Effect of Crumb Rubber Modified Bitumen in Hot Mix Asphalt Concrete

Abstract

Improving bituminous material using recycling waste (Crumb rubber) as modifier was emphasized in this paper. Crumb rubber (CR) waste was added by volume to the bitumen in 0, 5, and 7 %. The volumetric  properties tests  were conducted using the Marshall Test (ASTM D1559), others includes  Characterization of Binder  and Aggregate materials in HMA, (FTIR Analysis), Fundamental mechanical properties tests, also Rheological properties according with ASTM D7369-11, Dynamic Modulus Test, according with AASHTO R83-17, Rutting Test according with AASHTO T324-04, Fatigue Cracking Evaluation according with AASHTO TP124 and Flexural Beam Fatigue Beam Test according with AASHTO T 321-07. The result indicates that crumb rubber is very suitable as a modifier, with bitumen of 60/70 PEN grade. From the results, at the designed production temperature 135^oC for unmodified 60/70 Bitumen, the modified admixed samples (0% and 5% CR) at the same binder content show a high void percentage for mixes (5% CR). This is an indication that the modified asphalt mixtures exhibited volumetric properties with higher voids and lower density due to change in viscosity caused by modification and requires compaction at higher temperature to be at par with regular unmodified bitumen grade. However, the air voids of mixtures fall within the specification range of 3% to 5%, and as such acceptable for use as a modifier in 60/70 PEN grade bitumen.