Strength, microstructure and durability of concretes cured by flue gas vacuum carbonation

烟气真空碳化养护混凝土的强度、微观结构和耐久性

• 批准号: RGPIN-2016-03625
• 负责人: Shao, Yixin
• 金额: $ 2.62万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=664874
• 关键词: Strength; microstructure; durability; concretes; cured

Early age carbonation curing of concrete is considered as one of the promising technologies for carbon capture and utilization in greenhouse gas mitigation exercise. Gaseous carbon dioxide is converted into solid calcium carbonates by calcium silicate carbonation and stored in concrete as nano crystals for performance enhancement. The process makes concrete greener, stronger and more durable. Currently the carbonation process works in a pressure chamber and with a carbon dioxide gas of 99% purity. Although it provides the best conditions for high degree of reaction, there are technical and economical challenges for large scale implementation. The first challenge is the use of pressure chamber. Most of the concrete producers do not use pressure chamber. To promote carbonation technology, it is imperative to develop a system that requires no pressure chamber. The second challenge is the price of the high purity gas. The commercial carbon dioxide gas costs about $500/ton. Unless it can be reduced to $50/ton, the gas price will remain an obstacle for applications. The question is if the as-captured flue gas can be used directly without chemical separation. This proposed research is directed to address the two challenges. A flue gas vacuum carbonation system will be developed to replace the pressure chamber and the pure gas in early carbonation process. The research will be carried out in four tasks: Task 1 is to establish a vacuum carbonation system with pure gas in a sealed-only chamber. It will serve the scenario when the recover CO2 is affordable. Task 2 is to develop a flue gas carbonation process in a pressure chamber to study the reaction efficiency with low concentration gas. Task 3 is to combine the techniques developed in Tasks 1 and 2 to examine the possibility of the flue gas carbonation in a vacuum system without pressure chamber. Task 4 will perform comprehensive microstructural and durability analysis of the concrete produced by early carbonation. Innovative carbonation devices will be designed and implemented to meet industry scale and the effectiveness of the technology will be assessed by strength gain and carbon uptake. Two typical concrete products will be used to test the developed process. They are concrete paving stones as precast product and concrete slabs such as pavements or bridge decks as cast-in-place product. Both products serve in severe outdoor exposure conditions and will benefit from carbonate precipitation for durability improvement. If successful, early carbonation curing can find more applications in both precast and cast-in-place concretes for carbon storage and performance enhancement at an affordable price. The developed technology will become the "game changer" in the construction industry.

混凝土的早期碳化养护被认为是温室气体减排活动中碳捕获和利用的有前途的技术之一。气态二氧化碳通过硅酸钙碳化转化为固体碳酸钙，并以纳米晶体的形式储存在混凝土中以增强性能。该工艺使混凝土更环保、更坚固、更耐用。 目前，碳酸化过程在压力室中进行，二氧化碳气体纯度为 99%。尽管它为高度反应提供了最佳条件，但大规模实施仍存在技术和经济挑战。第一个挑战是压力室的使用。大多数混凝土生产商不使用压力室。为了推广碳酸化技术，开发一种不需要压力室的系统势在必行。第二个挑战是高纯度气体的价格。商业二氧化碳气体成本约为500美元/吨。除非能降至50美元/吨，否则天然气价格仍将是申请的障碍。问题是捕获的烟气是否可以直接使用而无需化学分离。这项拟议的研究旨在解决这两个挑战。开发烟气真空碳酸化系统，以取代早期碳酸化过程中的压力室和纯气。该研究将分四项任务进行： 任务1是在密闭室中建立纯气体真空碳酸化系统。当回收二氧化碳的费用可以承受时，它将服务于这种情况。任务2是开发压力室中的烟气碳酸化工艺，以研究低浓度气体的反应效率。任务3是结合任务1和2中开发的技术来检查在没有压力室的真空系统中烟气碳酸化的可能性。任务 4 将对早期碳化产生的混凝土进行全面的微观结构和耐久性分析。将设计和实施创新的碳酸化装置以满足行业规模，并且将通过强度增益和碳吸收来评估该技术的有效性。将使用两种典型的混凝土产品来测试所开发的工艺。它们是作为预制产品的混凝土铺路石和作为现浇产品的混凝土板，例如人行道或桥面。这两种产品都在恶劣的户外暴露条件下使用，并将受益于碳酸盐沉淀，从而提高耐用性。如果成功，早期碳化固化可以在预制混凝土和现浇混凝土中以可承受的价格找到更多应用，以实现碳储存和性能增强。所开发的技术将成为建筑行业的“游戏规则改变者”。