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首页> 外文期刊>Bulletin des Laboratoires des Ponts et Chaussees >La formation differee de l'ettringite dans les betons de parties d'ouvrages massives Synthese des etudes de ponts degrades
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La formation differee de l'ettringite dans les betons de parties d'ouvrages massives Synthese des etudes de ponts degrades

机译：块状结构中混凝土中钙矾石的延迟形成退化桥梁研究的综合

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摘要

The Delayed Ettringite Formation is a chemical reaction that may lie at the origin of deterioration in concrete. This internal sulfate reaction is capable of altering the entire concrete structure without relying upon an external sulfate source; it thereby causes swelling of the material, which in turn incites cracking of the structure. The approach undertaken herein has consisted of appraising five structural concretes submitted exclusively to an alteration due to the delayed Ettringite Formation. The simultaneous existence of an alkali-silica reaction was not observed, and the determinant factors involved in the reaction have been sought. The study of materials employed has revealed that this deterioration does not solely entail heat-treated concretes, but may also be encountered within large-scale solid concrete facilities. For this latter material application, the heat cycle appears more intense given the duration in which high temperatures are maintained (> 70℃ over several days). A number of parameters stand out as being essential to the development of the reaction: solid concrete specimen, concrete casting during the summer period, a high cement proportion, type of cement (Portland cement, alkaline content, SO_3 and C_3A), more humid ambient conditions and mineralogical nature of the aggregates. The combination of such parameters serves in all likelihood to limit the number of structures affected by this type of degradation.
机译：延迟钙矾石形成是一种化学反应，可能是混凝土变质的起点。这种内部硫酸盐反应能够改变整个混凝土结构，而无需依靠外部硫酸盐源。因此，它导致材料溶胀，进而引起结构破裂。本文采用的方法包括评估仅因延缓钙矾石形成而提交变更的五种结构混凝土。没有观察到碱-二氧化硅反应同时存在，并且已经寻找了反应中涉及的决定因素。对所用材料的研究表明，这种变质不仅需要热处理的混凝土，而且在大型固体混凝土设施中也可能遇到。对于后一种材料应用，考虑到维持高温的持续时间（几天内> 70℃），热循环显得更加强烈。有许多参数对于反应的发展至关重要：固态混凝土试样，夏季的混凝土浇铸，高水泥比例，水泥类型（硅酸盐水泥，碱含量，SO_3和C_3A），环境更潮湿骨料的条件和矿物学性质。此类参数的组合极有可能用于限制受此类降解影响的结构数量。

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