1993 Volume 4 Issue 2 Pages 69-78
It is necessary to clarify how concrete will be degraded for super long term, when thinking of the use of concrete for construction of nuclear waste repositories. In order to develop an acceleration test method for predicting deterioration due to dissolution of extremely small amount of cement hydrate, the authors examined the amount of Ca2+ dissolved in water and the deterioration of the hydrated cement structure under electrical potential gradient conditions. The results were as follows. (1) Application of potential gradients to the specimen significantly accelerated the dissolution of Ca2+ compared with the result in case of no potential gradient. The amount of Ca2+ dissolved in water was almost proportionate to the amount of potential gradient. (2) As Ca2+ is gradually dissolved, deteriorated region enlarged toward to the interior of the specimen. This deterioration rate is also in proportion to potential gradient. (3) Porosities of the hydrated cement structures increase with above deterioration.
