The produc- erties such as workability, pumpability, strength, and modulus tion of aggregates may require less energy than cement, of elasticity, depending on the aggregate properties. The use and because they occupy the greatest volume in concrete, of admixtures and mixture design can help overcome or limit reduced energy in production may reduce the embodied these effects Mindness( et al. 2002). energy and CO2 emissions, thereby contributing to sustain- Given that transporting aggregates long distances uses ability. Calculations should be made to determine conclu- additional energy and produces more CO2 compared to local sively if using a greater percentage of aggregates reduces aggregates, local aggregates should be used when feasible, the embodied energy and GHG emissions, depending on the including recycled materials to promote sustainability. The production and transportation-related emissions and energy impact of materials should be looked at holistically over of individual components such as cementitious materials the life of the structure; an overall reduced environmental and aggregates. impact can be achieved by using materials with a larger The aggregate type can dramatically change fresh and embodied energy and CO2 emissions, if they significantly hardened concrete properties. Aggregates that are well- increase the service life or substantially reduce cementitious graded can decrease the quantity of cementitious materials material requirements. required while allowing the concrete to perform as desired (Graves 2006). The use of larger maximum-size aggre- 4.2—Natural sand and gravel gates, when feasible, is effective in reducing cementitious Historically, natural aggregates have been the most widely materials and shrinkage. Without durable aggregates, long- used aggregates in the production of concrete; however, lasting, durable concrete is much more difficult to produce. the production of natural aggregates is declining and is Durability issues with local aggregates can often be miti- predicted to continue to do so in relation to crushed aggre- gated using blended cements, pozzolans, admixtures, or fine gates (USGS 2011) (Fig. 4.1). When properly proportioned, lightweight aggregate (LWA), by changing the chemical and both natural sand and gravel are capable of producing high- --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`---quality, sustainable concrete (Graves 2006). Natural aggre-

Fig. 4.1—Production of aggregates in the United States. (USGS 2015a,b).

gates often require little or no mechanical crushing when 4.3—Crushed stone sizing for use in concrete. Producing natural aggregate in There are over 10,000 crushed stone mines in the United many locations, therefore, requires less energy than other States, yet only 1 percent are below ground. Most under- types of aggregates. ground aggregate mines are a maximum of only a few Because natural aggregates are generally crushed less, hundred feet (meters) deep. Underground operations are they tend to have rounded edges and smoother surface becoming more common, especially for limestone mining textures, which further lends itself to many sustainable in the central and eastern parts of the United States, as the concrete features. For example, smoother surface textures advantages of such operations are increasingly recognized by lead to easier concrete consolidation compared with crushed the producers. By operating underground, a variety of prob- aggregates. Easier consolidation means less water is needed lems usually connected with surface mining, such as envi- to achieve workability of the concrete. Less water generally ronmental impacts and community acceptance, are signifi- means higher strength, improved durability, and usually less cantly reduced (USGS 2015a,b). Crushed stone has been an drying shrinkage. As strength increases, it may be possible increasingly valuable source of aggregates for concrete for to reduce the ordinary portland cement content while still decades, but the use of crushed fine aggregate has been more achieving the required design concrete strength or work- limited primarily due to concerns about workability and, ability. Reducing the ordinary portland cement content further in some cases, the difficulty in meeting ASTM C33/C33M reduces the overall embodied energy and CO2 emissions of specifications with respect to the minus No. 200 content. the concrete. While admixtures such as high-range water- Workability, which is affected by sharp, angular shapes reducing admixtures will also improve workability, they bring generally produced in the crushing process, can be over- emissions and embodied energy costs of their own. come to some extent by the proper use of admixtures, Using natural aggregate for sustainable concrete, however, supplementary cementitious materials (SCMs), or both. requires consideration of basic issues during concrete design. Crushed stone aggregates have increased aggregate-to-paste For example, the rounded edges and smooth surface texture bond strength due to the aggregate shape and texture that that have many benefits in fresh concrete also may present usually results in higher flexural and compressive strengths. issues such as reduced interfacial transition zone bond This may permit reduced ordinary portland cement content strength once the concrete hardens. Clay and clay coatings and a corresponding reduction in the embodied energy and that naturally occur in the aggregate should be minimized CO2 emissions. to ensure an adequate interfacial transition zone. As for ASTM C33/C33M, originally developed for natural sand, crushed aggregates, properly sizing the aggregate grading to limits the amount of material passing the No. 200 (75 μm) achieve maximum aggregate packing should be considered sieve to minimize the silt and clay often associated with natural to further minimize the paste content. This is discussed in sand deposits. Unfortunately, many crushed fine aggregates do detail in ACI 211.1. not meet the grading requirements. Particularly, the amount of Natural aggregate reserves are often located in proximity minus No. 200 (75 μm) fines is generally much greater than to rivers, creeks, and streams. Once permitted reserves are permitted by ASTM C33/C33M.Washing to remove excess exhausted, the mining areas are reclaimed and often returned microfines is usually required to meet ASTM C33/C33M, but to ponds, lakes, and wetland vegetation. These wetland areas this practice has both economic and environmental costs. Trial become home to many species of wildlife and serve as a batching should be employed to determine whether the fines natural--`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- filter to help cleanse runoff water. in a particular aggregate are deleterious.

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Research has shown that the microfines can be success- fill with water within the first few hours to few days of expo- fully used in much larger percentages—as much as 15 percent sure to moisture. Interior pores often fill extremely slowly, or more of the total fine aggregate than permitted byASTM with many months of submersion required to approach full C33/C33M—to produce concrete with excellent strength and water absorption and are essentially non-interconnected; durability when the mixtures are properly designed and the a small fraction remains unfilled after years of immer- microfines do not contain a significant amount of clayFowler ( sion (ACI 213R). Commercially, LWA is most commonly et al. 2006; Fowler and Rached 2011). Research has also prewetted by sprinklers or by vacuum saturation before it shown that abrasion resistance is generally greater when up is used for internal curing or when the lightweight concrete to 15 percent microfines are used compared to concrete made will be pumped. When crushed, ESCS tends to absorb water with good-quality natural sand (Fowler and Quiroga 2004). more quickly. The microfines can be considered as part of the total powder The embodied energy to manufacture ESCS includes content—that is, ordinary portland cement and supplementary mining, manufacturing, and transporting the material to the cementing materials—and, in some cases, the cement can be job site or building product manufacturer. The use of ESCS reduced by 20 percent or more and still achieve the same or has been a design choice in thousands of existing struc- greater strength. Under these conditions, the use of suitable tures as the cost of the embodied energy is often paid back microfines in concrete, instead of being removed from the in a very short period of time due to reduction in material fine aggregate and wasted, strongly supports sustainability resulting from reduced loads. Reduced dead loads allow (Juenger et al. 2006). The use of performance specifications for smaller columns, beams, and foundations, resulting in should be encouraged to enable the use of higher amounts of less overall material being used. Lighter concrete improves microfines than those permitted in ASTM C33/C33M. thermal performance, lower transportation costs, and reduc- Crushed stone quarries can be reclaimed into usable farm- tion of labor costs associated with the building elements, land or pasture, or converted into landfills, lakes, and other especially when these elements are handled by workers, recreational sites. These reclamation areas support wildlife such as with concrete masonry (Friggle and Reeves 2008; in many cases to a greater extent than before the mining Holm et al. 1984). operations commenced. ESCS structural LWA concrete contributes to sustainability by: 4.4—Lightweight aggregates (a) Reducing the concrete unit weight by 25 to 30 percent, Lightweight aggregate (LWA) has a long history, with leading to a higher strength-to-weight ratios that requires the first known use dating back 2000 years to the Clas- less concrete and, hence, less dead load to be carried by the sical Roman period from which there are several remaining structure lightweight concrete structures in the Mediterranean region. (b) Greater fire resistance, resulting in thinner sections The first modern use of high-performance LWA concrete when used for fireproofing came when lightweight concrete ships (1917 to 1921) were (c) Internal curing provided by water absorption in the built in which specified compressive strengths of 5000 psi porous LWA, which improves hydration, reduces shrinkage, (35 MPa) were obtained with a unit weight of less than 110 and reduces cracking; the lower weight resulting from lb/ft3 (1760 kg/m3), using rotary-kiln-produced expanded the addition of LWA also contributes to reduced cracking shale and clay LWA. Commercial normalweight concrete (ESCSI 2007) strengths of that time were approximately 2500 psi (17 MPa) (ESCSI 1971). After 80 years of floating in seawater, 4.5—Recycled/reused aggregates core samples verified that the lightweight concrete strength There are many recycled and reused materials that have was over 8000 psi (55 MPa) and the samples were in good been used for aggregates in concrete. These include recycled condition (Sturm et al. 2002). concrete, crushed returned concrete aggregate, screenings,

