An innovative sustainable roller-compacted concrete using stabilized reclaimed asphalt aggregates: Mechanical and durability assessments

The increasing demand for sustainable construction materials has intensified interest in maximizing the utilization of Reclaimed Asphalt Pavement (RAP) within Roller-Compacted Concrete (RCC); however, conventional practices severely restrict RAP content due to the aged asphalt film's detrimental effects on interfacial bonding, workability, and overall mechanical durability. To address these inherent limitations, this study introduces a novel dual-action surface pre-treatment methodology that synergistically combines controlled mechanical abrasion with a targeted chemical conditioning protocol. The mechanical abrasion selectively removes the brittle, oxidized outer layer of the aged asphalt film, exposing a fresher bituminous surface and generating favorable micro-roughness, while the subsequent chemical conditioning actively functionalizes this new surface to promote robust adhesion with the fresh cementitious paste, thereby strengthening the critical interfacial transition zone. This stabilization strategy fundamentally permits the complete replacement (100%) of natural aggregates with treated RAP in RCC mixtures, effectively surpassing the strict replacement thresholds imposed by current standard specifications. Comprehensive experimental characterization reveals that mixtures incorporating stabilized RAP exhibit a remarkable 28% enhancement in 28-day compressive strength relative to untreated control specimens, alongside substantial gains in flexural capacity and splitting tensile strength, rendering them viable for demanding structural pavement applications. Furthermore, although an inherent increase in water permeability is observed, this adverse effect is considerably mitigated through the optimized treatment process; additionally, abrasion resistance, evaluated through mass loss metrics, reaches its optimum performance level at a 75% RAP replacement ratio. All treated RCC mixes successfully satisfy the requisite mechanical and durability benchmarks for standard heavy-duty pavements.