A COMPREHENSIVE EVALUATION OF ENVIRONMENTAL CONDITIONING SYSTEM (WITH DISCUSSION)

Many highway agencies face the problem of premature failure of asphalt concrete pavements due to moisture damage. Two test methods, modified Lottman and boiling tests, are commonly used to evaluate the stripping potential of asphalt concrete in the laboratory. Unfortunately, these tests are not always able to accurately discriminate between well and poor performing mixes; that is, the laboratory test results may sometimes not correlate well with the field performance. Studies performed under the Strategic Highway Research Program (SHRP) indicate that the environmental conditioning system (ECS) is a device that better simulates the field conditions. A study conducted by the Colorado Department of Transportation suggested that the ECS device and testing procedure needed further evaluation before it could be incorporated into routine use. A study to evaluate the ECS was undertaken. Based on the results from this study, the ECS is promising. Improvements, both in terms of conditioning of asphalt concrete mixture, as well as, resilient modulus test setup, are needed. Specifically, the resilient modulus test setup of the ECS needs improvement in the precision and accuracy of the measurements.