Understanding the setting and hardening process of wollastonite-based brushite cement. Part 2: Influence of the boron and aluminum concentrations in the mixing solution

Priscillia Laniesse (1) , Céline Cau Dit Coumes (1) , Gwenn Le Saout (2) , Adel Mesbah (3)

1 DPME - Département de recherche sur les Procédés et Matériaux pour les Environnements complexes
2 DMS - Durabilité des éco-Matériaux et Structures
3 ICSM - UMR 5257 - Institut de Chimie Séparative de Marcoule

The mixing solution of wollastonite-based brushite cement is a phosphoric acid solution containing metallic cations and borax. This work complements a previous study devoted to the influence of the H3PO4 concentration, Ca/P and liquid-to-solid (l/s) ratios on the setting and hardening process of the binder by providing new insight into the role of aluminum and boron. Boron retards the setting and decreases the heat released during the process. It also contributes to reduce the macroporosity of the hardened material but yields to poor compressive strength. With aluminum in the mixing solution, the mechanical properties are greatly improved thanks to the precipitation of an amorphous aluminophosphate which increases the density of the cement matrix. But aluminum alone leads to fast setting. A joint addition of boron and aluminum to the mixing solution makes it possible to get a material with optimized properties both in fresh and hardened states.

Mots clés: Hydration; Hydration products; Microstructure; Compressive strength; Chemically bonded ceramics

Domaines: Matériaux

Priscillia Laniesse, Céline Cau Dit Coumes, Gwenn Le Saout, Adel Mesbah. Understanding the setting and hardening process of wollastonite-based brushite cement. Part 2: Influence of the boron and aluminum concentrations in the mixing solution. Cement and Concrete Research, 2021, 140, pp.106288. ⟨10.1016/j.cemconres.2020.106288⟩. ⟨hal-03007174⟩