부산대학교 도서관

In order to study the influence of the maturation type on the behavior of concrete containing fly ash, specimens of mixtures and mortars have been made with a water/binder ratio of 0.40. In all cases, the proportion of fly ash has been constant and equal to 20%. Different maturation types have been studied: the confinement in an aluminum foil, the immersion in a lime saturated solution and the immersion in an NaOH and KOH solution simulating the interstitial solution that is found in concrete. At different times, the composition of the interstitial solution, the resistance to compression, the content of chemically bound water as well as the quantity of portlandite have been measured in order to evaluate the maturation effect. The results show that the maturation type has an influence on the fly ash hydration rate. The data also indicate that it is essential that the specimens have enough water to hydrate themselves. In the case of the confinement of samples, evaporation must absolutely be avoided. In order to qualify mineral additions representatively, and to measure their properties on representative specimens of the conditions usually found in the concrete structure mass, the alkalinity of the interstitial solution must be preserved. Immersion of samples in an NaOH and KOH solution at a concentration simulating that of the interstitial solution is suggested. The maturation in lime water provides enough water for hydration but pulls down the alkalinity of the interstitial solution too rapidly, which reduces the fly ash hydration rate.