Self healing of early age cracks in cementitious materials

水泥材料早期裂缝的自愈

• 批准号: RGPIN-2022-05436
• 负责人: Chidiac, Samir
• 金额: $ 1.89万
• 依托单位: McMaster University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=749313
• 关键词: Self; healing; early; age; cracks

Concrete, the world's most used construction material, is susceptible to cracking that tends to compromise its structural integrity and durability. Traditional concrete repairs have failed in part to mitigate the problem because, in most cases, damage is only detected after concrete deterioration has already progressed. The implications have been economically, socially, and economically disastrous owing to a deteriorated built infrastructure that is costing Canada about $10 billion annually of public funds to repair or replace. The American Society of Civil Engineers estimated $2.2 trillion are needed to repair and retrofit the infrastructure over 5 years. As a result, a need exists to develop a new concrete that is either crack free or can heal itself in the event of cracking. Hence, self-healing concrete has emerged as an alternative and sustainable solution by emulating nature's time-tested strategy. Accordingly, this study aims to develop a cementitious mortar that can self-seal when cracking occurs. The long-term objective is to develop specifications and tools for designing and printing autonomic self-healing cementitious material. The self-healing mortar utilizes encapsulated healing agents that are not intrinsic to concrete. The healing agents are released when cracks cross the capsules and react and bind the cracked faces together. The efficiency of the autonomic self-healing mortar depends on the survivability of the capsules during mixing, mechanical compatibility of capsules and mortar, capsules bond strength, healing agents flow properties, and distribution of the capsules. Accordingly, experimental and analytical programs were developed to 1) quantify the likelihood of a 3-D crack intersecting capsules and self-healing in cementitious material, 2) investigate analytically the mechanical interaction between capsules and mortar as the mortar hardens and shrinkage cracks develop, 3) determine experimentally the capsules' properties necessary to survive during mixing and placing of mortar, and 4) study experimentally the efficacy and durability of capsules as mortar hardens and shrinkage cracks develop. This research is novel in many ways. It provides a holistic approach to study the mechanical and chemical aspects of self-healing mortar which includes cementitious material, polymeric capsules and healing agents, and their interactions. This research which addresses major areas of self-healing mortar that lack quantitative knowledge and measures, will yield analytical models and test methods for evaluating the performance and durability of self-healing mortar, and quantification tools for reliably and effectively designing self-healing mortar. In the long-term, translating and mobilizing the generated knowledge will significantly improve our understanding of the performance and durability of concrete, and ensure sustainable Canadian concrete infrastructure that will endure for many generations and provide economic growth to Canada.

混凝土是世界上使用最多的建筑材料，容易开裂，这往往会损害其结构的完整性和耐久性。传统的混凝土修补在一定程度上未能缓解这一问题，因为在大多数情况下，只有在混凝土劣化已经进展之后才能发现损坏。其影响在经济、社会和经济上都是灾难性的，因为基础设施的恶化每年要花费加拿大大约100亿美元的公共资金来维修或更换。美国土木工程师协会估计，在5年内需要2.2万亿美元来修复和改造基础设施。因此，需要开发一种新的混凝土，该混凝土是无裂纹的或者在裂纹的情况下能够自我修复。因此，自我修复混凝土已经成为一种替代和可持续的解决方案，通过模仿大自然的久经考验的战略。因此，本研究的目的是开发一种水泥砂浆，可以自密封时发生裂缝。长期目标是开发用于设计和打印自主自愈水泥材料的规范和工具。 自愈合砂浆利用不是混凝土固有的封装愈合剂。当裂缝穿过胶囊时，愈合剂被释放，并反应并将裂缝面结合在一起。自主自愈合砂浆的效率取决于胶囊在混合期间的存活性、胶囊和砂浆的机械相容性、胶囊粘合强度、愈合剂流动性质和胶囊的分布。因此，开发了实验和分析程序，以1）量化与胶囊相交的3-D裂纹和胶凝材料中的自愈合的可能性，2）分析地研究随着砂浆硬化和收缩裂纹的发展胶囊和砂浆之间的机械相互作用，3）实验地确定胶囊在砂浆的混合和放置期间存活所必需的性质，（4）试验研究胶囊在砂浆硬化和收缩裂缝发展过程中的功效和耐久性。这项研究在许多方面都是新颖的。它提供了一个整体的方法来研究自愈合砂浆的机械和化学方面，包括胶凝材料，聚合物胶囊和愈合剂，以及它们之间的相互作用。本研究针对自愈合砂浆缺乏定量知识和措施的主要领域，将产生用于评估自愈合砂浆性能和耐久性的分析模型和测试方法，以及用于可靠有效地设计自愈合砂浆的量化工具。从长远来看，翻译和调动所产生的知识将大大提高我们对混凝土性能和耐久性的理解，并确保加拿大混凝土基础设施的可持续性，使其能够持续几代人，并为加拿大提供经济增长。