Cracking in Asphalt Concrete under Wet and Dry Conditions

Abstract

This study evaluates cracking in asphalt concrete under wet and dry conditions. Three Superpave mixes are considered. Semi-circlular notched asphalt concrete specimens are fractured in the laboratory using a strain-based load in three point bending. Crack opening displacement (COD) data is captured in real-time along the length of the crack using linear variable displacement transducers (LVDTs). Three parameters derived from the laboratory data are used to characterize the mix cracking in terms of resistance to crack initiation and crack propagation in dry and wet conditioned samples. These parameters are namely ultimate load, slope of the crack propagation curve, and crack velocity. It is shown that wet samples can carry a higher ultimate load than the dry samples. Wet samples tend to show higher load decrease (higher slope) during crack propagation than the dry samples. Mix type has very little effects on the crack velocity, although wet samples have slower cracks than dry samples.