Study On Mechanics And Carbonation Effect Of Cement Composites Solidified Nickel Copper Contaminated Soils

There are nearly one million industrial pollution sites in China.Once the pollution control is not strict,the industrial waste gas,liquid and residue produced by these enterprises in the process of operation will invade the soil,change the physical and chemical properties of the soil,and form a serious heavy metal contaminated soil(Pb2+,Cu2+,Ni2+,Zn2+,etc.).At present,the remediation of heavy metal contaminated soil has become an urgent problem and a hot topic for scholars.Rehabilitation methods of solidifying and stabilizing heavy metal contaminated soil by inorganic binders such as cement,fly ash and lime are commonly used,which have the advantages of mature technology and suitable economic benefits.In this thesis,the mechanical properties and anti-carbonization ability of nickel-copper ion contaminated soil,which is a mixture of cement,fly ash and desulfurization gypsum,are analyzed through laboratory tests and theoretical analysis,macro and micro perspectives.The main contents of this study include:In this thesis,the stabilized nickel-copper contaminated soil solidified by cement-fly ash-aesulfiirization gypsum was taken as the research object.The compressive strength and permeability of flexible wall of the solidified contaminated soil under standard curing and carbonization conditions were studied.The carbonization depth,scanning electron microscopy and XRD diffraction tests were designed.The effects of nickel-copper ion concentration,curing age and content of curing agent on the strength,deformation,permeability and carbonization resistance of solidmed soils were compared and analyzed.The mechanism of action of solidified nickel-copper contaminated soils and carbonization was preliminarily analyzed from macro and micro perspectives.The test results show that the existence of nickel and copper ions will reduce the compressive strength of solidified soil.The influence of different heavy metal ions concentration on the strength can be roughly divided into three situations:first,the low concentration of heavy metals(NiO,Ni0.02),second,the medium concentration of heavy metals(Ni0.4),third,the high concentration of heavy metals(Nil,Cul,NilCul),and the establishment of strength prediction model with the maintenance;With the increase of curing age,the strength of solidified soils increases gradually,the strength of solidified soils increases rapidly in the first and middle stages(3 d-14 d),slowly in the middle and later stages(14 d-28 d),and the permeability coefficients of samples with different concentrations of heavy metal ions are decreasing.A prediction model for the permeability coefficient and curing age of solidified nickel-copper contaminated soils is established.With the increase of the content of solidifying agent,the permeability coefficients of samples will increase.The carbonization resistance of solidified contaminated soils is as follows:NilCul>NiOCuO>Nil>Cul>Ni0.02>Ni0.4.The fitting formulas of the square root of the carbonization depth and the carbonization time are derived.Figure[60]table[15]reference[81]...