Experimental investigation of impact of crumb rubber on modified bitumen

ABSTRACT Population growth and industrialisation have led to the accretion of rubber waste which increased public concern about environmental pollution. The use of crumb rubber (CR) as a bitumen modifier is an effective way to protect the environment from pollution. The study of different properties of crumb rubber modified bitumen (CRMB) is the substance area of today’s research. Base bitumen having penetration grade 60/70 and crumb rubber proportions from 4% to 12% by weight of bitumen content following wet process was used. Physical properties, rheological properties, chemical properties and binding properties of unaged CRMB and aged CRMB were evaluated by using conventional tests, dynamic shear rheometer (DSR), Fourier transform infrared spectroscopy (FTIR) and bitumen bond strength (BBS) test, respectively. Modification index of complex shear modulus (G*) of bitumen increased with an increase in CR content. FTIR spectra of aged CRMB illustrated that rate of change in indices decreased with an increase in CR content which shows ageing resistance of CRMB. Crumb rubber influenced the adhesion phenomenon of bitumen and aged CRMB tends to achieve better adhesion effects. BBS results revealed that in dry conditions, POTS values of samples after peaking tended to decrease with an increase in the concentration of crumb rubber above 8%.