Effect of n(SiO2)/n(Al2 O3) molar ratio on physical properties and microstructure of foamed geopolymer
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Graphical Abstract
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Abstract
Thefoaminggeopolymerwaspreparedbyexperimentsusingcirculatingfluidizedbedcom⁃ bustionflyash(CFAS),silicafume(SF),waterglass(WG),NaOHandH2O2,andsilicafumewas usedtoadjustthen(SiO2)/n(Al2O3)molarratioofthegeopolymers,thefreshpastewastestedforfoa⁃ mingexpansionfactorandfoamingrate*Thestrengthandapparentdensityofthepasteweretestedafter hardening*ThispaperanalyzedtheporesizedistributionbyImage-ProPlussoftware,andthemicro⁃ structuresofthefoamedgeopolymerswereanalyzedbyX-raydiffraction(XRD),Fouriertransformin⁃ fraredspectroscopy(FTIR) andscanningelectronmicroscope(SEM)*Theresultsshowthatthein⁃ creaseofthemolarratioofn(SiO2)/n(Al2O3)acceleratesthehydrationreactionrate,andtheappro⁃ priateratiomakesthefoamingtimeadvance*ThewavelengthshiftintheFTIRindicatesthattheSi—OandAl—Obondsrearrangeafteralkali-excited,andtheappropriateratioisfavorablefortherearrange⁃ mentreactionofthegeopolymerandincreasesthedegreeofpolymerization*Theproductsuchaszeolite wasformedfoundbyXRDpattens*Whenthen(SiO2)/n(Al2O3)molarratiois2*79,thestrengthand apparentdensityofthespecimenin28dare1*06MPaand231g/L,andthemicrostructureofthe specimenhasgoodcompactness*
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