Method to investigate mix design parameters of pervious concrete mixtures

Abstract

Proportioning of the constituents of pervious concrete (PC) mixtures is an intricate task, as it is sensitive to the balance of two intrinsic properties: air voids content and compressive strength. The research presented in this paper proposes a novel volumetrics-based method for proportioning PC mixtures by evaluating the relationships between and the impact of the aggregates volume needed to form the skeleton of the mix, the mortar volume needed to coat those aggregates, and the bridge between them, in addition to the air voids content. The paper also examines the effect of mortar constituents, PC specimen diameter, and the characteristics of the mortar bridging the aggregates on the proportioning and mechanical properties of PC mixes. The study shows that the compressive strength of PC is mainly governed by the volume of mortar between the aggregates, in addition to the air voids content, and not by the mechanical properties of the mortar. The study also recommends that specimens with a diameter of 150 mm be used to measure the void content and compressive strength of PC. Finally, a mathematical model that relates the compressive strength of PC to its void content is proposed. The model can be used to predict the mean compressive strength of PC for air voids content ranging from 15% to 43%. © 2016, National Research Council. All rights reserved.