Development of a relationship between specifications and in situ testing for concrete durability

建立混凝土耐久性规范和现场测试之间的关系

• 批准号: 312213-2007
• 负责人: Nokken, Michelle
• 金额: $ 1.38万
• 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: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=481182
• 关键词: Development; relationship; between; specifications; situ

The long-term durability of concrete infrastructure is highly dependant on its mixture design and subsequent handling and placement. However, rarely is concrete tested in the field to determine its adherence to specifications especially when they contain requirements for durability. Most commonly specified performance-based durability tests are conducted under standard laboratory conditions. However, the major drawback to most of these methods is that they are performed on concrete specimens 14 to 56 days after casting. In addition, these specimens may be prepared on-site, but are frequently relocated to a laboratory after casting. These relatively small specimens are subjected to different placement and curing techniques as well as a different temperature history. The program will investigate various techniques for their potential applicability for field-testing of durability as well as to assess their sensitivity to factors encountered on site (poor curing, poor compaction). The novelty of this program is that concrete will be tested for durability in the field conditions rather than in a laboratory environment. Ideally, the testing should be performed well before 28 days as tight construction schedules typically necessitate pouring large volumes of concrete in a short time period. Previous work by the applicant indicated that the majority of the changes occur in the first 7 days after casting. By testing as early as possible, any potential defects can be found quickly and corrective action taken. Durable concrete infrastructure is important to the Canadian economy as repair and replacement costs are significant as well as the associated decreases in productivity. In addition, the program will test existing structures to determine adherence to specifications and the likelihood of potential premature failure. The program results are expected to change the manner in which concrete is tested. By testing field concrete rather than standard lab specimens, project owners and engineers will have a more realistic indication of the expected long-term performance of the concrete structure. In turn, by becoming involved with monitoring site performance, contractors will become invested in the process of constructing a durable end product.

混凝土基础设施的长期耐久性在很大程度上取决于其混合物设计以及随后的处理和浇筑。然而，混凝土很少在现场进行测试，以确定其是否符合规范，特别是当它们包含耐久性要求时。最常见的基于性能的耐久性测试是在标准实验室条件下进行的。然而，这些方法中的大多数的主要缺点是，它们是在混凝土样本上进行14至56天后铸造。此外，这些样品可以在现场制备，但在铸造后经常被转移到实验室。这些相对较小的试样经受不同的放置和固化技术以及不同的温度历史。该计划将研究各种技术，以确定其在耐久性现场测试中的潜在适用性，并评估其对现场遇到的因素（固化不良，压实不良）的敏感性。该计划的新奇在于，混凝土将在现场条件下而不是在实验室环境中进行耐久性测试。理想情况下，测试应在28天之前进行，因为紧张的施工进度通常需要在短时间内浇注大量混凝土。申请人以前的工作表明，大多数变化发生在铸造后的前7天。通过尽早测试，可以快速发现任何潜在的缺陷并采取纠正措施。耐用的混凝土基础设施对加拿大经济很重要，因为维修和更换成本很高，而且生产力也会下降。此外，该计划将测试现有结构，以确定是否符合规范以及潜在过早失效的可能性。该计划的结果预计将改变混凝土测试的方式。通过测试现场混凝土而不是标准的实验室样本，项目业主和工程师将对混凝土结构的预期长期性能有更现实的指示。反过来，通过参与监测现场性能，承包商将投资于建造耐用最终产品的过程。