Effect of additives and aging on moisture-induced damage potential of asphalt mixes using surface free energy and laboratory-based performance tests

ABSTRACT

Lack of mechanistic foundation and poor correlations with field performance of conventional laboratory-based tests has accelerated the search for a mechanistic-based approach for screening of asphalt mixes for moisture-induced damages. According to recent studies, surface free energy (SFE) method can be used to mechanistically quantify bond strength and debonding of binder-aggregate system in presence of water. This study was undertaken to evaluate the effects of different additives, namely warm mix asphalt (WMA) additive (amine-derived), amine-based anti-stripping agent (ASA), polyphosphoric acid (PPA) and reclaimed asphalt pavement (RAP) on the moisture-induced damage performance of asphalt mixes through the use of laboratory-based performance tests and SFE method. For this purpose, different energy parameters were determined from SFE components of binder blends and aggregate. Asphalt mixes with different additives were produced to evaluate moisture-induced damage using indirect tensile strength (ITS) and Illinois semi-circular bend (IL-SCB) tests. A new parameter, known as fracture energy ratio (G_f ratio) obtained from IL-SCB test, was used to correlate fracture energy with moisture-induced damage potential of mixes. Also, the effect of short-term and long-term aging on the moisture-induced performance of asphalt mixes were evaluated. Furthermore, correlations between moisture-induced damage parameters from laboratory-based performance tests and SFE method were investigated.

KEYWORDS:

• Moisture-induced damage
• surface free energy
• fracture energy ratio
• tensile strength ratio (TSR)
• semi-circular bend test

Acknowledgement

The authors gratefully acknowledge the financial support provided by Oklahoma Department of Transportation (ODOT) and the Southern Plains Transportation Center (SPTC) to conduct this study. The authors are also thankful to binder suppliers, Silver Star Construction Co., Ingevity, ArrMaz and Valero refinery (Ardmore, Oklahoma) for their support. The assistance and support provided by the members of the OU Asphalt Group are gratefully acknowledged and appreciated.

Disclosure statement

No potential conflict of interest was reported by the author(s).