Cellulose ether ntawm morphology ntawm ettringite thaum ntxov

Cov teebmeem ntawm hydroxyethyl methyl cellulose ether thiab methyl cellulose ether ntawm morphology ntawm ettringite hauv cov cement slurry thaum ntxov tau kawm los ntawm scanning electron microscopy (SEM). Cov txiaj ntsig tau pom tias qhov ntev-inch piv ntawm ettringite muaju nyob rau hauv hydroxyethyl methyl cellulose ether hloov slurry yog me dua li cov slurry zoo tib yam, thiab cov morphology ntawm ettringite muaju yog luv luv-zoo li pas nrig. Qhov ntev-inch ratio ntawm ettringite crystals nyob rau hauv methyl cellulose ether hloov slurry yog loj dua li nyob rau hauv zoo tib yam slurry, thiab lub morphology ntawm ettringite muaju yog koob-qws. Cov ettringite muaju nyob rau hauv cov cement slurries zoo ib yam muaj qhov sib piv ntawm qhov chaw. Los ntawm txoj kev tshawb fawb saum toj no, nws pom tseeb ntxiv tias qhov sib txawv ntawm qhov hnyav molecular ntawm ob hom cellulose ether yog qhov tseem ceeb tshaj plaws cuam tshuam rau morphology ntawm ettringite.

Cov lus tseem ceeb:thiab lwm yam; Ntev-inch ratio; Methyl cellulose ether; Hydroxyethyl methyl cellulose ether; morphology

Ettringite, raws li cov khoom lag luam nthuav dav me ntsis, muaj qhov cuam tshuam loj rau kev ua haujlwm ntawm cov cement pob zeb, thiab ib txwm yog qhov kev tshawb fawb hotspot ntawm cov khoom siv cement. Ettringite yog ib hom trisulfide hom calcium aluminate hydrate, nws cov tshuaj formula yog [Ca3Al (OH)6·12H2O]2·(SO4)3·2H2O, los yog sau ua 3CaO·Al2O3·3CaSO4·32H2O, feem ntau abbreviated li AFt. . Nyob rau hauv Portland cement system, ettringite yog tsim los ntawm cov tshuaj tiv thaiv ntawm gypsum nrog aluminate los yog ferric aluminate minerals, uas plays lub luag hauj lwm ntawm ncua hydration thiab thaum ntxov lub zog ntawm cement. Kev tsim thiab morphology ntawm ettringite raug cuam tshuam los ntawm ntau yam xws li kub, pH tus nqi thiab ion concentration. Thaum ntxov li 1976, Metha et al. siv scanning electron microscopy los kawm txog morphological yam ntxwv ntawm AFt, thiab pom tias cov morphology ntawm xws li nthuav me ntsis hydration khoom yog txawv me ntsis thaum qhov chaw loj hlob loj txaus thiab thaum qhov chaw txwv. Lub qub yog feem ntau slender koob-qhib-zoo li tus spherules, thaum lub tom kawg yog luv luv pas nrig-shaped prism. Yang Wenyan txoj kev tshawb fawb pom tias AFt cov ntaub ntawv sib txawv nrog cov kab mob sib txawv. Qhov chaw ntub dej yuav ncua AFt tiam hauv kev nthuav dav-doped pob zeb thiab ua rau muaj peev xwm ntawm pob zeb o thiab tawg. Ib puag ncig sib txawv cuam tshuam tsis yog tsuas yog tsim thiab microstructure ntawm AFt, tab sis kuj nws qhov ntim ruaj khov. Chen Huxing et al. pom tias qhov kev ruaj ntseg ntev ntawm AFt poob nrog qhov nce ntawm C3A cov ntsiab lus. Clark thiab Monteiro et al. pom tias nrog kev nce ntawm ib puag ncig siab, AFt siv lead ua qauv hloov los ntawm kev txiav txim mus rau qhov tsis sib haum xeeb. Balonis thiab Glasser tshuaj xyuas qhov kev hloov ceev ntawm AFm thiab AFt. Renaudin et al. tau kawm txog cov qauv kev hloov pauv ntawm AFt ua ntej thiab tom qab immersion hauv kev daws teeb meem thiab cov txheej txheem tsis zoo ntawm AFt hauv Raman spectrum. Kunther et al. tau kawm txog kev cuam tshuam ntawm CSH gel calcium-silicon ratio thiab sulfate ion ntawm AFt crystallization siab los ntawm NMR. Tib lub sijhawm, raws li kev siv AFt hauv cov khoom siv cement, Wenk et al. kawm AFt crystal orientation ntawm pob zeb seem los ntawm hard synchrotron radiation X-ray diffraction finishing technology. Kev tsim ntawm AFt hauv cov cement sib xyaw thiab kev tshawb fawb hotspot ntawm ettringite tau tshawb nrhiav. Raws li kev ncua sij hawm ettringite cov tshuaj tiv thaiv, qee cov kws tshawb fawb tau tshawb fawb ntau txog qhov ua rau AFt theem.

