Very high early strength calcium aluminate based binary and ternary cementitious systems: properties, hydration and microstructure

Abstract

Calcium aluminate cement (CAC) is a cement type that has superior properties such as rapid strength gain, high resistance to high temperatures and harmful chemicals. However, the result of the using of CACs in the production of structural elements occur strength decreases at later ages as a result of a series of chemical reactions called ‘conversion reactions’ seen in these cements. In this study, the hydration kinetics and the crystalline and amorphous structures formed as a result of hydration were investigated in CAC containing different amounts and types of main oxides-based binary and ternary systems. Considering the results obtained, the main hydration product seen in these specimens was ettringite. Unlike many studies in the literature, metastable structures which cause conversion reactions, such as CAH₁₀, C₂AH₈, have not been observed. Instead of conversion of the phases, ettringite needles were became thin and elongate which causes the paste structure porous and thus causing expansion and strength reduction at the later stages of hydration in some mixtures produce high amounts of ettringite. On the other hand, it is understood that the formation of strätlingite was limited strength decreases in systems where high silica fume is used.

Graphical abstract

Keywords:

• Calcium aluminate cement
• ternary systems
• rapid strength mortar
• dimensional stability
• cement microstructure

Acknowledgements

This study was prepared from the PhD thesis of Murat Saydan with the advisor of Ülkü Sultan Keskin and co-advisor of Burak Uzal, which was accepted by Konya Technical University, Graduate Education Institute, Department of Civil Engineering.

Data availability statement

The data that support the findings of this study are available from the corresponding author, [MS], upon reasonable request.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This study was funded by the Scientific and Technological Research Council of Turkey (TUBITAK) [ARDEB 1002 grant number 119M159]; and the researcher training program by Council of Higher Education (Turkey) [grant number 2016-ÖYP-049].