Optimization of Recycled Asphalt Aggregate Treatment for High-Strength Prepacked Concrete: Influence of Immersion Duration and Replacement Ratio

Abstract

This study systematically investigates the use of gasoline-treated recycled asphalt aggregates in high-strength prepacked concrete, focusing on the combined effect of the aggregate replacement ratio and solvent immersion duration. Asphalt aggregates were immersed in gasoline for 2, 4, and 8 h and used to replace natural coarse aggregate at 25-100%. The compressive strength was evaluated at 7 and 28 days, whereas the tensile strength was assessed at 28 days. The results revealed that the mechanical performance was governed not only by the asphalt content but also by the duration of gasoline immersion, which has rarely been quantified in pre-packed concrete systems. While increasing asphalt content led to progressive strength reductions, the prepacked technique significantly mitigated strength loss at later ages, reducing the 28-day compressive strength reductions to approximately 10-24% at 25-50% replacement. In contrast, prolonged immersion caused additional deterioration, with tensile strength losses exceeding 30% at high replacement levels. Among all the conditions, 2 h of gasoline immersion consistently provided optimum performance, achieving effective contaminant removal while preserving aggregate integrity. The novelty of this study lies in identifying an optimum solvent treatment window for recycled asphalt aggregates within a high-strength prepacked concrete framework, demonstrating that excessive treatment is detrimental and that controlled immersion enables the sustainable use of asphalt aggregates without severe mechanical penalties.