Microwave energy at a frequency of 2.45 GHz with a multi-mode applicator was used to accelerate the early-age hydration reaction in type I-Portland cement pastes. The influence of curing procedures on the microstructural evolution of Portland cement paste with a water-to-cement mass ratio (w/c) of 0.38 was investigated. By varying the sequential application processes, the phases and microstructural characteristics were assessed using a scanning electron microscope (SEM) associated with energy dispersive X-ray spectroscopy (EDS), and weight changes by thermogravitric analysis (TGA). Furthermore, the efficiency of the curing procedures was evaluated by comparing the compressive strength with pastes that were cured by soaking in limesaturated deionized water. From the test results it can be concluded that curing procedures strongly influence the temperature rise inside the microwave-cured pastes, and also the development of microstructures and compressive strength.

Keywords: Microwave, Curing procedures, Microstructures, Strength, Portland cement pastes.