Pavement stabilisation of municipal wastes using foamed bitumen and supplementary binders

Foamed bitumen stabilisation (FBS) is widely used to enhance durability, moisture resistance, and road flexibility while reducing cracking. Addressing knowledge gaps in its application with recycled materials can expand their usage in road construction. This study focused on stabilising mixes of 50% recycled concrete aggregate (RCA) and 50% fine recycled glass (RG) using foamed bitumen (FB). Recycled toner aggregate (RTA) and geopolymers derived from ground granulated blast furnace slag (S) and fly ash (FA) were evaluated as potential alternatives to conventional secondary binders, such as Portland cement for FBS of recycled material blends. To assess the performance of RTA, a fixed 3% FB dosage was combined with varying RTA amounts (1%–4%). Geopolymers including FA, S, and (FA + S) at dosages of 10%, 20%, and 30% by mass of RCA and RG blend were tested alongside 3% FB for their stabilising effectiveness. FB-stabilised samples with RTA initially failed the indirect tensile modulus tests, but their performance improved significantly after extended curing. The blend incorporating geopolymers, RCA + RG + 3% FB + 20% (FA + S), met local road authority standards. These results demonstrate the potential of sustainable secondary binders for the stabilisation of RCA and RG mixtures in road construction.