Impact-echo is a nondestructive test method for concrete structures which is based on the use of transient stress waves. The usefulness of the method has been demonstrated in previous research. This project outlines research to determine the accuracy and precision of the method for measuring the thickness of and depth of flaws in slabs. The research includes numerical, laboratory, and field studies directed at determining what factors affect the accuracy and precision of impact-echo measurements. A procedure for calibration of instrumentation will also be developed. A tentative test procedure will be developed and used in field work carried out in conjunction with the Federal Highway Administration and State highway departments to determine new pavement thickness. Results will be verified by sample cores. The knowledge and data acquired from this project will be used to write a research report which will lay the basis for developing a draft standard.
