| The geopolymer is a green,environmentally friendly and novel inorganic cementitious material prepared by the action of an alkaline activator.It is mainly composed of crystalline or amorphous silicon tetrahedron and aluminum oxide.The three-dimensional network-like junction group consists of geopolymers with high strength,high temperature resistance,corrosion resistance,good radiation resistance and high solidification ability of heavy metals.It has broad application prospects in airport runway,nuclear industry and medical care Geopolymers can replace cement and reduce the environmental pollution caused by carbon dioxide produced by cement,which is in line with the path of sustainable green developmentIn order to prepare alkali leading lead-zinc slag powder geopolymer with certain mechanical properties,radiation protection and heavy metal curing ability,in this paper,alkali leaching lead zinc slag powder and metakaolin were used as raw materials,sodium silicate solution and sodium hydroxide were mixed to prepare alkali activator,and alkali leached lead zinc slag powder geopolymer was prepared by alkali excitation polymerization.Firstly,the effects of modulus,liquid-ash ratio and lime-sand ratio on the strength of alkali-impregnated lead-zinc slag powder geopolymer were studied by orthogonal test,and XRD and SEM characterization were carried out.Secondly,the length and amount of PVA fiber were studied.The effect of immersion lead-zinc slag powder geopolymer on mechanical properties,and SEM analysis;finally,By researching the effect of alkali-lead lead-zinc slag powder content and calcination temperature on the radiation and leaching toxicity of alkali-lead lead-zinc slag powder geopolymer,it can make some conclusions like following:(1)The research of mechanical propertiesAccording to the three-factor four-level orthogonal test analysis,the 28d compressive strength and flexural strength of the alkali-leached lead-zinc slag powder geopolymer were 44.49MPa and 5.54MPa,respectively,and the optimum ratio was 1.0 for the composite alkali activator,the ratio of liquid to ash was 0.50,and the ratio of lime to sand was 0.30;the compressive strength of 28d was higher than 42.5MPa,indicating that it is feasible to prepare alkali leached lead zinc slag powder geopolymer.(2)PVA fiber reinforced alkali leaching lead zinc slag powder geopolymerThrough single factor experiment,it is concluded that the addition of PVA fiber can significantly improve the compressive strength and flexural strength of the geopolymer.When the fiber length was 3 mm and the dosage was 0.6%,The maximum flexural strength and compressive strength of the alkali leading lead-zinc slag powder geopolymer of 28d were 7.68 MPa and 50.61 MPa,respectively,which were 63.40%and 78.64%higher than the reference group respectively.When the fiber length was 9 mm and the dosage was 0.9%,the largest value of 3d folding ratio was 20.15%,which was 25.39%higher than the baseline group,and the early toughness enhancement effect is remarkable.(3)Radiation protection performanceThe geopolymer prepared by alkali-impregnated lead-zinc slag powder with different dosage or different calcination temperature has certain anti-radiationproperties.The y-ray shielding effect increases with the increase of the content;the optimal dosage of alkali-leaching lead-zinc slag powder was 45%,and the optimal values of linear absorption coefficient and semi-attenuation layer thickness were 0.1822cm-1 and 3.8025cm,respectively.With the increase of calcination temperature,the changes of y-ray shielding effect show like this:going down and then going up a little bit and then going down.When the calcination temperature was 800?,the ?-ray shielding effect is the worst,and the shielding effect was best when the calcination temperature is 600?.(4)Leaching toxicityAlkali-lead lead-zinc slag powder geopolymer has strong heavy metal curing ability.The alkali leaching lead-zinc slag powder in the range of 5%to 45%,the leaching value of metal Pb and Zn increases with the increase of the content;when the calcination temperature was 800?,the leaching value of metal Pb and Zn was the lowest,the best effect.The leaching values of the alkali leached lead-zinc slag powder geopolymer meet the standard requirements.(5)Polymerization mechanism analysis of alkali leached lead-zinc slag powder geopolymerSEM characterization and analysis showed that the aluminosilicate gel phase of the alkali-lead lead-zinc slag powder geopolymer which did not participate in PVA fiber was tightly combined with the sand,the compactness was relatively high,and the polymerization reaction was relatively thorough;the alkali mixed with PVA fiber The cracks and porosity of the leached lead zinc slag powder geopolymer were relatively low,and the PVA fiber distribution is uniform,which plays a good bridging role,and the compressive strength and the flexural strength growth rate were relatively high.XRD analysis showed that the geopolymer was subjected to alkali-induced polycondensation reaction to form a complex inorganic aluminosilicate amorphous gelling material.The main product was nano zeolite(Na2Al2Si4O12·7H2O and Na2(Al,Si)9O18·8H2O)and complex network silicate(NaCa2.5(Si10Al16)O32·4H2O),Its possible polymerization is shown below:?x(SiO2,Al2O3)+Na2SiO3+2NaOH+10CaO+55H2O (?) 4NaCa2.5(Si10Al16)O32·14H2O?y(SiO2,Al2O3)+Na2SiO3+2NaOH+7H2O (?) 2Na2(Al,Si)9O18·8H2O?z(SiO2,Al2O3)+Na2SiO3+2NaOH+6H2O (?) 2Na2Al2Si4O12·7H2O... |
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