Cellulose ether pa morphology of early ettringite

Zotsatira za hydroxyethyl methyl cellulose ether ndi methyl cellulose ether pa morphology ya ettringite mu slurry yoyambirira ya simenti idaphunziridwa ndi scanning electron microscopy (SEM). Zotsatira zikuwonetsa kuti chiŵerengero cha kutalika kwa makhiristo a ettringite mu hydroxyethyl methyl cellulose etha wosinthidwa slurry ndi wocheperapo kusiyana ndi slurry wamba, ndipo morphology ya ettringite makhiristo ndi yaifupi ngati ndodo. The kutalika-m'mimba mwake chiŵerengero cha ettringite makhiristo mu methyl cellulose etha kusinthidwa slurry ndi yaikulu kuposa slurry wamba, ndi morphology wa ettringite makhiristo ndi singano ndodo. Ma khiristo a ettringite mu slurries wamba simenti amakhala ndi chiyerekezo chapakati penapake. Kupyolera mu kafukufuku woyesera pamwambapa, zikuwonekeratu kuti kusiyana kwa kulemera kwa maselo a mitundu iwiri ya cellulose ether ndi chinthu chofunika kwambiri chomwe chimakhudza morphology ya ettringite.

Mawu ofunikira:etringite; Kutalika kwa m'mimba mwake; Methyl cellulose ether; Hydroxyethyl methyl cellulose ether; morphology

Ettringite, monga mankhwala owonjezera pang'ono a hydration, imakhudza kwambiri ntchito ya konkire ya simenti, ndipo nthawi zonse yakhala malo opangira kafukufuku wa zipangizo zopangira simenti. Ettringite ndi mtundu wa trisulfide calcium aluminate hydrate, mankhwala ake ndi [Ca3Al (OH) 6 · 12H2O]2 · (SO4)3 · 2H2O, kapena akhoza kulembedwa monga 3CaO · Al2O3 · 3CaSO4 · 32H2O, nthawi zambiri amafupikitsidwa monga AFt. . Mu dongosolo la simenti la Portland, ettringite imapangidwa makamaka ndi momwe gypsum ndi aluminate kapena ferric aluminate minerals, yomwe imagwira ntchito yochedwetsa hydration ndi mphamvu yoyambirira ya simenti. Mapangidwe ndi morphology ya ettringite imakhudzidwa ndi zinthu zambiri monga kutentha, pH mtengo ndi ion concentration. Kuyambira 1976, Metha et al. anagwiritsa ntchito sikani ma electron microscopy kuti aphunzire makhalidwe a morphological a AFt, ndipo anapeza kuti morphology ya mankhwala owonjezera pang'ono a hydration anali osiyana pang'ono pamene danga la kukula linali lalikulu mokwanira komanso pamene malo anali ochepa. Yoyambayo nthawi zambiri inali yozungulira ngati singano, pomwe yotsirizira inali yachifupi ngati prism. Kafukufuku wa Yang Wenyan adapeza kuti mitundu ya AFt inali yosiyana ndi malo ochiritsa osiyanasiyana. Malo onyowa angachedwetse kubadwa kwa AFt mu konkriti yowonjezera ndikuwonjezera kuthekera kwa kutupa konkriti ndi kusweka. Madera osiyanasiyana amakhudza osati mapangidwe ndi microstructure ya AFt, komanso kukhazikika kwake kwa voliyumu. Chen Huxing et al. anapeza kuti kukhazikika kwa nthawi yaitali kwa AFt kunachepa ndi kuwonjezeka kwa C3A. Clark ndi Monteiro et al. adapeza kuti pakuwonjezeka kwa kupanikizika kwa chilengedwe, mawonekedwe a crystal a AFt adasintha kuchoka pa dongosolo kupita kuchisokonezo. Balonis ndi Glasser adawunikiranso kusintha kwa kachulukidwe ka AFm ndi AFt. Renaudin et al. adaphunzira kusintha kwamapangidwe a AFt isanayambe komanso itatha kumizidwa mu njira yothetsera vutoli komanso mapangidwe a AFt mu Raman spectrum. Kunther et al. adaphunzira zotsatira za kuyanjana pakati pa CSH gel calcium-silicon ratio ndi sulphate ion pa AFt crystallization pressure ndi NMR. Pa nthawi yomweyi, pogwiritsa ntchito AFt mu zipangizo zopangira simenti, Wenk et al. anaphunzira AFt galasi lolunjika pa gawo konkire kudzera molimba synchrotron cheza X-ray diffraction kumaliza luso. Mapangidwe a AFt mu simenti yosakanikirana ndi malo ofufuzira a ettringite adafufuzidwa. Kutengera kuchedwa kwa ettringite, akatswiri ena achita kafukufuku wambiri pazomwe zimayambitsa gawo la AFt.

