The feasibility of electromagnetic waves in determining the moisture content of concrete blocks

In some of the tropical countries such as Malaysia, various conditions of temperature and rainfall throughout the year are severe when compared to European countries. Humidity and rainfall throughout the year are likely to affect the durability of material used in buildings. Very high level of rainfall causes significant issues in concrete flat roofs due membrane failure. This would potentially contribute to the occurrence of severe roof leaks, especially for buildings that use flat roof design solutions. Membrane failure is hard to recognise due to the slow process of water leakage into the surface which most of the time causes dampness and reduces buildings' structural performance. To monitor this condition effectively, non-destructive test methods are required to recognise problems at an early stage to avoid further damages to concrete structure. This paper presents the use of electromagnetic waves for the purpose of monitoring concrete blocks' moisture level which will be highlighted. This study experimentally investigated the propagation of EM waves through the concrete blocks and their interaction with water. Novel microwave sensor described in the paper operates in the 2 GHz to 6 GHz frequency range using a Vector Network Analyser. Results of experimental tests confirmed that microwaves could be used as an alternative non-destructive method for identifying water ingress into the concrete blocks.