Behaviour of rubberized asphalt mixture subjected to thermal loading

Abstract

This study investigated the behaviour of dry mixed rubberised asphalt mixture subjected to permanent deformation under high temperature variation. Crumb rubber, obtained from recycled scrap tyres was used as an aggregate replacement within the asphalt mixture as it could potentially provide greater elastic recovery to the mixture. The elements of natural and synthetic rubber within the scrap tyres have been identified to improve the thermal stability of the tyre compound and provide wider working temperature range. Therefore, to use the crumb rubber as a modifier in asphalt mixture could possibly improve the properties of asphalt mixture at various service temperatures and consequently, improve the resistance against permanent deformation. Additionally, this could provide an alternative in recycling the scrap tyres as non-decaying waste material. In this study, a mixture of Asphaltic Concrete of AC14 (dense graded with nominal maximum aggregate size 14 mm) was modified with 1, 2 and 3% of crumb rubber (coarse size, 5 mm) from the total weight of aggregate using dry process method. The properties of the rubberised mixtures were compared to the control mixture (with no rubber). Samples were prepared using Marshall Compactor and tested under Resilient Modulus at 25 and 40ºC to measure the material stiffness. In addition, Dynamic Creep Test was conducted to determine the permanent deformation at four temperature conditions; 25, 40, 50, and 60°C. The analysis was focused on the effect of adding crumb rubber in asphalt mixture in terms of accumulated permanent strain under the influence of temperature variation. Based on this study, it was observed that the susceptibility of asphalt mixture to high temperature was reduced by the crumb rubber modification.