Study On The Fly Ash Geopolymer Material And Its Properties

Based on the studies of fly ash geopolymer materials by Zhu Xiaomin, the effects ofblast furnace slag used as mineral supplementary, calcium oxide and sodiumhydroxide as alkali activators on the strength of geopolymers are studied byorthogonal test in the paper. The fly ash geopolymer materials are synthesized usingslag or zeolite as mineral supplementary under normal temperature of which the alkaliaggregate reaction (AAR) is studied by accelerated method and the brittleness isanalyzed by orthogonal test, while the volume stability is investigated by determiningthe length of the samples in different curing time. And also the immobilization ofheavy metal in the material is discussed in the paper. The Electron ProbeMicroanalyzer is used to analyze the microstructure and the compositions of thesorption body. These results will be beneficial to the application of the fly ashgeopolymer materials.The strength results of orthogonal test show that the synthesized material is of relatively high strength (The compressive strength is 27.72MPa and flexural strength is 7.18MPa on the 28th day), which is influenced mainly by the dosage of CaO and the concentration of NaOH solution and slightly by the dosage of slag. But the slag can accelerate the synthesis and improve the early strength of the material. The brittleness analysis results reveals that the amount of the alkalis is the main factor influencing the brittleness of the synthesized material with slag but the slag will increase the brittleness of the material when the dosage increases, while the dosage of zeolite is the main factor and the alkalis is the secondary factor in the material with zeolite and the zeolite will increase the brittleness of the material when the dosage increases, but the effect of the alkalis cannot be ignored.The results of AAR test indicate that the resistance of the material to AAR is excellent and the material can restrain expansion of AAR when used in corrosive environment. The research on the volume stability reveals that the shrinkage of the material is slight higher than Portland cement.