Sulfate resistance of Portland cement stone with aluminum-containing setting accelerators.

comparative study was made of sulfate resistance of cement stone samples with basic sulfates addition (composed of Al(OH)1.78(SO4)0.61) and amorphous aluminum hydroxide. After 3 months the samples with addition of Al(OH)3 stored in a solution of sodium sulfate showed the most significant linear deformation and destruction. During tests of sulfate resistance by solid-state NMR spectroscopy with 27Al nuclei the correlation between aluminum ions in AFt (ettringite) and AFm phases was studied, and the influence of aluminum-containing additives, conditions and duration of testing was identified. According to NMR spectroscopy, in the samples with addition of Al(OH)3 the rate of secondary ettringite formation determining the sulfate expansion becomes noticeable one month after the beginning of the experiment. Development of deformities and the nature of changes occurring in the composition of sulfoaluminate phases in the samples with the Al(OH)1.78(SO4)0.61 additive were comparable to those in additive-free cement stone.

Section: Science and production

Keywords: X-ray fluorescence spectrometer, elemental analysis, materials for cement production.