Assessment of Reclaimed Asphalt Pavement as Recycled Aggregates for Green Roads

The construction of road pavements requires large amount of aggregates, which contributes to the depletion of natural resources, greenhouse gas emissions, and high cost. The use of reclaimed asphalt pavement (RAP) contributes to achieving green roads by reducing aggregate exploitation, haulage, cost, emissions and dumping. However, the presence of aged binder in RAP had limited the incorporation of RAP to a small amount in asphalt pavement. In order to achieve sustainable high content utilization of RAP, this research provides an assessment of extracted RAP aggregates with an emphasis on characterization, strength, durability, and performance. RAP samples were found to contain 6.5% aged binder and 93.5% aggregates, which were separated using a centrifuge extraction process with 100% of aggregates recovered. The gradation of RAP aggregates was sufficient for asphalt production without outsourcing virgin aggregates to complement for meeting with standards. The bulk of extracted RAP aggregates showed good physical properties, gradation and hardened qualities from the obtained aggregate impact value of 17.4% and aggregate crushing value of 19.5%, making them an effective replacement for natural aggregates in asphalt. The asphalt mixtures demonstrated acceptable volumetric properties and performance with a peak stability of 31.91 KN at 5.3% optimum bitumen content. It was observed that extracted RAP aggregate contained absorbed bitumen that contributed to higher weight, higher specific gravity and lower water absorption, which could also reduce the consumption and demand of fresh bitumen in large road projects.