Lub ntim nthuav dav tshwm sim los ntawm kev tsim ntawm ettringite yog qee zaum zoo, thiab nws tuaj yeem ua "expansion" zoo ib yam li magnesium oxide expansion tus neeg saib xyuas kom muaj qhov ntim ruaj khov ntawm cov khoom siv cement. Qhov sib ntxiv ntawm polymer emulsion thiab redispersible emulsion hmoov hloov cov macroscopic zog ntawm cement-based cov ntaub ntawv vim lawv cov teebmeem tseem ceeb ntawm microstructure ntawm cement-based cov ntaub ntawv. Txawm li cas los xij, tsis zoo li cov hmoov emulsion redispersible uas feem ntau txhim kho cov khoom sib txuas ntawm cov tshuaj khib nyiab, cov dej-soluble polymer cellulose ether (CE) muab cov mortar tshiab sib xyaw zoo dej tuav thiab cov nyhuv thickening, yog li txhim kho kev ua haujlwm. Tsis yog-ionic CE feem ntau siv, suav nrog methyl cellulose (MC), hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (HPMC),Hydroxyethyl methyl cellulose (HEMC), thiab lwm yam, thiab CE plays lub luag haujlwm hauv cov tshuaj khib nyiab tshiab tab sis kuj cuam tshuam rau cov txheej txheem dej ntawm cov cement slurry. Cov kev tshawb fawb tau pom tias HEMC hloov pauv tus nqi ntawm AFt tsim los ua cov khoom siv dej. Txawm li cas los xij, tsis muaj kev tshawb fawb tau muab piv rau cov txiaj ntsig ntawm CE ntawm microscopic morphology ntawm AFt, yog li daim ntawv no tshawb txog qhov sib txawv ntawm cov nyhuv ntawm HEMC thiab MC ntawm microscopic morphology ntawm ettringham thaum ntxov (1-hnub) cement slurry los ntawm cov duab tsom thiab kev sib piv.

1. Kev sim

1.1 Cov khoom siv raw

P·II 52.5R Portland cement tsim los ntawm Anhui Conch Cement Co., LTD raug xaiv los ua cov cement hauv kev sim. Ob lub cellulose ethers yog hydroxyethyl methylcellulose (HEMC) thiab methylcellulose (methylcellulose, Shanghai Sinopath Group) feem. MC); Cov dej sib tov yog dej kais dej.

1.2 Cov txheej txheem sim

Cov dej-cement piv ntawm cov cement paste qauv yog 0.4 (qhov loj ntawm cov dej rau cement), thiab cov ntsiab lus ntawm cellulose ether yog 1% ntawm cov cement. Kev npaj ntawm cov qauv no tau ua raws li GB1346-2011 "Testing Method for Water Consumption, Setting Time and Stability of Cement Standard Consistency". Tom qab tsim cov qauv, yas zaj duab xis tau ntim rau saum npoo ntawm cov pwm los tiv thaiv cov dej evaporation thiab carbonization, thiab cov qauv tau muab tso rau hauv chav kho mob nrog qhov kub ntawm (20 ± 2) ℃ thiab cov av noo ntawm (60 ± 5). ) %. Tom qab 1 hnub, cov pwm raug tshem tawm, thiab cov qauv tau tawg, tom qab ntawd ib qho qauv me me tau muab coj los ntawm nruab nrab thiab muab tso rau hauv cov dej tsis muaj ethanol kom tshem tawm cov dej, thiab cov qauv raug coj tawm thiab qhuav ua ntej kuaj. Cov qauv qhuav tau muab tso rau hauv cov qauv qauv nrog cov nplaum ob sab, thiab ib txheej ntawm cov yeeb yaj kiab kub tau txau rau saum npoo los ntawm Cressington 108auto tsis siv neeg ion sputtering ntsuas. Sputtering tam sim no yog 20 mA thiab lub sij hawm sputtering yog 60 s. FEI QUANTAFEG 650 ib puag ncig Scanning electron Microscope (ESEM) tau siv los soj ntsuam cov yam ntxwv morphological ntawm AFt ntawm cov qauv ntu. Lub tshuab nqus tsev siab theem ob electron hom tau siv los soj ntsuam AFT. Lub acceleration voltage yog 15 kV, beam qhov chaw txoj kab uas hla yog 3.0 nm, thiab kev ua hauj lwm nyob deb tswj ntawm txog 10 mm.

