Experimental investigation on flexural behavior of hybrid fibers reinforced recycled brick aggregates concrete

This paper aims to investigate the flexural strength, deformation and toughness of steel-polyolefin hybrid fibers reinforced recycled brick aggregates concrete (HFRBAC) through the testing of the beam specimens with the size of 150 x 150 x 550 mm. The test parameters were water/cement ratios (0.28, 0.33, 0.38, 0.43), recycled brick coarse aggregates (RBA) replacement ratios (0%, 25%, 50%, 100%), fiber volume fractions (0%, 0.5%, 1%, 1.5%) and fiber types. The experimental results showed that steel-polyolefin hybrid fibers lead to significant improvement of the compressive strength and flexural behavior of HFRBAC, due to the synergistic interaction of fibers with RBA and natural coarse aggregates (NA). The average compressive strengths of HFRBAC with different testing parameter range from 34.69 MPa to 51.62 MPa. It was observed that the load-axial deformation curves of HFRBAC beams shows the similar tendency with the relevant load-deflection curves. The addition of steel-polyolefin hybrid fibers significantly enhances the post-cracking behavior of recycled brick aggregates concrete (RBAC), especially the flexural toughness at the first-peak point, L/600 point and L/150 point. Under the same fiber volume fraction, the effects of steel-polyolefin hybrid fibers on compressive strength and flexural behavior of HFRBAC are weaker than that of steel fiber, but better than that of polyolefin fiber. (C) 2019 Elsevier Ltd. All rights reserved.