This book presents an in-depth analysis of microwave interactions with cementitious materials. Specially, the cementitious behavior of pozzolan and Type I Portland Cement has been discussed and compared when subjected to conventional and microwave processing. As-received waste rice husk ash was used to study the effect of microwave-assisted sintering. The interaction between microwave energy and Type I cement–based materials with and without pozzolan materials during the first 24-hours hydration period was investigated. The microstructural characteristics of hydration products in cementitious materials subjected to microwave-irradiated energy based on constant microwave-power levels were studied and compared that with conventional and high-temperature-curing methods. Based on the results of these investigations, this study proposes a theoretical microwave-heating model of cement paste under high-temperature curing using microwave energy and compares the results from experiments using this model with those obtained from more established approaches.