Recycled asphalt shingles (RAS) constitute a widely generated material with significant potential to reduce construction costs and contribute to environmentally friendly practices by diverting waste from landfills, thereby promoting greener construction. Many researchers have underscored the importance of considering both negative and positive impacts of incorporating RAS into pavement structures. This approach offers sustainability, cost-effectiveness, and effective dust and noise control, coupled with low maintenance requirements when utilized in the surface layer of the pavement, as compared to the underlying disadvantages, including potential separation of RAS and aggregates, reduced cohesiveness, lower stability, and adverse effects on the ground and wildlife. This study provides a comprehensive literature review of research on the utilization of RAS material in road construction, along with laboratory evaluations assessing the use of RAS as a substitute for a proportion of base course material. Recycled asphalt shingles (RAS) were sourced from the City of Lethbridge and processed into particles smaller than 19 mm. The granular base course material was replaced with 10%, 20%, and 30% RAS, and the particle size distribution of the materials was analyzed to assess compatibility with the City of Lethbridge base course material specifications. The literature review indicates that RAS utilization in road construction is a sustainable method for using waste material with some negative impacts on performance which could be decreased using selected additives like clay, fly ash, etc. The results indicate a decrease in optimum moisture content (OMC) and maximum dry density (MDD) of the mixture with increased RAS content. A reduction in the strength of the materials prepared for the base course with increasing RAS is observed, and 10% RAS is determined to be the optimum content to maintain the 80% and higher California Bearing Ratio (CBR) value.
Keywords: Recycled asphalt shingles (RAS), Granular Base Course, Sustainability, Grain size distribution, CBR
