Assessment of the hydraulic characteristics of unsaturated base-course materials:: a practical method for pavement engineers

This paper presents the results of a comprehensive laboratory investigation program on the influence of the properties of fines particles on the hydraulic characteristics of granular base-courses. The soil-water characteristic curve and the hydraulic conductivity were determined for three types of well-graded crushed aggregates (granite, limestone, and schist) with different amounts of fines (3.5-12.5%). A porosity model that considers the uniform dispersion of fines is proposed for well-graded material. Empirical relationships have been developed between the hydraulic parameters (i.e., the saturated hydraulic conductivity, the air entry value, the pore-size distribution index, the fines fraction porosity) and their specific surface area. A methodology is proposed for the assessment of the saturated and unsaturated hydraulic characteristics of base-course materials.