The Improvement of Properties Fly-Ash as Cementitious for Green Concrete

Fly-ash has a composition of silica that is dominant so that good used as cementitious. This research was conducted on the engineering materials of fly-ash from coal combustion waste at PLTU Tanjung Jati-B Jepara, Indonesia. Fly-ash which is synthesized by the method of reflux with through 5 M NaOH solution provided for 24 hours at a constant temperature of 1000C. Chemical testing done by X-Ray Difraction (X-RD) and Scanning Electron Microscope (SEM). The result test will compared with fly-ash ordinary and cement material. Physical properties of fly-ash synthesized by the method of reflux has the potential of great absorption rate than conventional fly-ash. This is described with the inspection results of fineness fly-ash treatment retrieved by 13.4 % and the value of consistency 37 %. The reactivity of fly-ash with method of reflux also looks better silica compounds than fly-ash ordinary in where silica-oxide (SiO2) of dominant 37, 69 % with amorphous phase reached 71, 31 % and round granules more smooth with size 6, 425 m. Changes the results of engineering materials, fly-ash with the reflux method can produce cementitious superior and environmentally friendly in the future.