Performance Evaluation of High RAP Asphalt Mixture with Fiber and Warm Mixing Agent

Warm recycled asphalt mixture (WRAM) is a new type of bituminous material for green, environmentally friendly pavement construction. The WRAM technology combines the benefits of hot recycled and warm mix. It significantly reduces energy consumption and gas effusion due to lower mixing and compact temperature. However, related research indicated that low temperature and water stability of WRAM with high RAP content (more than 30% by weight) cannot meet the requirements of the specification. In this research, the fiber was applied to improve the performance of AC-20 WRAM with 40% and 50% RAP content. The composition design was carried out using the Marshall test. The optimum bitumen content is 4.9% and 5.1%, respectively. A series of laboratory tests — such as wheel tracking before and after conditioning and beam bending at low temperature — were carried out to evaluate the performance properties of AC-20 WRAM with reinforcing fiber. It was shown that this method can effectively improve the low temperature and water stability of asphalt concrete pavement. The properties of WRAM meet the requirements of the specification.