Design and optimization of a rubber-bitumen blend in preparation for a rubberized-asphalt road trial in the state of Kuwait

Abstract

In this paper, test results are presented from laboratory trials of blending discarded tire derived crumb rubber with 60/70pen grade Kuwaiti bitumen. The virgin bitumen, in addition to 15% and 18% crumb rubber blends were tested for PG grading and multiple stress creep recovery at temperatures in the range from 40°C to 70°C. Elastic recovery and nonrecoverable creep compliance showed optimum performance at 18% rubber content. The optimized rubberized-bitumen blend was next converted into a pelletized form which was then used as a partial substitute to the conventional bitumen in the manufacture of continuously graded hot mix asphalts at various binder contents. The rubberized-bitumen pellet contents trialed were 2.5%, 3.0% and 3.5% by mass of mix. The Marshall method of mix design was used to assess the various mixes and the overall volumetric, stability and flow results, though satisfactory, was not entirely sufficient to aid in the selection of the best performing formulation.