Expanded shale, clay, and slate (ESCS) structural LWAs blast-furnace slag, crushed glass aggregate, waste plastic --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- are produced in manufacturing plants from suitable raw aggregate, recycled scrap tire aggregates, and recycled materials. ESCS is made using the pyroprocessing method asphalt pavement aggregates. that includes a rotary kiln in which raw material is fed into 4.5.1 Recycled concrete—In-service concrete can be a long, slowly rotating, slightly inclined cylinder where removed and recycled as aggregate for concrete. Recy- it’s fired to approximately 2000°F (1100°C), resulting in cling concrete is a sustainable practice because it redirects approximately 1.34 MBtu/yd3 (1.85 GJ/m3) or 2.16 MBtu/ the demolished materials, including concrete and rein- ton (2.07 GJ/ton) of energy consumed. This manufacturing forcing steel, from landfills to new construction. Recycling process, which is similar to that of portland cement, produces concrete contributes to reduced environmental impacts of a uniform, high-quality ceramic aggregate that is structurally land disturbance, especially at a time when the numbers of strong, stable, and durable, yet also lightweight and insula- adequate disposal sites are diminishing and the sources of tive (Holm and Ries 2007). good-quality aggregates are rapidly becoming depleted. In ESCS LWAs contain a uniform distribution system of most urban areas in the United States, where there is a high pores that have a size range of approximately 5 to 300 μm, concentration of in-service concrete, the lack of disposal embodied in a continuous high-strength vitreous phase. Pores sites can substantially increase disposal costs and environ- close to the surface of some LWA are readily permeable and mental costs, including land use and longer transportation

distances. The use of recycled concrete aggregate (RCA) can controlled gradation can be successfully used as a fine be economical and sustainable, particularly in metropolitan aggregate or powder component in concrete, resulting in areas, when there are higher costs of virgin aggregate mate- similar or improved concrete properties. Potential benefits rials and higher transportation costs to dispose the removed may include reduction in cementitious content, improved concrete and deliver the virgin aggregate. durability, increased volume of aggregate per unit volume Fresh concrete produced with RCA can be batched, mixed, and increased abrasion resistance (Fowler and Rached 2011; transported, placed, and compacted in the same manner as Juenger et al. 2006). Concrete using these products as a fine conventional concrete. However, mixture proportions for aggregate constituent can be proportioned, mixed, placed, structural concrete produced with RCA should be adjusted and finished using traditional methods and materials. to account for differences in the physical properties of RCA 4.5.4 Blast-furnace slag—Blast-furnace slag is a nonme- compared to crushed stone. RCA is produced from construction tallic material produced in the production of iron. Iron ore, debris, which makes the possibility of contamination from rein- iron scrap, and fluxes such as limestone, dolomite, or both, forcing bar, oils, deicing salts, and other building components are charged into a blast furnace along with coke for fuel. higher. Contamination can be deleterious to the performance The coke is combusted to produce carbon monoxide, which of RCA in concrete. In many European countries, the use of reduces the iron ore to a molten iron product. This molten 20 percent RCAs in structural concrete is standard practice iron can be cast into iron products but is most often used as (Federal Highway Administration 2004; RILEM 2005). a feedstock for steel production. Approximately 20 percent 4.5.2 Crushed returned concrete aggregate—Every year, by mass of iron production is slag. The molten slag, which it is estimated that an average of 5 percent of the estimated absorbs much of the sulfur from the charge, consists primarily 455 million cubic yards (348 cubic meters) of ready mixed of silicates, aluminosilicates, and calcium-aluminosilicates. concrete produced in the United States (est. 2006) is returned Different forms of slag products are produced depending to the concrete plant. A common approach to recycling on the method used to cool the molten slag. These products returned concrete is to first discharge the returned concrete include air-cooled blast-furnace slag (ACBFS), expanded from the concrete truck in an appropriately designated area of or foamed blast-furnace slag, pelletized blast-furnace slag, the concrete plant. When hardened, the discharged concrete and granulated blast-furnace slag. Air-cooled blast-furnace can be subsequently crushed by a crusher, and the crushed slag can be crushed and screened in a process similar to concrete aggregate (CCA) can be used as a portion of the crushed stone. aggregate component in new concrete. CCA is prepared from Expanded or foamed blast-furnace slag results if the molten concrete that has never been in service and thus is not contam- slag is cooled and solidified by adding controlled quantities inated from in-service exposure, as compared to RCA. of water, air, or steam; the process of cooling and solidifi- In research conducted by the National Ready Mixed cation can be accelerated, increasing the cellular nature of Concrete Association, CCA was produced at a ready mixed the slag and producing a lightweight expanded or foamed concrete plant at three strength classes (Obla et al. 2007). product. Foamed slag is distinguishable from ACBFS by its The properties of coarse and fine CCA were found to be relatively high porosity and low bulk density. different than that of virgin aggregates. It was determined Pelletized blast-furnace slag results when the molten that although the use of CCA had impacts on the concrete slag is cooled and solidified with water and air quenched properties, these could be addressed through mixture design in a spinning drum; pellets, rather than a solid mass, are and testing. produced. By controlling the process, pellets can be made The use of returned concrete aggregate strongly contrib- more crystalline, which is beneficial for aggregate use or utes to sustainability by diverting an otherwise waste mate- more vitrified (for example. glassy), which is more desirable rial from landfills. Its use in concrete eliminates the need for in a cementitious application. producing an equal volume of natural or crushed aggregate, Granulated blast-furnace slag is rapidly cooled by large which reduces or eliminates fuel requirements and associ- quantities of water to produce a sand-like granule. While ated emissions. (Obla et al. 2007; Kim and Bentz 2007). most granulated slag is further processed by grinding into 4.5.3 Screenings—Crushed stone screenings are a fine a cementitious material commonly known as slag cement aggregate by-product from the crushing, screening, and (Chapter 3), unground granulated blast-furnace slag can be washing of coarse aggregate sizes. These products typically used as an aggregate material. In Australia, granulated blast- range in size from minus 3/8 or 1/4 in. (9 or 6 mm) and may furnace slag has been used as a partial replacement for fine include fines as small as 2 µm. aggregate in the production of portland-cement concrete. These materials are produced in the same processes used Another aggregate application in Australia is the incorpo- to produce the coarse sizes, therefore using the same energy ration of 20 percent by volume of granulated slag with 80 per unit. It is advantageous to find uses for these by-products percent by volume dense graded ACBSF crushed aggregate so that the energy expended for production is not wasted. base. The granulated slag acts as a binder material in the The use of screenings leads to sustainability because the fine production of a high-quality bound aggregate base course particles are not washed from the aggregate and, therefore, (Australasian Slag Association Inc 2002). According to the are not wasted. USGS, 69 percent of blast-furnace slag in the United States Research has shown that some of these products having was air cooled with 49.7 percent of this portion being used

suitable mineralogy, consistent--`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- physical properties, and in road base applications (USGS 2015c). The proportion of

