Laboratory simulation tests of effect of mechanical damage on moisture damage evolution in hot-mix asphalt pavement

Abstract

Moisture damage of hot-mix asphalt (HMA) pavement is an extremely complicated mode of distress. Previous researches on moisture damage mainly focused on the performances of undamaged pavement at the initial stage of opening to traffic. So with the permeability tests and the Hamburg Wheel Tracking Device (HWTD) tests, trial works were done to study the effect of traffic-load-induced mechanical damage on the evolution of moisture damage in HMA pavement. The monotonous uniaxial compression loading method and the repetitive compression loading method were employed to make the mechanical damages of the styrene–butadiene–styrene block copolymer-modified HMA specimens, respectively. Comparisons demonstrated that there were slight differences between the damages from the two kinds of damage making methods. The damages were characterised with two kinds of nondestructive testing methods (dynamic modulus testing method and ultrasonic wave testing method), and the relationship of the characterised damages with the two methods was obtained. The permeability tests of HMA showed that the coefficient of permeability initially decreases and then increases with the damage. HWTD test results implied that the mechanical damage had a significant influence on the moisture damage, especially in hot and humid environment. In HWTD test, the mechanical damage induced by the undesirable stress state in pavement accelerates the appearance of the striping inflection point and increases the cumulative deformation of HMA specimen. Therefore, in order to reflect the performance of asphalt pavement during its life cycle, the effect of mechanical damage on the evolution of moisture damage should be considered in pavement design and construction.