Coupled effects of Crumb Rubber and zeolite on the performance of dense-graded asphalt mixture: a study using a balanced mix design approach

This research aims to investigate the effect of different levels of Zeolite and Crumb Rubber (CR) on the durability and mechanical performance of dense-graded asphalt mixture to specify a suitable dosage of these additives. 2%, 4%, and 6% of Zeolite as a water-based warm mix additive and 8% and 16% CR were used. Indirect Tensile Strength (ITS), Semi-Circular Bending (SCB), and Hamburg Wheel Tracking (HWT) tests were respectively used to investigate the moisture damage, fracture and rutting resistance. Moreover, performance interaction diagrams are used to determine the appropriate percentage of the additives. The results showed that modified asphalt with Zeolite and CR have better resistance to rutting and cracking, and with the increase in the amount of these additives, this improvement has been more significant. However, CR diminished the resistance against moisture damage; Zeolite had a positive effect on moisture damage and it compensates for the weakness of modified dense-graded asphalt mixtures with CR. The performance interaction diagram of dense-graded asphalt mixtures has recommended the use of 4%, and 6% of zeolite with and without 8% of CR as the most ideal percentages of employing these additives, taking into account their correct performance against cracking, moisture damage, and rutting damage.