ASTM D8303-20 PDF Download

ASTM D8303-20 is a standard test method used to determine the thermal cracking properties of asphalt mixtures by measuring thermally induced stress and strain. The test method involves cooling the asphalt mixture specimens at a constant rate from an initial equilibrium temperature and measuring the resulting stress and strain using a uniaxial thermal stress and strain tester (UTSST).

The standard provides procedures for preparing and testing asphalt mixtures to measure thermal stress and strain and calculate the coefficient of axial thermal contraction and the modulus of the asphalt mixture over a range of temperatures. These measurements allow for the determination of thermal viscoelastic and fracture properties of the asphalt mixtures.

The derived modulus, thermal viscoelastic, and fracture properties obtained from the test can be used to evaluate the low-temperature cracking resistance of the asphalt mixtures. The standard is applicable to both field-cored and laboratory-compacted specimens with a maximum aggregate size of 19 mm or less. It can be used for various types of asphalt mixtures, including conventional and nonconventional mixtures such as hot mixtures, mixtures with recycled materials, cold mixtures, warm mixtures, and neat or modified mixtures.

Additionally, the standard provides information on thermal stress buildup, thermal strain as a function of temperature, and other properties such as the UTSST cracking resistance index (CRI) and CRI adjusted for environmental conditions (CRI_Env). It is important to note that the quality of the results obtained from this standard depends on the competence of the personnel performing the procedure and the calibration and maintenance of the equipment used. Compliance with specified guidelines is necessary for reliable results.