New approach to proportion pervious concrete

The purpose of this study was to determine the effects of aggregate size and gradation as well as the paste volume on unit weight, compressive and tensile strength, porosity, and permeability of pervious concrete (PC). Three different coarse aggregate (CA) types with nominal maximum size of 2.5/10 mm (CA-10), 5/14 mm (CA-14), and 10/20 mm (CA-20) were used. Binary combinations of these aggregate were optimized to provide a wide range of uniformity coefficients (Uc) and packing density values. All PC mixtures were proportioned with a fixed water-to-cement ratio (w/c) of 0.30. For each aggregate gradation, the inter-particle void index was determined and used as a design parameter. Various PC mixtures were proportioned using different ratios of paste volume (PV) to inter-particle void (IPV). Test results indicated that the increase in PV/IPV ratio increased strength and density, but decreased porosity and permeability of PC. A PV/IPV ratio value comprises between 30% and 60% seems to be an optimum range to achieve good balance between mechanical properties and permeability of PC. In general, as the packing density of the aggregate increased, the strength increased, whereas the permeability decreased. Furthermore, test results showed the beneficial effect of fine particles on strength development of PC.