The Influence of the Acceleration Admixture Type and Composition of Cement on Hydration Heat and Setting Time of Slag Blended Cement

Abstract

This article presents recent research on cements containing GGBFS and their modifications with accelerating admixtures. The initial setting time and hydration heat evolution results are presented for cement CEM II/B-S and CEM III/A manufactured with three Portland clinkers of various phase compositions. The research was carried out at 8 °C and 20 °C. The main objective is to assess the behavior of blended cements in cooperation with modern admixtures that contain nucleation seeds. The authors aimed to compare and evaluate different methods to reduce setting time, namely, the effects of temperature, the specific surface area of cement and GGBFS, the type of Portland clinker, the content of GGBFS, and presence of accelerators. Many of these aspects appear in separate studies, and the authors wanted a more comprehensive coverage of the subject. Those methods of reducing the setting time can be ranked: the most effective is to increase the temperature of the ingredients and the surroundings, the second is to reduce the GGBFS content in cement, and the use of accelerators, and the least effective is the additional milling of Portland clinker. However, of these methods, only the use of accelerators is acceptable in terms of sustainability. Prospective research is a detailed study on the amounts of C-S-H phase and portlandite to determine the hydration rate.

Keywords

• cement
• slag blended cement
• accelerating admixtures
• concrete
• hydration heat
• initial setting time