The role of pH in thaumasite sulfate attack
The role of pH in thaumasite sulfate attack
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DOI：
10.1016/j.cemconres.2005.01.003
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发表时间：
2006
影响因子：
11.4
通讯作者：
Q. Zhou;J. Hill;E. Byars;J. Cripps;C. J. Lynsdale;J. Sharp
中科院分区：
文献类型：
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作者：
Q. Zhou;J. Hill;E. Byars;J. Cripps;C. J. Lynsdale;J. Sharp
近年来，碳硫硅钙石形式的硫酸盐侵蚀（TSA）被认为是一种独特的机制，通过这种机制，在外部硫酸盐离子源存在的情况下，地下混凝土会发生降解。然而，关于pH值的作用存在分歧。有人提出，由黄铁矿氧化产生的硫酸的侵蚀有时是变质的主要原因。其他人认为，酸被迅速中和，使土壤中硫酸根离子浓度更高，从而增加了侵蚀的程度。这里报告的实验室研究的目的是通过检查混凝土立方体来了解硫酸在TSA中的作用，混凝土立方体由三种类型的水泥和两种类型的骨料制成，在低温下浸入两种溶液中，一种碱性溶液对应于BRE设计硫酸盐DS-3级，另一种酸性溶液。酸的存在不会促进碳硫硅钙石的形成。虽然在酸性条件下观察到混凝土的降解，但其机制并不是在碱性条件下观察到的TSA。
The thaumasite form of sulfate attack (TSA) has been recognised in recent years as a distinct mechanism by which degradation of buried concrete can occur in the presence of an external source of sulfate ions. There is, however, disagreement about the role of pH. It has been proposed that attack by sulfuric acid, produced by oxidation of pyrite, is sometimes the primary cause of deterioration. Others believe that the acid is rapidly neutralised giving a higher concentration of sulfate ions in the ground, hence increasing the extent of attack. The aim of the laboratory study reported here was to understand the role of sulfuric acid in TSA by examining concrete cubes, made from three types of cement and two types of aggregate, immersed at low temperature in two solutions, one alkaline corresponding to BRE Design Sulfate Class DS-3 and the other acidic. It is concluded that the presence of acid does not promote the formation of thaumasite. Although degradation of the concrete was observed in acid conditions, the mechanism was not TSA as observed in alkaline conditions.