Laboratory Investigation of Moisture Damage in Warm-Mix Asphalt Containing Moist Aggregate

Abstract

In recent years, rising energy prices, global warming, and more stringent environmental regulations have generated interest in warm-mix asphalt (WMA) technologies as a means to decrease energy consumption and emissions associated with conventional hot-mix asphalt. In this study, a laboratory investigation was conducted of moisture damage in WMA mixtures containing moist aggregates. Indirect tensile strength (ITS), tensile strength ratio, deformation, and toughness tests were performed to determine the mixtures’ moisture susceptibilities. The experimental design included two percentages of moisture content (0% and ∼0.5% by weight of the dry mass of the aggregate), two WMA additives (Asphamin and Sasobit), and three aggregate sources. In this study 15 mix designs were performed, and 180 specimens were tested. Test results indicated that, as expected, dry ITS values were affected by aggregate moisture and hydrated lime contents, whereas a WMA additive did not significantly alter the dry ITS and toughness values. Statistical analysis showed no significant differences in the wet ITS values of WMA mixture of three types of mixtures (control, Asphamin, and Sasobit) under identical conditions (same moisture and lime contents). Statistical analysis also showed that wet ITS values, generally, were statistically different for mixtures made with various aggregate sources. The deformation resistance values of mixtures containing moisture were lower than those of mixtures made with dry aggregate. However, the results indicated that the addition of hydrated lime increased the deformation resistance of all mixtures.