Shear Capacity of Reinforced Concrete Beams Made with Recycled-Aggregate

The use of recycled-aggregate concrete is increasing faster than the development of appropriate design recommendations. This paper reports limited experimental data on the shear capacity of reinforced concrete beams recycled-aggregate. Twelve beams were tested to determine their diagonal cracking and ultimate shear capacities. The variables in the test program were shear-span/depth ratio a/d = 1.5, 2.0, 3.0 and 4.0; aggregate types; and shear reinforcement ratio = 0, 0.089, 0.244, 0.507, and 0.823 percent. Six of the test beams had no web reinforcement and the other six had web reinforcement along the entire length of the beam. Test results indicate that the ACI Building Code predictions of Eq. (11-3) and (11-5) for recycled aggregate concretes are unconservative for beams with a tensile steel ratio of 1.11% and a/d ratios greater than 3.0.