Detection of precast concrete beam defects using finite-difference time-domain modelling

Abstract

Structural failures and concrete structure collapses still remain as an unsolved issue in the building and construction industry although many researches has been done on it. In recent years, ground penetrating radar (GPR) emerged as one of the most promising nondestructive testing (NDT) techniques for civil engineering applications, especially in concrete structures inspection. Although the use of precast concrete beam is gaining its popularity in building and construction industry, there are lacks of publication focusing on defects detection of precast concrete beam with GPR. Therefore, this study is conducted to test the capability of 2 GHz high frequency GPR antenna in monitoring the inner structure and detecting defects in precast concrete beam. The aim of this study is to detect the defects, such as cracks or voids in the precast concrete beam with the assistance of Finite-Difference Time-Domain (FDTD) numerical modelling. Results indicated that defects with different sizes can be detected; even fine cracks with 3mm can be detected. This proved that 2 GHz high frequency GPR antenna is an ideal NDT solution for concrete surveying, particularly for small size cracks. Results from this study offer new applications of GPR for building structural health assessment and maintenance.