Dense graded rubber mixtures and chemkrete (81-09-1)

Abstract

This report discusses the application of three ground rubber additives and a chemical additive as ingredients in dense graded asphalt concrete (AC) overlays. A two inch layer of Type C dense graded AC vith fabric reinforcement io being used as a comparison. The goal of this project is to find better methods of controlling distress cracking and to slow the deterioration of the AC overlay. The construction methods for each product mixture are discussed. The Cbemkrete method closely resembles conventional mixing and laying methods. A chemical agent was added to the asphalt holding tank and thoroughly mixed. Ground tire rubber crumbs of the Arm-R-Shield and Overflex processes were added and mixed with 85-100 penetration asphalt. The Plusride product ia also ground tire rubber but is added as an aggregate. Fabric reinforcement was not used with the asphalt rubber mixes. ln this experimental application, one and one-half inches of Chemkrete costs about the same as two inches of AC. Two inches of Plusride cost about twice the standard AC. Arm-R-Shield and Overflex cost about 3 1/2 times the standard AC for their respective 2 inch layers. Evaluations of the performance of these products will continue for three years. Initial performance evaluations indicate some stress conditions are beginning to come into view.