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ACBFS currently being produced, however, is decreasing concrete after years of seemingly satisfactory service. The relative to granulated and pelletized blast-furnace slag complexity of this phenomenon makes it difficult to prede- production. The production of expanded blast-furnace slag termine whether a specific aggregate is potentially reactive is no longer favored and is being replaced by the pelletizing or not. If soda lime glass, the common material of household procedure. and beverage containers, is used as aggregate in concrete, ACBFS has been used as an aggregate for concrete, there is reasonable certainty that ASR-induced damage will concrete masonry, asphalt pavement, and road bases. Many occur, provided there is sufficient moisture available to drive specifying agencies consider ACBFS to be a conventional the reaction. aggregate, thereby recognizing a by-product of iron produc- The recommended methods for mitigating ASR in tion in everyday construction. Pelletized blast-furnace slag concrete using glass aggregate alone or in combination are has been used as LWA and for cement manufacture. Foamed (Jin et al. 2000): slag has been used as an LWA for concrete. (a) Grind the glass fine enough to pass No. 100 (0.149 4.5.5 Crushed glass aggregate—There are demonstrated mm) mesh sustainable uses of post-consumer glass aggregate for (b) Use pozzolans such as metakaolin as a coating on glass commodity products that divert waste glass into concrete, or additive to concrete, fly ash, slag cement, or fine LWA including concrete masonry block units and paving stones (c) Apply a protective coating to the glass—for example, with up to 100 percent glass aggregate. Concrete mixtures zirconium as for alkali-resistant glass fibers with 100 percent glass aggregate and 28-day compressive (d) Modify the glass chemistry to make it less reactive strengths exceeding 15,000 psi (103.5 MPa) have already (e) Seal the concrete to prevent moisture ingress been made using standard procedures (Jin et al. 2000; Meyer (f) Use a low-alkali cement 1999). More than 12 million tons (10.9 million metric Note that ASR is an extremely complex phenomenon. tons) of glass products are discarded in the United States Even small changes in glass chemistry can make large on an annual basis, and almost three-fourths of this waste differences in the reactivity. Each concrete product and stream is landfilled at significant cost to the public (EPA glass source needs to be evaluated and tested thoroughly to 2009). As more beneficial applications are developed, a ensure an acceptable quality and durability of the concrete higher volume of post-consumer glass can be integrated into produced with such glass. Also, replacing natural aggregate concrete. There is a wide variety of architectural and decora- with glass aggregate has significant repercussions on the tive concrete applications that could be produced with glass mixture design and concrete production technology, particu- aggregate, including architectural concrete blocks, building larly if fully automated production processes are used. façade elements, wall tiles, panels, partitions, stair treads, 4.5.6 Waste plastic aggregate—There has been a tremendous countertops, and outdoor furnishings. increase in waste plastics, and many uses have been proposed. Crushed glass has special properties that are beneficial for There has been a moderate level of research conducted on its use as aggregate to produce sustainable concrete. Because the use of post-consumer plastic aggregate in concrete. Post- of the lack of water absorption and the smooth surfaces of consumer plastic aggregate can be used as an alternative LWA glass particles, the flow properties of fresh concrete with source to achieve a more sustainable concrete. A reduction in glass aggregate are improved compared to fresh concrete unit weight of concrete lowers the total dead load within a with crushed stone. This means that either workability can structure. At the same time, lightweight concrete containing be improved at given a w/cm, or the w/cm can be reduced plastic aggregate can have reduced heat loss and improved to achieve a specified workability, which in turn increases thermal insulation properties, which can lead to a reduction in mechanical strength and durability properties. The smooth energy consumption and costs. surfaces of crushed glass have so far not been shown to Post-consumer plastic can be derived from numerous negatively affect the mechanical properties of concrete. products and can consist of different polymers. The most Glass also has high hardness and abrasion resistance, which common source that has been studied is shredded polyeth- makes it a suitable aggregate for paving stones, floor tiles, ylene terephthalate (PET) bottles, which requires minimal and other applications subject to long-term surface wear. processing and therefore less cost to produce. Its use can Glass powder has pozzolanic properties when finely ground, become cost-effective, especially in urban areas with a large so the finest fraction of crushed glass aggregate is excellent volume of disposed plastic bottles. Experimental concrete as a filler because of its bond to the surrounding matrix. has been produced with 100 percent shredded PET aggre- With reduced water requirements and improved long-term gate, but with reduced strength and modulus of elasticity properties, crushed glass aggregate can contribute to a more mechanical properties. Replacement of less than 50 percent sustainable concrete. seems to have much less effect on mechanical properties The use of glass as an aggregate for concrete was contem- when compared to a control mixture. plated decades ago, but alkali-silica reaction (ASR) caused Eight different plastics representing those found in munic-

an--`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- insurmountable problem (Philips et al. 1972; Johnson ipal solid waste streams and in industrial waste plastics were 1974). ASR can occur with aggregates that contain reactive investigated for use as aggregate in concrete (Vishwakarma amorphous silica. In the presence of moisture, the resulting 1994). Slump was not affected when 1 percent plastic was ASR gel swells and can cause severe concrete cracking. used regardless of particle size and shape; for 4 percent addi- This is a long-term problem that may manifest itself in tions, the slump reduced by 10 to 77 percent, depending on

the shape and size. When very fine plastic vent dust was 4.6—Mineral filler used, the cohesiveness was greatly improved. Concrete Mineral filler (MF) is a finely divided mineral product, at strength was greatly influenced by size and shape of filler, least 65 percent of which passes the No. 200 (75 μm) sieve. but strength was always reduced. Strength reduction was Gradation is given by ASTM C1797, clay/smectite content generally less when the filler size and shape was similar to is indicated by AASHTO T 330, and chloride content by the coarse aggregate than for finer sizes. Impact resistance ASTM C1218/C1218M (optional). on concrete specimens made with plastic filler as measured In general, there are two different categories of MF: by the Los Angeles abrasion test was improved for only one siliceous base and carbonate base. The siliceous MF is a plastic, high-density polyethylene fines. Concrete made with by-product of crushing siliceous stone and is captured as dry six of the eight plastics showed an increase in abrasion resis- fines or wet fines in aggregate quarry ponds. Most quarries tance when the amount of plastics was increased from 1 to 4 producing crushed siliceous rocks will produce by-product percent. The use of the plastics in concrete resulted in equal fines. Production of this MF will vary among quarries or lower scaling resistance (Akçaözoğlu et al. 2010; Yesilata depending on the type of rock and processing equipment. et al. 2009; Remadnia et al. 2009; Marzouk et al. 2007; Vish- In general, siliceous materials are higher in hardness (Mohs wakarma 1994; Sander 1993). hardness 7 or higher) and have high resistance to crushing. 4.5.7 Recycled scrap tire aggregates—Millions of scrap The use in concrete will help to reduce by-product and pond automotive tires are landfilled each year. They pose a fire fines, and therefore improves sustainability. The energy to hazard and a habitat for mosquitoes. Scrap tires in the form produce siliceous MF is similar to that required for crushing of crumb rubber have been proposed as aggregates for the siliceous stone and will depend on the type of rocks and concrete. They have been used as a fine aggregate replace- equipment being used. ment--`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- and as an additive to the concrete mixture. With The carbonate MF, also called ground calcium carbonate increasing rubber content: (GCC) or calcium carbonate fines (CCF), is normally (a) The workability as measured by slump decreases. produced for various purposes including use in concrete. (b) The entrained air content increases; compressive The GCC is available in dry and wet (slurry) form. Dry- strength decreases approximately 35 psi (240 kPa) per powder GCC is more common for concrete applications. percent increase in crumb rubber when used as fine aggre- The most effective process is normally using ball mills and gate replacement. air classifiers. (c) Flexural strength decreases approximately 5 psi (35 Ground calcium carbonate is not hydraulic binder; kPa) per percent increase in crumb rubber. however, it can provide nucleation sites for cement hydra- (d) The modulus of elasticity is reduced approximately 40 tion and accelerating the development of C-S-H phases at ksi (275 MPa) per percent increase in rubber. early ages. (Hooton et al. 2007; Tennis et al. 2011; Schmidt (e) Permeability, as indicated by ASTM C1202, increased 1992a,b; Hawthorn 1993; Mikhailova et al. 2013). 66 coulombs per percent increase in crumb rubber (Ajibola There are no data available to quantify the energy reduc- 1994). tion in the concrete-making process with and without Because of its drawbacks, the only use of crumb rubber mineral filler. It is easier to handle concrete with more paste in concrete as a replacement of conventional aggregates to and mortar compared to mixtures that lack the desired work- support sustainability would appear to be in the construction ability and consistency due to a deficiency of mortar or of applications such as walkways, cycling tracks, or pave- aggregate fines, and it is intuitive that less energy is required ments subjected to low loads (Ajibola 1994). for placement and finishing. 4.5.8 Recycled asphalt pavement aggregates—Recycled The use of mineral filler has been studied for many years. In asphalt pavement (RAP) has been proposed for use as practice, MF is used to replace sand, coarse aggregate, or both, concrete aggregate, particularly in areas in which good- by up to 20 percent. When properly proportioned, mineral quality virgin aggregates are limited and to eliminate fillers can be used to reduce the consumption of cement while the placement of RAP into landfills. Research has been keeping the workability and strength to the target strength of performed to use RAP as a replacement of the coarse and concrete (Juenger et al 2006). The use of MF in concrete can fine aggregate in concrete on an equal weight basis. With be economically beneficial, saving energy and reducing CO2 increasing RAP content, slump and air content increases; the emissions, thereby contributing to sustainability (Juenger et compressive strength decreases approximately 80 psi (550 al. 2006; Fowler and Quiroga 2004). kPa) and flexural strength decreases approximately 8 psi (55 kPa) per percent increase in RAP; the modulus of elas- CHAPTER 5—CHEMICAL ADMIXTURES AND ticity decreases approximately 40 ksi (275 MPa) per percent ADDITIVES increase in RAP; and permeability, as indicated by ASTM C1202, increases approximately 80 coulombs per percent 5.1—Overview increase in RAP (Ajibola 1994). A chemical admixture is a material that is used as an ingre- As with crumb rubber, RAP can be used in concrete to dient in a cementitious mixture such as concrete, mortar, or contribute to sustainability in applications in which low grout, usually in small quantities to modify one or more of loads are applied and high-quality concrete is not essential. the properties of the mixture in the fresh or hardened state. (Ajibola 1994)

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Table 5.3a—Potential environmental impacts of chemical admixtures per kg of admixture GWP ODP AP POCP Solids content, Typical dosage, Admixture type percent percent of cement kg CO2-Eq kg CFC 11-Eq kg SO2-Eq kg ethene-Eq Retarders 10 to 60 0.2 to 2.0 1.31 3.50E-10 1.04E-02 6.73E-04 Set accelerators 10 to 70 1.0 to 3.0 1.33 1.80E-10 2.56E-03 3.64E-04 Air entrainers 5 to 13 0.05 to 1.0 5.27E-01 7.56E-11 1.30E-03 3.45E-04 Hardening accelerators 10 to 70 1.0 to 3.0 2.28 1.74E-10 6.60E-03 4.84E-04 Plasticizers/high- range water-reducing 30 to 45 0.2 to 2.0 1.88 2.30E-10 2.92E-03 3.12E-04 admixutres

