Factors Affecting Joint Efficiency of Roller-Compacted Concrete Pavement Joints and Cracks

Abstract

The mechanism of joint efficiency for roller-compacted concrete (RCC) pavement joints and cracks is affected primarily by aggregate interlock or friction at the vertical interface of the joint. Current U.S. Army Corps of Engineers design procedures for RCC pavements make the conservative assumption that no joint efficiency is achieved at RCC pavement joints and cracks. The purpose of this study was to determine the degree of joint efficiency achieved at RCC pavement joints and cracks; to determine the factors that affect the joint efficiency, and to what degree; and to develop a regression model to predict the joint efficiency using those factors. The heavy weight deflectometer (HWD) and other devices were used to conduct nondestructive joint efficiency tests at 12 different RCC pavement sites around the United States. The joint efficiency results ranged from 22 percent to 89 percent, depending on the type of joint or crack tested. The joint efficiencies decreased significantly with increasing crack width, crack spacing, and decreasing temperature. Cores were taken from some of the sites, and crack width measurements with depth indicated little evidence of crack skewing. The HWD load magnitude significantly affected the joint efficiency, and the individual effects of slab thickness and modulus of subgrade reaction did not appear to be significant from observation of the data. A regression was developed that predicts the joint efficiency of RCC pavement joints or cracks, with an R² of 62 percent.