Enhancing the asphalt binder's performance against oxidative ageing and solar radiations by incorporating rubber from waste tyres

This study investigates the ageing of neat and crumb rubber modified bitumen (CRMB) under various conditions. Bitumen was modified with a high content of crumb rubber (CR) (22.5% by weight of base bitumen) and subjected to the equivalent amount of UV radiation occurring in one year in Melbourne, Australia. Long-term ageing via pressure ageing vessel was also used to age CRMB. Fourier transform infrared spectroscopy (FTIR) was used to capture the mechanism and evaluate the ageing effect that UV radiation and PAV ageing had on both types of binders. It was found that PAV ageing, due to its high temperature and pressure, mainly involves the evaporation of volatiles, oxidation of bitumen, and the conversion of aromatics to asphaltenes, while UV radiations, on the other hand, destroy the molecular structure of bitumen in addition to providing oxidation. The effect of ageing on rheological performance parameters such as crossover modulus, Jnr, and %R was also found in line with the findings from the FTIR spectroscopy. The ageing index developed from the crossover modulus showed that applying a 1-year equivalent of UV radiations in Melbourne (Australia) provides 1.51 times increase in ageing to the neat bitumen while ageing is up to 2.64 times after 20-hour PAV. When the same neat bitumen was modified with CR, the ageing resistance against both PAV and UV radiations was enhanced by limiting the level of ageing to 1.16 and 1.12 times, respectively. Kruskal-Wallis test showed that there is no significant difference between the unaged and aged samples of CRMB in terms of Icom. That showed 20-h PAV ageing and 1-year UV ageing did not significantly affect the CRMB, which is evidence of the ageing resistance of CRMBs.