High-Speed Photography of Asphalt Cracking

Cracking in asphalt occurs mainly due to repeated traffic loadings and temperature fluctuations. To prevent propagating cracks and to reduce unwanted rehabilitation and maintenance costs, understanding crack characteristics of an asphalt mix is of critical importance in many pavement designs. Using the indirect tensile splitting test, also known as the IDT method, this study aims to evaluate the crack propagation pattern in several asphalt mixes with the help of high-speed photography techniques. Crack initiation and crack pattern (i.e. development of tensile and/or shear cracks) were investigated and are reported in this paper. Unlike the Brazilian test for rock testing, results indicate that macro (visible) tensile cracks could appear at stress levels below the maximum peak stress in the stress-strain domain during an IDT asphalt test.