Density and SCB measured fracture resistance of temperature segregated asphalt mixtures

Segregation is a serious challenge for high quality constructions of asphalt pavements. Temperature segregation (or temperature differential) in uncompacted asphalt mats has been identified with the use of infrared thermal cameras at the paving site. Four Louisiana asphalt rehabilitation projects were selected for investigating the effects of temperature segregation on the quality and performance of asphalt pavements. A multi-sensor infrared temperature scanning bar (IR-bar) system mounted behind the paver measured the real-time thermal profile. The quality of paving mats was measured by the density of field cores while the performance was measured by the mix’s intermediate temperature fracture resistance using the semi-circular bend (SCB) test. Results showed that temperature-segregated samples generally had lower densities than the control samples, although the differences were mostly statistically insignificant. On the other hand, temperature segregated samples generally had lower fracture resistance than the control samples measured by the SCB Jc values. Four out of six comparison cases showed the differences were statistically significant. Further verification effort was recommended for confident implementation of the IR thermal imaging technology to the asphalt pavement construction specification.