Improved durability testing for field placed concrete and emerging cement systems

改进现场浇筑混凝土和新兴水泥系统的耐久性测试

• 批准号: RGPIN-2018-06715
• 负责人: Nokken, Michelle
• 金额: $ 1.89万
• 依托单位: Concordia University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=714401
• 关键词: Improved; durability; testing; field; placed

The move towards performance-based specifications brings both innovation and challenges to new concrete infrastructure. Producers have the ability to add new materials as they are no longer constrained by prescriptive limitations. In some cases, these new materials may be yet unproven in concrete construction, but may have benefits of extending service life or decreasing the need or frequency of repair. Another complication of these new methods of specification are that a quantitative assessment must be undertaken not only at the prequalification stage, but over time as the project proceeds. Ideally, these tests should be performed field placed concrete rather than cylinders that have not received the same compaction or curing and certainly not the same non-standard exposure conditions. The objectives of the program are: 1) Investigate the hydration, strength development and durability of emerging cement systems, with particular attention to nanoparticles. 2) Examine and develop in situ testing methods for durability compliance, specifically, rapid, non-destructive methods, such as absorption and surface resistivity. Establish methods to convert temperature/moisture influences to a standardized condition. 3) Utilize embedded temperature/moisture sensors onsite to better understand processes related to deterioration due to ASR and freezing. Traditionally, concrete deterioration can be lessened through a three-prong approach of low water to cement ratio, the use of supplementary cementing materials and adequate curing. Unfortunately, many of the supplementary cementing materials, particularly fly ash, do not react with water rather with by-products of cement hydration. In practice, this often translates in low early strength and a delayed period required until adequate strength and durability can be obtained. Nanoparticles have gained interest among the research community due to their ability to act as nucleation sites for cement hydration and therefore overcoming some obstacles associated with other cement replacements. Water absorption and surface resistivity are rapid and simple non-destructive techniques. However, one disadvantage of both these techniques are that the effects of in-situ moisture and ambient temperature can significantly affect the test results. This research program will further investigate the saturation required to obtain reliable data that can be linked to service life predication or repair requirements. As concrete is a porous material, water ingress plays a significant role in deterioration. Small wireless temperature and humidity sensors will be used in both lab and outdoor concrete to understand the role of moisture in degradation.

朝着基于绩效的规范的转变为新的具体基础设施带来了创新和挑战。生产商具有添加新材料的能力，因为它们不再受到规定限制的限制。在某些情况下，这些新材料在混凝土结构中可能尚未得到证实，但可能会延长使用寿命或减少维修的需求或频率。这些新规范方法的另一个复杂性是，不仅必须在资格预审阶段进行定量评估，而且随着项目的进行。理想情况下，应将这些测试放置在没有接受相同压实或固化的混凝土而不是圆柱体上，肯定不是相同的非标准暴露条件。 该程序的目标是： 1）研究新兴水泥系统的水合，强度发育和耐用性，特别关注纳米颗粒。 2）检查并开发原位测试方法是否有耐用性依从性，具体来说，快速，无损的方法，例如吸收和表面电阻率。建立将温度/水分影响转换为标准化条件的方法。 3）现场利用嵌入式温度/水分传感器，以更好地理解与ASR和冷冻导致恶化有关的过程。 传统上，可以通过低水与水泥比，使用补充水泥材料和足够的固化方法来减少混凝土恶化。不幸的是，许多补充胶结材料，尤其是粉煤灰，都不与水反应，而不是与水泥水合的副产品反应。在实践中，这通常会以低早期强度转化，并且需要延迟的时间，直到获得足够的强度和耐用性为止。纳米颗粒由于能够充当水泥水化的成核位点的能力，因此克服了与其他水泥替代物相关的一些障碍，因此纳米颗粒在研究界中引起了人们的兴趣。 吸水和表面电阻率是快速而简单的非破坏性技术。但是，这两种技术的缺点之一是原位水分和环境温度的影响可以显着影响测试结果。该研究计划将进一步调查获得可靠的数据所需的饱和，这些数据可与服务寿命或维修要求相关联。 由于混凝土是一种多孔材料，因此水入口在恶化中起着重要作用。实验室和室外混凝土将使用较小的无线温度和湿度传感器，以了解水分在降解中的作用。