Numerical Simulation of Hygrothermomechanical Deformations of Bituminous Pavements in the City of Ouagadougou Subjected to Tropical Dry Showers

The waters of the torrential rains in the city of Ouagadougou lead to the appearance or amplification of damage to the surface of asphalt pavements during the rainy season. Road infrastructure maintenance campaigns follow one another almost every rainy season to fill potholes and cracks observed on the pavements. Several hypotheses can be put forward as to the origin of the action of water on the surface of pavements: the pressure of runoff water, infiltration, thermal expansion during the rainy episode, etc. These various reasons reveal the need to take rainwater into account when designing pavements. A previous study on the effect of heat waves on pavement design made some recommendations for better design. It has raised the interest to observe the impact of rain on pavement deformability.

The objective of this article is to estimate, as a first approach, the effect of tropical rains on the Thermomechanical behaviour of bituminous pavements formulated with pure grade 35/50 bitumen and grade 10/65 modified bitumen without trafic.

The properties of the road materials and the data from the statistical treatment of rainfall in the city of Ouagadougou were determined. The software based on the finite element method was used to model the phenomena coupling the meteorological conditions to the mechanical structure of the pavement for the quantification of hygrothermal and mechanical deformations.

The bituminous pavements studied were subjected to maximum rainfall intensities of 53.06 mm/h, and 99 mm/h with respective frequencies of occurrence of 2 years and 15 years.

The comparison of the temperature profiles at the surface of the studied pavements, allowed to highlight the viscous character of the asphalt subjected (35/50 bitumen and grade 10/65 modified bitumen) to the rains of maximum intensity of 99 mm/h. The maximum deformations simulated during these rains are about 1.2 times greater in the wearing course than in the base course, which does not disrupt the classical order of temperature evolution in the different pavement layers under dry tropical conditions. These deformations obtained also respect the admissibility criteria in terms of pavement design for T2 trafic (151 to 300 Heavy Truck/day). This study could be expanded to include the permeability of bituminous surfaces and runoff phenomena that could provide information on the origin of the observed deterioration.