ABSTRACT

This paper presents a study to evaluate low temperature rheological properties of crumb rubber modified binders and the impact of the rubber particle size and content on such properties. Three sizes of the crumb rubber (0.18 mm, 0.425 mm and 2.0 mm), a control (0 percent) and two levels of crumb rubber content (12 percent and 24 percent) were used with four asphalt binders. The measured rheological properties consisted of creep stiffness (St) and logarithmic creep rate (m). Results showed that: increasing the crumb rubber content decreased the creep stiffness which improves thermal cracking resistance. The impact of crumb rubber content on the m-value was very highly inconsistent. The crumb rubber size did not have a significant effect on the low temperature properties. Any effect of the size of the crumb rubber on the resistance to thermal cracking was dependent on the asphalt binder type. The analysis of the data generated in this experiment showed that some combinations of crumb rubber size and content can either improve or jeopardize the PG low temperature grade of the asphalt binder.