| Mineral polymer was prepared using fly ash, one of the industrial solid wastes, andmetakaolinite, standardized sand, sodium silicate and alkaline solution in this study. Theoptimized processing condition was determined considering the compressive strength ofthe products as the main criterion. The compressive strength of the mineral polymerproducts cured for 7 days in this study reached 56.92 MPa. Compared with Portlandcement, the properties of the mineral polymer products prepared in this experimentpossesses many characteristics especially in their resistance to acid attacks. The Portlandcement and mineral polymer products were put into 0.5mol/L H2SO4 and 1.35mol/L HClfor 25 days, respectively. Mass loss rate of them are 32.17% and 19.56% for the Portlandcement, 4.1% and 5.62% for the mineral polymer products.On the basis of the optimized processing condition, the reaction mechanism wasresearched by X-ray Diffraction, Scanning Electron Microscope, Infrared Red analysis,Nuclear Magmatic Resource. The process of the reaction deduced from these data was:firstly, the Si-O, Al-O bonds of the fly ash/metakaolinite were broken in the high molaralkaline solution;Parallel to this process, complexes and polymerized species(Si-O-Na,Al(OH)4-, Al(OH)52-, Al(OH)63-) were formed in the solution;these groups or speciesformed zeolite precursors or precipitates with the changes of dissolution or/anddepolymerization;finally, these zeolite precursors formed amorphous phases bydehydration. Q4(2Al) were the major forms of Si element and tetrahedral aluminum of Alelement in matrix phases of the mineral polymer products cured for 28 days.Comparison of mineral polymer with the Portland cement, firstly, the forming processof mineral polymer was depolymerization and depolymerization, while the process of thePortland cement was dehydration. Secondly, the compositions of the mineral polymer andthe Portland cement were different. Mineral polymer belonged to SiO2-Al2O3-Na2O(K2O)system,while the Portland cement was SiO2-Al2O3-CaO-Fe2O3 system.Thirdly, theproperties of them were different particularly in its resistance to acid attacks. The cementclinker had 64% CaO, which reacted with water and changed into Ca(OH)2. Ca(OH)2composition reacted with SO42-forming gypsum, giving rise to 123% expansion by volumeand mortar broken. There was little CaO in mineral polymer, thus, no reaction like thishappened. This was why mineral polymer had good resistance to acid attacks.During the preparation of mineral polymer, a certain amount of alkaline solutions wereused, which caused the production consumption increased. The dissolution reaction ofpotassium feldspar were studied in the thesis and the preparation of mineral polymer usingthe leached residue were done to reduce the cost. Two methods were used, one wascalcined the potassium feldspar by potassium carbonate at 890℃. The other was thedissolution reaction of potassium feldspar with CaO as the reactant by hydrothermalreaction, with the extracted K2O prepared K2CO3/K2SO4and the leached residue formedtobermorite.The mechanism of the dissolution reaction was studied. The experimental resultsshowed the reaction was controlled by chemical reaction under alkaline condition and theapparent activation energy of this reaction was 45.64kJ/mol. The process of the dissolutionof potassium feldspar was: the first was the relatively rapid equilibrium between hydrogenand alkali ions, such as K+,Na+,Ca2+, on the mineral grain surface;secondly, the reversibleexchange of hydrogen with Al3+ on the surface produced Si-rich/Al-deficient precursorcomplexes, and the last, the decomposition of the precursor complexes (SiO2·nH2O)· toform the product-tobermorite. The dissolution rates of potassium feldspar with CaO as thereactant by hydrothermal method were measured in this study and the highest of whichreached 89.01%.Compared the energy consumption, environment affect, the properties of the mineralpolymer and the Portland cement products, mineral polymer was superior for low energyconsumption and no use of limestone. At the same time, fly ash could be used during thepreparation of mineral polymer, which was good for reducing the quantity industrial solidwastes and protecting the local environment, and the manufacturing processes of themineral polymer was clear and no CO2, NOX, dioxins produced during the whole process.
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