Kukula kwa voliyumu komwe kumachitika chifukwa cha mapangidwe a ettringite nthawi zina kumakhala kokondweretsa, ndipo kumatha kukhala ngati "kukulitsa" kofanana ndi magnesium oxide expansion agent kuti asunge kukhazikika kwazinthu zopangira simenti. Kuwonjezera kwa polymer emulsion ndi redispersible emulsion powder kumasintha macroscopic katundu wa zipangizo zopangira simenti chifukwa cha zotsatira zake zazikulu pa microstructure ya zipangizo za simenti. Komabe, mosiyana ndi redispersible emulsion ufa amene makamaka timapitiriza kugwirizana katundu wa matope owuma, ndi madzi sungunuka polima mapadi efa (CE) amapereka matope atsopano osakaniza bwino posungira madzi ndi thickening tingati kuwongolera ntchito. Non-ionic CE imagwiritsidwa ntchito kwambiri, kuphatikiza methyl cellulose (MC), hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (HPMC),hydroxyethyl methyl cellulose (HEMC), etc., ndipo CE imagwira ntchito mumatope osakaniza kumene komanso imakhudzanso njira ya hydration ya slurry ya simenti. Kafukufuku wasonyeza kuti HEMC imasintha kuchuluka kwa AFt yopangidwa ngati mankhwala a hydration. Komabe, palibe maphunziro omwe adayerekeza mwadongosolo zotsatira za CE pazambiri zazing'ono za AFt, kotero pepalali likuwunika kusiyana kwa zotsatira za HEMC ndi MC pa microscopic morphology ya ettringham koyambirira (1-day) simenti slurry kudzera kusanthula zithunzi ndi kuyerekeza.

1. Yesani

1.1 Zida Zopangira

P · II 52.5R Portland simenti yopangidwa ndi Anhui Conch Cement Co., LTD idasankhidwa ngati simenti pakuyesako. Ma cellulose ethers awiriwa ndi hydroxyethyl methylcellulose (HEMC) ndi methylcellulose (methylcellulose, Shanghai Sinopath Group) motsatana. MC); Madzi osakaniza ndi madzi apampopi.

1.2 Njira zoyesera

Chiŵerengero cha madzi-simenti ya chitsanzo cha phala la simenti chinali 0,4 (chiŵerengero cha madzi ndi simenti), ndipo zomwe zili mu cellulose ether zinali 1% ya misa ya simenti. Kukonzekera kwa chitsanzocho kunachitika molingana ndi GB1346-2011 "Njira Yoyesera Yogwiritsira Ntchito Madzi, Kuyika Nthawi ndi Kukhazikika kwa Cement Standard Consistency". Pambuyo popanga chithunzicho, filimu yapulasitiki idakulungidwa pamwamba pa nkhungu kuti madzi asasunthike komanso kutulutsa mpweya, ndipo chithunzicho chinayikidwa m'chipinda chochiritsira chokhala ndi kutentha kwa (20 ± 2) ℃ ndi chinyezi chachibale cha (60 ± 5). . Pambuyo pa tsiku la 1, nkhunguyo inachotsedwa, ndipo chitsanzocho chinathyoledwa, ndiye chitsanzo chaching'ono chinatengedwa kuchokera pakati ndikuviika mu ethanol anhydrous kuti athetse hydration, ndipo chitsanzocho chinachotsedwa ndikuwumitsidwa musanayesedwe. Zitsanzo zoumazo zidamatidwa patebulo lachitsanzo ndi zomatira zambali ziwiri, ndipo filimu yagolide idapopera pamwamba ndi chida cha Cressington 108auto automatic ion sputtering. Mphamvu ya sputtering inali 20 mA ndipo nthawi ya sputtering inali 60 s. FEI QUANTAFEG 650 chilengedwe Scanning electron Microscope (ESEM) idagwiritsidwa ntchito kuyang'ana mawonekedwe a AFt pagawo lachitsanzo. Njira yachiwiri ya vacuum yachiwiri idagwiritsidwa ntchito kuyang'anira AFT. Magetsi othamanga anali 15 kV, m'mimba mwake mwake anali 3.0 nm, ndipo mtunda wogwirira ntchito unkayendetsedwa pafupifupi 10 mm.

