Fracture and Tensile Characteristics of Asphalt-Rubber Concrete

Abstract

Fracture and tensile characteristics of asphalt concrete mixtures affect the structural performance of pavements, particularly under low-temperature conditions. This paper reports a study of the tensile and fracture properties of asphalt-rubber (AR) concrete mixtures that formed the basis for the recommendation of an optimum asphalt mixture design incorporating crumb rubber from scrap tires. The work involved a full-factorial experiment with three different rubber contents (19, 22, and 24%), and three different AR binder contents (6, 7.5%, and 9%) in a surface mixture. Fracture and indirect tension tests were performed on AR concrete beams and Marshall test samples, respectively, at two different test temperatures of 25 and 5°C. The variables studied were indirect tensile strength, peak center-point load carried, load-point displacement, and unit fracture energy. The results show that higher mean values of indirect tensile strength and fracture energy were obtained corresponding to the highest AR binder content (9%), irrespective of rubber contents, particularly at lower temperatures. A statistical analysis of the test results reveals that there are no significant differences among the means of most of the variables studied corresponding to different rubber contents. However, the differences are significant for different binder contents.