Performance of Portland limestone cements in mortar prisms immersed in sulfate solutions at 5 °C
Performance of Portland limestone cements in mortar prisms immersed in sulfate solutions at 5 °C
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DOI：
10.1016/s0958-9465(98)00009-2
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发表时间：
1999-04
影响因子：
10.5
通讯作者：
A. Barker;D. Hobbs
中科院分区：
文献类型：
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作者：
A. Barker;D. Hobbs
描述了在5 °C下在硫酸镁和硫酸钠溶液中浸泡长达12个月的砂浆的抗硫酸盐性的测试程序的结果。该砂浆由四种水泥制备：一种波特兰水泥、一种抗硫酸盐波特兰水泥和两种波特兰石灰石水泥，所述两种石灰石水泥包含15质量%的鲕状石灰石和石炭纪石灰石。砂浆样品经受BS 5328 4A和4 B级硫酸盐暴露条件。这些是在需要表面保护之前使用抗硫酸盐波特兰水泥（SRPC）制备的混凝土的最高等级，并且分别比使用波特兰水泥（PC）和波特兰石灰石水泥（PLC）制备的混凝土的推荐等级高两个和三个等级。使用两种游离水-水泥比，0.5和0.75。通过目视评估、膨胀以及弯曲和压缩强度的变化来监测性能。在自由水灰比为0.75时，PC砂浆和PLC砂浆表现出视觉上非常严重的侵蚀，前者表现出膨胀和强度降低，而后者主要是强度降低。在游离水-水泥比为0.50时，PC砂浆和PLC砂浆均显示出轻微/中度至严重的视觉侵蚀，PLC砂浆中的劣化程度似乎略高，尤其是那些用鲕状石灰石制成的砂浆。PLC砂浆还表现出压缩破坏载荷的降低。SRPC砂浆表现出很少的视觉恶化，没有膨胀，弯曲强度略有增加，抗压强度没有显着降低。在0.75的游离水-水泥比下，大量的碳硫硅钙石与钙矾石一起存在于劣化的PLC砂浆的表面层中，而钙矾石存在于劣化的PC砂浆的表面层中。得出的结论是，用C3 A含量为约10质量%的PC制成的砂浆在5 °C下对硫酸盐侵蚀的脆弱性与含有15质量%石灰石的PLC砂浆大致相似，尽管侵蚀模式不同。
The results of a test programme to investigate the sulfate resistance of mortars, immersed up to 12 months at 5 °C in magnesium sulfate and sodium sulfate solutions, is described. The mortars were prepared from four cements; a Portland cement, a sulfate-resisting Portland cement and two Portland limestone cements containing 15% by mass of an oolitic limestone and a carboniferous limestone. The mortar specimens were subject to BS 5328 Class 4A and 4B sulfate exposure conditions. These are the highest classes for concretes prepared using sulfate-resisting Portland cement (SRPC) before surface protection is required and are two and three classes higher than those recommended for concretes prepared using Portland cement (PC) and Portland limestone cement (PLC), respectively. Two free water-cement ratios were used, 0.5 and 0.75. Performance was monitored by visual assessment, expansion and changes in flexural and compressive strengths. At a free water-cement ratio of 0.75, the PC mortars and PLC mortars exhibited visually very severe attack with the former showing expansion and reductions in strength, and the latter mainly reductions in strength. At a free water-cement ratio of 0.50 both the PC mortars and PLC mortars showed slight/moderate to severe visual attack, the degree of deterioration appearing slightly greater in the PLC mortars, more especially those made with oolitic limestone. The PLC mortars also exhibited reductions in compressive failure load. The SRPC mortars exhibited little visual deterioration, no expansion, a small increase in flexural strength and no significant reductions in compressive strength. At a free water-cement ratio of 0.75 substantial amounts of thaumasite, together with ettringite was present in the surface layers of the deteriorated PLC mortars whilst ettringite was present in the surface layers of the deteriorated PC mortars. It is concluded that mortars made with a PC with a C3A content of about 10% by mass were broadly similar in their vulnerability to sulfate attack at 5 °C as PLC mortars containing 15% limestone by mass, although the mode of attack was different.