Effect of Rice Husk Ash and Lime on Properties of Bitumen

This study investigates the effect of rice husk ash (RHA) and lime on the rheological propertiesof bitumen. Modifying bitumen with sustainable additives like RHA and lime can enhance itsperformance and durability. To assess the impact of these additives, experiments were carriedout on penetration, ductility, softening point, viscosity, and flash/fire point of bitumen modifiedwith RHA and lime at varying percentages (0%–20% at 2.5% intervals). The penetration testshowed a gradual reduction in penetration values, with RHA decreasing from 93 pen (0%) to70 pen (20%) and lime decreasing from 93 pen (0%) to 67 pen (20%), indicating increasedstiffness. The ductility test exhibited a slight improvement, with RHA increasing from 104 cm(0%) to 107 cm (20%) and lime increasing from 104 cm (0%) to 114 cm (20%), suggestingenhanced flexibility. The softening point test showed minor variations, with RHA decreasingfrom 43°C (0%) to 40°C (20%) and lime maintaining stability around 43°C–48°C. Viscosityvalues decreased for both additives, indicating a change in flow characteristics. The flash andfire point test revealed an increase in temperature for both RHA (264°C to 289°C) and lime(264°C to 274°C), implying improved thermal resistance. Overall, the results indicate that bothRHA and lime can enhance bitumen properties, with lime demonstrating better penetrationresistance and ductility, while RHA contributed to slight thermal improvements. These findingssuggest that RHA and lime are viable stabilizers for bitumen modification, promotingsustainability and improved pavement performance.