2. Cov txiaj ntsig thiab kev sib tham

SEM dluab ntawm ettringite nyob rau hauv hardened HEMC-hloov cement slurry pom tau hais tias txoj kev loj hlob ntawm txheej txheej Ca (OH) 2 (CH) tau pom tseeb, thiab AFt pom qhov tsis sib xws ntawm cov pas nrig luv-zoo li AFt, thiab qee qhov luv luv-zoo li AFT tau npog. nrog HEMC membrane qauv. Zhang Dongfang et al. kuj pom luv luv-zoo li AFt thaum soj ntsuam cov kev hloov microstructure ntawm HEMC hloov cov cement slurry los ntawm ESEM. Lawv ntseeg hais tias cov cement slurry tau hnov ​​​​mob sai sai tom qab ntsib dej, yog li AFt siv lead ua yog slender, thiab qhov txuas ntxiv ntawm lub hnub nyoog hydration coj mus rau qhov nce ntawm qhov ntev-inch ratio. Txawm li cas los xij, HEMC tau nce qhov viscosity ntawm cov tshuaj, txo qhov sib txuas ntawm ions hauv cov tshuaj thiab ncua sij hawm tuaj txog ntawm cov dej ntawm cov khoom clinker, yog li qhov ntev-inch ntawm AFt nce hauv qhov tsis muaj zog thiab nws cov yam ntxwv morphological pom. luv qws zoo li lub cev. Piv nrog AFt hauv cov cement slurry zoo tib yam ntawm tib lub hnub nyoog, qhov kev xav no tau raug txheeb xyuas qee qhov, tab sis nws tsis muaj feem xyuam rau piav qhia txog kev hloov pauv ntawm AFt hauv MC hloov cov cement slurry. SEM dluab ntawm ettridite nyob rau hauv 1-hnub hardened MC hloov cov cement slurry kuj pom orientated kev loj hlob ntawm txheej txheej Ca(OH)2, qee qhov AFt nto kuj tau them nrog zaj duab xis qauv ntawm MC, thiab AFt pom morphological yam ntxwv ntawm pawg loj hlob. Txawm li cas los xij, los ntawm kev sib piv, AFt siv lead ua hauv MC hloov cov cement slurry muaj qhov loj dua qhov ntev-inch piv thiab ib qho kev sib luag morphology, uas qhia txog cov acicular morphology.

