Identification of parameter to assess cracking resistance of asphalt mixtures subjected to aging and moisture conditioning

This study comprehensively evaluated different parameters based on tensile strength testing to assess the cracking resistance of asphalt mixtures subjected to aging and moisture conditioning. For this purpose, two sources of aggregates were selected to produce hot and warm mix asphalt mixtures. Asphalt mixtures were subjected to short term and long term aging, three levels of moisture conditioning (freeze thaw cycles), and tested at two temperatures (15 ℃ and 25 ℃). The load-displacement data was used to determine the fracture work density, fracture energy, toughness index, cracking resistance index, cracking tolerance index, and rate dependent cracking index. It was noticed that moisture conditioning increased the variability of the different parameters. The cracking tolerance index and rate dependent cracking index parameter had a much higher coefficient of variation (CoV) with a maximum value close to 50%. Indirect tensile strength, fracture energy, and fracture work density appropriately captured the effect of moisture on cracking resistance of mixtures. The cracking resistance index, cracking tolerance index, and rate dependent cracking index increased with an increase in the moisture conditioning level. The Statistical analysis showed that tensile strength, fracture work density, and fracture energy were significantly influenced by different aging and moisture conditions evaluated. Fracture energy showed better association with fatigue life of asphalt mixtures subjected to three freeze-thaw cycles compared to tensile strength. Further, the fatigue life prediction models showed that both indirect tensile strength and fracture energy significantly influence the fatigue life of asphalt mixtures subjected to aging and moisture conditioning.