For fresh concrete, chemical admixtures are typically used Note, however, that processing of the constituent materials to reduce mixture water content, entrain air, increase work- can be more complex than just blending, which can result ability, reduce segregation, control rate of bleeding, reduce in a potentially higher environmental footprint upstream. rate of slump loss, improve pumping, improve finishing, An admixture Environmental Product Declaration (EPD) control time of setting, or a combination of these. The poten- captures all the environmental impacts from all processes tial benefits of chemical admixtures in the hardened state from raw material extraction through final manufacturing. include increased strength, impact and abrasion resistance, With respect to application, chemical admixtures generally improved aesthetics, reduced drying shrinkage and perme- constitute a very small fraction of the total volume or mass ability, and an overall increase in durability (ACI 212.3R). of concrete—usually less than about 0.2 percent of concrete Chemical admixtures are governed by several industry volume for most admixtures and up to about 3.0 percent for standards, but the predominant and most widely used stan- some corrosion inhibitors and permeability-reducing admix- dards are ASTM C260/C260M and ASTM C494/C494M. tures. Therefore, the contribution of chemical admixtures to A review of their benefits shows that chemical admixtures the environmental impact of a concrete mixture is typically play an important role in the construction of environmen- low relative to other concrete-making materials. tally friendly, sustainable concrete structures, while helping Although chemical admixtures fall below typical cutoff to conserve natural resources. Admixtures can contribute criteria by mass or energy use for a life-cycle assessment to the embodied energy and emissions or consume raw (LCA) of concrete, they may still contribute to a concrete’s materials. The typical dosage used, however, is low and environmental impact. The European Federation of Concrete the benefit in terms of fresh or hardened properties of the Admixture Associations (EFCA) has reported environmental concrete is significant. Accordingly, the sustainability bene- impacts of chemical admixtures through EPDs for different fits of their use can be great. The benefits of chemical admix- types of chemical admixtures taking into consideration the tures with respect to sustainability in concrete construction environmental impact from cradle-to-gate production (EFCA are discussed in the sections that follow. 2015). Table 5.3a provides results for some of the key environmental impacts from chemical admixture production per 5.2—Materials used in admixture formulations unit of admixture, while Table 5.3b reports the key environ- Materials used in chemical admixture formulations vary mental impacts from chemical admixture production per unit depending on type and may be derived from natural material of concrete produced. The environmental impacts in terms of sources, by-products of other manufacturing processes, or global warming potential (GWP), depletion potential of the synthetic. For example, the basic ingredients used in water- stratospheric ozone layer (ODP), acidification potential of reducing and retarding admixtures—corn syrup and ligno- land and water (AP), and formation potential of tropospheric sulfonates—have for decades been obtained from corn or ozone photochemical oxidants (POCP) are included. Note wood. In addition, lignosulfonates are by-products from the that the EFCA-validated declarations exclusively apply to production of wood pulp using the Kraft Process (Driessen plants operated in Belgium, France, Germany, Italy, Nether- et al. 2000; Mockos et al. 2008). Polycarboxylate ethers lands, Norway, Spain, Sweden, Switzerland, Turkey, and the and polyvinyl copolymers, the primary materials currently United Kingdom by EFCA National Association members used in the high-range water-reducing admixture formula- and are provided only for informational purposes. tions and pozzolanic-based cement activators are synthe- Chemical admixtures in and of themselves contribute sized materials. Details on the types of raw materials used in very little to the total environmental burden of concrete. chemical admixtures are given in ACI 212.3R. This addition is dwarfed by the net reduction in the environmental impacts of concrete that use of chemical admixtures 5.3—Environmental impact can provide. Chemical admixtures can affect the environment both The data show that on a cubic meter basis, the GWP, for during their manufacture and in concrete mixtures. The example, associated with chemical admixtures is small. Even manufacture of a chemical admixture typically only requires at the high end of the typical dosage range, the potential CO2eq blending of its constituent materials prior to shipment. --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`---emissions associated with a hardening accelerator admixture

Table 5.3b—Potential environmental impacts of chemical admixtures per m3 of concrete mixture* GWP ODP AP POCP Solids content, Typical dosage, Admixture type percent percent of cement kg CO2-Eq kg CFC 11-Eq kg SO2-Eq kg ethene-Eq Retarders 10 to 60 0.2 to 2.0 8.78 2.35E-09 0.070 4.51E-03 Set accelerators 10 to 70 1.0 to 3.0 13.37 1.81E-09 0.026 3.66E-03 Air entrainers 5 to 13 0.05 to 1.0 1.77 2.53E-10 0.004 1.16E-03 Hardening 10 to 70 1.0 to 3.0 22.91 1.75E-09 0.066 4.86E-03 accelerators Plasticizers/ high-range water- 30 to 45 0.2 to 2.0 12.60 1.51E-09 0.020 2.09E-03 reducing admixtures *Assuming 30 MPa (4350 psi) concrete mixture with 335 kg/m3 (565 lb/yd3) of cementitious materials and high end of dosage range for each admixture type.

is less than 10 percent of the amount contributed by portland cement for a 30 MPa (4350 psi) reference concrete mixture with 335 kg/m3 (565 lb/yd3) of cementitious materials used in the calculations (Marceau and VanGeem 2007).

5.4—Sustainable benefits of chemical admixtures 5.4.1 Reduction in cementitious materials content— Water-reducing admixtures are also used to optimize the amount of cementitious materials required in a concrete mixture without compromising workability, strength, or other properties. Indeed, reducing the quantity of cementitious material at the same w/cm has been shown to improve permeability properties of concrete (Buenfeld and Okundi 1998; Dhir et al. 2004). Water-reducing admixtures enable increased amounts of SCMs, such as fly ash, metakaolin, and slag cement, as partial replacements for portland cement. As discussed previously, the overall benefit of using supplemental cementitious materials (SCMs) in concrete is a net reduction in the embodied energy and greenhouse gas (GHG) emissions associated with the production of portland cement. In this regard, water-reducing admixtures provide a net sustainability benefit. As reported in Marceau et al. (2007) and shown in Fig. Fig. 5.4.1—Effect of SCMs on embodied energy of concrete 5.4.1, the embodied energy of concrete can be reduced (Marceau et al. 2007). through partial replacement of portland cement with SCMs, such as fly ash and slag cement. To offset the potential water consumed in concrete production and, as such, will adverse effects of increased levels of SCMs on time of setting contribute to water conservation while maintaining fresh, and early-age strength development, chemical admixtures— hardened, and plastic concrete properties. As required specifically mid- and high-range water reducers in conjunc- by ASTM C494/C494M, normal and high-range water- tion with accelerating admixtures—are typically used. reducing admixtures must reduce mixing water content by

In high-strength concrete applications, high-range water- a minimum of 5 and 12 percent, respectively. Most high---`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- reducing admixtures are needed to produce workable range water-reducing admixtures, however, provide up to 30 concrete mixtures at the low w/cm required to achieve the percent water reduction and, depending on type and applica- desired strengths. The use of high-strength concrete can tion, up to 40 percent water reduction for polycarboxylate result in smaller member sizes that would invariably require ethers in self-consolidating concrete, for example. The data less concrete; less concreting materials overall; and, conse- in Fig. 5.4.2 show that high-range water-reducing admix- quently, conservation of natural resources, even though tures have provided increased levels of savings in mixture cementitious materials content in a mixture may be higher. water use within the U.S. concrete industry since the mid- 5.4.2 Reduction in water use—Concrete is a very efficient 1980s. The data plotted in Fig. 5.4.2 were estimated using material in terms of water use at approximately 3 L/liters per industry data for concrete production and high-range water- kg (Ashby 2012); however, the large quantity of concrete reducing admixture usage, and assuming a modest water used globally makes reducing this quantity important. The reduction of 20 percent. The data do not include the mixing use of water-reducing admixtures is one way to reduce the water content savings derived from the use of normal and mid-range water-reducing admixtures. Copyright American Concrete Institute Provided by IHS Markit under license with ACI American Concrete Institute – CopyrightedLicensee=http://www.GigaPaper.ir © Material – www.concrete.org No reproduction or networking permitted without license from IHS Not for Resale, 04/01/2019 08:49:59 MDT 22 REPORT ON THE ROLE OF MATERIALS IN SUSTAINABLE CONCRETE CONSTRUCTION (ACI 130R-19)

Fig. 5.4.2—Estimated annual water savings due to use of high-range water-reducing admixtures in U.S. concrete industry (Nmai 2013). (Note: 1 gal. = 3.785 L.)

