Development of Aggregate Skeleton–Cementitious Paste-Coating Pervious Concrete

Abstract

To avoid cumbersome casting procedures in the production of pervious concrete, a new type of casting method through coating cementitious paste onto the preplaced aggregate skeleton is developed. To optimize the key performances and reveal their governing mechanism, aggregate skeleton–cementitious paste-coating pervious concrete (ACPC) mixes with different porosity, water/cement (w/c) ratio and sand ratio were produced and had their permeability and strength tested. This study demonstrated that it is successful to produce pervious concrete by the novel casting method. Vibration of aggregate skeleton and high w/c ratio should not be adopted to avoid the formation of a layer of hardened paste at the bottom of the mix to block the vertical passage of water. In contrast to conventional concrete, a higher w/c ratio (from 0.23 to 0.34) generally resulted in a higher strength (from 3.77 to 8.71 MPa) of ACPC. A small amount of sand increased both the permeability and strength through the balling bearing effect and filling effect, respectively. Both the optimum sand ratio to achieve the highest vertical permeability and strength were found to be 0.05, which offered this porous structure concurrently satisfactory permeability (permeability coefficient higher than grade K2) and acceptable strength (compressive strength higher than 5 MPa). Key influencing factors of permeability and strength of ACPC were analyzed. This study can advance the technology of casting concrete and the production of pervious concrete as road pavement in the construction of “sponge city”.