Development of a novel approach to detect damage in concrete structures with millimeter wave radar assessment system

Abstract

Nonintrusive damage assessment of concrete structures is evolving using newer technological interventions. Researchers are using different assessment techniques having their intrinsic limitations. A few are partially destructive, whereas others only provide qualitative information about the damages. Therefore, there is a need for a method using high-resolution imaging techniques for the assessment of exact damages and their depth along with intensity. Millimeter wave may be one of the good options for damage assessment. It is an efficient technique used in imaging applications due to its high resolution and effective penetration. Therefore, a novel millimeter wave assessment method is used in this study as a nondestructive post-fire damage test of concrete based civil engineering structures. An active millimeter wave radar system of 55-65 GHz has been used to measure the complex relative permittivity of concrete cube specimens for evaluation of damages caused by fire. In this study, fire damaged and control concrete cube specimens of 150 mm size were used for the measurement. The results were compared with the existing technique of ultrasonic pulse velocity, and it was found to be in good agreement.