Fly ash based geobrick production

Energy efficient, sustainable construction materials production is recently the fashionable subject of construction materials science. Thus this thesis is dealing with recycling of F and C type fly ash deposits on use with brick production having high strength by researching geopolymerisation. Geopolymer is a new generation material invented firstly by Prof. Dr. Joseph Davidovits in 1970s. Geopolymer is synthesized by alkalination and polycondensation of geologic source materials. Fly ash based geopolymer products are energy efficient because of already calcined source material. At the beginning of this research many resources of fly ashes, from several Turkish thermic coal plants were investigated to define appropriate mineral composition for geopolymeric synthesis in alkaline media. The worst C Class fly ash composition and the best F class composition were chosen for further research. Pressure formed geobricks were produced with pressing stress of 30 MPa. Compressive strength, water content of geobricks were investigated which are produced by applying heat treatments between the ranges of 40-60-80-100 º C at several duration (2-4-6-24-48-72) hours. Densities of all compacted specimens were defined. Geobricks produced by using F class fly ash has reached the optimum compressive strength of 45 MPa at 60 º C for 24 hours curing in oven with Si:Al molar ratio of 2. Geobricks produced by using C Class fly ash has reached physical capacity of conventional bricks standards, after the pretreatment application of solving fly ash in water, heat drying and grinding, before geopolymeric reactions.Keywords: Geobrick, alkalinaton, fly ash, water content, density, compressive strength.