Shear behaviour of RC beams made with natural, recycled aggregate concrete and reclaimed asphalt aggregates under normal and elevated temperature

This paper experimentally investigate the structural performance of RC beams made with natural aggregate (NA), recycled aggregate concrete (RAC) and reclaimed asphalt pavement concrete (RAP) under normal and elevated temperature. The NA was replaced by RAC at two replacement ratios (20% and 40%). Also there was three mixes of 90%RAC-10%RAP, 80%RAC-20%RAP, and 60%RAC-40%RAP. Twelve reinforced concrete beams with a cross-section 150 mm wide, 250 mm high, and a length of 1200 mm were casted and tested. All beams were constructed without stirrups. Six RC beams were tested after exposed 400 °C. Shear strength, ultimate load and mid span deflection were measured. The experimental shear strength was compared to the analytical shear strength calculated using ACI-318-14 and Eurocode-2 formulations. The results showed that temperature has an adverse effect on the shear strength, load capacity, elastic stiffness and deflection of RC beams. Specimens made with RAP and RAC combination exhibited a significant loss in their load carrying capacity under elevated temperature while temperature effect was relatively less remarkable in specimens made with RAC and NA. Increasing RAP percentage in the concrete mix increased the loading carrying capacity of specimens significantly while increasing RAC percentage resulted in a decrease of their load carrying capacity. ACI and EC2 were highly conservative in predicting the shear strength of recycled aggregate.