Shear Behavior of High-Volume Fly Ash Concrete versus Conventional Concrete: Experimental Study Mahdi Arezoumandi, Ph.D., M.ASCE 1 ; Jeffery S. Volz, M.ASCE 2 ; Carlos A. Ortega, Ph.D., M.ASCE 3 ; and John J. Myers, Ph.D., P.E., F.ASCE 4 Abstract: The production of portland cement—the key ingredient in concrete—generates a significant amount of carbon dioxide. However, due to its incredible versatility, availability, and relatively low cost, concrete is the most consumed synthetic material on the planet. One method of reducing concrete’ s contribution to greenhouse-gas emissions is the use of fly ash to replace a significant amount of the cement. This paper compares two experimental studies that were conducted to investigate the shear strength of full-scale beams constructed with both high-volume fly ash concrete (HVFAC)—concrete with at least 50% of the cement replaced with fly ash—and conventional concrete (CC). The primary difference between the two studies involved the amount of cementitious material, with one mix having a relatively high-total cementitious content [502 kg=m 3 (850 lb=yd 3 )] and the other mix having a relatively low-total cementitious content [337 kg=m 3 (570 lb=yd 3 )]. Both HVFAC mixes used a 70% mass replacement of portland cement with Class C fly ash. Each of these experimental programs consisted of 16 beams—eight constructed from HVFAC and eight constructed from CC—with three different longitudinal reinforcement ratios. The beams were tested under a simply supported four-point-loading condition. The experimental shear strengths of the beams were compared with both the shear provisions of selected standards (United States, Australia, Canada, Europe, and Japan) and a shear database of CC specimens. This comparison indicates that the HVFAC beams possess superior shear strength compared with the CC beams. DOI: 10.1061/(ASCE)ST.1943-541X.0001003. © 2014 American Society of Civil Engineers. Author keywords: Reinforced concrete; Fly ash; Experimentation; Structural behavior; Shear strength; Concrete and masonry structures. Introduction Concrete is the most widely used synthetic material in the world, and cement is an essential ingredient in the production of portland cement concrete. The cement industry plays a key role in the world, from both an economic and an environmental perspective. In 2011, world cement output was estimated at 3.4 × 10 9 t(U.S. Geological Survey 2012). Cement production is also a relatively significant source of global carbon dioxide (CO 2 ) emissions, accounting for approximately 4.5% of global CO 2 emissions from the industry in 2007 (Marland et al. 2008). According to the World Business Council for Sustainable Development, emissions from cement manufacturing vary across worldwide regions from 0.73 to 0.99 kg (1.6 to 2.2 lb) of CO 2 for each kilogram (pound) of cement produced (Hanle et al. 2012). One of the solutions for this global concern is the use of supplementary cementitious materials as replacement of cement. The most available supplementary cementitious material world- wide is fly ash, a by-product of coal-burning thermal power stations (Bilodeau and Malhotra 2000). The ASTM C618 (ASTM 2012d) defines fly ash as “the finely divided residue that results from the combustion of ground or powdered coal and that is transported by flue gasses. ” According to the American Concrete Institute (ACI) 232.2R-03 standard, fly ash is categorized into the following three classes: class N, F, and C based on the chemical compositions (ACI Committee 232 2003). Fly ash has been used in the United States since 1930; Davis et al. (1937) were the first researchers to publish their results about using fly ash in concrete (ACI 232.2R-03; ACI Committee 232 2003). Initially, fly ash was used in massive structures like the Thames Barrage in the United Kingdom and the Upper Stillwater Dam in the United States, with about 30–75% mass replacement of hydraulic cement to reduce heat generation (ACI 232.2R-03; ACI Committee 232 2003). Subsequent research (Dunstan 1976, 1980, 1984) has shown several beneficial aspects of using fly ash in con- crete such as low permeability and high durability. Traditionally, fly ash used in structural concrete as a replace- ment or supplementary material has been limited to 15–25% ce- ment replacement (ACI Committee 211 1993; Berry et al. 1994), except in high-strength concrete where replacement levels of port- land cement at 35% are more common to control peak hydration temperature development (Myers and Carrasquillo 1999). When a significant amount of fly ash is used, how it contributes to the strength development of the concrete and the hydration character- istics of this type of material are of significant research interest. High-volume fly ash concrete (HVFAC) is a concrete generally 1 Ph.D. Candidate/Graduate Research Assistant, Dept. of Civil, Archi- tectural and Environmental Engineering, Missouri Univ. of Science and Technology, 302 Engineering Research Lab, 500 West 16th St., Rolla, MO 65409 (corresponding author). E-mail: ma526@mst.edu 2 Assistant Professor, Dept. of Civil, Architectural and Environmental Engineering, Missouri Univ. of Science and Technology, 331 Butler Carlton Hall, 1401 North Pine St., Rolla, MO 65409. E-mail: volzj@ mst.edu 3 Graduate Research Assistant, Dept. of Civil, Architectural and Environmental Engineering, Missouri Univ. of Science and Technology, 326 Butler Carlton Hall, 1401 North Pine St., Rolla, MO 65409. E-mail: caof34@mst.edu 4 Associate Professor, Dept. of Civil, Architectural and Environmental Engineering, Missouri Univ. of Science and Technology, 325 Butler Carlton Hall, 1401 North Pine St., Rolla, MO 65409. E-mail: jmyers@ mst.edu Note. This manuscript was submitted on August 9, 2012; approved on November 13, 2013; published online on April 9, 2014. Discussion period open until September 9, 2014; separate discussions must be submitted for individual papers. This paper is part of the Journal of Structural Engineer- ing, © ASCE, ISSN 0733-9445/B4014006(11)/$25.00. © ASCE B4014006-1 J. Struct. Eng. J. Struct. Eng. 2015.141. Downloaded from ascelibrary.org by LIBRARY PERIODICALS on 03/17/15. Copyright ASCE. For personal use only; all rights reserved.