Study On The Fly Ash Geopolymer Materials

It is imperative for the search of environmentally friendly construction materials, as the world is facing serious problems due to environmental degradation. The geopolymer is just the "green material".The geopolymer, a new ceramic material, is being researched actively abroad, which is synthesized from predominantly clays (metakaolinite) or other alumino-silicate containing source materials by simple manufacture process, activated by alkaline solution and cured below 150℃ or even at room temperature.The fly ash geopolymer presented at this paper possesses these advantages such as saving energy, easily making full use of the waste materials and simple synthesized condition as well as economic and utilitarian property. The fly ash as the predominant source material, the applicable w/c, the supplementary mineral material and exciting agent mixed together can manufacture the new low price and excellent properties fly ash geopolymer if activated by alkaline liquid. The production of fly ash geopolymer cement can reduce the emissions of carbon dioxide up to 80% or so compared to the production of ordinary Portland cement. Therefore, it relieves the pollution to environment and shows promising future.The optimum mix proportions of fly ash geopolymer are determined by analyzing the influence of different factors on the strength of the geopolymer by the approaches of orthogonal experiment and graphing. The X-ray diffraction, scanning electronic micrograph and infrared analysis are employed to discern the chemical composition and microstructure of the different fly ash geopolymer synthesized from different origin source materials. The research result shows that the alkli aggititives (NaOH and CaO) are the main factors having impact on the strength of the fly ash geopolymer. The suggestions of crystalline particles are found at the framework like zeolite and quarts and the basic structure is amorphous and glass-like consisting of a three-dimensional framework of SiO₄ and AlO₄ tetrahedra. The products show different strength and characteristics of microstructure because of different supplementary minerals. The product with the zeolite as the supplementary mineral has excellent sulphate resistance property. According to the comprehensive analysis, the flexural strength of the product with the zeolite as the supplementary is higher than that of the product with the bentonite as the supplementary. As for the compressive strength, the result shows the contrary regularity.