Depth evolution of mechanical properties of fugitive dust cemented by microbe cement based on carbon dioxide capture and utilisation

Fugitive dust, which was cemented with microbe cement based on carbon dioxide capture and utilisation, was prepared and the evolution of mechanical properties over the sample depth was investigated. The microstructure of samples at different depths was analysed by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. The calcite content and hardness of samples at different depths were also verified. Three-dimensional (3D) reconstruction evolution and cross-section evolution of porosity at different depths were demonstrated by X-ray computed tomography. The experimental results indicate that calcite could be formed at different depths with the use of microbe cement. Compared with the structure of the lower region of the sample, fugitive dust particles cemented with microbe cement in the upper region were found to be more dense, of lower porosity and with more calcite formed. The calcite content and hardness significantly decreased with an increase in sample depth: at 0, 5, 10, 15 and 20 mm, the respective calcite content was 10·51%, 8·32%, 4·93% and 1·70% and the hardness was 18·2 GPa, 17·1 GPa, 10·9 GPa and 3·6 GPa. 3D reconstructions and cross-section evolutions of porosity at different depths indicate that the inner structure of the sample was not uniform, with the structure of the upper region better than that of the sample bottom. With an increase in sample depth, pores and cracks in the cross-section significantly increased.