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Effect of de-icing salt and aluminous supplementary cementitious materials on the mechanisms of the alkali-silica reaction in concrete

除冰盐和高铝辅助胶凝材料对混凝土碱硅反应机理的影响

基本信息

批准号：
196752921
负责人：
Professor Dr.-Ing. Detlef Heinz
金额：
--
依托单位：
Centrum Baustoffe und Materialprüfung (cbm)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2011
资助国家：
德国
起止时间：
2010-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/196752921?language=en
关键词：
Effect de icing salt aluminous

项目摘要

The aim of the second phase of this project is to characterize the damaging process of alkali silica reaction (ASR) with natural aggregates under field temperature conditions in the presence of sodium chloride taking into account that the aluminium content of supplementary cementitious materials (SCMs) in the binder contribute to the composition and the swelling properties of ASR gels.The project focusses on the damage mechanisms and processes in concretes with a highly reactive, artificial aggregate and concretes with less reactive, natural aggregates (e.g. diabase, granite). In particular, the formation of the ASR gel is considered, as a new approach, in the light of the effect of aqueous siliceous species in the concrete pore solution. What effects do the properties (especially mineralogical composition and microstructure) of the reacting aggregate have on the reactions? Furthermore, the effect of variations in temperature and in composition of the penetrating salt (e.g. NaCl or KCl) on the formation and the stability of the siliceous species is investigated. Based on these results, a correlation between the composition and swelling properties of the gels and therefore concrete damage can be made.To further the investigations of the first proposal, the storage period of the current concrete prisms will be extended. A further funding period would provide answers for the following open and new questions.1. What long-term changes occur in the concrete pore solution during an ongoing ASR in natural aggregates in the presence of NaCl?2. Can NaCl cause a damaging ASR in concrete when natural aggregates (e.g. diabase and granite) are used which are at present considered as non-reactive?3. What is the composition of ASR gels formed in presence of NaCl and how is it affected by the binder (cement and SCM) and the properties of the reacting aggregate?4. Which siliceous species form in the concrete pore solution in presence of NaCl or KCl and how do they affect the severity of the ASR?5. Is damaging ASR enhanced at winter temperatures (2 °C) in combination with de-icing salt owing to changes in pore solution composition, despite a slower chemical reaction at lower temperatures?

本项目第二阶段的目的是在现场温度条件下，在氯化钠存在的情况下，表征碱硅反应（ASR）与天然聚集体的破坏过程，同时考虑到粘合剂中补充胶凝材料（SCMs）的铝含量对ASR凝胶的组成和膨胀性能的影响。该项目侧重于高活性人工骨料混凝土和低活性天然骨料混凝土（如辉绿石、花岗岩）的损伤机制和过程。特别是，考虑到混凝土孔隙溶液中含水硅质组分的影响，ASR凝胶的形成被认为是一种新的途径。反应聚合体的性质（特别是矿物组成和微观结构）对反应有什么影响？此外，还研究了温度和渗透盐（如NaCl或KCl）组成的变化对硅质矿物的形成和稳定性的影响。基于这些结果，可以得出凝胶的组成和膨胀特性与混凝土损伤之间的相关性。为了进一步研究第一项建议，将延长目前混凝土棱镜的储存期。再延长一段供资期将为下列悬而未决的新问题提供答案。在NaCl的存在下，天然骨料在进行ASR时，混凝土孔隙溶液会发生什么长期变化？当使用天然骨料（如辉绿石和花岗岩）时，氯化钠会在混凝土中引起破坏性的ASR吗？在NaCl存在下形成的ASR凝胶的组成是什么？它如何受到粘合剂（水泥和SCM）和反应集料性质的影响？在NaCl或KCl的作用下，混凝土孔隙溶液中形成了哪些硅质组分，它们对ASR的严重程度有何影响？尽管低温下的化学反应较慢，但在冬季温度（2°C）下，由于孔隙溶液成分的变化，破坏性的ASR是否会增强？