Microstructure of -Dicalcium Silicate after Accelerated Carbonation

The present work presents the microstructure of -Ca2SiO4 (-C2S) after accelerated carbonation. The synthesis procedure of -C2S was examined first, and the crystalline and amorphous structure, the distribution and the pore structure of -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 Si-29 magic angle spinning nuclear magnetic resonance (29Si NMR), N-2-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 -C2S are distributed hierarchically.