Study On Earlyage Physicaland Mechanical Properties Of Flyash Filling Materialand Its Hydration Process

Filling mining is an important part of the green mining, currently fillingmining has made some achievements. Fly ash is a good kind of filling material,fly ash filling has made some achievements in controlling surface subsidenceand solving waste, but there is a low early strength, large deformation, lowslump, secreting water and a series of serious problems, making a large amountof surface subsidence, face displacement increases, and affecting the workingsurface normal production. In this paper, Xishan coal and electricity to powerplant fly ash, coal gangue Zhenchengdi and Xishan Coal Hing cement plant forraw materials can study the physical and mechanical properties and hydrationprocess of filling materials, in order to grasp the structure of the filling materialdevelopment stage and provide a theoretical basis for optimizing the fillingmaterial ratio, improve material properties.Based on material property test and ratio optimization of raw material,several experiments were carried out to study the bulk resistivity, pore solutionresistivity, hydration products, porosity, uniaxial compressive strength, elasticmodulus and correlation among them with three different ratios. The researchachievements are as follows：(1) Fly ash particles are larger than10μm test sieve margin was90.4%,greater than45μm sieve margin was56.7%, greater than210μm sieve marginwas9.4%, as substandard ash, its mineral composition of quartz8.3%mullite29.8%and non-crystalline silicon aluminum vitreous phase of61.9%, the mainchemical composition of SiO246.3%, Al2O328.84%, CaO7.68%, Fe2O34.24%,as lower activity low calcium fly ash, pulverized coal gray spherical particles surface uneven, showing porphyritic texture block, and attached a small amountof calcium oxide or mica surface bonding material; test gangue crusherprocessing needs, broken graded particle size of less than25mm, whichaccounted for less than5mm50%,5~10mm accounted for35%,10~25mmaccounted for15%, mainly mineral composition of mullite48.5%,36.2%quartzand muscovite14.3%, the main chemical components of SiO248.78%,Al2O321.86%, Fe2O35.38%and CaO3.87%, belong to the clay rocks gangue,coal particle surface are mostly clastic and sheet pile body, irregular shape,forming a fold uneven surface morphology of the particles.(2) The volume resistivity showed that as the hydration process, the bulkresistivity showed increase-decrease-increased variation. Pore solution of ashfilling material resistivity variation was stabilized after the first drop. With theincreasing of fly ash, cement content is reducing, there is less soluble ions, poorconductivity, so resistivity is relatively larger. Uniaxial compressive strength andmodulus of elasticity of filling materials with prolonged hydration timeincreases, with increasing fly ash content decreased.(3)When taking into account the starting material for the hydrationsaturation100%solid-liquid two-phase body, the Archie formula and apply itto the promotion of filling materials, and materials based on the volume of wateris the ratio of the total volume hydration1d porosity initial porosity of thematerial and measured by mercury porosimetry, the ratio of the materialobtained five kinds of the porosity changes over time the negative exponentialcurve.(4) Based on the test results of the analysis, the correlation between thelogarithm late hydration five kinds of uniaxial compressive strength ratio of thesample and elastic modulus and volume resistivity, the results for the rapidnon-destructive prediction mechanical properties of fly ash filling materialprovides a new approach.(5) According to the ratio of the volume resistivity of the material and the rate of change of hydration products generated with five kinds of changes andhydration process of time, as well as related research, will fly early agehydration process of filling materials division adsorption period, four stages ofdissolution, coagulation and hardening of the like period, the duration of eachphase and the length ratio of the material, the hydration process of ionconcentration, change in the structure and porosity of the formation and so onrelated products.(6) Selected four different admixtures of different admixtures of fillingmaterials resistance curves, and the effect of various additives on the hydrationprocess. By early composite water reducer, accelerator, expanders andadmixtures used as filling material ratio can provide scientific guidance.