Fabrication, microstructure, and hydration of nano β-Ca2SiO4 powder by co-precipitation method

Abstract

As the main component of belite cement, nanosizing (decreasing the average particle sizes) of β-C2S is one of the important methods to improve its activity. In this paper, nano β-Ca2SiO4 (β-C2S) powders were synthesized by co-precipitation method which was a facile and easy route. Ca(NO3)2, Tetraethyl orthosilicate (TEOS), and NaOH were used as calcium source, silicon source, and precipitant respectively to make the precursor, which was then sintered into β-C2S phase at 700-1100 °C. The synthesized powders were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), Brunauer Emmett-Teller (BET), transmission electron microscopy (TEM), and isothermal calorimetry. The results indicated that the sintering temperature had a great influence on the properties of synthesized powders. β-C2S prepared at lower sintering temperature exhibited smaller crystal and particle size, lower crystallinity, higher specific surface area, lower purity (higher f-CaO content) and higher hydration activity. High purity nano-sized β-C2S particles were prepared at sintering temperatures of 900 °C with low relative crystallinity (41.6%), high specific surface area (8.67 m2/g), low f-CaO content (0.66%), nanoparticle size(around 65 nm). Compared with ordinary β-C2S, the hydration activity of nano β-C2S has been greatly improved, which also provides a large imagination space for its future application.