Laboratory Evaluation of Fatty Acid Amide Foaming Agent Foamed Asphalt Mixtures Containing Reclaimed Asphalt Pavement

Cold recycling technology for asphalt mixtures is an energy-efficient and environmentally friendly method, with foamed asphalt serving as a key material for enhancing performance. This study introduces foamed asphalt (BAF) obtained by adding fatty acid amide (FAA) foaming agent to base asphalt. The foaming characteristics of BAF were determined, and its adhesion and fatigue properties with aggregates were evaluated. A mix gradation with 60%–70% reclaimed asphalt pavement (RAP) admixture was designed. This study investigates the variations in the mechanical properties (tensile strength, compressive strength, and shear strength) of foamed asphalt cold recycled mixtures (FACRM) under different influencing factors. The results indicate that, compared to base asphalt, the adhesion performance of BAF with limestone improved by 21.4%, and the stripping time of RAP increased by 121.5%. Compared to conventional mixtures, the dry/wet splitting strength of the foamed asphalt mixture increased by 13.0% and 12.8%, while the tensile strength ratio (TSR) increased by 1.3%. The optimal values of foamed asphalt, water, curing temperature, and cement were 3%, 80%, 80°C, and 1.5%, respectively. The research findings contribute to the widespread application of foamed asphalt cold recycled mixtures, thereby improving resource utilization.