Volume 8, Issue 9 (October 2011)
Moisture Susceptibility of Polymerized Stone Matrix Asphalt Mixtures using Warm Mix Asphalt Technologies using Moist Aggregates
The present study is focused on evaluating the moisture susceptibility of polymerized stone matrix asphalt (SMA) mixtures using moist aggregates and three different warm mix asphalt (WMA) additives. Indirect tensile strength (ITS), tensile strength ratio (TSR), deformation, and toughness were performed to determine the moisture sensitivity of these mixtures. The experimental design included two aggregate moisture contents (0% and ∼0.5% by weight of dry mass of the aggregate), three sources of aggregates (A, B, and C) and three WMA additives (Asphamin, Sasobit, and Evotherm) along with control mixture, and four different types of binders (i.e., PG 64-22 + 10% crumb rubber (−40 mesh CR), PG 64-22 + 15% CR, PG 64-22 + 20% CR, and PG 76-22 with fibers) were used in this study. In total, 384 samples were utilized for the ITS testing in this study. Test results indicated that even though by using 2% hydrated lime as an anti-stripping agent, 32% of the mixtures failed to meet the TSR requirement of 85% as per SCDOT specifications. Mixtures with PG 76-22 + fibers showed improved wet ITS values compared to rubberized SMA mixtures as using moist aggregates. No significant differences in the wet deformation values were observed for mixtures using WMA additives using moist aggregates. Mixtures with 15% CR content showed improved resistance to the percent toughness loss under a warm water bath treatment. Test results indicated that recycled rubberized asphalt binder can be effectively used to improve resistance to moisture-induced damage of SMA mixtures as using WMA technology.