Production of modified bitumen from used engine oil, coal tar and waste tyre for construction applications

Abstract

Bitumen plays an important role especially in the community in terms of infrastructure where its properties are utilized. It is a semi-solid hydrocarbon product which is produced by removing the lighter fractions such as liquid petroleum gas from heavy crude oil during the refinery processes of crude oil. It consists of a mixture of organic liquids and it has a black colour, high viscosity and it is a sticky material. The most common method for its manufacture is fractional distillation of atmospheric residue from vacuum distillation where waxy distillates are used. To reduce the expenses for its production from crude petroleum, used engine oil, coal tar and used tyres from automobiles can be used in their correct ratio to produce bitumen. The process involves heating and mixing using a high-speed shear mixer. The oil is a medium to heat and melt the crumb rubber so that it will begin to degrade (depolymerize). Several key tests as per ASTM standards were performed to check if the bitumen was up to standard, and these included: (i) viscosity, (ii) specific gravity, (iii) softening point, (iv) thin film test, (v) flash point and (vi) fire point. The best formulated bitumen had a ratio of 20% engine oil, 50% crumb rubber and 30% coal tar with a viscosity of 93 cP, a specific density of 1.089, a softening point temperature of 65°C, thin film oven test of 0.35% mass loss, a flash point temperature of 218°C and a fire point temperature of 223°C. This bitumen showed better resistance to permanent deformation but less resistance to fatigue cracking, was less susceptible to temperature change meaning it could withstand hot climates, had less volatiles to give off and was a lower fire hazard.

Keywords

• Modified bitumen
• Used engine oil
• Used tyres
• Coal tar
• Viscosity test
• Softening point test