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To investigate the effects of sulfate on the properties of cementitious materials, mortar specimens with water-cement ratio of 0. 5 and 0. 35 were designed and subjected to full immersion tests to study the effects of different sulfate concentrations on the water transport properties, mechanical properties and sulfate ion transport properties of cementitious materials at different depths. The results show that the water absorption of cementitious materials after sulfate attack increases with the age of attack. The flexural and compressive strength of cementitious materials shows a trend of increasing and then decreasing with the age of sulfate attack and the concentration of attack solution. The concentration of sulfate ions increases with the increase of sulfate concentration and the concentration of sulfate ions at the same depth. The sulfate attack of cementitious materials produce swelling products to fill the internal pores and increase the mechanical properties of the specimens. [ABSTRACT FROM AUTHOR]

To investigate the effects of different compressive stresses and lithium slag admixture on the chloride ion flux and gas permeability coefficient of concrete, concrete specimens with three different water-cement ratios and four lithium slag admixtures were fabricated, and 10%, 30% and 50% of the ultimate compressive load were applied to the specimens as continuous compressive stresses for chloride ion diffusivity and gas permeability tests. The results show that there is a significant correlation between the gas permeability coefficient, chloride ion flux, lithium slag admixture and compressive stress ratio of the concrete. The chloride ion flux decreases with the increase of lithium slag admixture and increases with the increase of compressive stress ratio. The gas permeation coefficient increases with the increase of lithium slag doping, and increases with the increase of compressive stress ratio. Considering the electric flux and gas permeability coefficient, the optimum dosing of C20, C30 and C40 concrete is 15%, 20% and 15% respectively. [ABSTRACT FROM AUTHOR]