| This paper comes from the Ministry of water resources public welfare industry research project?201501003?:"Research,development and demonstration of complete technology for the utilization of sediment resources in the Yellow River".Preparation of low-cost filling materials for coal mine goaf by using abundant sediment resources of the Yellow River can not only effectively reduce the pressure caused by the sedimentation of the Yellow River,but also reduce the cost of coal mining,promote the sustainable development of environmental resources and the green development of social economy,it fully reflects the social and economic benefits of the utilization of the sediment resources of the Yellow River.In this paper,the working and mechanical properties of the filling materials in the goaf of coal mine with the Yellow River sediment are studied.The main research contents and conclusions are as follows:1.In this paper,the influence of water-binder ratio about filling material,the proportion of fly ash and cementitious material and the proportion of Yellow River sediment and cementitious material on the properties of filling material in goaf of coal mine is studied respectively,through single factor test.Based on the experimental study of the slump,bleeding rate,setting time and compressive strength of the filling material,the optimal water-binder ratio is 0.60,the ratio of fly ash to cementitious material is 0.60,and the ratio of Yellow River sediment to cementitious material is 1:1.On this basis,the orthogonal test was carried out to analyze the influence of three factors on the properties of filling materials.The results show that the water binder ratio has the greatest influence on the slump,bleeding rate,setting time and 28 day compressive strength of the filling materials.Under the condition of no activator,the amount of filling materials in the goaf of coal mine is determined to be310kg/m3 of cement,460kg/m3 of fly ash,770kg/m3 of sediment,460kg/m3 of water and0.31kg/m3 of water reducer.2.In this paper,NaOH,Ca?OH?2 and sodium silicate,NaOH/Ca?OH?2,as well as sodium silicate/NaOH were added to the Yellow River Sediment based filling materials respectively,and the test results were analyzed.The results show that the addition of activator can improve the compressive strength,reduce the setting time and improve the bleeding rate of the filling materials.The effects of different kinds and dosages of activators on the properties of filling materials are also different.It is found that the combination of NaOH and sodium silicate has the best active excitation effect on the filling materials.The results show that the optimum mix proportion of filling materials in the goaf of Yellow River sediment coal mine is determined as follows:cement 310kg/m3,fly ash 460kg/m3,the Yellow River sediment770kg/m3,water 460kg/m3,water reducer 23.10kg/m3,activator NaOH 3.85kg/m3 and activator sodium silicate 100.10kg/m3.The prepared filling materials can meet the requirements of the performance of the coal mine goaf filling mining. |
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