A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineeri ng in Structural Engineering, School of Engineering and Technology

Thesis (M.Eng.) - Asian Institute of Technology, 2010

Microwave energy is applied to estimate the prediction of long-term compressive strength of normal cured fly ash concrete with and without admi xtures. The optimal process is determined through factorial design and the a pplied to fly ash concrete with and without admixtures multiple mix proportions based on ACI. The combination of two different power level of microwave oven with a rest time between is determined as the optimal process. Power level one of P10 (43 watt) for 73 minutes, power le vel two of P30 (184 watt) for 30 minutes with a rest time of 20 minutes between the power le vel is applied to fly ash concrete with 30% replacement by weight of cement. The equation to estimate the prediction is based on the correlation of accelerated strength of microwave cured concrete and normal cured concrete with reasonable accuracy of + 3.45 percentage of error at 28 days. From the investigation of calcium hydroxide and calcium silicate hydroxide analyzed by Thermogravimetry analysis (TGA), the amount of calcium hydroxide and calcium silicate hydroxide cured by one step microwave energy at one day is higher than two step microwave energy application. However, at 7 days the am ount of calcium hydroxide and calcium silicate hydroxide is almost equal for two different method of microwave energy application.