Clogging Evaluation of Permeable Bases

The clogging of the void spaces within the permeable base by foreign particles can severely reduce its drainage capacity. This will, in turn, reduce the service life of the permeable base layer within the pavement. In this paper, the reduction in the vertical permeability of several permeable base mixes as a result of clogging has been studied. The clogging materials used are mixtures of sand and residual soil. An empirical theoretical formulation has been derived from the Kozeny-Carmen equation in order to predict the reduction in permeability of the permeable bases. The equation has been expressed in terms of the initial vertical permeability of the permeable base specimen, porosity, amount of clogging material retained, and an experimental empirical coefficient. This coefficient is found to be dependent on the ratio of the D15 size of the permeable base to the d85 size of the clogging material and coefficient of uniformity, Cu, of the clogging material. The theoretical predictions have been compared with experimental results, with good agreement.