Interactions Between Electromagnetic and Thermal Fields in Microwave Heating of Hardened Type I-Cement Paste Using a Rectangular Waveguide (Influence of Frequency and Sample Size)

Microwave heating-drying of hardened Type I-cement paste using a rectangular waveguide is a relatively new area of cement-based materials research. In order to gain insight into the phenomena that occur within the waveguide together with the temperature distribution in the heated cement paste samples, a detailed knowledge of absorbed power distribution is necessary. In the present paper, a three-dimensional finite difference time domain scheme is used to determine electromagnetic fields (TE10-mode) and microwave power absorbed by solving transient Maxwell's equations. Two-dimensional heat transport within the cement paste located in rectangular waveguide is used to evaluate the variations of temperature with heating time at different frequencies and sample sizes. A two-dimensional heating model is then validated against experimental results and subsequently used as a tool for efficient computational prototyping.