Evaluation of moisture damage mechanisms and effects of hydrated lime in asphalt mixtures through measurements of mixture component properties and performance testing

This study presents an approach to help understand moisture damage mechanisms and to evaluate the effects of hydrated lime as moisture damage resisting agents. To this end, various performance testing of hot mix asphalt (HMA) samples induced by moisture damage and several fundamental property measurements (stiffness, strength, toughness, and bonding energy) of mixture components were conducted. Testing data and analyses demonstrated that hydrated lime contributed to moisture damage resistance due to synergistic effects of mastic stiffening, toughening, and advanced bonding characteristics at mastic-aggregate interfaces. However, a well-controlled lime treatment is required to maximize distribution and dispersion of lime particles on aggregate surfaces. In addition to the clear effects of hydrated lime, mineral filler in the HMA samples showed its effects on damage resistance in an early stage of moisture damage due to substantial stiffening-toughening effects from filler addition. Properties and damage characteristics of mixture components measured in this study were related to macroscopic performance behavior of asphalt concrete samples, which infers that the approach herein based on the mixture components can be effectively used to evaluate (or predict) moisture damage of asphalt mixtures and pavements with much less effort.