Sustainable Dense Bituminous Mixtures using Reclaimed Asphalt Pavement,Construction & Demolition Waste:Performance Comparison of VG-30 and CRMB-55 Binders

Abstract

The increasing consumption of natural aggregates and bituminous materials, together with the generation of reclaimed asphalt and construction and demolition waste, creates a need for sustainable pavement construction practices. This study experimentally investigates the combined utilization of Reclaimed Asphalt Pavement(RAP) and Processed Construction and Demolition(PCD) waste in Dense Bituminous Macadam DBM) mixtures using VG-30 and Crumb Rubber Modified Bitumen(CRMB-55) binders. The experimental programme included characterization of binders and recycled aggregates, Marshall mix design, determination of optimum RAP and PCD contents, and performance evaluation using Marshall Stability, Flow Value, Indirect Tensile Strength(ITS), Tensile Strength Ratio(TSR), and Retained Stability (RS). DBM Grade-II gradation was maintained for the investigated mixtures to permit comparison of recycled-material combinations and binder types. For VG-30, the Marshall Stability increased from 13.14 kN for the natural-aggregate control mixture to 19.88 kN at 30% RAP, which was selected as the optimum RAP level. Subsequent incorporation of PCD increased optimum binder demand because of the comparatively high absorption of the recycled demolition aggregate. The final sustainable VG-30 mixture containing 30% RAP and the investigated combination of PCD fractions achieved 14.75kN Marshall Stability, approximately 12.25% above the control mixture. Performance evaluation showed that the final VG-30 mixture satisfied the investigated ITS, RS and TSR requirements. In contrast, the corresponding CRMB-55 mixture containing 30% RAP and 33.5% PCD did not satisfy the minimum TSR requirement of 80%. RAP improved ITS and moisture resistance in the VG-30 system, while PCD generally reduced tensile and moisture-related performance. The results indicate that the engineering suitability of high-recycled-content mixtures depends on both recycled-material proportions and binder compatibility. Under the conditions investigated, VG-30 showed better overall compatibility with high RAP and PCD contents than CRMB-55.