Performance of Hot Mix Asphalt Mixtures Made of Recycled Aggregates

The generation of construction, renovation, and demolition waste in large quantities poses a major challenge for town planners. Recycling can provide an effective solution to this problem, in addition to reducing the rapid depletion of natural resources. This article examines the results of experimental studies that have been conducted to investigate the use of recycled aggregates (RAs) in mixtures of hot mix asphalt. Sources of RA consisted of waste concrete and reclaimed asphalt pavement. Three levels of RA addition with natural crushed stone aggregates (CSAs) and three types of mixtures were considered. The mixtures made with CSA were used as control samples. Marshall mix samples of asphalt-aggregate mixtures were prepared and tested in a Marshall testing machine. The air voids and stability/flow characteristics of these mixtures were investigated. The optimum asphalt contents (OACs) of mixtures were determined using air void data. The performance of the employed mixtures was compared with the criteria established by the National Highway Authority (NHA) for wearing course material in Pakistan. Rutting samples of mixtures similar to those used in the Marshall stability tests were prepared using the OAC data for bituminous binder. These samples were tested in a wheel tracking device. All three types of mixtures used in the studies conformed to the specification requirements for wearing course material given by the NHA. The rutting behaviors of the majority of the mixtures were also satisfactory.