Figure 5.4.2 indicates that high-range water-reducing admixture use in the U.S. concrete market alone provides an annual savings of approximately 500 million gal. (1.9 billion L) of water. Taking into account the water savings derived from the use of normal and mid-range water-reducing admixtures, the total annual water savings provided by all water-reducing admixtures is estimated to be approximately Fig. 5.4.3—Effect of w/c on permeability (Neville and 1 billion gal. (4 billion L). Brooks 1987). 5.4.3 Improvement to concrete durability—One of the principal factors affecting the durability of concrete is its reaction and prevent the destructive cracking associated with permeability, which is influenced by, among other things, it. Shrinkage reducers have been used in concrete since the w/cm, SCMs, and chemical admixtures. High-range water- mid-1980s to reduce the magnitude of autogenous/drying reducing admixtures, in particular, facilitate the production shrinkage and related issues such as cracking and curling of workable low-w/cm concrete mixtures with low diffusion in slabs. Increasingly, shrinkage reducers are being used to coefficients and low permeability (Fig. 5.4.3). A reduction improve water tightness in water-retaining structures and to in permeability and other fluid transport properties help reduce midpanel cracking and joint deterioration in slabs. to minimize the intrusion of aggressive chemicals such as The use of lithium-based admixtures and shrinkage-reducing chlorides and sulfates and improve the corrosion and sulfate admixtures allow the use of aggregates indigenous to a region resistance of concrete. that otherwise may be rendered unusable in construction. Latex-based admixtures also provide significant reduc- Using regional materials lowers the economic burden of tions in concrete permeability and are typically used in transporting aggregates from other areas, as well as lowering bridge deck applications to reduce chloride ingress from the the embodied energy from transportation of aggregates. application of deicing chemicals. Overall, durability-enhancing admixtures and SCMs In aggressive environments, concrete durability can can be used to help produce concrete mixtures for long be significantly improved through the use of durability- design service lives, such as 75 to 100 years for bridges, in enhancing admixtures such as air entrainers, corrosion aggressive environments. The use of chemical admixtures inhibitors, permeability-reducing admixtures, lithium-based to further enhance concrete durability and achieve longer admixtures, and shrinkage reducers. Developed in the mid- design service lives will, therefore, minimize the need for 1930s, air entrainers are used to develop a finely-divided major repairs and replacement of concrete structures due to system of air bubbles to increase the resistance of concrete premature deterioration. In this regard, one of the net bene- to deicer salt scaling and damage from cyclic freezing and fits of using chemical admixtures to achieve greater design thawing. Corrosion inhibitors are used to increase protec- service lives is conservation of natural resources. tion for steel reinforcement in concrete exposed to chlo- 5.4.4 Improvement in the solar reflectance index of rides in service and thereby help to achieve design service concrete—For materials with the same thermal emittance, lives. Since the 1960s, permeability-reducing admixtures surfaces that are darker in color absorb heat and require have been developed to improve concrete durability through additional illumination whereas lighter colored surfaces controlling water and moisture movement and associated reflect heat and require less illumination, thereby- mini dissolved salts and other aggressive agents (Aldred 1989; mizing energy demands both for cooling and lighting as Roy et al. 1999; ACI 212.3R). In geographic areas where well as reducing the heat island effect of concrete surfaces. the aggregates may be prone to alkali-silica reaction (ASR), Consequently, concrete surfaces can provide energy savings lithium-based admixtures can be used either solely or in --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`---relative to asphalt by virtue of the lighter color of concrete. combination with pozzolans or slag cement to mitigate the Copyright American Concrete Institute Provided by IHS Markit under license with ACI American Concrete Institute – CopyrightedLicensee=http://www.GigaPaper.ir © Material – www.concrete.org No reproduction or networking permitted without license from IHS Not for Resale, 04/01/2019 08:49:59 MDT REPORT ON THE ROLE OF MATERIALS IN SUSTAINABLE CONCRETE CONSTRUCTION (ACI 130R-19) 23

Research has shown that typical gray concrete, without ened properties of the blended concrete are dependent on the added pigments, can meet USGBC LEED (United States percentage of concrete returned used and its age (Lobo et al. Green Building Council Leadership in Environmental and 1995; Lobo and Gaynor 1998). The use of HCAs to stabilize Engineering Design) requirements for solar reflective index returned plastic concrete diverts such concretes from being (SRI) (Marceau and VanGeem 2007). Liquid-coloring disposed of in landfills or more energy-intensive recycling admixtures and pigments, which are used in concrete for of hardened concrete. Hydration-controlling admixtures can aesthetic purposes, can also be used to further increase the also be used to stabilize concrete washwater in truck drums. SRI of concrete, depending on the specific color or pigment. The stabilized washwater can then be used in subsequent As an alternative to the use of white cement or high-slag loads, with a corresponding reduction in the mixture water cement, titanium dioxide (TiO2) has also been used to batched into the concrete. In addition to reducing or elimi- lighten gray cement and increase the SRI of concrete. TiO2 nating the disposal of concrete washwater, stabilization of is one of the four most common types of pigments used in concrete washwater also uses less water than is typically coloring concrete with the others being iron oxide pigments, required to clean the drums of concrete trucks. chrome oxides, and cobalt blue pigments. Most manufac- The use of HCAs to stabilize fresh concretes for long- turers provide an SRI value for pigments used in concrete. haul applications, returned plastic concrete for same-day or overnight applications, and concrete washwater effectively 5.5—Reducing concrete waste helps to reduce construction waste while addressing envi- The disposal of returned plastic concrete and concrete ronmental issues associated with the disposal of concrete washwater is an environmental challenge for concrete waste and washwater, thereby reducing landfill waste.

producers.--`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- According to the National Ready Mix Concrete Association (NRMCA 2018), approximately 2 to 10 percent CHAPTER 6—WATER (average 5 percent) of ready mixed concrete produced in the United States is returned to the concrete plant (Obla et 6.1—Overview al. 2007). With overall production reaching 351 million yd3 Concrete production relies on the use of water. The unit (268 million m3) (NRMCA 2018) there are approximately 18 consumption of water for concrete is low in comparison million yd3 (13 million m3) of returned concrete processed to other building materials, as shown in Fig. 6.1 (Ashby annually. Concrete waste can be reduced by reducing the 2012). Although the unit consumption of water is low, the perishability of fresh concrete and by managing the disposal large quantity of concrete made worldwide makes efforts to of returned plastic concrete and concrete washwater. The reduce this quantity important. Potable water is the preferred perishable nature of fresh concrete can be reduced through water for making concrete. Water is used in the manufacture the use of retarding admixtures and workability-retaining of concrete mixtures, during curing of the concrete, and to admixtures that help to maintain slump and workability for clean out the truck drums after delivery of concrete. This longer periods of time, facilitating placement. chapter reviews the standards for water as a constituent Chapter 6 will detail the aspects of water used as a material in concrete mixtures and presents strategies for reagent in concrete. This section will deal with admixtures reducing the amount of potable water in concrete mixtures. to treat water at the plant. Concrete waste and washwater can be effectively managed through the use of hydration- 6.2—Standards for water in concrete mixtures controlling admixtures (HCAs) and may also be known as Research on the effect of process water on ready mixed extended-set control admixtures (ACI 212.3R) or hydration- concrete (Lobo and Mullings 2003) has been conducted in stabilizing admixtures (ASTM C1798/C1798M). Hydration- the United States and other countries (Sandrolini and Fran- controlling admixtures are a highly potent class of retarding zoni 2001; Rickert and Grube 2003; The New Zealand Ready admixtures that provide effective control over the hydration Mixed Concrete Association Inc. 2006). Research indi- of hydraulic cement and delay the time of setting of concrete cates that process water, referred to as water from concrete over extended periods to facilitate long-haul applications, production, as well as other sources of nonpotable water, address delays, and slow concrete placements. As a result, have been permitted in many national standards, including HCAs provide significant benefit by reducing the perishable ASTM International. Testing is used to ensure it has minimal nature of concrete and help to minimize, if not eliminate, adverse effects on concrete performance. rejected loads due to workability loss. The use of HCAs for ASTM C94/C94M specifies that water used in concrete these applications will require a waiver of typical restrictions mixture proportion shall conform to ASTM C1602/ on time to total discharge and maximum drum revolutions. C1602M. ASTM C1602/C1602M states that potable water Hydration-controlling admixtures are also used to effec- can be used without testing. Nonpotable water, which tively manage returned plastic concrete and concrete wash- includes wells, streams, or other water-retention areas, and water (Ragan and Gay 1995). With respect to returned process water, when combined with other sources of water, plastic concrete, depending on time after batching, concrete, should be tested for 7-day compressive strength and time and ambient temperatures, HCAs can be used to stabilize of initial set (Table 6.2a). returned concrete and later blended with fresh concrete prior Comparisons are based on fixed proportions for a concrete to use in another application (ASTM C1798/C1798M). In mixture made with the unknown water supply and a control blending new and returned concretes, the plastic and hard- mixture using 100 percent potable water or distilled water.

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Fig. 6.1—Unit consumption of water by different building materials (Ashby 2012).

