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

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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.