ABSTRACT
Frost action is one of the most important factors contributing to pavement damage. However, during winter, frost action induces an important increase in the bearing capacity of flexible pavements due to the viscoelastic response of asphalt concrete and to the freezing of pore water in granular materials and soils. Pavement strengthening with frost penetration has led some transportation agencies to allow winter weight premiums for the trucking industry. There is currently no rational decision criterion for the application of an axle load limit increase based on the mechanical behavior of frozen pavements. The objective of this project was thus to document the mechanical behavior of freezing pavements and develop a rational criterion for the onset of winter load premiums. The Laval University full-scale heavy vehicle simulator was used to monitor the response of two flexible pavements built in a 24 m3 indoor test pit over a silty sand and low plasticity clay sub grade soils, respectively. The pavements were instrumented to monitor temperature profiles, surface deflection, as well as stress, strain and moisture content in each layer. The simulator was used to apply the air freezing temperature (–10°C) and to periodically load the pavement surface using a standard dual-wheel set (half axle) varying in the range of 4500 to 6250 kg. The results collected allowed documenting how the response of different pavement structures changes with respect to frost penetration and temperature, and allowed quantifying the effect of the load magnitude on the change of the pavement response.
