Strength and microstructural properties of pervious concrete made with different powder to aggregate ratios

Pervious concrete (PC) is a type of highly porous concrete with number of environmental benefits and predominantly accumulates stormwater runoff, recharges the ground water. The present study aimed at evaluating the strength and microstructural properties of PC made with variable p/a ratios and substitution of coarser fine aggregate (CFA) at 0%, 10% and 20%. A total number of nine PC mixes were cast with three p/a ratios of 0.25, 0.2 and 0.16. Four variable gradations of aggregates were used in three different proportions. Firstly, the influence of p/a ratio on different properties of PC are presented. Secondly, the study was extended to observe the microstructural analysis of PC in terms of scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX). A significant development of 17.1% in compressive strength was observed for mix made with p/a ratio of 0.25 at 20% substitution of CFA at 28 days. Subsequently, microstructural analysis of PC prepared with p/a ratio of 0.25 at 10%, and 20% substitution of CFA show higher concentration of C-S-H gel. Moreover, the microstructural observations of the PC immersed in the sulphuric acid solution shows the presence of loose C-S-H and C-H gel with lumps of gypsum.