Linearized Approach for Predicting Thermal Stresses in Asphalt Pavements due to Environmental Conditions

Abstract

Temperature fluctuations in asphalt pavements significantly affect pavement stability and the selection of asphalt grading. Ability to accurately predict asphalt pavement temperatures at different depths and horizontal locations based on environmental conditions will greatly help pavement engineers, not only in the selection of the asphalt grade to be used in various pavement lifts, but also in the accurate assessment of thermal stresses in and between various asphalt lifts. This is especially critical when the asphalt pavement is exposed to extreme freeze and thaw conditions. In this paper, a simulation model is proposed that uses a transient, two-dimensional finite difference approach to calculate the temperature distribution in asphalt pavements in response to hourly thermal environmental conditions and to calculate associated thermal stresses. Previous attempts to determine thermal stresses in asphalt sections range from correlations of observed cracking to ambient environmental conditions, to detailed numerical solutions of stress equations. The difficulty lies in adequately describing rheological properties of asphalt as a function of temperature. This paper uses the stiffness index to estimate the thermal stress distribution in asphalt pavements, and preliminary thermal stress maps during seasonal and diurnal freeze/thaw cycles are presented. Simulation results show that the greatest thermal stresses are observed in cases where pavement lifts have dissimilar thermal properties.