New method of mixture proportioning is proposed for concrete made with coarse recycled concrete aggregates (RCA). The proposed method, dubbed the “equivalent mortar volume” method, is predicated on the fact that RCA is a two-phase material comprising mortar and natural aggregate; therefore, when proportioning a concrete mixture involving RCA, one must account for the quantity and quality of each phase and adjust both the coarse aggregate and fresh paste content of the mix accordingly to achieve the same total mortar volume as a companion mix with the same specified properties but made entirely with coarse natural aggregates of similar properties to the coarse natural aggregate contained in RCA. Using the proposed method and the conventional aggregate replacement method, a large number of mixes was made with RCA obtained from two demolition waste recycling plants. For each mix, its slump, fresh and hardened densities, compressive strength, and elastic moduli were measured. The results showed that using the...

Seven beams were tested in bending to determine the concrete contribution to their shear resistance. The beams had similar dimensions and concrete strength and were reinforced with carbon fiber reinforced polymer bars for flexure without transverse reinforcement. They were designed to fail in shear rather than flexure. The test variables were the shear span to depth ratio, varying from 1.82 to 4.5, and the flexural reinforcement ratio, varying from 1.1 to 3.88 times the balanced strain ratio. The test results are analyzed and compared with the corresponding predicted values using the American Concrete Institute, the Canadian Standard, and the Japan Society of Civil Engineers (JSCF) fiber reinforced polymer design recommendations. Based on these results and previous experimental data, it is shown that the ACI recommendations are extremely conservative whereas the Canadian and JSCE recommendations, albeit still conservative, are in closer agreement with the experimental data. Overall the Canadian Standard’s predictions are in better agreement with experimental data than the JSCE predictions.