Study of Steam and Microwave Curing of Concretes Containing Slag, Fly Ash or Silica Fume

This study investigates the effects of steam and microwave curing on concretes containing fly ash, blast-furnace slag, or silica fume. Two steam curing treatments, four microwave curing times, and four types of concrete mix were used in this study. The test results indicated that microwave heating could further increase the compressive strength of mortar and concrete. Pozzolanic reaction of silica fume, fly ash, and blast-furnace slag was observed to be further promoted by steam-microwave curing. Mortar and concrete samples with 10% silica fume added responded well to microwave curing. The strength gain development of mortar and concrete appeared to level off after 40 min of microwave curing. Thus, a 40-min microwave heating time appeared to be the optimal time for energy saving consideration. The microwave-cured concrete did not show an increase in permeability relative to the concrete that was steam-cured, but showed an increase in strength. Thus, the microwave techniques could provide the advantage of quick and uniform heating for curing of cement mortar and concrete.