Abstract
Calcium sulpho-aluminate (CSA) cements all contain ye’elimite, either as the main phase or in intermediate amounts, while they differ in their content of accessory phases. Belite is the main phase in most CSA cements, however, alite - CSA cements have been produced. The hydrate phases formed during hydration of CSA cements depend on the type of CSA cement and the amount of gypsum added. The hydration reactions of the main phases are by themselves well documented, whereas the simultaneous hydration of CSA cement components is not fully understood in terms of hydration products and kinetics.
To further study these aspects of CSA cement hydration, the present work investigates the hydration kinetics of ternary model systems of ye’elimite, gypsum and alite as well as ye’elimite, gypsum and belite. All blends were prepared from pure, synthesized phases of ye’elimite, belite and alite. They all employed a ye’elimite content of minimum 50 wt.%, to have ye’elimite as the principal phase, and gypsum contents optimized according to the actual amount of ye’elimite. Paste samples were prepared for the individual blends and the hydrate phase assemblages were established after hydration for 6h, 12h, 24h, 2 days, 7 days, 14 days and 28 days from a combination of solid-state NMR spectroscopy, powder X-ray diffraction, and thermal analysis. The degrees of reaction for the individual phases were derived from these experiments and used to identify and evaluate the factors influencing the reactivity and hydration kinetics.
The improved understanding of the hydrate phase assemblages as well as the hydration kinetics for the model systems will form the fundamental basis for further optimizations of blended systems including ye’elimite with the aim of maximizing the reaction degree of the main clinker phases during the first few weeks of hydration.
To further study these aspects of CSA cement hydration, the present work investigates the hydration kinetics of ternary model systems of ye’elimite, gypsum and alite as well as ye’elimite, gypsum and belite. All blends were prepared from pure, synthesized phases of ye’elimite, belite and alite. They all employed a ye’elimite content of minimum 50 wt.%, to have ye’elimite as the principal phase, and gypsum contents optimized according to the actual amount of ye’elimite. Paste samples were prepared for the individual blends and the hydrate phase assemblages were established after hydration for 6h, 12h, 24h, 2 days, 7 days, 14 days and 28 days from a combination of solid-state NMR spectroscopy, powder X-ray diffraction, and thermal analysis. The degrees of reaction for the individual phases were derived from these experiments and used to identify and evaluate the factors influencing the reactivity and hydration kinetics.
The improved understanding of the hydrate phase assemblages as well as the hydration kinetics for the model systems will form the fundamental basis for further optimizations of blended systems including ye’elimite with the aim of maximizing the reaction degree of the main clinker phases during the first few weeks of hydration.
| Original language | English |
|---|---|
| Publication date | 10 Oct 2016 |
| Publication status | Published - 10 Oct 2016 |
| Event | 2nd International Conference on the Chemistry of Construction Materials - Technische Universität München, München, Germany Duration: 10 Oct 2016 → 12 Oct 2016 Conference number: 2 |
Conference
| Conference | 2nd International Conference on the Chemistry of Construction Materials |
|---|---|
| Number | 2 |
| Location | Technische Universität München |
| Country/Territory | Germany |
| City | München |
| Period | 10/10/2016 → 12/10/2016 |