الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The amount of construction and demolition waste has increased considerably over the last few decades. from the viewpoint of environmental preservation and effective utilization of resources to produce coarse aggregate for the production of new concrete is one common mean for achieving a more environmental-friendly concrete.In this study figured out that research was conducted in two phases. In the first phase, the selection of the materials was carried out which consists of the physical and mechanical characteristics of these materials. Sixteen different types of concrete mixes were designed. Parameters studied in this research were recycled concrete aggregate (RCA) ratios (0%, 30%, 60% and 100%), and RCA grading four sizes of recycled concrete aggregate (9.5 mm, 12.5 mm, 19 mm and 25 mm). The mechanical properties of all mixes were evaluated based on compressive strength and workability results. Accordingly, six mixes have been chosen to be used in the next phase. In the second phase, the study of the structural behavior of the concrete was developed gradually. Sixteen beams were casted to investigate the effect of RCA ratios (0%, 30% and 60%), effect of RCA sizes (9.5 mm and 25 mm), and shear span to depth ratios three conditions of shear span to depth ratios (1.25, 2 and 2.5)] on the shear behavior, all those beams were designed to fail in shear. In addition, test results of concrete compressive strength indicated that replacement of natural aggregate by up to 60% recycled concrete aggregates in mixtures with 350 kg / m3 cement content led to decrease of concrete compressive strength. Moreover, the tensile strength of the specimens with RCA has different values from those with natural aggregates.The ultimate shear strength of beams with both sizes of recycled concrete aggregates (9.5 mm and 25 mm) is close to or more than those with natural aggregates indicating the possibility of using RCA to produce concrete. The ultimate shear strength of beams with RCA size 25 mm is higher than those with RCA size 9.5 mm; therefore, RCA size 25 mm is better than that RCA 9.5 mm to produce concrete. The validity of the ECP 203-2007, ACI 318-2011, BS 8110-1997 and NZS 3101:2006 Code were used as the procedures for estimating the shear strength for the tested RCA beams. It was found out that the standard codes Procedure led to very good estimation for shear strength.