Warm Mix Asphalt Performance Modeling Using the Mechanistic-Empirical Pavement Design Guide

Abstract

Warm mix asphalt (WMA) is a cost effective means for reducing the mixing and compaction temperature of hot mix asphalt (HMA). These additives, which come in several forms, reduce the mixing and compaction temperatures by approximately 30°C. The challenge for researchers has been determining how the additives impact or change traditional HMA mixes. The purpose of this research is to use collected laboratory data as inputs into the Mechanistic-Empirical Pavement Design Guide (MEPDG) to determine if there are statistically significant differences in the amount of pavement cracking when comparing HMA and WMA. The MEDPG is a model that has been developed into software for the purpose to provide state-of-the-practice pavement design for both new and rehabilitated pavement structures. The pavement design includes site condition parameters such as traffic, climate, subgrade, and existing pavement conditions in the case of rehabilitation. The MEPDG evaluates a proposed design for various distresses such as rutting, fatigue cracking, longitudinal cracking, transverse cracking, and roughness. Samples from field produced WMA mixes have been tested and material information has been collected and statistically analyzed over a period of several years. Data analysis showed some statistically significant differences in laboratory dynamic modulus (E*) data when comparing HMA control mix with the WMA mix. This study will use the laboratory measured E* as input into the MEPDG model to predict the pavement cracking in order to determine if there are differences in the pavement distresses. Within the design inputs, various factors can be manipulated such as various traffic loading and pavement thickness. Changing these inputs show which site condition variables have the most impact on pavement performance, how pavement distresses may differ when comparing HMA and WMA and how this translates to differences in pavement life.