Setting reaction of a olivine-based Mg-phosphate cement

• Published in: Cement and concrete research 2024-12, Vol.186, p.107694, Article 107694
• Main Authors: Bernasconi, Davide, Viani, Alberto, Zárybnická, Lucie, Bordignon, Simone, Godinho, Jose R.A., Maximenko, Alexey, Celikutku, Cem, Jafri, Sadaf Fatima, Borfecchia, Elisa, Wehrung, Quentin, Gobetto, Roberto, Pavese, Alessandro
• Format: Article
• Language: English
• Subjects: Alternative binders; Magnesium cement; Olivine; Phosphate cement
• ISSN: 0008-8846
• DOI: 10.1016/j.cemconres.2024.107694

The cementitious properties of natural Mg-rich olivine when reacted with a phosphoric acid solution are investigated, as a function of acid concentration and liquid/solid mass ratio. The obtained cements are composed of residual olivine crystals and amorphous silica nanoparticles dispersed in a dense and compact newberyite (MgHPO4∙3H2O) matrix. The latter was mostly formed by packed micrometric tabular crystals, although evidence of the presence of a fraction of amorphous MgHPO4 was also found. Water content in the raw mix was observed to play a pivotal role on the reaction pathway, either promoting porosity or hindering the crystallization of the products. Up to 57 % of olivine reactivity, whose dissolution was promoted by the curing temperature (60 °C) and low pH, was achieved. All in all, these results indicate that the industrial mineral olivine may serve a viable source of Mg for the production of phosphate cements. [Display omitted] •Mg-olivine is tested for the first time as raw material in the production of MPC.•The cements are made of amorphous silica dispersed in a dense newberyite matrix.•The precipitated Mg-phosphates are mostly crystalline.•Water plays a pivotal role in defining the reaction pathways.•Up to 75 MPa of compressive strength is reached.