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Durability Evaluation of Concrete Subject to the Attack of Corrosive Acidic Substances

混凝土受酸性腐蚀性物质侵蚀的耐久性评价

基本信息

批准号：
18360209
负责人：
KAWAI Kenji
金额：
$ 5.43万
依托单位：
Hiroshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

The purpose of this study is to comprehensively evaluate durability of concrete subject to the attack of both weak and strong acids. Corrosive weak acid includes carbon dioxide, while corrosive strong acid includes sulfuric acid of which typical deterioration is found in sewage and wastewater treatment plants. In this study, research on the effects of weak and strong acids on concrete deterioration was carried out.Regarding the research on the effect of weak acid on concrete deterioration, consideration of the rates of chemical reaction associated with carbonation of concrete was investigated. Using synthesized C-S-H, ettringite, monosulfate and Friedel's salt, simulation tests for carbonation of cement hydrates were carried out and a modeling for decomposition of C-S-H, ettringite, monosulfate and Friedel's salt due to carbonation was developed considering their rates of carbonation reaction. Compared with a current model, the proposed model showed better agreement with experimental results. The necessity of consideration of the rates of chemical reaction in modeling was suggested.Regarding the research on the effect of strong acid on concrete deterioration, the effects of pH, use of mineral admixtures and a flow of solution on deterioration of concrete were investigated. Cement paste and mortar specimens containing blast furnace slag, fly ash and silica fume were prepared and immersed in sulfuric acid solution at pH=1.0 and 2.0. Some of the specimens were immersed in flowing solution. A flow was generated by circulating the solution with a pump. As a result, erosion of specimens immersed in flowing sulfuric acid solution at pH=2.0 was accelerated compared with that immersed in static solution, while erosion of specimens immersed in static and flowing sulfuric acid solutions at pH=1.0 was almost the same. Therefore, a shearing force acting on the surface of a specimen could accelerate erosion due to sulfuric acid attack according to the value of pH.

本研究的目的是综合评价混凝土在弱酸和强酸侵蚀下的耐久性。腐蚀性弱酸包括二氧化碳，腐蚀性强酸包括硫酸，其典型的劣化发生在污水厂和污水处理厂。本文研究了弱酸和强酸对混凝土劣化的影响，在弱酸对混凝土劣化影响的研究中，考虑了与混凝土碳化相关的化学反应速率。以合成的C-S-H、钙矾石、单硫酸盐和弗里德盐为原料，进行了水泥水化模拟试验，建立了考虑其碳化反应速率的C-S-H、钙矾石、单硫酸盐和弗里德尔盐的碳化分解模型。与现有模型相比，该模型与实验结果吻合较好。提出了在模拟中考虑化学反应速率的必要性，结合强酸对混凝土劣化影响的研究，考察了pH值、矿物掺合料的使用和溶液流量对混凝土劣化的影响。制备了含有高炉矿渣、粉煤灰和硅灰的水泥净浆和砂浆试件，并将其浸泡在pH=1.0和2.0的硫酸溶液中。一些标本被浸泡在流动的溶液中。通过用泵使溶液循环而产生流动。结果表明，在pH=2.0的流动硫酸溶液中浸泡试件的冲蚀速度比浸泡在静态溶液中的试件快，而在pH=1.0的静态和流动的硫酸溶液中浸泡试件的冲蚀速度几乎相同。因此，根据pH值的不同，作用在试件表面的剪切力会加速硫酸侵蚀的速度。