Study On Mine Foamed Filling Material And Its Mechanical Properties

The filling of high caving area in coal mine needs a kind of material with good integrity,low density,high strength,simple filling technology,low cost and no high temperature in the filling process.After investigation,the foamed cement used to make thermal insulation layer of buildings has the above characteristics,which may be suitable for filling in high caving areas of coal mines.In order to discuss the feasibility of using foamed cement as filling material in high falling area of coal mine,foamed cement with different proportion was developed,and its physical and mechanical properties were tested,and the foamed cement suitable for filling in high falling area of coal mine was optimized.(1)To determine the reasonable water-cement ratio of cement slurry and foaming agent for making foaming cement materials.The slurry was manufactured according to different water cement ratio,and the reasonable water cement ratio was determined to be 0.5 by comparing its fluidity and binding ability to foam.The results show that the cement slurry with water cement ratio of 0.5 has better fluidity,cement and water can combine fully,and can combine with foam to the greatest extent.By comparing the foaming ability and foam properties of different foaming agents,the plant cement foaming agent was optimized for making foamed filling materials.By comparing the foaming ability of foaming agent with different concentrations,the foaming agent with 40%,50%,60% concentration was selected to make foaming cement filling material.(2)Compressed air foaming method was used to mix the foams with different foaming agent concentrations and cement slurry with water cement ratio of 0.5,and then natural curing was carried out after uniform mixing,and uniaxial compression tests of foamed cement specimens with different curing periods were carried out by using RMT301 rock mechanics experimental system.The results show that the more the foam is added into the cement slurry,the lower the strength of the foamed cement is.When the foam is too much,the foamed cement will collapse.When the mass ratio of foaming agent to cement is 1:100,the foam combined by cement slurry is the most,and the collapse will not occur.With the increase of cement content,the uniaxial compressive strength of foamed cement specimens is obviously improved,and when the cement content is 15 kg,The uniaxial compressive strength of the foamed cement specimen cured for 28 days is more than 6 MPa.(3)Mine foamed backfilling materials with different strengths were developed.The water cement ratio was 0.5,the concentration of foaming agent was 40%,the mass ratio of foaming agent to cement was 1: 100,1: 120 and 1:150,respectively.The uniaxial compressive strength of the prepared foaming filling material after curing for 28 days was 1 MPa,3 MPa and 6 MPa respectively.The developed foaming filling material can be used as an alternative filling material for high caving areas in coal mines.There are 41 figures,20 tables and 67 references in this paper.