Shear performance of reinforced concrete beams incorporating recycled concrete aggregate and high-volume ﬂy ash Seyedhamed Sadati a, * , Mahdi Arezoumandi b , Kamal H. Khayat c , Jeffery S. Volz d a Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, 204 Engineering Research Laboratory, 500 W. 16th Street, Rolla, MO 65409, USA b Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, 212 Butler Carlton Hall,1401 N. Pine Street, Rolla, MO 65409, USA c Department of Civil, Architectural and Environmental Engineering, Missouri University of Science and Technology, 224 Engineering Research Laboratory, 500 W. 16th St., Rolla, MO 65409-0710, USA d School of Civil Engineering and Environmental Science, University of Oklahoma, 423 Carson Engineering Center, 202 W. Boyd St., Norman, OK 73019-1024, USA article info Article history: Received 24 September 2015 Received in revised form 8 December 2015 Accepted 11 December 2015 Available online 20 December 2015 Keywords: High-volume ﬂy ash Recycled concrete aggregate Reinforced concrete Shear strength Structural behavior Sustainable concrete abstract The study reported in this paper investigates the shear capacity of full-scale reinforced concrete beams fabricated with high volume ﬂy ash and coarse recycled concrete aggregate (RCA). The study involved testing 24 full-scale beams. The beams were fabricated with three different longitudinal reinforcement ratios of 1.27%, 2.03%, and 2.71%. Four concrete mixtures were employed for casting the beams: con- ventional concrete (CC) without any ﬂy ash or RCA as the reference; ﬂy ash concrete with 50% of Class C ﬂy ash replacement (FA50 beams); RCA concrete with 50% coarse RCA replacement (RCA50 beams); and sustainable concrete (SC) proportioned with 50% Class C ﬂy ash and 50% RCA. In order to evaluate the performance of concrete in shear, the beams were cast without any stirrups in the shear zone. The test results were compared with theoretical models provided by different design codes as well as a shear data base for CC. The experimental results were also compared to analytical approaches based on fracture mechanics as well as the modiﬁed compression ﬁeld theory method. On the average, the SC beams had a 10% lower shear capacity than the CC beams. The average shear capacity of the SC beams was 18% and 16% lower than those of the FA50 and RCA50 beams, respectively. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Concrete is the most widely used construction material. Efforts aimed at producing environmentally friendly concrete can play a major role in securing environmentally friendly construction. Candidate technologies for sustainable concrete materials include the incorporation of supplementary cementitious materials (SCMs), such as ﬂy ash as a partial replacement for portland cement, the incorporation of recycled materials in concrete production, and, in particular, recycled concrete aggregate (RCA), as well as the use of highly durable concrete to increase service life. Portland cement production accounts for a signiﬁcant portion of the total greenhouse gas emission. The production of Portland cement is responsible for about 7% of total worldwide CO 2 emissions (Nuaklong et al., 2015). Therefore, replacing portland cement with an alternative cementitious material and/or industrial by-products can decrease the carbon footprint of the concrete. Over 900 million tons of construction and demolition waste is produced annually in Europe, the U.S., and Japan (WBCSD, 2012). Although the use of RCA does not signiﬁcantly reduce CO 2 emis- sions, it can signiﬁcantly contribute to reducing the depletion of natural resources (virgin aggregate) and decreasing the need for landﬁlls. When using a high volume of RCA and SCMs, it is necessary to understand the structural performance of this new class of concrete materials. Limited studies regarding the structural performance of high-volume ﬂy ash concrete (HVFAC) are available. Arezoumandi et al. (2013) replaced 70% of cement with Class C ﬂy ash in full- scale beams with longitudinal reinforcement ratios of 1.27%, 2.03%, and 2.71%. The concrete had compressive strengths at 28 days of 31 MPa. Results of the studies showed that the HVFAC beams can develop a shear strength that is around 12% higher than the reference beam made without any ﬂy ash, which had a 28-day * Corresponding author. E-mail addresses: sscn3@mst.edu (S. Sadati), ma526@mst.edu (M. Arezoumandi), khayatk@mst.edu (K.H. Khayat), volz@ou.edu (J.S. Volz). Contents lists available at ScienceDirect Journal of Cleaner Production journal homepage: www.elsevier.com/locate/jclepro http://dx.doi.org/10.1016/j.jclepro.2015.12.017 0959-6526/© 2015 Elsevier Ltd. All rights reserved. Journal of Cleaner Production 115 (2016) 284e293