Cellulose ether ntawm morphology ntawm ettringite thaum ntxov

Cov teebmeem ntawm hydroxyethyl methyl cellulose ether thiab methyl cellulose ether rau ntawm morphology ntawm ettringite hauv cov cement slurry thaum ntxov tau kawm los ntawm scanning electron microscopy (SEM). Cov txiaj ntsig qhia tau hais tias qhov sib piv ntev-txoj kab uas hla ntawm ettringite siv lead ua hauv hydroxyethyl methyl cellulose ether hloov kho slurry yog me dua li ntawm cov slurry ib txwm muaj, thiab morphology ntawm ettringite siv lead ua yog luv luv zoo li pas nrig. Qhov sib piv ntev-txoj kab uas hla ntawm ettringite siv lead ua hauv methyl cellulose ether hloov kho slurry yog loj dua li ntawm cov slurry ib txwm muaj, thiab morphology ntawm ettringite siv lead ua yog koob-rod. Cov siv lead ua ettringite hauv cov cement slurries ib txwm muaj qhov sib piv qhov twg nyob nruab nrab. Los ntawm 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 uas cuam tshuam rau morphology ntawm ettringite.

Cov lus tseem ceeb:ettringite; Qhov ntev-txoj kab uas hla piv; Methyl cellulose ether; Hydroxyethyl methyl cellulose ether; morphology

Ettringite, ua ib yam khoom hydration uas nthuav me ntsis, muaj qhov cuam tshuam loj rau kev ua haujlwm ntawm cov cement concrete, thiab yeej ib txwm yog qhov chaw tshawb fawb ntawm cov ntaub ntawv cement. Ettringite yog ib hom trisulfide hom calcium aluminate hydrate, nws cov mis tshuaj yog [Ca3Al (OH)6·12H2O]2·(SO4)3·2H2O, lossis tuaj yeem sau ua 3CaO·Al2O3·3CaSO4·32H2O, feem ntau luv ua AFt. Hauv Portland cement system, ettringite feem ntau yog tsim los ntawm kev sib xyaw ntawm gypsum nrog aluminate lossis ferric aluminate minerals, uas ua lub luag haujlwm ntawm kev ncua hydration thiab lub zog thaum ntxov 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 xyoo 1976, Metha et al. siv lub tshuab ntsuas hluav taws xob los kawm txog cov yam ntxwv ntawm AFt, thiab pom tias cov morphology ntawm cov khoom siv dej uas nthuav dav me ntsis no txawv me ntsis thaum qhov chaw loj hlob loj txaus thiab thaum qhov chaw tsawg. Tus thawj yog feem ntau yog cov spherules zoo li rab koob, thaum tus tom kawg feem ntau yog cov prism luv luv. Yang Wenyan txoj kev tshawb fawb pom tias cov qauv AFt txawv nrog ntau qhov chaw kho. Cov chaw ntub dej yuav ncua AFt tiam hauv cov pob zeb nthuav dav thiab ua rau muaj kev o thiab tawg. Cov chaw sib txawv cuam tshuam tsis yog tsuas yog kev tsim thiab microstructure ntawm AFt, tab sis kuj tseem nws qhov ntim ruaj khov. Chen Huxing et al. pom tias qhov ruaj khov mus sij hawm ntev ntawm AFt txo qis nrog kev nce ntawm C3A cov ntsiab lus. Clark thiab Monteiro et al. pom tias nrog kev nce ntawm kev nyuaj siab ib puag ncig, AFt siv lead ua qauv hloov pauv los ntawm kev txiav txim mus rau kev tsis sib haum xeeb. Balonis thiab Glasser tshuaj xyuas cov kev hloov pauv ntawm AFm thiab AFt. Renaudin et al. kawm txog kev hloov pauv ntawm AFt ua ntej thiab tom qab kev sib xyaw hauv cov tshuaj thiab cov qauv ntawm AFt hauv Raman spectrum. Kunther et al. tau kawm txog qhov cuam tshuam ntawm kev sib cuam tshuam ntawm CSH gel calcium-silicon piv thiab sulfate ion ntawm AFt crystallization siab los ntawm NMR. Tib lub sijhawm, raws li kev siv AFt hauv cov ntaub ntawv cement, Wenk et al. tau kawm txog AFt crystal orientation ntawm cov ntu pob zeb los ntawm kev siv tshuab synchrotron radiation X-ray diffraction finishing technology. Kev tsim ntawm AFt hauv cov cement sib xyaw thiab qhov chaw tshawb fawb ntawm ettringite tau tshawb nrhiav. Raws li kev ncua sijhawm ettringite reaction, qee cov kws tshawb fawb tau ua ntau qhov kev tshawb fawb txog qhov ua rau AFt theem.

