IMPACT OF ANTI-STRIP ADDITIVES ON LONG-TERM AGING PROPERTIES OF ASPHALT MIXTURES
AdvisorHajj, Elie Y
Civil and Environmental Engineering
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The objective of this study was to evaluate the impact of lime and liquid anti-strip additives on the long-term aging properties of asphalt binders and mixtures sampled from five different U.S. locations. The HMA mixtures were evaluated in terms of their resistance to fatigue cracking and thermal cracking. The asphalt binders were evaluated for intermediate and low temperature rheological properties at different aging stages.Aggregate and asphalt binders were collected from five different sources: Alabama, California, Illinois, South Carolina, and Texas. Each source was evaluated with three different mixtures; un-treated, liquid-treated, and lime-treated. Lime was obtained from the National Lime Association (NLA) and the liquid anti-strips were obtained from relevant states. Mix design were conducted according to Superpave mix design method with a minimum dry tensile strength (TS) at 70°F of 70 psi and a tensile strength ratio (TSR) of 80%. All fifteen mixtures were evaluated for fatigue resistance using the flexural beam fatigue test in a strain control mode of testing and for thermal cracking using the Thermal Stress Restrained Specimen Test (TSRST). Additionally, three different asphalt binders were prepared and evaluated for each source; un-treated, blended with liquid anti-strips, and blended with lime. All asphalt binders were long-term aged for 100, 400, and 800 hr at 140°F with 2.1 kPa confining pressure. The asphalt mixtures' Rheological properties were determined and compared after aging.