Revolutionizing Marshall Mix Design: Sustainable Integration of Recycled Aggregates Partially in Hot-Mix Asphalt Concrete

This study explores the use of recycled aggregates (RA) in Dense Bituminous Macadam (DBM) through the Marshall Mix method. Five mixes were evaluated: 100% natural aggregates (NA) and four blends with 25%, 50%, 75%, and 100% RA. Marshall Properties, stripping, drain down, & indirect tensile strength (ITS) tests were performed. The optimum binder content (OBC) ranged from 4.5% to 4.72%, meeting the MoRTH minimum of 4.5%. Air voids decreased with more RA but stayed within 3%–5%. VMA values were above 13%, and VFB ranged from 69.24% to 75%, meeting limits. All mixes exceeded 9 kN stability, with 50% RA showing the highest at 15.7 kN. Flow values (2.2–3.4 mm) were within the 2–4 mm range. ITS results showed maximum tensile strength ratio (TSR) of 96% at 50% RA. Stripping and drain down tests confirmed RA's suitability. The findings indicate that RA can be used in DBM mixes while meeting MoRTH standards.