Moisture Damage Resistance of Sulfur Extended Asphalt Mixes Containing a Crumb Rubber Modified Bitumen

Asphalt pavements are damaged continuously due to premature failures and exceeded traffic loads. Among the various failures, moisture damage is the most widely spread failure in asphalt pavements. Sulfur extended polymer is a newly developed additive that is used to increase loading capacity of asphalt pavement designed. However, the role of these additives are purely investigated in term of their effect on moisture resistance of asphalt mixes. In this research by replacing 30, 40 and 50 percent of Googas (a sulfur extended additive produced in Mashhad, Iran), Marshall size specimens were prepared. Modified Lattman testing was performed on mixes and their Tensile Strength Ratio (TSR) parameter was determined on all mixes. The results showed that above additive cannot attributed on moisture resistance of asphalt mixes as its present status. In order to overcome this lack of resistance, a crumb rubber modified containing 20 percent rubber was replaced with the original 60/70 pen bitumen of the mix. repeating all ITS testing on the above mix combination with this new binder, it resulted in improvement of mixes (about 15 percent increase in TSR value). This exceeded the minimum requirement of TSR for asphalt mixes which could not be achieved neither with conventional mix, nor with those containing Googas and 60/70 pen graded bitumen.