Determining the Sustainable Component of Wax-Based Warm Mix Additives for Improving the Cracking Resistance of Asphalt Binders

Abstract

The cracking resistance performance of an asphalt binder is a significant factor affecting the durability of asphalt pavements, and wax-based warm mix additives are devoted to improving the crack resistance of asphalt pavements. However, different components of wax-based warm mix additives (Fischer–Tropsch (F–T)-, fatty acid amide (FAA)-, polyethylene (PE)-, and linear aliphatic hydrocarbon (LAH)-based waxes) have different effects on the cracking resistance performance of the asphalt binder. Therefore, the optimum component of additives was determined by the combination of a microscopic method and a macroscopic test. The average carbon numbers of four additives were determined by a high-temperature gas chromatography (HTGC) test. The multiple stress creep recovery (MSCR), double-edge-notched tension (DENT), and extended bending beam rheological (ExBBR) tests were used to characterize the macroscopic performance of a modified asphalt binder. The F–T wax with long-chain molecules improved the high-temperature performance and lowered the degree of acceleration of thermoreversible aging. The FAA, PE, and LAH waxes with short-chain molecules enhanced the ductile fracture resistance performance. Therefore, the average carbon number as the optimum component of wax-based additives was recommended as C40 to C60.