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Thaumasite form of sulfate attack(TSA)is a major concern in evaluating durability of concrete structures subjected to sulfate and carbonate ions.By means of Fourier transform infrared spectroscopy (FT-IR),X-ray diffraction(XRD),scanning electron microscopy(SEM),and energy dispersive spectrum(EDS) as well as Raman spectra of erosion substances,effect of fly ash on TSA resistance of Portland cement-based material were investigated.Immersed in magnesium sulfate solution with 33 800 ppm mass concentration of SO 4 2-at 5±2℃for 15 weeks,ratio of compressive strength loss decreased as binder replacement ratio of fly ash increased.Furthermore,when binder replacement of fly ash was 60%,compressive strength increased.When thaumasite came into being in samples with 0,15%binder replacement ratio of fly ash,ettringite and gypsum appeared in those with 30%,45%,60%binder replacement ratio of fly ash.Results mentioned above showed that fly ash can restrain formation of thaumasite and improve TSA resistance of Portland cement-based material sufficiently.
Thaumasite form of sulfate attack (TSA) is a major concern in evaluating durability of concrete structures subjected to sulfate and carbonate ions. By means of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) SEM), and energy dispersive spectrum (EDS) as well as Raman spectra of erosion substances, effect of fly ash on TSA resistance of Portland cement-based material were investigated. Immersed in magnesium sulfate solution with 33 800 ppm mass concentration of SO 4 2 -at 5 ± 2 ° C for 15 weeks, ratio of compressive strength loss decreased as binder replacement ratio of fly ash increased. Frthermore, when binder replacement of fly ash was 60%, compressive strength increased.When thaumasite came into being in samples with 0 , 15% binder replacement ratio of fly ash, ettringite and gypsum appeared in those with 30%, 45%, 60% binder replacement ratio of fly ash.Results mentioned above that that ash ash can restrain formation of thaumasite and improve TSA re sistance of Portland cement-based material sufficiently.