An Evaluation Of Dense Graded Asphalt-Rubber Concrete In Minnesota

The Minnesota Department of Transportation is continually investigating ways to improve the cold temperature performance of its asphalt concrete pavements. One reported method is to modify the asphalt binder with ground reclaimed automobile and truck tire rubber. In 1984, a project on TH 7 (State Project 4703-17) was selected for the field trial of an asphalt-rubber cement dense graded concrete utilizing a product produced by Arizona Refining of Phoenix Arizona.

Construction of the asphalt-rubber cement dense graded asphalt concrete required some special effort and specialized equipment to maintain adequate mixing and placing temperatures. Evaluations included crack counting, resilient modulus, inplace air voids rutting, roughness, recovered penetration and cost considerations.

Interesting results regarding the resilient modulus of the asphalt rubber samples were found. However, the formulation used provided little or no perceived benefits to the roadway at much higher costs. The high costs were due in part to the nature of the project. However, this appears to be a cumbersome and expensive procedure with the primary benefit being waste tire utilization.