MACROSCOPIC MECHANICAL PROPERTIES AND MECHANISM OF SUPERFINE PORTLAND CEMENT-BASED COMPOSITE SEALING MATERIAL FOR GAS DRAINAGE

Superfine Portland cement is a kind of inorganic grouting material widely used, which can be used to prepare cementitious material with short solidification time, high strength and good effect on micro-crack grouting, which is of great significance to the prevention and control of coal mine gas disaster. This paper combines macroscopic mechanical property test and microstructure observation to study the mechanical properties and mechanism, the hydration products, and microstructure of superfine cement-based composite sealing materials. The results show excessive additives will lead to defects and decrease the mechanical properties of the composite material. The results of SEM and XRD analysis show that the hydration of superfine cement-based sealing materials produces a large amount of Aft (Calcium aluminate hydrated from cement hydration products combined with sulfate ions can make cement structure more compact). The more sufficient the hydration, the more compact the overall microstructure and the higher the mechanical property. The study also shows that the composite material containing 8% expansion agent, 0.3% water reducer and 0.03% retarder has high mechanical properties and low cost.