Microstructure of β-Dicalcium Silicate after Accelerated Carbonation

Abstract

The present work presents the microstructure of β-Ca₂SiO₄ (β-C₂S) after accelerated carbonation. The synthesis procedure of β-C₂S was examined first, and the crystalline and amorphous structure, the distribution and the pore structure of β-C₂S carbonation products were also determined by X-ray diffraction (XRD) quantitative analysis, simultaneous thermal analyzer (TG/DTA), Fourier transform-infrared spectroscopy (FT-IR), high resolution ²⁹Si magic angle spinning nuclear magnetic resonance (29Si NMR), N₂-sorption techniques, and scanning electron microscopy (SEM), respectively. Test results indicate that carbonation products are dramatically formed in the initial 2 h. The main carbonation products are crystalline calcite and amorphous three-dimensional network silica gels, which contain nanometer-sized pores. The calcite, silica gels and un-carbonated β-C₂S are distributed hierarchically.

Keywords

dicalcium silicate / carbonation / silica gels / nanometer size pores

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