Design and Evaluation of Heat-Resistant Asphalt Mixture for Permafrost Regions

Abstract

This study focused on the design of heat-resistant asphalt mixture for permafrost regions. Vermiculite powder with low thermal conductivity was used to replace some of the fine aggregates in the asphalt mixture to lower the thermal conductivity of asphalt mixture. Asphalt mixtures with different mass ratios (0, 3, 6, 9 and 12 %) of vermiculite powder were prepared for performance evaluation and thermal property evaluation. Wheel tracking test, low-temperature bending beam test, freeze–thaw splitting test and fatigue test were conducted to evaluate the influences of vermiculite powder on the high-temperature rutting resistance, low-temperature cracking resistance, moisture stability and anti-fatigue performance of asphalt mixture. Mathis TCI analyzer was used to analyze the influences of vermiculite powder on the thermal conductivity of asphalt mixture. Temperature monitor system was used to figure out the influences of vermiculite powder on the inside temperature of asphalt mixture. It is proved that vermiculite powder has no significant influences on the performances of asphalt mixture, while it obviously affects the thermal property of asphalt mixture. By the addition of 9–12 % vermiculite powder in asphalt mixture, the performances of asphalt mixture can still well meet the performance requirements for permafrost regions; the thermal conductivity can be reduced by 40–55 %; and the inside temperature of asphalt mixture can be lowered by 1–2 °C. It proves the feasibility of using vermiculite powder to produce heat-resistant asphalt mixture for permafrost regions.