Performance evaluation of hydrated lime pretreated crumb rubber modified asphalt concrete using superpave mix design
Author(s): Wendimu Medo and Dr. Melaku Sisay
Abstract: Performance and durability of asphalt pavement is an alarming issue due to time to time increase in demand of high quality road. On the other hand currently number of discarded waste tire is increasing and becoming an environmental concern globally as well as in Ethiopia. This study was conducted to evaluate performance of Hydrated Lime pretreated crumb rubber modified asphalt concrete by dry Fatigue Life, Also rutting test was performed using Double Wheel Track (DWT) with specimens produced by slab compactor. The TSR value decreased for addition of more than 3% CR whereas the value improved with addition of HL. As per the DWT test result smaller rate of rutting and final rut depth compared to control mix obtained using 1% CR with and without HL and 3% CR with HL. The minimum to maximum value of resilient modulus for all mix was obtained as 765 to process. A 12.5 mm Nominal Maximum Aggregate Size and 1609 MPa and 226 to 385 MPa at temperature of 25 C and 40 bitumen with penetration grade of 80/100 was used to prepare all mix. Crumb Rubber (CR) 100% passing 1.18 mm sieve with 1, 3 and 5% by total mass of aggregate and also 2.5% Hydrate Lime (HL) was proposed to pretreat crumb rubber. A total of 70 specimens were prepared using gyratory compactor to determine Moisture Susceptibility, Resilient Modulus and °C respectively. Resilient modulus of mix increased except for 5% CR regardless of temperature and HL. Also resilient modulus of CR mix improved with addition of HL. Fatigue life Increased for mix with up to 3% CR replacement of aggregate whereas the value decreased for both temperature of 25 °C and 40 °C for further increment in CR.