Study On The Preparation And Properties Of Mine Microfine Cement Grouting Material

Coal is one of the most important primary energy consumption, accounting for more than 70 % of the total energy consumption in our country. In the next few decades, coal is still the industrialization process of the fundamental energy. Coal mining requires to meet the condition of safe, efficient and green. Coal in the mining process will encounter different problems, like mining coal crushing, gas drainage sealing lax and so on. So safety is the most important issue of coal mining. Due to high reaction temperation, pollution, toxic and high cost of chemical grouting material, poor groutability and stability of Portland cement grouting material, low strength and cohesiveness of fly ash grout, etc., these disadvantages limit the use and development of grouting material. So these factors which make studies of microfine cement as coal grouting material become inevitability.In this paper, different fineness of commercially available microfine cement as a raw material to analyze the impact of microfine cement fineness on its grout properties. Reference to the performance requirements of mining technology standards of polymer grouting material on coal mine, some problems was obtained through experimental analysis that the microfine cement exist lager dry shrinkage, strength retrogression, high inter temperature, et al.. According existed problems of microfine cement, select the fly ash and slag to solve the strength retrogression and high internal temperature, select expanders to solve the problem of shrinkage, select dispersants to solve the problem of stability. Research the relationship between the composition and properties of the material, and derived optimum dosage of the regulation performance materials, preparated coal microfine cement grouting material, then preparate the mining microfine cement grouting material. Research the properties of mine microfine cement grouting material on the bleeding rate, viscosity, setting time, compressive strength, volume changes and internal temperature. Analysis the reason of microfine cement grouting improved performance. These can provide a basis for further study of microfine cement. By studying the main research results as following:(1) The fineness of microfine cement have an significant influence on the grout performance of microfine cement; With increasing fineness, the bleeding rate of microfine cement slurry was decreased, the concretion rate was increased; setting time, drying shrinkage with increases the fineness was reduced, but the volume deformation and internal temperature of paste was increased; the compressive strength of microfine cement at 3 days increases, but the 28-day compressive strength appear retraction, the compressive strength of 1250 mesh microfine cement at 28 days was reduced 22.16% compare with the 3 days strength. The internal temperature, porosity and average pore diameter of microfine cement paste increases with increasing fineness.(2) Selecting the fly ash, slag, expansive agents, dispersing agents as regulating material to improve the properties of microfine cement. Through the experiment, draw that the bleeding rate, setting time was increased with the increasing of mineral admixture content, viscosity, shrinkage rate and compressive strength decrease. Because of the different expansive agent, the compensate the dry shrinkage of microfine cement is also different. And the drying shrinkage of ultrafine cement paste was reduced with increasing superfine expansive content. Bentonite, Mce reduced the bleeding rate of superfine cement paste, and improve the stability of the slurry, but after the mixed these dispersant the viscosity of slurry was increased.(3) Select 20% fly ash, slag 10%, expansive agent 10%(MgO-1, UEA), dispersant(bentonite 5%, methyl cellulose ether 0.3%) to study the performance of the composite grouting material. The experimental results shows that the drying shrinkage of the composite material microfine cement grouting material was reduced, the viscosity was increased, and improved the late strength of pure superfine cement. Though a comprehensive comparative analysis, results show that when MC: FA: SL: UEA: Bentonite = 70%: 20%: 10%: 10%: 5%, the composite microfine cement grouting material have better properties on viscosity, fluidity, strength, drying shrinkage, internal temperature compared with 1250 mesh microfine cement. In addition, the cost of the composite microfine cement grouting material was decreased.