Laboratory Investigation of Incorporating Vermiculite Powder into SMA towards Low Thermal Conductivity

This paper focused on the design and evaluation of an asphalt mixture with low thermal conductivity. Based on a designed SMA13 asphalt mixture, vermiculite powder was used to replace part of the fine aggregates to get an asphalt mixture with lower thermal conductivity. The Marshall test, wheel tracking test, low temperature bending beam test, and freeze-thaw splitting test were conducted to obtain a full evaluation of asphalt mixtures with different contents of vermiculite powder. A Mathis TCI thermal analyzer was used to test the thermal conductivity of asphalt mixtures, and the T-monitor temperature measuring system was used to compare the inside temperature of asphalt mixtures with and without vermiculite powder. It was found that with 10% vermiculite powder in the asphalt mixture, all of the road performances were satisfied, while thermal conductivity was lowered by 40%, and the inside temperature of the asphalt mixture was lowered by up to 2℃. The findings in this paper proved the feasibility of using vermiculite powder to reduce the thermal conductivity of asphalt mixtures.