Preparation And Properties Of Fly Ash Geopolymer

The Geopolymer is a new type of environmentally friendly inorganic composite materials with the distinguishing features of superior performance and low price. In this paper, two methods were used to optimize the ratio of fly ash Geopolymer. Alkali-activation as the first method is used to prepare the fly ash Geopolymer and the orthogonal test is used to optimize its ratio.Pressure forming as the second method is used to prepare the fly ash Geopolymer and control variables is used to optimize the ratio .Finally,the good performance of the fly ash Geopolymer material was prepared.The various factors that affecting fly ash Geopolymer's strength were analyzed in detail and the durability of the material was tested.The study shows that,in all the fadtors,Na₂SiO₃·9H₂O is the most important to impact on the Alkali-activated fly ash Geopolymer's strength. The milling time, water proofing agent,water-fly ash ratio and conservation time are all important impact on the strength.The relationship between the bending strength and compressive strength of fly ash Geopolyme is complex.When milling time is lh,waterproofing agent is 8%,water-fly ash ratio is 0.34,Na₂SiO₃·9H₂O is 6% and conservation time is 4h,bending strength to achieve the greatest;When milling time is lh,waterproofing agent is 4%,water-fly ash ratio is 0.34,Na₂SiO₃·9H₂O is 10% and conservation time is 24h the compressive strength to achieve the greatest.Volume of cement is the greatest to impact on the suppressed fly ash Geopolymer's early strength. Molding pressure and sand are important factors to impact on its strength. Without sand,fly ash Geopolymer's best ratio is cement:CaSO₄·2H₂O:Ca(OH)₂:fly ash=7:5:18:70.fly ash Geopolymer's best ratio with sand is cement:CaSO₄·2H₂O:Ca(OH)₂:fly ash:sand=5:5:18:52:20.The molding pressure of 10MPa should be elected in this two preparation programs.The fly ash Geopolymer sample has good alkali-aggregate-reactionand(AAR) -resisted performance and good alkali,salt,H₂O-resisted performance.By alkali-aggregate reaction,volume expansion ratio of the fly ash Geopolymer sample is 0.1% below and its greatest bending strength and compressive strength can be achieved 9.5MPa and 57.2MPa.The sample has a higher early strength in the acid solution. However,with increasing corrosion,materials are severely damaged.