Microwave decontamination of concrete

Abstract

Microwave heating has been recently considered as an effective method to remove the contaminated surface layer of concrete elements. In such applications, an accurate simulation of the microwave–concrete interaction involves the solution of Maxwell's equations. However, owing to the inherent complexity of Maxwell's equations, some studies have used approximate methods such as Lambert's law to estimate the microwave power dissipation in concrete. Invariably, such approximations are prone to introduce errors in the results and verification using the more accurate methods is thus necessary. In this paper, Maxwell's equations are numerically solved to simulate accurately the microwave–concrete interaction. The electric field and energy dissipation as well as the resulting temperature rise and thermal stress development in concrete are computed. The results are used to verify the results obtained using a modified Lambert's law approximate method. Moreover, the effect of steel reinforcing bars embedded in a concrete specimen on the microwave decontamination process is investigated. The results show that Lambert's law can be satisfactorily used as an easy-to-use method to predict the temperature rise and stress development within a concrete specimen subjected to microwave heating.