Effects of Mix Design Parameters on Indirect Tensile Strength and Field Cracking Performance of Asphalt Pavements

Abstract

Thermal cracking of asphalt concrete pavements is a severe problem in cold climate regions. Thermal cracking occurs due to asphalt pavements contracting when subjected to very cold temperatures. This cold environment also leads to the embrittlement of asphalt materials. This combination of thermal contraction and increased brittle behavior leads to formation of transverse cracks in the pavement surface. These cracks decrease the integrity of the pavement and reduce the ride quality thus increasing the maintenance and rehabilitation expenses. Presently, no laboratory performance test is required by the Minnesota Department of Transportation (MnDOT) asphalt material specification, as part of acceptance criteria. This significantly increases the risk for poor transverse cracking performance. The objective for this research study is to analyze the effects of mix design parameters on the indirect tensile strength and field cracking performance of asphalt pavements. A comprehensive database of existing mix design information, laboratory test results and pavement performance records was created to perform a statistical analysis. The data obtained from MnDOT was used to create the aforementioned database. The analysis was done to investigate if any mix design parameters (such as, asphalt film thickness, voids in mineral aggregate, asphalt binder grade) had a statistically significant effect on the field cracking performance. It also investigated the suitability of the indirect tensile strength from the modified Lottman test (AASHTO T 283) as a laboratory performance measure to predict pavement cracking.