Direct Measurement of Asphalt Binder Thermal Cracking

Abstract

A new simple test device is proposed to directly measure the critical temperatures for thermal cracking of asphalt binders. Using the dissimilar coefficients of thermal expansion for asphalt binders and common metals, the asphalt binder cracking device (ABCD) was developed to simulate thermal cracking of asphalt pavement in the laboratory. The ABCD consists of a metal ring, a strain gauge glued to the inner side of the ring, an environmental chamber, and a data acquisition system. Development of thermal stress within the asphalt binder during cooling is monitored by the strain gauge and the cracking temperature can be directly determined from the strain reading. A simplified theoretical analysis of the ABCD shows that the effects of thermal contraction of the asphalt binder and aggregate and the elastic properties of aggregates on thermal cracking could be reproduced in an ABCD test by adjusting the specimen and device geometries. Preliminary test data support the concept of the ABCD.