Effect of crumb rubber size and content on the properties of dry mixed rubberized asphalt mixtures

Abstract

Developing and producing high quality asphalt is essential in satisfying the current demands for roads. Crumb rubber obtained from scrap tires has proven to be an effective additive for modifying the properties of asphalt mixture in a form of Crumb Rubber Modified Asphalt Mixtures. This study presents a laboratory evaluation on the properties of crumb rubber modified asphalt mixture using a dry process method by adding three different sizes of crumb rubber which are: fine (≤1.18mm), coarse (≤1.18 mm), coarse (≥1.18 and ≤3.35 mm) and combination of both fine and coarse, (50/50), at three different percentages of crumb rubber 0, 1.5 and 2.5% from the total weight of the aggregate. In this study, the crumb rubber was used to modify the dense graded mixture; AC14 (asphalt concrete with the nominal maximum size of aggregate is 14 mm). The effect of crumb rubber in the mixture was investigated in terms of the volumetric properties using Marshall Mix Design and the mixture‟s performance in terms of resilient modulus, dynamic creep and durability (Cantabro test). It was found that fine crumb rubber has improved most the asphalt mixture properties compared to other mixtures which could be due to the partial interaction between the rubber particles and the bitumen and simultaneously act as elastic aggregates within the mixture