Comparative Study on Conventional Bitumen Mix and Gilsonite Modified Bitumen Mix

In a bituminous concrete mix, bitumen is used as an adhesive or binder to bind the aggregate ingredients of the mix. Bitumen has a significant effect on the performance of the asphalt mix, depending upon the quality and type of bitumen used. To improve the performance of bitumen and bituminous concrete mix, the use of modifiers is increasing worldwide. Different kinds of modifiers used to increase the performance of bitumen and its mix are ethylene vinyl acetate, styrene buta Diene, Bakelite and crumble rubber, etc. In this work, Gilsonite is used as a part of bitumen and a modifier to improve the performance of asphalt mix. The main aim of this work is to study the effect of Gilsonite on the various properties of a bituminous concrete mix and to compare the results with the conventional bituminous mix. Gilsonite contains a large number of polar compounds and resins, so it is easily compatible with bitumen and also helps in enhancing its performance. An experimental study is conducted to find the effect of Gilsonite on the various properties of the mix such as bulk specific gravity of mix (GM), air voids (VA), voids in mineral aggregates (VMA), voids filled by bitumen (VFB), Marshall stability value and flow value and compare them with the conventional properties of the mix by conducting volumetric analysis and marshall stability test. In the present study, the Gilsonite is doped in bitumen at the percentages of 2.5%, 5%, 7.5%, 10%, 12.5%, 15% and 17.5%. The results showed that the addition of Gilsonite as a modifier in bitumen results in an increase in softening point, a decrease in penetration increase in Marshall stability, and a decrease in flow value of bituminous concrete mix.