| At present, the portland cements or high-water materials are generally used as thecementing agents to build filling body in order to improve the extent of actual mining ofmineral resources in the mines. But the setting time of portland cement is too long, and thehigh-water materials are costly, unstable and weather easily. Therefore, a new kind of minefilling material is prepared by mixing high-water materials and slag based cementingmaterials to consolidate mud. The main contents and conclusions are as follows:Firstly, high-water materials and super-high-water materials were successfully achieved.The results indicated that each component paste of two-part mix high-water materials won’tprecipitates and sets within24hours but rapidly sets and attains strength after mixed witheach other. When water cement ratio is2.0, the compressive strength of high-water materialssolidified body is2.56MPa after mixed for2hours and reaches6.65MPa after mixed for7days. When water cement ratio is11.00, the super-high-water materials won’t solidify within1day and reach3days compressive strength up to0.08MPa.Secondly, the influence of the gypsum-lime, sodium silicate-caustic soda and the bothcompound activated system on slag based cementing materials were studied. It were foundthat the activated effect of gypsum-lime on slag is best when the water cement ratio is0.75and slag:gypsum:lime is1:0.125:0.375, and the28days compressive strength of test blocksreaches up to37.50MPa. Activated system of sodium silicate-caustic soda to slag basedmaterials exhibites high early period compressive strength with the3days compressivestrength41.70MPa when water cement ratio was0.273and slag:sodium silicate:caustic sodawas1:0.43:0.053, and complex activation of sodium silicate-caustic soda and gypsum-limewill reduce strengthes of slag based cementing materials.Thirdly, based on high-water materials and slag based cementing materials, the curingeffects of silica/high-water materials, clay/high-water materials, slag/high-water materials and(sodium silicate and caustic soda)/slag on the mud solidification mine backfill materials were studied with the orthogonal experiment methods. The mud solidified bodies possess relativelyhigh strength at early period(3and7days) and stably developed later period(28days)compressive strength. The effect of soil/high-water materials on the mud curing body is thelargest, sodium silicate and caustic soda improved the early strength of mud curing body, butreduces the later strength. However, slag and silica could improve the later strength, The orderto affect the compressive strength of mud solidified body at early period (3and7days) wasclay/high-water materials>silica/high-water materials>(sodium silicate and caustic soda)/slag,slag/high-water materials, and the order to affect the later period (28days) compressivestrength was clay/high-water materials>slag/high-water materials> silica/high-watermaterials>(sodium silicate and caustic soda)/slag. Moreover, the consolidation with adding flyashes to paste are conducted and the effects are not ideal.Fourthly, microstructures of the filling materials were characterized by scanning electronmicroscopy (SEM) and X-ray diffraction (XRD). The hydration products of mudsolidification mine backfill materials are ettringite, hydrated calcium aluminates (C-A-H) andhydrated calcium silicate (C-S-H), and ettringite contains high crystal water which absorbed alarge amount of water from the mud and made paste fastly harden and provided early strength.While C-A-H and C-S-H wrap and protect the ettringite crystals and mud particles fromweathering and hydrating. Then slag based cementing materials were gradually hydrated toettringite crystals, which solidified clay particles and stably improved the later strength of thefilling materials.The mud solidification mine backfill materials have high water content, cheapness andconvenience to use with high early strength and stably later strength and will have wideapplication in mining industry. |
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