A Review of Roadway Water Movement for Beneficial Use of Recycled Materials

Abstract

The purpose of this chapter is to provide a comprehensive review of water movement in roadways so that this knowledge may be used in environmental impact studies of traditional and recycled pavement materials. Long term leaching of contaminants is dictated in part by the hydrology of the roadway environment. To determine the hydraulic regimes in the field, ingress and egress routes and the hydraulic conductivity of the materials need to be known. This paper demonstrates that the major water ingress routes are along cracks, joints, and shoulders. It is shown that both saturated and unsaturated conditions in the field occur, suggesting that the contaminant leaching studies that consider saturated conditions only may overlook the effects of unsaturated conditions and the effects of wetting and drying. Furthermore, moisture content and unsaturated conditions have significant spatial and temporal variations in pavement systems. The hydraulic conductivity of pavement materials presented in the literature vary significantly due to various pavement designs, however, the hydraulic conductivity of pavement is less significant in influencing pavement system hydraulic regime than are cracks, joints, shoulders, and drainage systems.