Similar performance, within limits set in the specifica- Table 6.2a—Concrete performance requirements tion, compared with a control concrete mixture containing for mixing water potable water should be attained. The water source should Limits Test methods be tested before initial use. Optional limits for the combined Compressive strength, mixing water exist for alkalis, sulfates, chlorides, and total ASTM C31/C31M, minimum percent control at 90 C39/C39M solids by mass (Table 6.2b) where warranted by anticipated 7 days exposure conditions and type of construction. Time of set, deviation from From 1:00 earlier ASTM C403/ Testing frequency is permitted to be reduced to once every control, h:min to 1:30 later C403M month when the results of 2 months of consecutive tests indicate compliance with the requirements of Table 6.2a. Table 6.2b—Optional chemical limits for combined

Testing--`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- frequency to qualify water increases as mixing water mixing water (ASTM C1602/C1602M) with higher solids content (specific gravity greater than 1.0) is intended to be used. Maximum concentration ASTM test in combined water Limits, ppm methods ASTM C1603 provides a method to establish a relationship between the measured relative density and solids Chloride as Cl– content of water sample for a range of solid concentrations Prestressed 500 C114 that cover the anticipated solids content range in the plant. Other reinforced concrete 1000 From this relationship, the relative density measured during Sulfate as SO 3000 C114 regular production can be used to quantify the solids content 4 Alkalies as (Na O + in the process water. If such a relationship is not developed, 2 600 C114 ASTM C1603 suggests simplified equations that relate 0.658K2O solids content and relative density. The appendix of ASTM Total solids by mass 50,000 C1603 C1603 provides some guidance on blending two sources of water to comply with target solids. materials content in the mixture. A few examples of how cementitious content can be reduced include: 6.3—Strategies for reducing consumption of (a) Use efficient design practices that minimize possible potable water in production of concrete overdesign of structural elements in terms of strength, dura- There are several strategies that can be implemented to bility, and the owner’s intended design life for the structure. reduce the consumption of potable water in the production of (b) Minimize the use of cementitious materials and the concrete mixture. The following strategies provide means supplementary cementitious materials (SCMs) as filler in the to reduce use of potable water in the production of concrete. concrete mixture through optimizing gradation of aggregate Reduce cementitious material content in the mixture in the mixture. design. One simple way to reduce the demand for potable (c) Specify high-performance concrete where justified water in concrete mixtures is to reduce the cementitious by project design parameters. Almost to the contradic- tion of reducing cementitious material content, there will

Fig. 7.1—Embodied energy of select construction materials.

be instances where providing a very durable structure are concrete industry should still be consistent with durable and justified. In these instances, reducing thew /cm may improve sustainable concrete products. durability characteristics as well reducing the demand for water in the concrete mixture. In addition, specifying high- CHAPTER 7—REINFORCEMENT performance concrete may allow the designer to reduce the size of members, which in turn reduces total amount of 7.1—Introduction materials, including water that is consumed. Reinforcing materials are an integral part of most concrete (d) Incorporate water-reducing admixtures in the mixture structures. While fiber-reinforced polymers are well proportion, which is currently the most common strategy for described (ACI 440R), most structures use steel reinforce- reducing the water content of concrete. ment. In reinforced concrete structures, the reinforcement is (e) Incorporate internal curing in the process. Use nonpo- necessary to overcome the low tensile strength of concrete. table mixing water in place of potable mixing water. Sources Although modern steel typically contains a high percentage of nonpotable water include recovered and reused process of recycled material, this reinforcement still adds its own water from the concrete production and batching process. environmental impacts to concrete structures. An example is The topic of recovering and reusing nonpotable water from embodied energy as shown in Fig. 7.1. the concrete operation is discussed in detail in Chapter 6. Typically, most reinforcing materials consist of deformed steel bars and wires. More recently, however, new materials 6.4—Summary such as stainless steel deformed bars, glass fiber bars, and 6.4.1 Reducing water consumption—The basic sustain- carbon fiber sheets have been used in several applications. ability challenge is that the best water for concrete is the Additionally, small fibers of steel, glass, and other synthetic water used for human consumption, which is in diminishing materials uniformly dispersed through the concrete matrix

--`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- supply. Despite the low unit water consumption in the manu- have been successfully used to produce desired properties, facture and use of concrete, reducing the amount water used often together with steel reinforcement. Generally, rein- in the process of manufacturing concrete through reuse of forcement should have the following properties for durable process water and other nonpotable sources increases its concrete construction: sustainability. (a) High strength 6.4.2 Solutions—The concrete industry has the poten- (b) Sufficient bond to the concrete matrix tial to reduce the volume of potable water used in concrete (c) Thermal compatibility to the concrete matrix mixtures by using available nonpotable water sources, (d) Durability from elements in the concrete matrix and aligning design parameters to the intended use and expected from elements to which the concrete could be exposed life of the structure, and by implementing various equip- ACI 318 and ACI 301 provide code requirements for rein- ment use technologies and production processes at produc- forcing amount, spacing, concrete cover, and best practices tion facilities to create new sources of nonpotable water. The to minimize cracking of the concrete and prevent corro- policies, procedures, methods, and materials adopted by the sion of the reinforcing material. Corrosion of reinforcing materials is a major cause of concrete deterioration. Many

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materials and strategies are available to designers to protect ASTM A1035/A1035M is for a relatively new series of internal reinforcing from corrosion. very-high steel reinforcing materials. ACI 318 has adopted In this chapter, different types of reinforcing and their the limited use of ASTM A1035/A1035M Grade 100 (yield corrosion-resistant properties are discussed. strength of 100 ksi [700 MPa]) material for use as confinement reinforcement such as ties or spirals in compression elements. 7.2—Steel reinforcement The use of higher-strength Grade 80 (yield strength of 80 Steel reinforcement typically contains a high percentage ksi [560 MPa]) and Grade 100 (yield strength of 100 ksi [700 of recycled material content and is highly recyclable at the MPa]) reinforcing products can, in some instances, allow end of the usable service life of the structure. The ability reductions in the required cross-sectional area of reinforcing to recycle steel reinforcement easily enables the manufac- steel. If such replacements can be accomplished, financial turing of new steel products from old steel reinforcement, and environmental impact savings can be realized, resulting thus minimizing waste. from the reduction in material requirements and in fabrica- The Concrete Reinforcing Steel Institute (2009) has tion and transportation logistics from the potential reduction provided the following information regarding the recycled in structural mass (if member size can be reduced). content of steel reinforcement: 7.3.1 Corrosion protection strategies—Corrosion protection of concrete structures is a system of strategies aimed at The vast majority of domestically produced, minimizing the exposure of the reinforcing steel to corrosive conventionally available reinforcing steel has a elements, improving the corrosion protection of the concrete recycled material content typically greater than matrix, and the use of coatings or alternate chemistries to 97 percent (ASTM A615/A615M, ASTM A706/ protect the reinforcing steel. Proving durability from corro- A706M). Specialty reinforcing steel products, such sion can significantly increase the life cycle of a concrete as ASTM A1035/A1035M low-carbon, chromium structure, increasing its service life and reducing the impacts steel, and ASTM A955/A955M stainless steel, have of costly and disruptive repairs. a recycled content typically greater than 75 percent. Coatings specified by ASTM A775/A775M and ASTM A934/A934M provide a barrier to protect the reinforcing steel Welded wire reinforcement is typically produced with 92 bars from corrosive elements and to interrupt the formation to 97 percent recycled material content. of corrosive galvanic cells. ASTM A767/A767M specifies the coating of reinforcing bars to provide both a sacrificial 7.3—Steel reinforcing bars protective layer and a barrier to corrosive elements, thereby The standard specifications for steel reinforcement protecting the underlying steel. ASTM A1055/A1055M published by ASTM International are generally accepted for incorporates a thermally sprayed zinc coating and an epoxy construction in the United States. ASTM A615/A615M and coating to provide an additional level of protection using two ASTM A706/A706M are presently the most common steel different strategies for protecting the reinforcing steel. reinforcing bars used for reinforced concrete construction. Stainless steel reinforcing bars specified byASTM A955/ Both ASTM A615/A615M and ASTM A706/A706M spec- A955M are made from steel alloys that are significantly ifications include Grade 60 (yield strength of 60 ksi [420 more resistant to the corrosive elements, mainly chlorides MPa]) and Grade 80 (yield strength of 80 ksi [560 MPa]) and and carbonation, typically associated with reinforcing Grade 100 (yield strength of 100 ksi [700 MPa]); however, steel. Stainless-steel-clad reinforcing bars, which are not Grade 60 (yield strength of 60 ksi [420 MPa]) material is covered by ASTM specifications, have limited availability. currently the most commonly used strength grade, repre- As these materials are currently not produced in the United senting over 90 percent of all grades of reinforcing steel States, transportation logistics and associated environmental products (Concrete Reinforcing Steel Institute 2009). ASTM impacts should be carefully evaluated. A615/A615M does include Grade 40 (yield strength of 40 ksi [280 MPa]), a material predominantly used in residential 7. 4 —Welded-wire reinforcement construction, and Grade 75 (yield strength of 75 ksi [525 Welded-wire reinforcement is used to control crack widths, MPa]) which, after a transition period, will be replaced by resulting in lower maintenance for concrete slabs. As stated Grade 80 (yield strength of 80 ksi [560 MPa]). previously, the recycled content of steel reinforcement is typi- ASTM A996/A996M is for unique materials that are cally 92 to 97 percent. Produced in accordance with ASTM produced by reusing, rather than recycling, steel rails and A1064/A1064M, welded-wire reinforcement is available train axles. The rails and axles are simply reheated and in yield strengths between 60 to 80 ksi (420 to 560 MPa). rerolled into reinforcing steel products. Rail-steel and axle- Using material with higher yield strength, it may be possible steel reinforcing bars are not generally available except in a to reduce the total amount of reinforcing steel needed, thus few areas of the country. In those areas where such bars are reducing the environmental impacts resulting from material --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- currently available, not all bar sizes and grades are produced savings, and reduced production and transportation logistics. and furnished. Before specifying ASTM A996/A996M 7.4.1 Corrosion protection strategies—Steel conforming reinforcement, local availability should be investigated to ASTM A884/A884M incorporates a protective barrier to (Concrete Reinforcing Steel Institute 2009). corrosive elements and interrupts the formation of corrosive galvanic cells to protect the underlying steel. Stainless steel

