Influence of crumb rubber gradation on asphalt-rubber properties

摘要

Asphalt rubber is a material produced by the incorporation of crumb rubberobtained from ground tires in straight asphalt and its properties are influenced by thecomponents properties. The crumb rubber gradation is one of the variables which have asignificant influence on asphalt rubber properties. Thus, this work studies the influence ofcrumb rubber gradation on the asphalt rubber properties expressed by penetration,rotational viscosity (using the Brookfield viscometer), resilience and softening point. Testsamples were produced with a 50/70 penetration grade straight asphalt and a crumb rubberobtained by the grinding process which basically consists in a tearing and crushing the oldtires at ambient temperature. The digestion time was 60 minutes and the digestiontemperature was 170 ºC. The results show that the rotational viscosity and the resilienceare the properties most affected by the crumb rubber. It was also observed that the increaseof the crumb rubber specific surface (fine crumb rubber) produces asphalt rubber withhigher viscosity and lower resilience. The use of coarse crumb rubber influences mainly theresilience.