Porous Concrete Pavements

Abstract

A study evaluating the mechanical and hydraulic properties of several porous concrete pavement mix designs is presented. Objectives of the study were to examine various mix designs with constituents available in Vermont, evaluate compressive strength and hydraulic conductivity of laboratory and field-cured specimens, compare results with those found in the literature, and characterize the effects of specimen size on measured parameters. To evaluate the role of sample size on these testing procedures, experiments were performed on specimens of three diameters: 76.2 mm (3 in.), 101.6 mm (4 in.), and 152.4 mm (6 in.). Multiple specimens were tested for a particular size. A specimen size of 101.6 mm (4 in.) was found to be optimal for the experiments performed and is therefore recommended. The measured compressive strength and hydraulic conductivity for the various mix designs showed a clear linear dependence on sample density. Also, the measured values fall within the expected range obtained from a review of the literature. Parametric studies included effects of the water-to-cement ratio and admixtures. Generally, increased water content yielded a higher density, higher compressive strength, and reduced hydraulic conductivity. Admixtures such as a high-range water reducer and viscosity modifying admixture had insignificant effects on the compressive strength, hydraulic conductivity, and workability of the porous concrete mixes examined. Field cores displayed a much greater variability in hydraulic conductivity than that of laboratory-prepared specimens, largely because of differences in compaction effort that are inherent to porous concrete placement in the field.