Criado Maria, Bernal Susan A, Garcia-Triñanes Pablo, Provis John L
1Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Sheffield, S1 3JD UK.
Wolfson Centre for Solids Handling Technology, University of Greenwich at Medway, Chatham Maritime, ME4 4TB UK.
J Mater Sci. 2018;53(7):5016-5035. doi: 10.1007/s10853-017-1919-3. Epub 2017 Dec 18.
Among the minor elements found in metallurgical slags, sulfur and manganese can potentially influence the corrosion process of steel embedded in alkali-activated slag cements, as both are redox-sensitive. Particularly, it is possible that these could significantly influence the corrosion process of the steel. Two types of alkali-activated slag mortars were prepared in this study: 100% blast furnace slag and a modified slag blend (90% blast furnace slag + 10% silicomanganese slag), both activated with sodium silicate. These mortars were designed with the aim of determining the influence of varying the redox potential on the stability of steel passivation under exposure to alkaline and alkaline chloride-rich solutions. Both types of mortars presented highly negative corrosion potentials and high current density values in the presence of chloride. The steel bars extracted from mortar samples after exposure do not show evident pits or corrosion product layers, indicating that the presence of sulfides reduces the redox potential of the pore solution of slag mortars, but enables the steel to remain in an apparently passive state. The presence of a high amount of MnO in the slag does not significantly affect the corrosion process of steel under the conditions tested. Mass transport through the mortar to the metal is impeded with increasing exposure time; this is associated with refinement of the pore network as the slag continued to react while the samples were immersed.
在冶金炉渣中发现的微量元素中，硫和锰可能会影响埋入碱激发矿渣水泥中的钢的腐蚀过程，因为这两种元素都对氧化还原敏感。特别是，它们很可能会显著影响钢的腐蚀过程。本研究制备了两种类型的碱激发矿渣砂浆：100%高炉矿渣和一种改性矿渣混合物（90%高炉矿渣 + 10%硅锰矿渣），均用硅酸钠激发。设计这些砂浆的目的是确定在暴露于碱性和富含碱性氯化物的溶液中时，氧化还原电位的变化对钢钝化稳定性的影响。在存在氯化物的情况下，两种类型的砂浆都呈现出高度负的腐蚀电位和高电流密度值。暴露后从砂浆样品中取出的钢筋没有显示出明显的坑或腐蚀产物层，这表明硫化物的存在降低了矿渣砂浆孔隙溶液的氧化还原电位，但使钢能够保持在明显的钝态。在测试条件下，矿渣中大量MnO的存在对钢的腐蚀过程没有显著影响。随着暴露时间的增加，通过砂浆向金属的质量传输受到阻碍；这与随着样品浸泡时矿渣持续反应导致孔隙网络细化有关。
