Impact of Antistrip Additives on Pavement Performance Using Mechanistic-Empirical Pavement Design Guide

AbstractA comprehensive study was conducted to evaluate the impact of liquid and lime additives on the pavement performance of asphalt mixtures from five different sources around the United States. Three types of mixtures were evaluated from each source: untreated, liquid-treated, and lime-treated. The measured properties of the 15 mixtures included the dynamic modulus and their resistance to rutting and fatigue at the undamaged and moisture-damaged conditions. The measured performance properties of the mixtures were then used to conduct 20 years’ worth of structural designs for actual projects selected from the five sources of mixtures. For each project, a total of three structural designs were established using the Mechanistic-Empirical Pavement Design Guide by changing the type of mix used in the hot mix asphalt (HMA) layer. The percent cost savings or additional costs were estimated relative to the cost of the HMA pavement with the untreated HMA mixtures. Overall, the use of lime additives in HMA mixtures consistently resulted in significant savings that was sometimes as high as 45%. The use of liquid antistrip additives in HMA mixtures resulted in savings between 13 and 32%, or an additional cost, in some cases as high as 50%. The additional cost for the liquid-treated mixes was observed for mixtures that were not considered to be moisture sensitive, as measured by retained tensile strength ratio.