Restrained shrinkage and creep of self-consolidating concrete: Fid-Bau Portal

Restrained shrinkage and creep of self-consolidating concrete

D'Ambrosia, Matthew D. / Lange, David A. / Brinks, Andrew J.

An investigation of the early age mechanical behavior of SCC material has revealed a potentially high risk for cracking. Analysis of a database of SCC mixture proportions indicates a trend to use high cement paste content and a relatively low w/cm ratio. As a result, autogenous shrinkage may cause significant stress at an early age and the creep capacity may be diminished in low w/cm ratio materials. These factors contribute to increasing the cracking risk at early age. On the other hand, the tendency for SCC to have higher early age strength gain and ultimate strength decreases the cracking risk. SCC mixtures are often developed with certain flow characteristics in mind, but caution should be used so that cracking is avoided. A strategy that minimizes cement paste content to achieve the necessary flow characteristics is beneficial. Using w/cm ratio that avoids significant autogenous shrinkage will reduce the potential for shrinkage stress development. Providing external water during curing in field applications will also delay shrinkage stress development at early age and reduce the overall magnitude of shrinkage. In general, it is best not to treat SCC as a group of materials with comparable mechanical behavior. Different strategies for mixture proportioning may lead to SCC materials that have the common ability to flow into formwork without mechanical vibration, but have very different behavior when considering mechanical performance and early age cracking risk.