bars that conform to ASTM A1022/A1022M are also avail- these materials have a relatively low melting point, which able and can be used as part of a corrosion protection strategy. makes them vulnerable when exposed to elevated temperatures, as in the case of fire. However, melting fibers has been 7.5—Fiber reinforcement shown to increase resistance to explosive spalling in fires by Steel bars or welded wire have been the common rein- providing pathways for steam to escape. forcement materials for more than a century; however, a 7.5.3 Glass fibers—Glass fibers are very popular in the bar reinforces the concrete only in the direction in which façade element industry, but glass and similar amorphous it is oriented. Numerous uniformly dispersed and randomly compounds tend to be attacked by the alkaline cement oriented short fibers, on the other hand, strengthen the mate- matrix, which is similar to alkali-silica reaction, thus weak- rial in any direction more or less equally, literally changing ening and eventually fracturing the fibers. To make glass the properties of the composite material itself (Chawla et al. fibers more alkali-resistant (AR-glass), manufacturers typi- 2013; Chawla 2016). cally add zirconium to the glass melt. Most fiber reinforcement dosages are 1 percent of the 7.5.4 Basalt fibers—Basalt fiber is obtained by drawing concrete volume or less. At such dosages, the strengthening the molten natural occurring basalt rock into thin continuous effect of fibers is not substantial, and if the elastic modulus glassy filaments of 9 to 15 μm diameter. Despite their brittle of the fiber is less than that of the concrete, such aswith nature, the small size of the fibers limits the dimension of polypropylene fiber, it can be negative. Once a crack of the flaws in the material so that tensile strengths as high as 215 concrete matrix opens, it is likely to be bridged by only a to 430 ksi (1500 to 3000 MPa) can be obtained. Although small number of fibers with a combined strength unlikely their availability is still limited, the high strength, high- to exceed that of the concrete matrix. However, the large temperature resistance, and low cost are expected to increase amount of work needed to either fracture the fiber reinforce- their popularity. ment or to pull the fibers out of the matrix can increase the 7.5.5 Natural fibers—Natural fibers are renewable, having ductility and fracture energy by an order of magnitude. This a minimum amount of embodied energy, and instead of is particularly true if the fiber aspect ratio and other design releasing CO2 into the atmosphere, they can actually absorb or parameters are carefully selected to result in multiple cracks sequester carbon. Some of the materials that have been used forming along a single fiber and thereby provide strain as reinforcement of concrete are sisal, kenaf, hemp, coconut, hardening. In this case, the composite is referred to as high- jute, flax, sugar cane bagasse, and bamboo as individual performance fiber-reinforced cement compositeNaaman ( fibers, strips, and bars. All these natural materials are vulner- and Reinhardt 1996). able to chemical reactions with the alkaline cement matrix, In these materials, the primary function of the fibers is moisture, or both, deteriorating their material properties over to control cracking, and not to increase the compressive time. These fibers require protection against such reactions by or tensile strength of the composite. By keeping the cracks suitable treatments. ACI 544.1R contains a summary and an small, the permeability and, therefore, the durability of the extensive reference section on natural fibers. composite is greatly improved, which in turn increases its sustainability. Another way to increase the durability of the 7.6—Nonferrous reinforcement fiber composite is to combine two or more different types of 7.6.1 Carbon fiber reinforcement—A recent development fibers, each of which controls cracking of the cement matrix in nonferrous reinforcing is the development of carbon-fiber on a different length scale ACI( 544.1R). reinforcing. Made of thin fibers of carbon (0.005 to 0.010 mm Fiber dosages exceeding 1 percent by concrete volume are in diameter), carbon fiber has a very high tensile strength of likely to impair the workability of the mixture and potentially 250 ksi (1.75 GPa), or approximately four times the tensile increase fiber balling. To counteract these negative effects, the strength of conventional reinforcing bars. Previously, carbon fibers may be preplaced within the formwork, with cement fiber was used primarily in the aerospace and sports equip- slurry added afterward to infiltrate all void spaces. The result ment industries. Now it is manufactured in sheets or grids/ is the so-called slurry-infiltrated fiber concrete. mesh for the concrete industry. The grids or mesh are manu- 7.5.1 Steel fibers—Steel fibers are among the most widely factured by using epoxy to hold carbon fibers interlaced used short fibers. Steel fiber-reinforced concrete fails only together in two directions. Carbon fiber’s noncorrosive and after the fibers break or are pulled out from the cement matrix. nonconducting properties provide greater potential for more By changing their aspect ratio (that is, length-to-diameter sustainable concrete design and construction. Examples for ratio) or by changing their surface properties, it is possible to common uses are shown in 7.6.1.1 through 7.6.1.3. control the failure mode. Shorter fibers may be used and still 7.6.1.1 Precast insulated sandwich wall panels—Carbon delay fiber pullout by adding hooks at the fiber end, crimping fiber grid is cut into strips to tie an outer wythe of concrete to the fibers, or adding other deformations that increase the an inner wythe of concrete with a middle layer of insulation bond strength between the fibers and cement matrix.ACI 318 sandwiched between. Previous methods using steel trusses --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`--- allows the use of steel fibers for shear reinforcement. required more concrete cover to protect against corrosion 7.5.2 Synthetic fibers—There exist a multitude of and the steel trusses themselves are a source of thermal synthetic fibers, most of them of polymeric in nature. The bridging that reduces the overall insulating value of the most common materials are polypropylene, polyethylene, wall panel. Precast sandwich wall panels with carbon fiber polyvinyl alcohol (PVA), nylon, and polyester. Most of ties are being manufactured with thinner concrete sections

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that reduce materials, energy consumed, and energy associ- AASHTO M 240M/M 240:2018—Standard Specification ated with transportation by the corresponding reductions in for Blended Hydraulic Cement weight. Reduction in thermal bridging also results in higher AASHTO T 330-07(2015)—Standard Method of Test for thermal performance of the building envelope, which lowers The Qualitative Detection of Harmful Clays of the Smectite the HVAC energy used by the building. Group in Aggregates Using Methylene Blue 7.6.1.2 Precast double tees in parking structures—Some precast double-tee members commonly used in parking American Concrete Institute structures are now using carbon fiber mesh for the flange ACI 211.1-91—Standard Practice for Selecting Propor- deck reinforcement in place of traditional steel mesh. Carbon tions for Normal Weight Concrete fiber’s noncorrosive properties enable the double-tee flange ACI 212.3R-16—Report on Chemical Admixtures for to be thinner, thus saving concrete and lightening the overall Concrete structure, which may also reduce the size of the required ACI 213R-14—Guide for Structural Lightweight-Aggre- support and foundation. Reduced damage due to corrosion gate Concrete in a parking deck also means that the structure will be more ACI 232.1R-12—Report on the Use of Raw or Processed durable and have a longer life cycle. Natural Pozzolans in Concrete 7.6.1.3 Seismic retrofitting and repairs—Carbon fiber ACI 232.3R-14—Report on High-Volume Fly Ash sheets and wraps can be applied to existing concrete struc- Concrete for Structural Applications tures with epoxy. Glass fiber can also be used in this method. ACI 233R-17—Guide to the Use of Slag Cement in It is being used to strengthen existing concrete columns Concrete and Mortar to resist earthquake forces and for repair of deteriorating ACI 301-16—Specifications for Structural Concrete concrete structures. By repairing structures and extending ACI 318-14—Building Code Requirements for Structural their life, the improved life cycle of concrete greatly contrib- Concrete and Commentary utes to sustainability. ACI 440R-07—Report on Fiber-Reinforced Polymer (FRP) Reinforcement for Concrete Structures CHAPTER 8—CONCLUSION ACI 544.1R-96(09)—Report on Fiber Reinforced Concrete The initial selection of construction materials may depend ACI 234R-06(12)—Guide for the Use of Silica Fume in on numerous complex and often intangible factors, but the Concrete total initial and long-term cost of using any construction material is one of the most important parameters. Environ- ASTM International mental and economic evaluations are necessary components ASTM A615/A615M-18—Standard Specification for in identifying, assessing, and selecting building material. Deformed and Plain Carbon-Steel Bars for Concrete When used in combination with service life performance Reinforcement requirements, these factors provide a balance of economic, ASTM A706/A706M-16—Standard Specification for environmental, and societal impacts for material selection. Deformed and Plain Low-Alloy Steel Bars for Concrete Infrastructure and building systems represent an enor- Reinforcement mous investment of materials, energy, and capital, resulting ASTM A767/A767M-16—Standard Specification in significant environmental impacts and social costs. Devel- for Zinc-Coated (Galvanized) Steel Bars for Concrete opment of innovative materials, construction practices, and Reinforcement employment of appropriate inspection and maintenance strat- ASTM A775/A775M-17—Standard Specification for egies is critical to ensure reduced environmental impacts, Epoxy-Coated Steel Reinforcing Bars adequate safety, serviceability, and extended service life that ASTM A884/A884M—Standard Specification for Epoxy- minimizes the risk of failure for structures and infrastruc- Coated Steel Wire and Welded Wire Reinforcement ture. Design, construction, maintenance, climate adaptation, ASTM A934/A934M-16—Standard Specification for and resiliency are all considerations that contribute to the Epoxy-Coated Prefabricated Steel Reinforcing Bars overall sustainability of new assets. Hence, enhancing the ASTM A955/A955M-18—Standard Specification for resilience of infrastructure through designed robustness, Deformed and Plain Stainless Steel Bars for Concrete durability, longevity, disaster resistance, and safety should Reinforcement also be a priority for the designer and engineer. ASTM A966/A966M-15—Standard Practice for Magnetic Particle Examination of Steel Forgings Using Alternating CHAPTER 9—REFERENCES Current Committee documents are listed first by document number ASTM A1022/A1022M-16—Standard Specification for and year of publication followed by authored documents Deformed and Plain Stainless Steel Wire and Welded Wire listed alphabetically. for Concrete Reinforcement ASTM A1035/A1035M-16—Standard Specification for American Association of State Highway Transpiration Deformed and Plain, Low-Carbon, Chromium, Steel Bars Officials for Concrete Reinforcement AASHTO M 85:2018—Standard Specification for Port- ASTM A1055/A1055M-16—Standard Specification for

