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

本项目第二阶段的目的是在野外温度条件下，考虑到粘结剂中辅助胶凝材料(SCM)中的铝含量对ASR凝胶体的组成和膨胀性能的影响，来表征ASR与天然集料在野外温度条件下的破坏过程。本项目的重点是研究高活性人工集料混凝土和活性较少的天然集料混凝土(如辉绿岩、花岗岩)的损伤机理和过程。特别是，ASR凝胶的形成被认为是一种新的方法，它是根据混凝土孔隙溶液中含水的硅质物种的影响来考虑的。反应集合体的性质(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(如氯化钠或氯化钾)组成的变化对硅质物种的形成和稳定性的影响。根据这些结果，可以建立凝胶的组成和膨胀特性之间的关联，从而导致混凝土损伤。为了进一步研究第一个建议，将延长现有混凝土棱柱的储存期。延长供资期限将为下列公开和新的问题提供答案。在存在氯化钠的天然集料中进行ASR的过程中，混凝土孔隙溶液中会发生什么长期的变化？2.当使用目前被认为是非活性的天然集料(例如辉绿岩和花岗岩)时，氯化钠会在混凝土中引起破坏性的ASR吗？3.在存在氯化钠的情况下形成的ASR凝胶的组成是什么，它是如何受到粘结剂(水泥和SCM)和反应集料的性能的影响的？4.在存在氯化钠或氯化钾的情况下，混凝土孔隙溶液中有哪些硅质形成，它们如何影响ASR的严重程度？5.冬季温度(2摄氏度)与除冰盐的结合是否由于孔隙溶液成分的变化而增加了对ASR的损害，

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?