2007 Volume 14 Issue 327 Pages 75-82
This study verified an effect of their steam curing method on their delayed expansion when using the ettringite generating type high strength additive, to propose their safe using method.
When increasing the steam curing temperature, anhydrite contained in the additive will remain to be unreacted. Thereafter, it was found that the anhydrite reacted at a wet environment, to increase formation of the ettringite to bring the delayed expansion. And, it can be thought that by thermal decomposition of the ettringite there increases SO3 in CSH, to further rise risk of the delayed expansion.
When the steam curing temperature exceeds 80°C, there would form a risk to further increase the delayed expansion. To control the delayed expansion, it was found to be important to endeavor not to excessively rise the curing temperature, to fix sulfate ion as the ettringite, and not to form transfer of the sulfate ions into solidified concrete.
