THE EFFECT OF CRUMB RUBBER GRADATION AND BINDER-RUBBER INTERACTION TIME ON THE MECHANICAL PROPERTIES OF ASPHALT-RUBBER MIXTURES (DRY PROCESS)

摘要

In Brazil it is estimated the existence of approximately 900 million scrap tires improperly placed in the environment. Forty-six million more are scrapped every year. With the purpose of contributing to the solution of this problem, as well to enhance the properties of pavement asphaltic surfaces, the present study investigates asphaltic mixtures with crumb rubber incorporated using the dry process. The effect of different rubber gradations and the time of interaction between the rubber and the binder are investigated. A single aggregate gradation (DNER - C) was used for all mixtures, and 2.5% of mineral aggregate was substituted by crumb rubber of same gradation. Three rubber gradations were analyzed: #10-#16, #40-#200 and#10-#200. The effect of a 1-hour interaction time at 150℃ temperature was also investigated. The results indicate a decrease in the resilient modulus and tensile strength, and an increase in the fatigue life for the asphalt-rubber mixtures. Small size rubber particles and the interaction time were observed to positively affect the mixture properties.