ASPHALT-RUBBER STRESS-ABSORBING MEMBRANES: FIELD PERFORMANCE AND STATE OF THE ART

Abstract

Pavement cracking and subsequent reflection through overlays are directly associated with pavement deterioration and maintenance problems. During the early 1960s a process was developed using a composition of 25 percent ground tire rubber reacted with 75 percent hot asphalt. This process has been in full-scale field projects in the form of stress-absorbing seal coats and interlayers and as waterproof membranes. Results from approximately 3200 lane-km (2000 lane-miles) of construction clearly show that this basic elastomeric material performs as a waterproof membrane and has a high capacity to absorb direct tensile, flexural, and shearing stresses. The paper reviews the performance of the asphalt-rubber seal coats placed 1967 and the present state of the art of design and construction. It further reviews the potentials of stress-absorbing membranes placed to (a) prevent reflective cracking of overlays placed over both flexible and rigid pavements; (b) provide bridge deck protection; (c) control differential movement of existing pavements constructed over expansive clays; (d) provide economical construction for low-volume roadways; and (e) provide improved elastomeric sealing of cracks and joints.