Evaluating the use of recycled concrete aggregate and pozzolanic additives in fiber-reinforced pervious concrete with industrial and recycled fibers

The aim of this study is to investigate the effects of using recycled concrete aggregate (RCA) and pozzolanic materials as a partial replacement of natural coarse aggregate (NCA) and cement, respectively, on the mechanical and permeability properties of fiber-reinforced pervious concrete mixes. For this purpose, mixes were prepared with 25%, 50%, 75%, and 100% (by weight) RCA as coarse aggregate, and cement was partially replaced with 10% silica fume (SF) and 1%, 2%, and 3% nano-clay (NC). In order to enhance the mechanical strength of mixes, steel fiber (STF) and waste plastic fiber (WPF) were incorporated in the mixtures at a volume fraction of 1% and 2%. The experiments were carried out on a total number of 2310 samples casted from 110 mixes. Based on the test results, up to 25% increase in permeability and about 60% reduction in strength properties of mix incorporating 100% RCA were observed. The use of SF and NC led to enhancements in the strength properties because of micro-filling ability and pozzolanic reactivity. In general, the addition of fibers enhanced both compressive and flexural strengths up to 65% and 79%, respectively, over that of the unreinforced counterpart mix by incorporating 2% STF. WPF-reinforced mixes showed inferior performance compared to the STF-reinforced counterparts, due to the low quality and poor dispersion of WPF in mixes. It was found that, incorporating 100% RCA combined with 2% STF and 2% NC yields a pervious concrete suitable for structural applications.