Flexural performance and evaluation method of steel fiber reinforced recycled coarse aggregate concrete

This paper presents the experimental results on the flexural performance of steel fiber reinforced recycled coarse aggregate concrete (SFRCAC). Test parameters include compressive strength (30 MPa, 45 MPa, 60 MPa), recycled coarse aggregate (RCA) replacement ratio (0, 30%, 50%, 100%), and steel fiber volume fraction (0, 0.5%, 1%, 1.5%, 2%). Evaluation method of flexural performance in ASTM C1609 and Chinese Standard JG/T 427-2015 was investigated with respect to the variance in test parameters. Test results showed that compressive strength has the similar influence on SFRCAC and normal concrete; with RCA replacement ratio increasing, the flexural performance of SFRCAC before crack is quite similar, flexural strength and flexural toughness increase slightly, deflection increases heavily; with the steel fiber volume fraction (Vf) increasing, the reinforcement effect is not obvious when Vf < 0.5%, improved significantly when Vf increases from 0.5% to 1%, growth trend becomes flatter when Vf is above 1%. The evaluation methods of flexural performance in ASTM C1609 and JG/T 427-2015 are not suitable for SFRCAC due to its deflection is much higher than normal concrete. A new set of evaluation indexes have been put forward and test results have demonstrated that this evaluation method is concise and effective.