Assessment, optimization, and modeling of concrete repairs for enhanced performance and durability

可见的基础设施下降已成为加拿大主要关切的一个原因。不仅是加拿大人的安全受到突然的不可预测的故障的损害，而且我们的社会有效运作的能力也受到目前在社区内运输货物和人员的挑战的危害。修复老化的基础设施被认为是一项关键的国家需求，目前一半以上的省市预算都用于修复和恢复。尽管如此，设计结构有效，坚固，耐用和可持续的维修仍然很困难，因为它被过去的失败所证明。修复效果和退化受到密切相关的机械、物理和化学现象的影响，其中一些现象目前在修复设计中没有得到适当考虑，主要是因为它们的性质和影响尚未得到充分了解。此外，人们越来越关注通常使用的普通波特兰水泥（OPC）混凝土的环境可持续性。OPC生产每吨水泥释放约一吨CO2，并开采可耗尽的自然资源为OPC生产提供原材料。虽然通常的做法是用更环保的外加剂部分取代OPC，但应寻求更可持续的解决方案。* 本项目的主要目标是调查维修的那些方面仍然不清楚，并提供工具，将其纳入结构和非结构维修的设计，评估和优化。研究成果将对基础设施的安全性和耐久性产生积极影响，减少所需的进一步维修和维护操作，从而最大限度地减少长期成本和碳足迹。通过不同应力条件下的力学性能试验，研究了基体修复粘结的韧性和粘结性能。各种材料和外加剂的性能进行了比较，并开发模型进行修复优化和结构和耐久性分析。修复电化学不兼容性和流体传输性能进行评估，建模和优化;这些是影响修复脆弱性的有害化学和物理过程，包括腐蚀，冻融，化学侵蚀和收缩的关键属性。此外，混凝土修复的可行性与替代低碳足迹的粘合剂获得与碱活化低钙粉煤灰，偏高岭土，偏高岭土和矿渣的组合进行了评估和应用领域的确定。最后，不同的研究成果应用在一个示范项目中的钢筋混凝土柱的康复，评估和证明开发的材料和解决方案的有效性和预测模型的准确性。

Visible declining infrastructure has become a reason for major concern in Canada. Not only is the safety of Canadians compromised by sudden non-predicted failures, but also the ability of our society to function effectively is jeopardized by the current challenges to moving goods and people within communities. Repairing aging infrastructure is considered a critical national need, with more than half of the municipal and provincial budgets now directed at repair and rehabilitation. Nonetheless, designing repairs that are structurally effective, robust, durable, and sustainable remains difficult as it was proven by past failures. Repair effectiveness and degradation are affected by strongly interrelated mechanical, physical and chemical phenomena, some of which are currently not properly considered in repair design, mainly because their nature and effects are not fully understood. Furthermore, there is increasing concern by the environmental sustainability of the Ordinary Portland Cement (OPC) concretes commonly employed. OPC manufacturing releases about a ton of CO2 for each ton of cement produced and exhaustible natural resources are exploited to supply raw materials for OPC production. Although it is common practice to partially replace OPC with more environmentally friendly admixtures, more sustainable solutions should be pursued. ***The main goal of this project is to investigate those aspects of repairs that remain unclear and provide tools for their inclusion in design, assessment, and optimization of structural and non-structural repairs. Research outcomes will positively impact infrastructure safety and durability, lead to a reduction of further repair and maintenance operations required and, thus, minimize long-term costs and carbon footprint. Substrate-repair bond toughness and cohesiveness are experimentally investigated through mechanical tests under different stress conditions. The performance of various materials and admixtures are compared and models are developed for repair optimization and for structural and durability analysis. Repair electrochemical incompatibility and fluid-transport properties are assessed, modeled, and optimized; these are critical properties affecting repair vulnerability to harmful chemical and physical processes, including corrosion, freeze-thaw, chemical attack, and shrinkage. Furthermore, the feasibility of concrete repairs made with alternative low-carbon-footprint binders obtained with alkali-activated low-calcium fly ash, metakaolin, and combination of metakaolin and slag is assessed and fields of applications are identified. Finally, the outcomes of the different studies are applied in a demonstration project regarding the rehabilitation of a reinforced concrete column, to evaluate and demonstrate the effectiveness of materials and solutions developed and the accuracy of the predictive models.