Modeling Moisture Damage in Saturated Semi-Rigid Pavements Using Pore Pressure and Strength Interaction

The degradation of semi-rigid asphalt pavements due to moisture remains one of the main durability concerns of these pavements; the situation is worsened when the soil is saturated, and the traffic is dynamic. The pore-water pressure is widely recognised as a significant parameter in dam engineering, but it cannot be used in pavement design because of difficulties in modelling and measurement. The current study presents a computationally effective finite-element model of moisture-damage susceptibility, which is done by correlating the response of pore-water pressure with the indirect tensile strength of bituminous mixtures. Based on generalised Biot consolidation theory, a two-dimensional fluid-solid coupled model is developed to model the evolution of pore-pressure in a representative semi-rigid pavement element. The investigation limits its design space to particular air-void configurations and loading frequencies of traffic relevant to highways with heavy traffic, unlike previous studies, which had a wide range of combinations of parameters. To assess the vulnerable pavement layers, a damage-susceptibility index is proposed; it is the ratio of maximum pore-water pressure to the indirect tensile strength of the bitumen mixture. The findings suggest that the risk of moisture damage is not determined by the air-void content alone but rather by the interaction of the air-void system with the transfer of the pore pressure to the cement-stabilized layers. The suggested framework is an efficient tool in terms of computation and suitable for use in the first stages of pavement evaluation and at the level of conference publication.