The transformation of physical and chemical performance was studied in the thaumasiteform of sulfate attack (TSA) process on cement mortars. A physical and chemical simulationof TSA process was established, and the mechanism of thaumasite formation is furtherdiscussed. The visual appearance, linear deformation, mass loss and strength were tested atdifferent storage times, and then the analysis towards the physical transformation in TSAprocess was carried on. X-ray diffractometer, Fourier transform infrared spectrometer andother modem testing technologies were used to analyze the chemical transformation in theTSA process. The macroscopical peculiarity due to the TSA process included corrosions fromsurface to inside. Gray mud without any strength appeared on the surface, and strength lossinside mortars. When the corrosion time arrived at 450th day, the FTIR results of mortars'surface showed the characteristic peak value of SiO6 (501cm-1), and confirm the thaumasiteformation. The physical process of TSA could be disparted to 3 periods: delitescence,expansion and crack period and intenerated and disaggregating period; the chemical processof TSA could be disparted to 4 periods: ionic migration period, ettringite formation period,gypsum formation period and thaumasite formation period.
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