Ob leeg HEMC thiab MC ncua cov txheej txheem dej thaum ntxov ntawm cov cement thiab nce cov viscosity ntawm cov tshuaj, tab sis qhov sib txawv ntawm AFt morphological yam ntxwv tshwm sim los ntawm lawv tseem tseem ceeb. Cov xwm txheej saum toj no tuaj yeem piav qhia ntxiv los ntawm qhov kev xav ntawm cov qauv molecular ntawm cellulose ether thiab AFt siv lead ua qauv. Renaudin et al. soaked lub synthesized AFt nyob rau hauv cov npaj alkali tov kom tau "ntub AFt", thiab ib nrab tshem tawm nws thiab qhuav nws nyob rau saum npoo ntawm saturated CaCl2 tov (35% txheeb ze humidity) kom tau "dry AFt". Tom qab kev txhim kho cov qauv kev tshawb fawb los ntawm Raman spectroscopy thiab X-ray hmoov diffraction, nws tau pom tias tsis muaj qhov sib txawv ntawm ob lub qauv, tsuas yog cov kev taw qhia ntawm cov khoom siv lead ua ntawm cov hlwb hloov pauv hauv cov txheej txheem ziab, uas yog, nyob rau hauv cov txheej txheem ntawm ib puag ncig. hloov ntawm "ntub" mus rau "qhuav", AFt crystals tsim cov hlwb raws li cov kev taw qhia ntawm ib tug maj mam nce. Cov AFt crystals raws li c ib txwm coj los ua tsawg thiab tsawg. Qhov chaw yooj yim tshaj plaws ntawm qhov chaw peb sab yog tsim los ntawm kab ib txwm, b ib txwm kab thiab c ib txwm kab uas yog perpendicular rau ib leeg. Nyob rau hauv cov ntaub ntawv uas b normals tau tsau, AFt crystals pawg raws li ib txwm, ua rau ib tug loj cell hla seem nyob rau hauv lub dav hlau ntawm ab normals. Yog li, yog tias HEMC "kho" dej ntau dua li MC, ib puag ncig "qhuav" tuaj yeem tshwm sim hauv thaj chaw hauv cheeb tsam, txhawb kev sib sau ua ke thiab kev loj hlob ntawm AFt crystals. Patural thiab al. pom tias rau CE nws tus kheej, qhov siab dua ntawm polymerization (los yog qhov loj dua qhov hnyav molecular), qhov viscosity ntawm CE ntau dua thiab cov dej tuav tau zoo dua. Cov qauv molecular ntawm HEMCs thiab MCS txhawb nqa qhov kev xav no, nrog rau pawg hydroxyethyl muaj qhov hnyav molecular ntau dua li pawg hydrogen.

Feem ntau, AFt crystals yuav tsim thiab nag lossis daus tsuas yog thaum cov ions cuam tshuam txog qee qhov saturation hauv cov txheej txheem daws teeb meem. Yog li ntawd, yam xws li ion concentration, kub, pH tus nqi thiab qhov chaw tsim nyob rau hauv cov tshuaj tiv thaiv muaj peev xwm cuam tshuam rau morphology ntawm AFt muaju, thiab cov kev hloov hauv cov khoom siv hluavtaws tuaj yeem hloov cov morphology ntawm AFt crystals. Yog li ntawd, qhov piv ntawm AFt muaju nyob rau hauv cov cement slurry zoo tib yam ntawm ob yuav tshwm sim los ntawm ib qho tseem ceeb ntawm cov dej haus nyob rau hauv thaum ntxov hydration ntawm cement. Txawm li cas los xij, qhov sib txawv ntawm AFt siv lead ua morphology tshwm sim los ntawm HEMC thiab MC yuav tsum yog vim lawv cov dej tshwj xeeb tuav cov txheej txheem. Hemcs thiab MCS tsim lub "kaw voj" ntawm kev thauj dej hauv microzone ntawm cov cement slurry tshiab, tso cai rau "lub sijhawm luv" uas cov dej "yooj yim nkag mus thiab nyuaj tawm." Txawm li cas los xij, lub sijhawm no, cov kua theem ib puag ncig hauv thiab ze ntawm microzone kuj tau hloov pauv. Cov yam ntxwv xws li ion concentration, pH, thiab lwm yam., Kev hloov pauv ntawm ib puag ncig kev loj hlob yog ntxiv rau hauv cov yam ntxwv morphological ntawm AFt crystals. Qhov "kaw voj" ntawm kev thauj dej yog zoo ib yam li cov txheej txheem ntawm kev ua tau piav qhia los ntawm Pourchez li al. HPMC ua lub luag haujlwm hauv kev khaws dej.

3. Cov lus xaus

(1) Qhov sib ntxiv ntawm hydroxyethyl methyl cellulose ether (HEMC) thiab methyl cellulose ether (MC) tuaj yeem hloov pauv morphology ntawm ettringite thaum ntxov (1 hnub) cov cement slurry.

(2) Qhov ntev thiab txoj kab uas hla ntawm ettringite siv lead ua nyob rau hauv HEMC hloov cement slurry yog me me thiab luv luv pas nrig; Qhov ntev thiab txoj kab uas hla ntawm ettringite crystals nyob rau hauv MC hloov cement slurry yog loj, uas yog rab koob-qws zoo li. Cov ettringite crystals hauv cov cement slurries muaj qhov sib piv ntawm ob qho no.

(3) Qhov sib txawv ntawm ob lub cellulose ethers ntawm morphology ntawm ettringite yog qhov tseem ceeb vim qhov sib txawv ntawm qhov hnyav molecular.