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Metakaolin as highly active mineral admixtures used in concrete, have to reduce or eliminate the alkali-aggregate reaction, improve the strength of concrete and compaction, anti-carbonation and acid and alkali resistance, etc.. The jet low concrete strength, brittleness, adhesion is not strong, the problem of the high rate of rebound, with the characteristics based on metakaolin used as a mineral admixture, the development of a new type for the coal mine construction and production of high performance shotcrete used in coal mines, can enhance the strength of the supporting body, to control the surrounding rock deformation, the protection of the supporting body is not destroyed, reduce roadway renovated, and can save roadway construction and maintenance costs, to ensure that the mine into production on schedule and safety in production. Focuses on the of metakaolin sprayed concrete compressive strength: in the sprayed concrete mixed with 10% metakaolin, compressive strength increased from 40 to 50%; metakaolin with quick-setting role, and with metakaolin dosage increase the setting time is shortened; doped with 15% to metakaolin and reduce the amount of accelerator half of the case, shotcrete can improve the compressive strength of 40 to 50%, and the beginning of the final setting time and does not slow down the amount of coagulant quite; ambient temperature and water temperature are important factors that affect the ejection early strength of concrete, the temperature and the higher the temperature, the higher the early strength. By shotcrete hydration product morphology and structure of the SEM image analysis to clarify the metakaolin to improve the performance of shotcrete mechanism: the metakaolin active ingredient Al 2 O of 3 and SiO 2 Ca (OH) and cement hydration 2 reaction, and metakaolin very fine particles (less than 10 um), filled with good performance, it is more good to improve the concrete's strength. In the Jiaozuo Zhaogu Mine underground field test results showed that: the the jet rebound rate than ordinary shotcrete reduced by 50%; the new shotcrete strength of the the mine commonly pouring concrete strength (C40); in the original leaking lots metakaolin, eliminating water leakage. Metakaolin concrete as a new generation of highly active mineral admixture, not only in the coal mine shotcrete be effectively utilized, is also about other underground engineering, thin-walled structural engineering, repair and reinforcement works, highway and railway slope treatment works, fire-resistant engineering and protection engineering field of civil construction play a huge role.
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