Effects of Recycled Concrete Aggregates on the Compressive and Shear Strength of High-Strength Self-Consolidating Concrete

The effectiveness of internal curing of high-strength self-consolidating concrete (SCC) using saturated recycled-concrete aggregates is examined in this study. Tests were performed on SCC using natural rock aggregate (NR-SCC) and recycled-concrete aggregate (RC-SCC). Fresh concrete tests included slump-flow, slump-flow with a J-ring, and L-box tests. All mixes tested were found to be highly flowable and stable. Strength tests included compression loading of cylinders and pushoff specimens. The RC-SCC was found to have superior compressive and frictional characteristics, indicating the beneficial effects of internal curing. However, the unconfined shear strength of NR-SCC was found to be superior to that of the RC-SCC. This was attributed to the fact that high-strength concretes fail in shear in planes that go through the aggregate rather than around it. The higher shear strength of the natural rock aggregate resulted in superior unconfined shear strength of the NR-SCC. However, the superior frictional characteristics of RC-SCC resulted in a reversal of this observation for the clamped (confined) specimens. DOI: 10.1061/(ASCE)MT.1943-5533.0000397. (C) 2012 American Society of Civil Engineers.