Brick-concrete recycled aggregate/powder synergistic preparation of pervious concrete

Abstract

In order to improve the resource utilization rate of brick-concrete construction waste (BC-CW) and meet the demand of 'sponge city' construction for pervious concrete, a kind of brick-concrete recycled pervious concrete (BC-RPC) was prepared by brick-concrete recycled aggregate (BC-RA) / powder (BC-RP). The design was carried out from the two levels of cementitious material pastes and aggregate. Firstly, BC-RP was used as the main silicon-aluminum raw material to prepare a brick-concrete recycled powder based geopolymer (BC-RPG) for pervious concrete. It was determined that the content of BC-RP in BC-RPG was 50%, and the alkali content and modulus of the best alkali activator were 12% and 1.2, respectively. Then, the effect of BC-RA gradation and substitution rate on the mechanical properties of BC-RPC was studied by using BC-RPG as cementitious material and BC-RA as aggregate. The method of 'double grain composite substitution' was proposed to control the strength loss rate of BC-RPC. At the same time, the volume structure parameters (design porosity and pastes-aggregate ratio) of BC-RPC were optimized, and the optimum design porosity and pastes-aggregate ratio for BC-RPC preparation were determined to be 27% and 0.39, respectively. Finally, BC-RPC with coordinated mechanical and water permeability properties was prepared.