land Cement --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`---Zinc and Epoxy Dual-Coated Steel Reinforcing Bars

ASTM A1064/A1064M-17—Standard Specification for Canadian Standards Association Carbon-Steel Wire and Welded Wire Reinforcement, Plain CSA A23.1/A23.2:2014—Concrete Materials and and Deformed, for Concrete Methods of Concrete Construction/Test Methods and Stan- ASTM C31/C31M-18—Standard Practice for Making dard Practices for Concrete and Curing Concrete Test Specimens in the Field CAN/CSA-A3001-03—Cementitious Materials for Use ASTM C33/C33M-18—Standard Specification for in Concrete Concrete Aggregates CSA A3004-E1:2013—Alternative Supplementary ASTM C39/C39M-18—Standard Test Method for Cementing Materials Compressive Strength of Cylindrical Concrete Specimens ASTM C94/C94M-17a—Standard Specification for National Research Council Canada Ready-Mixed Concrete NBC 2015—National Building Code of Canada ASTM C114-18—Standard Test Methods for Chemical Analysis of Hydraulic Cement Authored documents ASTM C150/C150M-18—Standard Specification for Ajibola, O., 1994, “Effects of Recycled Scrap Tires and Portland Cement Asphalt Pavement on the Engineering Properties of Portland ASTM C260/C260M-10a(2016)—Standard Specification Cement Concrete,” MS Thesis, The University of Texas at for Air-Entraining Admixtures for Concrete Austin, Austin, TX. ASTM C403/C403M-16—Standard Test Method for Time Akçaözoğlu, S.; Atis, C. D.; and Akçaözoğlu, K., 2010, of Setting of Concrete Mixtures by Penetration Resistance “An Investigation on the use of Shredded Waste PET Bottles ASTM C494/C494M-17—Standard Specification for as Aggregate in Lightweight Concrete,” Waste Management Chemical Admixtures for Concrete (New York, N.Y.), V. 30, No. 2, pp. 285-290. doi: 10.1016/j. ASTM C595/C595M-18—Standard Specification for wasman.2009.09.033 Blended Hydraulic Cements Aldred, J. M., 1989, “The Short-Term and Long-Term ASTM C618-17—Standard Specification for Coal Fly Ash Performance of Concrete Incorporating Dampproofing and Raw or Calcined Natural Pozzolan for Use in Concrete Admixtures,” Supplementary Papers of 3rd CANMET/ACI ASTM C1157/C1157M-17—Standard Performance Spec- International Conference on Superplasticizers and Other ification for Hydraulic Cement Chemicals in Concrete, Oct. pp. 1-19. ASTM C1202-17—Standard Test Method for Electrical American Coal Ash Association, 2011, “Coal Combustion Indication of Concrete’s Ability to Resist Chloride Ion Product Production and Use Survey Report 2011,” ACAA, Penetration http://www.coalashfacts.org/ (accessed July 31, 2018) ASTM C1218/C1218M-17—Standard Test Method for Ashby, M. F., 2012, Materials and the Environment—Eco- Water-Soluble Chloride in Mortar and Concrete Informed Material Choice, second edition, Butterworth- ASTM C1240-15—Standard Specification for Silica Heinemann (Elsevier), MA, 616 pp. Fume Used in Cementitious Mixtures Atis, C. D.; Bilim, C.; Celik, O.; and Karahan, O., ASTM C1600/C1600M-17—Standard Specification for 2009, “Influence of Activator on the Strength and Drying Rapid Hardening Hydraulic Cement Shrinkage of Alkali-Activated Slag Mortar,” Construc- ASTM C1602/C1602M-12—Standard Specification for tion & Building Materials, V. 23, No. 1, pp. 548-555. doi: Mixing Water Used in the Production of Hydraulic Cement 10.1016/j.conbuildmat.2007.10.011 Concrete Australasian Slag Association Inc, 2002, “A Guide to the ASTM C1603-16—Standard Test Method for Measure- Use of Slag in Roads,” second edition, Wollongong NSW, ment of Solids in Water Australia, 35 pp.

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Report, pp. 59-70. Reactivity of Fly Ash by Chemical Activation,” Cement --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`---

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Copyright American Concrete Institute Provided by IHS Markit under license with ACI Licensee=http://www.GigaPaper.ir No reproduction or networking permitted without license from IHS Not for Resale, 04/01/2019 08:49:59 MDT As ACI begins its second century of advancing concrete knowledge, its original chartered purpose remains “to provide a comradeship in finding the best ways to do concrete work of all kinds and in spreading knowledge.” In keeping with this purpose, ACI supports the following activities:

· Technical committees that produce consensus reports, guides, specifications, and codes.

· Spring and fall conventions to facilitate the work of its committees.

· Educational seminars that disseminate reliable information on concrete.

· Certification programs for personnel employed within the concrete industry.

· Student programs such as scholarships, internships, and competitions.

· Sponsoring and co-sponsoring international conferences and symposia.

· Formal coordination with several international concrete related societies.

· Periodicals: the ACI Structural Journal, Materials Journal, and Concrete International.

Benefits of membership include a subscription to Concrete International and to an ACI Journal. ACI members receive discounts of up to 40% on all ACI products and services, including documents, seminars and convention registration fees.

As a member of ACI, you join thousands of practitioners and professionals worldwide who share a commitment to maintain the highest industry standards for concrete technology, construction, and practices. In addition, ACI chapters provide opportunities for interaction of professionals and practitioners at a local level to discuss and share concrete knowledge and fellowship.

American Concrete Institute 38800 Country Club Drive Farmington Hills, MI 48331 Phone: +1.248.848.3700 Fax: +1.248.848.3701 www.concrete.org --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`---

Copyright American Concrete Institute Provided by IHS Markit under license with ACI Licensee=http://www.GigaPaper.ir No reproduction or networking permitted without license from IHS Not for Resale, 04/01/2019 08:49:59 MDT 38800 Country Club Drive Farmington Hills, MI 48331 USA +1.248.848.3700 www.concrete.org

The American Concrete Institute (ACI) is a leading authority and resource worldwide for the development and distribution of consensus-based standards and technical resources, educational programs, and certifications for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.

Individuals interested in the activities of ACI are encouraged to explore the ACI website for membership opportunities, committee activities, and a wide variety of concrete resources. As a volunteer member-driven organization, ACI invites partnerships and welcomes all concrete professionals who wish to be part of a respected, connected, social group that provides an opportunity for professional growth, networking and enjoyment. --`,,`,`,,,,,````,``,,,,,,`,,,,-`-`,,`,,`,`,,`---

9 781641 950480 Copyright American Concrete Institute Provided by IHS Markit under license with ACI Licensee=http://www.GigaPaper.ir No reproduction or networking permitted without license from IHS Not for Resale, 04/01/2019 08:49:59 MDT