Determining Coefficients of Thermal Contraction and Expansion of Asphalt Concrete Using Horizontal Asphalt Strain Gage

Thermal strain occurs in asphalt pavement from thermal contraction and expansion due to temperature decrease and increase, respectively. No standard procedure to measure thermal strain is available. This study determines thermal strain per unit increase or decrease in temperature (also referred to as coefficient of thermal contraction or thermal expansion (CTC or CTE)) in an instrumented pavement section on Interstate 40 (I-40) in New Mexico. Firstly, the Horizontal Asphalt Strain Gages (HASGs) are calibrated for temperature to measure thermal strain. In the second step, the thermal strain variations in fall, winter, and summer are determined. For validation, the CTC and the CTE values are measured in the laboratory on three field collected cylindrical cored samples using Linear Variable Displacement Transducers (LVDTs) and temperature sensors. The LVDTs are also calibrated using a cylindrical zerodur block to account the temperature effect on it. Results show that field CTC and CTE values are close to the laboratory findings.