Evaluating the physicochemical properties of pervious recycled aggregate concrete incorporating pozzolanic additives under acid rain attack

The utilization of recycled concrete aggregate (RCA) from construction and demolition wastes to produce pervious concrete show various environmental benefits in the construction of sponge city. However, its durability performance in an acid rain attack environment has received less attention. This study aims to understand the deterioration of mechanical properties and microstructure of pervious recycled aggregate concrete (PRAC) exposed to simulated acid rain attack and drying-wetting cycles. The effects of the ground granulated blast-furnace slag (GGBS) replacement ratios, the silica fume (SF) replacement ratios and the erosion times on the mass loss, compressive strength, relative dynamic elastic modulus, permeability coefficient and porosity of PRAC were evaluated. The results demonstrated that the acid rain attack caused obvious mass loss and compressive strength reduction for PRAC without pozzolanic additives, thus resulted in increase on the permeability coeffi-cient and porosity. Moreover, the physicochemical properties of PRAC decreased strongly with the increase of acid rain exposure time. Nevertheless, the addition of 20%GGBF and 7%SF in PRAC showed better resistance to acid attack due to the synergistic effect. The microscopic characterization revealed that the added pozzolanic additives declined the content of calcium hydroxide of matrix in PRAC and thereby inhibited the formation of gypsum, which delayed the acid rain erosion process.