Influence of Mineral Additives on the Efflorescence of Ettringite-Rich Systems.

Linglin Xu,Siyu Liu,Zhenghong Yang,Peiming Wang

doi:10.3390/ma14185464

Abstract

Efflorescence is aesthetically undesirable to all cementitious materials products and mainly results from the carbonation of hydrates and salt precipitation. Alternative binders without portlandite formation theoretically have much lower efflorescence risk, but in practice, the efflorescence of ettringite-rich systems is still serious. This study reports the impacts of mineral additives on the efflorescence of ettringite-rich systems and the corresponding microstructural evolution. The effects of silica fume, limestone powder, and diatomite on efflorescence and the capillary pore structure of mortars were investigated from a multi-scale analysis. The composition and microstructure of efflorescent phases were revealed by optical microscope (O.M.), in-situ Raman spectroscopy, and Scanning Electron Microscopy (SEM). Results indicate that the addition of mineral additives can efficiently inhibit the efflorescence of reference, especially with silica fume. Similar to the ettringite-rich system, the efflorescence substances of all modifies are composed of ettringite and CaCO3, indicating that the addition of mineral admixture does not lead to chemical reactions, lower capillary absorption coefficient of mineral additives modified specimen, the denser pore structure and the lower efflorescence degree.

Highlights

IntroductionEfflorescence of cementitious materials is a serious construction quality problem due to the migration of alkali ions from the inner pore solution to the surface of mortars, concrete, or brickwork
The impact of mineral additives on efflorescence of the ettringite-rich system hasfume, been limestone revealed from a multi-scale analysis
The efflorescence of the ettringite-rich system has been revealed from a multi-scale analySome main conclusions can be drawn as follows: sis

Summary

Introduction

Efflorescence of cementitious materials is a serious construction quality problem due to the migration of alkali ions from the inner pore solution to the surface of mortars, concrete, or brickwork. These ions gradually react with carbon dioxide and water from the atmosphere to form whitish deposits [1,2]. Visible severe efflorescence damages the aesthetics and deteriorates the physical properties of the cementitious materials [3]. Nowadays, how to decrease the efflorescence of cementitious materials has aroused increasing attention [4,5,6]

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Discussion

Conclusion