Applications of microwave energy in cement and concrete - A review

This paper provides a comprehensive review of the use of microwave energy to process cement and concrete materials, as well as a critical evaluation of currently utilized microwave heating mechanisms and high-performance microwave systems. The current status of microwave applications and future research and development trends are also discussed, including such thermal processing methods as the high-temperature sintering of cement materials, the accelerated curing of precast concrete products, as well as the drilling and cleaning of decontaminated concrete surfaces by the built-up internal pressure. The results of this review indicate that microwave heating is directly associated with dielectric loss by the cement and concrete. Microwave processing can be used to improve clinkering and to reduce the clinkering temperature by about 100 °C. Considerations when constructing mathematical models of microwave heating for cement and concrete should include the influences of heat and mass transfer during microwave curing on the temperature difference in the concrete, the degree of uniformity of the internal structure, and the ultimate performance of the product. Future studies of microwave energy in cement and concrete applications might include investigations of adaptive (time-dependent) dielectric properties, coupling chemical reactions in the presence of microwave energy, the design and construction of suitable microwave systems, and the prediction of related phenomena (e.g., thermal runaway, as a highly regulated safety issue).