Research On Solidification Of Slag And MSWI Fly Ash In Geopolymer

Geopolymers is a class of inorganic aluminosilicate polymer mainly composed of electrovalent bond and covalent bond. Its chemical structure is semi-crystaline or amorphous, and similar to zeolite. Therefore, geopolymers combine some characteristics of organic high polymer, ceraminc and cement, and show unique qualities including high strength, adiabatic, flame-resistant, low shrinkage, acid or alkali resistance and corrosion resistance, low energy consumption and long durability. In addition, its unique cage structure is similar to zeolite which can solidify heavy metals effectively. The main works and results of the dissertation are as followed:1 Using different fly ashs and metakaolin as basic ingredient, KOH as alkali activator, synthesized a series of fly ash-based geopolymers. Through the result of compressive strength it is concluded that geopolymers synthesized with caesious fly ash possess better compressive strength than red fly ash. X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicate that the structure of geopolymer is amorphous, but at 1000℃crystalline phase formation of geopolymers change to leucite.2 The fly ash, slag and metakaolin have been employed to prepare the geopolymer. Compressive strength test and the extraction text demonstrate that geopolymers based on fly ash and slag have certain compressive strength and excellent solidification efficiencies to heavy metals. Compressive strength and immobilization behavior are affected by alkali activator. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) observation indicate that the structure of geopolymer is amorphous. Fourier transform infrared spectrum reveals that infrared peak caused by octahedral [AlO6]9- shifts to higher wave number, and infrared peak caused by the bending vibration of T-O-Si (T=Al, Si)disappears.3 The fly ash from municipal solid waste incineration and calcined kaolin have been employed to prepare the geopolymer. And the geopolymer was used for the solidification/stabilization of heavy metals in MSWI fly ash. The results showed that: geopolymers based on MSWI fly ash have certain compressive strength 19.36 MPa and excellent solidification efficiencies to heavy metals. X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) observation and Fourier transform infrared spectrum indicate that the structure of geopolymer is amorphous. And MSWI fly ash was reacted with kaolin, synthesizing a new polymer.