Qhov kev nthuav dav ntawm cov khoom siv los ntawm kev tsim cov ettringite qee zaum zoo, thiab nws tuaj yeem ua haujlwm ua "kev nthuav dav" zoo ib yam li magnesium oxide expansion agent los tswj qhov ruaj khov ntawm cov khoom siv cement. Kev ntxiv cov polymer emulsion thiab cov hmoov emulsion redispersible hloov cov khoom macroscopic ntawm cov khoom siv cement vim lawv cov teebmeem tseem ceeb ntawm cov qauv ntawm cov khoom siv cement. Txawm li cas los xij, tsis zoo li cov hmoov emulsion redispersible uas feem ntau txhim kho cov khoom sib txuas ntawm cov mortar hardened, cov dej-soluble polymer cellulose ether (CE) muab cov mortar sib xyaw tshiab zoo khaws dej thiab thickening nyhuv, yog li txhim kho kev ua haujlwm. Non-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 ua lub luag haujlwm hauv cov mortar sib xyaw tshiab tab sis kuj cuam tshuam rau cov txheej txheem hydration ntawm cement slurry. Cov kev tshawb fawb tau qhia tias HEMC hloov pauv qhov ntau ntawm AFt tsim tawm ua cov khoom hydration. Txawm li cas los xij, tsis muaj kev tshawb fawb tau sib piv cov nyhuv ntawm CE rau ntawm microscopic morphology ntawm AFt, yog li daim ntawv no tshawb nrhiav qhov sib txawv ntawm cov nyhuv ntawm HEMC thiab MC rau ntawm microscopic morphology ntawm ettringham thaum ntxov (1-hnub) cement slurry los ntawm kev tshuaj xyuas duab 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 tau raug xaiv los ua 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.

1.2 Cov txheej txheem sim

Qhov piv ntawm dej-cement ntawm cov qauv cement yog 0.4 (qhov sib piv ntawm dej rau cement), thiab cov ntsiab lus ntawm cellulose ether yog 1% ntawm qhov hnyav ntawm cement. Kev npaj cov qauv tau ua raws li GB1346-2011 "Txoj Kev Ntsuas rau Kev Siv Dej, Teem Sijhawm thiab Kev Ruaj Ntseg ntawm Cement Standard Consistency". Tom qab tsim cov qauv, zaj duab xis yas tau muab tso rau ntawm qhov chaw ntawm pwm kom tiv thaiv kev ua kom dej noo thiab carbonization, thiab cov qauv tau muab tso rau hauv chav kho nrog qhov kub ntawm (20 ± 2) ℃ thiab qhov av noo ntawm (60 ± 5)%. Tom qab 1 hnub, cov pwm tau raug tshem tawm, thiab cov qauv tau tawg, tom qab ntawd ib qho qauv me me tau coj los ntawm nruab nrab thiab tsau rau hauv anhydrous ethanol kom tshem tawm cov dej noo, thiab cov qauv tau coj tawm thiab ziab ua ntej kuaj. Cov qauv qhuav tau nplaum rau ntawm lub rooj qauv nrog cov nplaum ob sab conductive, thiab ib txheej ntawm zaj duab xis kub tau txau rau ntawm qhov chaw los ntawm Cressington 108auto automatic ion sputtering instrument. Lub zog tam sim no yog 20 mA thiab lub sijhawm 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 ntu qauv. Hom electron theem nrab siab tau siv los soj ntsuam AFT. Lub zog hluav taws xob nrawm yog 15 kV, lub qhov chaw beam yog 3.0 nm, thiab qhov deb ua haujlwm tau tswj hwm ntawm kwv yees li 10 hli.

