Study on Dielectric Model for Capacitance-Based Nondestructive Testing of Water Content in Concrete

Water is one of the main factors causing the attenuation of compressive strength of concrete. Accurately measuring the water content of concrete is of great significance to evaluate the compressive strength of concrete and ensure the safety and stability of concrete structures. Thus, a dielectric model which can be applied to capacitance-based nondestructive testing of water content in concrete is proposed in this study. Firstly, a four-phase concrete meso-scale model composed of water, air, cement mortar and aggregate was established. A new numerical homogenization method was used to simulate and analyze the influence of the volume fraction of different components on the dielectric constant of concrete. The results of the numerical simulation were used to optimize the geometric factor in the LR (Lichtenecker-Rother equation) equation, and the LR equation with the optimized geometric factor was used to describe the influence. The LR equation with the optimized geometric factor provides the foundation for the capacitance-based nondestructive testing of water content in concrete and effectively improves the accuracy of the testing of water content.