Durability behaviour of concrete incorporating reclaimed asphalt pavement as aggregates: a comprehensive review

Abstract

This study reviews the use of reclaimed asphalt pavement (RAP) in Portland cement concrete, with a focus on its durability. The review evaluates various studies on the durability of RAP-based concrete, analysing key parameters such as transport properties (water permeability, absorption and sorptivity), resistance to chemical attacks (chloride, sulphate, acid and carbon dioxide) and physical deterioration factors (abrasion, shrinkage and freeze-thaw cycles). Findings on transport properties are inconsistent. High drying temperatures in experimental protocols soften the bitumen coating on RAP, filling pores and improving transport properties. However, when lower drying temperatures are used, RAP generally has a negative impact on these properties. RAP also tends to reduce resistance to chloride and acid attacks, though incorporating supplementary cementitious materials or mechanically treating RAP aggregates can enhance performance. The impact of sulphate-rich environments remains unclear, while carbonation appears unaffected by RAP quantity or quality. Abrasion resistance and shrinkage vary based on the type and proportion of RAP used, with slag and fly ash helping to reduce shrinkage. Concrete incorporating RAP demonstrates good resistance to freeze-thaw cycles. The main challenge to durability behaviour is the weak bond between RAP and the cement matrix. Further research is needed to enhance concrete durability with higher RAP content and to clarify the distinct effects of sulphate and acid ion interactions. Additionally, exploring cement alternatives in RAP-based concrete formulations is recommended.