Determination of Optimum Binder Content of Dry-Mixed Crumb Rubber in Stone Mastic Asphalt Using Sandstone Aggregate

The primary objective of this study is to evaluate the optimum binder content of the stone mastic asphalt blending different types of crumb rubber and locally available sandstone aggregate in Sabah, Malaysia. The crumb rubber was dry mixed from 0–3% and bitumen ranging from 5–7% of the aggregate weight, compacted at 150 °C compaction temperature. Gradation of stone mastic asphalt used was following the CR-SMA grading in the Malaysia Standard. The process was adapting the Marshall mix design method, including stability and flow test, and volumetric testing to discover the bulk density and voids in mix, and binder drain down test. In short, engulfing sandstone locally from Sabah in SMA with crumb rubber has some drawbacks finding compared to the past research.