Experimental Investigation on Fatigue Characteristics of Asphalt Mixes with Different Automobile Waste Tyres as Modifiers

Abstract

The prime concern of this investigation was to assess the fatigue behaviour of asphalt mixtures by the addition of waste rubber tyre obtained from different automobiles, in powdered form. Bituminous asphalt mixtures were prepared with crumb rubber (various automobile waste tyres) modified bitumen and crushed aggregates. The indirect tension (IDT) fatigue test was performed to investigate the fatigue performance of bituminous asphalt mixture. As per ASTM D 4123-82 (1995), the IDT fatigue test can be conducted for stress level of 10–50% of the indirect tensile strength, hence we have chosen a stress of 35% of the indirect tensile strength of the conventional mixture. The IDT fatigue test can be carried out at wide range of temperature from 5 to 40\xa0°C and many researchers performed fatigue test over different temperatures apart from 25\xa0°C. In India the average temperature ranges from 32 to 40\xa0°C, while performing test the measured temperature was 32\xa0°C. So, the IDT fatigue tests were executed in stress-controlled manner at a stress of 200\xa0kPa (i.e. 35% of the indirect tensile strength of conventional asphalt mixture), at a predominant temperature of 32\xa0°C and at a loading frequency of 1\xa0Hz. Outcomes from this research proved that the fatigue properties of asphalt mixtures were enhanced by the addition of crumb rubber as asphalt modifier. It was also perceived that the fatigue behaviour of asphalt concrete mixture modified with CRMB (crumb rubber modified bitumen) obtained from heavy automobile waste tyre was extensively higher compared to asphalt mixture modified with crumb rubber of light and medium automobiles. The fatigue life of modified asphalt mixture was higher in case of 9% crumb rubber content. And the least fatigue life among the three mixtures was light automobile waste tyre modified mixture.