Roles of mortar volume in porosity, permeability and strength of pervious concrete

Abstract

Pervious concrete is designed to be porous to allow permeation of water and air for combating the environmental and drainage problems arising from urbanization. However, despite extensive research, it is still not clear how best to design pervious concrete mixes to achieve good concurrent permeability-strength performance. In a previous study, the authors found that there is a necessity to distinguish between interconnected porosity and open porosity, and between unsubmerged permeability and submerged permeability. In this study, based on the thinking that fine aggregate may be added to reduce the paste volume provided the fine aggregate is fine enough to form a coherent mass with the paste, further research was conducted to develop the mortar type pervious concrete with reduced paste volume and investigate the roles of the mortar volume in porosity, permeability and strength. A new series of concrete mixes with varying mortar volume were tested and the results revealed that the interconnected porosity is the major factor determining the permeability while the open porosity and water/cement ratio are the major factors determining the strength. More importantly, the mortar volume plays a key role in each performance attribute.