Enhancing both strength and permeability of pervious concrete by optimizing pore structure: An experimental study

Abstract

AbstractThe large porosity enables pervious concrete to obtain water permeability, but seriously decreases its strength. Hence, how to coordinate the contradiction between strength and permeability is a critical challenge for pervious concrete. This research was mainly aimed at mix design of pervious concrete for enhancing both strength and permeability by optimizing the pore structure. Six groups of pervious concrete with 15% target porosity were prepared by 10–15 mm coarse aggregate and different fine aggregate (natural sand, basalt aggregate, and steel slag). Moreover, a group of pervious concrete with 20% target porosity as control samples was prepared by 4.75–9.5 mm aggregate. The compressive strength and permeability coefficient of these samples were tested. Based on CT scanning and image analysis, the influence of pore structure optimization on permeability and compressive strength was analyzed. The results show that though the porosity is reduced by 5% after pore structure optimization, the porosity of large pores and medium pores changes little, the porosity of small pores decreased significantly, and finally the average pore size is still increased. This can explain why the experimental groups gain a similar/better permeability as the control group. The experimental groups of cement or steel slag have an increased compressive strength compared to the control group, which is due to the decrease of porosity and “small pores” content, as well as more abundant hydration products.