This study investigated the sulfate resistance of Portland-dolomite cement (PDC) cured at different temperatures. Mortars of Portland cement (PC) and PDC with different dosages of dolomite, 10, 20, 30% by weight, were cured in water at 20 °C and 60 °C for 28 days before immersed in 50 g/L Na2SO4 solution at 20 °C. In addition to monitoring the length changes of mortars, MIP and XRD were performed to investigate microstructure and evolution of phase assemblages. Results show that PDC mortars cured at 20 °C give a poorer sulfate resistance than PC, and the higher the dosage of dolomite, the worse the sulfate resistance. On the contrary, when cured at 60 °C, PDC gives a much better sulfate resistance than PC, and the higher the dosage of dolomite, the better the sulfate resistance. The increases of critical pore size and porosity with the incorporation of dolomite lead to a poor sulfate resistance of PDC cured at 20 °C. However, for PDC cured at 60 °C, it is not the pore structure but the lack of available aluminate caused by the formation of hydrotalcite contributes to its sound sulfate resistance. The higher the dosage of dolomite from 10 to 30%, the larger amounts of hydrotalcite formation and the better the sulfate resistance. Hydrotalcite is stable in the presence of sulfate.

中文翻译：

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硅酸盐白云石水泥的耐硫酸盐性：性能和机理

本研究调查了波特兰白云石水泥 (PDC) 在不同温度下固化的抗硫酸盐性。波特兰水泥 (PC) 和 PDC 砂浆与不同剂量的白云石，按重量计 10%、20%、30%，在 20 °C 和 60 °C 的水中固化 28 天，然后浸入 50 g/L Na2SO4 溶液中 20 ℃。除了监测砂浆的长度变化外，还进行了 MIP 和 XRD 以研究微观结构和相组合的演变。结果表明，20℃固化的PDC砂浆的耐硫酸盐性比PC差，白云石用量越大，耐硫酸盐性越差。相反，在60℃固化时，PDC的抗硫酸盐性比PC好得多，白云石用量越大，抗硫酸盐性越好。随着白云石的掺入，临界孔径和孔隙率的增加导致 PDC 在 20°C 固化后的耐硫酸盐性较差。然而，对于在 60°C 固化的 PDC，不是孔隙结构而是由于水滑石的形成导致的可用铝酸盐的缺乏导致其良好的耐硫酸盐性。白云石用量10%～30%越高，水滑石生成量越大，耐硫酸盐性越好。水滑石在硫酸盐存在下是稳定的。水滑石的形成量越大，耐硫酸盐性越好。水滑石在硫酸盐存在下是稳定的。水滑石的形成量越大，耐硫酸盐性越好。水滑石在硫酸盐存在下是稳定的。