2018 Volume 72 Issue 1 Pages 114-121
The use of blast furnace slag cement for concrete production with air entrained agent（AE）for improving freeze-thaw resistance in cold climates such as Hokkaido region cause the decrease of the initial strength of concrete. In order to improve initial strength of concrete, a novel curing accelerator using a combination of a polyol type and a sulfate type has been developed, and a high hydration acceleration effect is obtained by previous reports. However, its hydration acceleration mechanism has not been clarified in detail. In this study, attempts were made to elucidate the mechanism of initial strength development of blast furnace slag cement by adding a new curing accelerator. Firstly, we confirmed the strength development and ultrasonic pulse velocity of hardened cement pastes with/without the hydration accelerator. And we investigated the phase assemblage in hardened cement pastes by XRD Rietveld method, and the degree of reaction of blast furnace slag in hardened blast furnace slag cement pastes was determined by backscattered electron image. As a result, it is possible to accelerate the hydration reaction of the aluminate phase by combining the polyol type and the sulfate type of agent, there is a possibility that the curing accelerator dissolves the portlandite to accelerate the reaction of the blast furnace slag fine powder.
