Asphalt Concrete Damage Associated with Extreme Low Temperatures

Current distress analysis practices and material specifications associated with low temperatures, including recent developments by the Strategic Highway Research Program, do not address the potential for localized damage associated with thermal incompatibility of asphalt concrete components. The analytical approach used to explain transverse surface cracking assumes a homogeneous pavement material. Although this approach produced satisfactory results for the prediction of low temperature cracking, it may obscure other forms of damage related to exposure to extreme low temperatures. This paper discusses localized forms of damage related to the vast difference in the coefficients of thermal contraction of asphalt concrete components (binders and mineral aggregates). Microscopic examination of asphalt concrete samples exposed to low temperatures revealed the presence of hairline cracks within the asphalt matrix. The examination also revealed deterioration of the bond at the aggregate/binder interface. The observed damage patterns explain the results of mechanical testing conducted using indirect tensile strength and three point bending procedure. Analysis demonstrates the potential impact of the observed forms of damage on pavement performance. It also explains results published by other researchers.