This report documents and presents the results of a study that evaluated currently available nondestructive testing systems that appeared to have potential for supplementing or replacing coring in determining concrete pavement thickness and reinforcement location. The evaluation was done primarily in the field. The principal work consisted of the systems under on-the-job conditions on eight paving projects in six states. The measurement technique were employed in conjunction with statistical acceptance criteria evolved in the course of the study. An ultrasonic gage developed by the Ohio State University was found to perform thickness measurements on hardened concrete for both plain and reinforced pavement with acceptable accuracy. Before it can be applied routinely, further improvement of its resistance to the rigors of job-site conditions is needed. An eddy current proximity gauge proved satisfactory for measuring the thickness of hardened plain concrete pavement, but not of reinforced pavement. A device called a "pachometer" was found to be satisfactory for determining the depth and position of steel reinforcement in both plastic and hardened concrete.
Samenvatting