The Effect of Microwave Curing on the Strength Development of Class-F Fly Ash-Based Geopolymer Mortar

This study investigates the influence of microwave (MW) curing on thestrength development of geopolymer. Since applying conventional oven heat curingmakes the heat move from the outer edge to the center of the specimen, it leads to anon-uniform of distributing heat within the specimen, which affects the mechanicalproperties of the geopolymer. On the other hand, the use of MW reduces the curingtime and allows uniform heat distribution within samples, and provides highermechanical properties in a short period. The influence of conventional heat curingand MW curing on class F fly ash based geopolymer activated with sodiumhydroxide and sodium metasilicate was investigated. The conventional heat curingwas applied at 75 and 90°C for 6 and 24 hours; on the other hand, additional MWcuring was applied for a different period (5-60 minutes) and different energy level(100, 180 and 300W) on hardened geopolymer samples cured with conventionaloven curing. The results show that the use of conventional heat curing for 6 hours,followed by MW curing, gave higher or equivalent strength compared to onlyconventional heat curing. While 24 hours conventional heat curing results with ageopolymer having 39.1 MPa compressive strength, 6 hours conventional heatcuring followed by 1 hour MW curing at 180W energy level results with ageopolymer with compressive strength in the order of 80 MPa.