暴露于硫酸和乙酸环境下的水泥砂浆与碱激发粉煤灰/矿渣砂浆腐蚀层微观结构的表征与比较

Characterization and Comparison of Corrosion Layer Microstructure between Cement Mortar and Alkali-Activated Fly Ash/Slag Mortar Exposed to Sulfuric Acid and Acetic Acid.

作者信息

Zhao Wenjing, Fan Zirui, Li Xin, Kong Lijuan, Zhang Liying

机构信息

School of Materials Science and Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, China.

State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures, Shijiazhuang Tiedao University, Shijiazhuang 050043, China.

出版信息

Materials (Basel). 2022 Feb 18;15(4):1527. doi: 10.3390/ma15041527.

DOI:10.3390/ma15041527

PMID:35208067

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC8880145/

Abstract

In this study, we investigated the formation and evolution of the corrosion layers in alkali-activated mortar and ordinary Portland cement mortar exposed to sulfuric acid and acetic acid environments with different pH values, and explored the differences in the deterioration mechanisms. The experimental results indicated that ordinary Portland cement (OPC) mortars experienced more severe deterioration in terms of appearance, mass loss, and strength loss as compared with alkali-activated mortars exposed to an acetic acid environment, but their neutralization depths were smaller. Alkali-activated fly ash (AAF) mortar had a the relatively intact appearance but the greatest neutralization depth, which was due to its stable three-dimensional network but highly porous structure. To sum up, alkali-activated fly ash/slag (AFS) mortar had the best resistance to acid attack. In addition, the mortars exposed to acetic acid suffered greater deterioration than those exposed to sulfuric acid with the same pH values, which was mainly due to the highly porous corrosion layer formed in acetic acid, whereas crystallization of gypsum in sulfuric acid had a pore filling effect. However, for alkali-activated slag (AAS) and OPC mortars exposed to a sulfuric acid environment, extensive gypsum resulted in the formation of micro-cracks, and the corrosion layer of OPC mortar was more prone to fall off. OPC mortar also had the greatest resistance difference values of the continuously connected micro-pores before and after acid corrosion, followed by AAS, AAF, and AFS mortars, and these values for all the specimens were smaller in sulfuric acid. Furthermore, the gaps between acetic and sulfuric acid attacks increased with increased calcium content in binders, which were 7%, 13%, 21%, and 29% for AAF, AFS, AAS, and OPC mortars, respectively. Thus, it can be inferred that an appropriate amount of gypsum existed in the corrosion layer which could act as a barrier to some extent ina sulfuric acid environment.

摘要

在本研究中，我们研究了暴露于不同pH值的硫酸和乙酸环境中的碱激发砂浆和普通硅酸盐水泥砂浆中腐蚀层的形成与演化，并探讨了劣化机制的差异。实验结果表明，与暴露于乙酸环境中的碱激发砂浆相比，普通硅酸盐水泥（OPC）砂浆在外观、质量损失和强度损失方面的劣化更为严重，但其中和深度较小。碱激发粉煤灰（AAF）砂浆外观相对完整，但中和深度最大，这是由于其稳定的三维网络结构但孔隙率高。综上所述，碱激发粉煤灰/矿渣（AFS）砂浆具有最佳的耐酸侵蚀性能。此外，暴露于乙酸环境中的砂浆比暴露于相同pH值硫酸环境中的砂浆劣化更严重，这主要是由于乙酸中形成了高度多孔的腐蚀层，而硫酸中石膏的结晶具有孔隙填充作用。然而，对于暴露于硫酸环境中的碱激发矿渣（AAS）和OPC砂浆，大量石膏导致微裂纹形成，OPC砂浆的腐蚀层更易脱落。OPC砂浆在酸腐蚀前后连续连通微孔的电阻差值也最大，其次是AAS、AAF和AFS砂浆，且所有试件在硫酸中的这些值较小。此外，乙酸和硫酸侵蚀之间的差距随着胶凝材料中钙含量的增加而增大，AAF、AFS、AAS和OPC砂浆的差距分别为7%、13%、21%和29%。因此，可以推断在腐蚀层中存在适量的石膏，在硫酸环境中能在一定程度上起到阻挡作用。