Research On Preparation And Properties Of Coal Gangue Foam Concrete For Filling

Filling in coal mine goaf area is essential for preventing earth surface subsidence andensuring safety mining. Currently, there are several filling methods to be used, cementedfilling and high water quick-setting filling et al. Foam concrete can be used as mine fillmaterial because of its excellent mobility. Accumulation of coal gangue surroundingcoalmine is one of the largest amount of solid waste. However, it is not only occupy a largeamounts of farmland, but also lead to polluting the air. Coal gangue foam concrete for goaffilling was prepared with coal gangue as mainly raw materials, which not only lower rawmaterial costs, but also eliminate environmental pollution caused by coal gangue having veryimportant significance.This paper mainly discussed the mechanism of foaming and stabilization of foam, andthe foam stability of commercially available foaming agents were investigated. Mixing D(foam stabilizer) and K12(lauryl sodium sulfate), the high stability foam was prepared withthe foaming agent (KD-1) for foam concrete for goaf filling, and coal gangue foam concretefor goaf filling was prepared with bulk density among800~1000kg/m3, with the maximumparticle size in5mm and high coal gangue addition content on76wt%.The influences of foamstabilizer addition on viscosity of foaming liquid, foaming ratio and foam stability wereinvestigated. The influences of bulk density, cement types and content of cement, curing wayon properties to foam concrete for filling were investigated. The pore structure andstress-strain of coal gangue foam concrete in different dry density was investigated. Theresults show that it is difficult to prepare foam concrete for goaf filling with commerciallyavailable foaming agents because of the foam instability. When K12was0.4%, foamstabilizing agent (D) is0.06%, the foam expansion rate is21.3, starting bleeding time is7min,settlement distance is38mm in90min for KD-1foam agent with the best properties. Theinfluences of bulk density on the uniaxial compressive strength of foam concrete wasoutstanding; the compressive strength of90days of coal gangue foam concrete with bulkdensity in800,900,1000,1200Kg/m3, respectively,were0.43,0.66,1.75,3.55MPa withP·O42·5cement. The1day strength of coal gangue foam concrete with P·O42·5cement wasclose to3days strength with P·C32·5cement, while the former with higher compressivestrength than latter in90days. The average pore size of coal gangue foam concrete decreaseswith its density increases. Instead of water curing does not reduce the strength of the foamconcrete, good for the development of the late strength. Coal gangue foam concrete hassuperior earthquake resistance because of increase of strain residual stress remains the sameat a given strain range, after reaching maximum stress.