Effect of aggregate gradation on low temperature performance of asphalt paving mixtures

Low temperature cracking has become one of the important factors that diminish asphalt pavement' s ride quality and service life.Especially in cold region, cracking caused by low temperature is the main distress form.This paper discussed the effect of aggregate gradation on the low temperature performance in asphalt paving mixtures.A total of 11 asphalt mixtures with 11 different aggregate gradations and one asphalt binder content were studied.Volumetric properties of the coarse aggregate and asphalt mixtures showed aggregate grading has a significant impact on the degree of aggregate interlock in asphalt mixtures.A trend is existed in the low temperature performance with the change of gradation.With the aid of mathematic statistics, it indicates gradation affects the low temperature performance significantly.The findings also indicate the relationship between the degree of aggregate interlock in asphalt mixtures and the low temperature performance: With the stone-tostone contact developed, the mixture has a high energy to resist contract and deformation at low temperature.The properties of fine aggregate and asphalt play an important part in resisting low temperature cracking in floating structure.But it provides lower energy to resist low temperature cracking compared to the skeleton structure.