INVESTIGATION ON THE ENGINEERING PROPERTIES OF BITUMINOUS PAVEMENTS INCORPORATING (SBR) LATEX

·                  The investigated coarse aggregate satisfied the reported quality criteria, with crushing value 18.43%, consolidated impact value 24.17%, Los Angeles abrasion value 24%, shape-test value 24.23% and specific gravity 2.93. ·                  The fine aggregate specific gravity was 2.74 and the stone-dust specific gravity was 2.62. ·                  The 80/100 penetration-grade bitumen showed penetration 95.66 (0.1 mm), softening point 48°C, ductility 67.5 cm and viscosity 3 s in the reported laboratory results. ·                  SBR latex contents of 0%, 3%, 5%, 7% and 9% by weight of bitumen were successfully incorporated into the investigated bituminous mixture. ·                  Marshall stability increased from 8.9 kN for the control to 15.7 kN at 5% SBR, corresponding to approximately 76.4% improvement relative to the control. Stability declined to 13.6 kN and 10.9 kN at 7% and 9%, respectively. ·                  Based on the numerical Marshall table, flow increased from 2.0 mm at 0% SBR to 3.0 mm at 5% and 4.0 mm at 9%. The 5% mixture remained within the reported MORTH comparison range. ·                  Air voids decreased from 4.80% to 3.43% at 5% SBR and then increased at higher dosages, indicating the most compact reported mixture at 5%. ·                  VMA decreased from 16.87% to 15.20% at 5% SBR and increased slightly at higher SBR contents. ·                  VFB increased from 70.3% to 77.5% at 5% SBR and subsequently decreased, indicating the most favorable binder-filling condition at the 5% dosage within the investigated range. ·                  Considering stability, flow and volumetric properties together, the attached project identifies 5% SBR latex by weight of bitumen as the optimum dosage for the investigated materials and mix proportions. ·                  The results support SBR latex as a promising elastomeric modifier for improving the Marshall performance of bituminous mixtures, but field-scale conclusions require additional durability, rheological, fatigue, rutting and ageing investigations.

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