Balancing the Use of Wax-Based Warm Mix Additives for Improved Asphalt Compaction with Long-Term Pavement Performance

Abstract

Using wax-based warm mix additives allows contractors to lower production and compaction temperatures of asphalt, thereby reducing greenhouse and other harmful gas emissions in pavement construction. However, excessive wax can adversely affect the long-term durability of the pavement. In order to quantify solid wax, the effects of selected commercial additives on spectral and thermal properties of asphalt binder were studied by variable-temperature Fourier-transform infrared spectroscopy (VT-FTIR) and differential scanning calorimetry (DSC). The VT-FTIR reduced spectral area versus temperature plots for wax-doped asphalt binder were found to have three distinct parts from which solid wax contents could be determined. The wax precipitation temperature (WPT), obtained from DSC measurements of heat flow during cooling, was found to increase with additive content. In contrast, the wax melting out temperature (WMT), determined upon heating, appears to be independent of the additive content.