Numerical simulation of water flow through dense graded asphalt mixture.

The flow of rain or other water that accumulates on the surface of paving and then permeates through it is a very important factor in the failure of asphalt paving layers. Overtime, this accumulation can reduce the adhesion forces between the asphalt binder and the aggregate particles, which allows raindrops to reach the hydrophilic aggregate, thus potentially causing moisture damage. In this study, the water permeability coefficient was calculated and used for calibration of the extent of the ability of the asphalt pavement to manage runoff, with a local device manufactured for the purpose of performing this calculation under different laboratory conditions to assess the basic factors that affect the permeability coefficient. These included the gradation of the used aggregate within the limits of the surface asphalt layer within the Iraqi specifications and the ratio of accumulated air voids in the asphalt mixture, based on the process of compaction. The models were represented numerically using the finite element method within the ANSYS Fluent program for the purpose of studying the effect of these factors, with the density criterion adopted as an alternative to the ratio of spaces for the purposes of obtaining better representation of the model numerically. The resulting numerical representation of the apparent flow of water through the surface layer showed that the permeability coefficient decreases with increasing density and increasing irrigation loads. [ABSTRACT FROM AUTHOR]