2. Cov txiaj ntsig thiab kev sib tham

Cov duab SEM ntawm ettringite hauv cov cement slurry HEMC-modified uas tau kho kom tawv qhia tau tias qhov kev loj hlob ntawm cov txheej Ca (OH) 2 (CH) tau pom tseeb, thiab AFt tau qhia txog kev sib sau ua ke ntawm cov pas luv luv zoo li AFt, thiab qee cov pas luv luv zoo li AFT tau npog nrog cov qauv membrane HEMC. Zhang Dongfang et al. kuj pom cov pas luv luv zoo li AFt thaum saib cov kev hloov pauv microstructure ntawm HEMC hloov kho cement slurry los ntawm ESEM. Lawv ntseeg tias cov cement slurry ib txwm muaj tshuaj tiv thaiv sai tom qab ntsib dej, yog li AFt siv lead ua nyias nyias, thiab kev ncua sijhawm ntawm lub hnub nyoog hydration ua rau muaj kev nce ntxiv ntawm qhov ntev-txoj kab uas hla. Txawm li cas los xij, HEMC ua rau cov viscosity ntawm cov tshuaj, txo qhov nrawm ntawm cov ions hauv cov tshuaj thiab ncua sijhawm tuaj txog ntawm dej ntawm qhov chaw ntawm cov khoom clinker, yog li qhov ntev-txoj kab uas hla ntawm AFt nce ntxiv hauv qhov sib txawv tsis muaj zog thiab nws cov yam ntxwv morphological tau qhia txog cov duab luv luv zoo li pas. Piv nrog AFt hauv cov cement slurry ib txwm muaj hnub nyoog tib yam, txoj kev xav no tau raug txheeb xyuas ib feem, tab sis nws tsis siv tau los piav qhia txog kev hloov pauv morphological ntawm AFt hauv MC hloov kho cement slurry. Cov duab SEM ntawm ettridite hauv 1-hnub hardened MC modified cement slurry kuj qhia txog kev loj hlob ntawm cov txheej Ca (OH) 2, qee qhov chaw AFt kuj tau npog nrog cov qauv zaj duab xis ntawm MC, thiab AFt qhia txog cov yam ntxwv morphological ntawm kev loj hlob ntawm pawg. Txawm li cas los xij, los ntawm kev sib piv, AFt siv lead ua hauv MC modified cement slurry muaj qhov sib piv ntev-txoj kab uas hla loj dua thiab cov morphology slimmer dua, qhia txog cov qauv acicular.

Ob qho tib si HEMC thiab MC ncua cov txheej txheem hydration thaum ntxov ntawm cov cement thiab ua rau cov viscosity ntawm cov tshuaj nce ntxiv, tab sis qhov sib txawv ntawm AFt morphological yam ntxwv tshwm sim los ntawm lawv 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. tsau cov synthesized AFt hauv cov kua alkali npaj kom tau txais "ntub AFt", thiab tshem tawm ib feem thiab ziab nws ntawm qhov chaw ntawm cov kua CaCl2 saturated (35% qhov av noo txheeb ze) kom tau txais "qhuav AFt". Tom qab kev tshawb fawb txog kev txhim kho qauv los ntawm Raman spectroscopy thiab X-ray hmoov diffraction, nws pom tias tsis muaj qhov sib txawv ntawm ob qho qauv, tsuas yog qhov kev taw qhia ntawm kev tsim cov siv lead ua ntawm cov hlwb hloov pauv hauv cov txheej txheem ziab, uas yog, hauv cov txheej txheem ntawm kev hloov pauv ib puag ncig los ntawm "ntub" mus rau "qhuav", AFt siv lead ua cov hlwb raws li qhov kev taw qhia ib txwm ntawm a maj mam nce. Cov siv lead ua AFt raws li qhov kev taw qhia ib txwm ua tsawg dua thiab tsawg dua. Lub chav yooj yim tshaj plaws ntawm qhov chaw peb-seem yog tsim los ntawm kab ib txwm, b kab ib txwm thiab c kab ib txwm uas yog perpendicular rau ib leeg. Yog tias b normals raug kho, AFt crystals sib sau ua ke raws li normals, ua rau muaj qhov loj ntawm lub cell hla ntu hauv lub dav hlau ntawm ab normals. Yog li, yog tias HEMC "khaws" dej ntau dua li MC, ib puag ncig "qhuav" tuaj yeem tshwm sim hauv thaj chaw ib cheeb tsam, txhawb kev sib sau ua ke thiab kev loj hlob ntawm AFt crystals. Patural et al. pom tias rau CE nws tus kheej, qhov siab dua ntawm polymerization (lossis qhov loj dua ntawm qhov hnyav molecular), qhov ntau dua ntawm viscosity ntawm CE thiab qhov zoo dua ntawm kev ua haujlwm khaws cia dej. Cov qauv molecular ntawm HEMCs thiab MCS txhawb nqa qhov kev xav no, nrog rau pawg hydroxyethyl muaj qhov hnyav molecular loj dua li pawg hydrogen.

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

3. Xaus Lus

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

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

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