Innovative hybrid curing method for accelerating the strength of high-performance cement paste using microwave heating coupling with low-pressure processing

In this study, cementitious materials (here defined as a high-performance cement paste produced by mixing Type 1 Portland cement with an effective amount of water) were manufactured in accelerated conditions using microwave-assisted low-pressure processing (i.e., accelerated curing). Based on the concept that the hydration reaction of cementitious materials comprises three main periods-a dormant period, an acceleration period, and a deceleration period-process parameters were determined for the most effective period (acceleration) for producing paste via microwave processing. The time-dependent dielectric characteristics of the cementitious paste and the water-cement ratio by mass influenced the temperature, i.e., caused it to increase, and the properties of the microwave-cured paste. The results show that the use of microwave-assisted low-pressure processing improved the paste's mechanical properties. Specifically, microwave energy can accelerate compressive strength development 15 min after the completion of microwave-assisted low-pressure curing. With a delay time of 60 min, microwave energy can process the paste almost a day faster than water curing, which is the standard method for curing paste. The use of microwave energy, therefore, can significantly reduce the required energy and production time in the manufacture of high-performance paste.