2. Zotsatira ndi zokambirana

Zithunzi za SEM za ettringite mu slurry yolimba ya simenti ya HEMC yosinthidwa idawonetsa kuti kukula kwa magawo a Ca (OH) 2 (CH) kunali kodziwikiratu, ndipo AFt idawonetsa kusakhazikika kwa AFt yaifupi ngati ndodo, ndipo AFT yayifupi ngati ndodo idaphimbidwa. ndi HEMC membrane kapangidwe. Zhang Dongfang et al. adapezanso ndodo yayifupi ngati AFt powona kusintha kwa microstructure kwa HEMC kusinthidwa simenti slurry kudzera mu ESEM. Iwo ankakhulupirira kuti wamba simenti slurry anachita mwamsanga atakumana ndi madzi, kotero AFt kristalo anali woonda, ndi kutambasuka kwa hydration zaka kumabweretsa kuwonjezeka mosalekeza chiŵerengero cha m'mimba mwake kutalika. Komabe, HEMC inachulukitsa kukhuthala kwa yankho, kuchepetsa kumangidwa kwa ayoni mu yankho ndikuchedwa kufika kwa madzi pamwamba pa tinthu tating'onoting'ono tating'onoting'ono, kotero kuti chiŵerengero cha kutalika kwa AFt chinawonjezeka mofooka ndipo makhalidwe ake a morphological amasonyeza. mawonekedwe amfupi ngati ndodo. Poyerekeza ndi AFt mu slurry wamba simenti wa msinkhu womwewo, chiphunzitso ichi chatsimikiziridwa pang'ono, koma si ntchito kufotokoza morphological kusintha AFt mu MC kusinthidwa simenti slurry. Zithunzi za SEM za ettridite mu 1-day hardened MC zosinthidwa simenti slurry zidawonetsanso kukula kokhazikika kwa wosanjikiza Ca (OH)2, malo ena a AFt adaphimbidwanso ndi mawonekedwe a filimu a MC, ndipo AFt adawonetsa mawonekedwe a morphological a kukula kwa tsango. Komabe, poyerekezera, AFt crystal mu MC yosinthidwa simenti slurry ili ndi chiŵerengero chokulirapo cha kutalika kwa m'mimba mwake ndi morphology yowonda kwambiri, yomwe imasonyeza mawonekedwe a acicular morphology.

Zonse ziwiri za HEMC ndi MC zinachedwetsa kuyambika kwa hydration ya simenti ndikuwonjezera kukhuthala kwa yankho, koma kusiyana kwa makhalidwe a AFt morphological chifukwa cha iwo kunali kofunikira. Zomwe zili pamwambazi zitha kufotokozedwa momveka bwino kuchokera pamawonekedwe a maselo a cellulose ether ndi mawonekedwe a crystal a AFt. Renaudin et al. adaviika AFt yopangidwa mu njira ya alkali yokonzedwa kuti "yonyowa AFt", ndikuichotsa pang'ono ndikuyiwumitsa pamadzi odzaza a CaCl2 solution (35% chinyezi chachifupi) kuti "AFt youma". Pambuyo pa kafukufuku woyengedwa ndi Raman spectroscopy ndi X-ray ufa diffraction, anapeza kuti panalibe kusiyana pakati pa nyumba ziwirizi, kokha malangizo a kristalo mapangidwe maselo anasintha mu kuyanika ndondomeko, ndiko kuti, mu ndondomeko ya chilengedwe. kusintha kuchokera ku "nyowa" kupita ku "zouma", AFt makhiristo anapanga maselo motsatira njira yachibadwa ya kuwonjezeka pang'onopang'ono. Makhiristo a AFt motsatira njira yanthawi zonse adacheperachepera. Gawo lofunikira kwambiri la danga la magawo atatu limapangidwa ndi mzere wabwinobwino, b mzere wabwinobwino ndi c mzere wabwinobwino womwe uli wolunjika kwa wina ndi mnzake. Ngati ma b normals adakhazikika, makhiristo a AFt amalumikizana motsatira njira zanthawi zonse, zomwe zimapangitsa kuti pakhale gawo lokulitsa la cell mu ndege ya ab normals. Choncho, ngati HEMC "ikusungira" madzi ochulukirapo kuposa MC, malo "ouma" amatha kuchitika m'malo omwe amakhalapo, kulimbikitsa kugwirizanitsa ndi kukula kwa makristasi a AFt. Patural et al. adapeza kuti ku CE komweko, kuchuluka kwa polymerization kumakwera (kapena kulemera kwa maselo), kumapangitsa kukhuthala kwa CE komanso kusunga bwino madzi. Mapangidwe a molekyulu a HEMCs ndi MCS amachirikiza lingaliro ili, ndi gulu la hydroxyethyl lomwe lili ndi kulemera kwakukulu kwa maselo kuposa gulu la haidrojeni.

Nthawi zambiri, makhiristo a AFt amapangika ndikutsika pokhapokha ma ion oyenerera afika pakuchulukira kwina mu njira yothetsera. Choncho, zinthu monga ndende ion, kutentha, pH mtengo ndi mapangidwe danga mu njira yankho zingakhudze kwambiri morphology wa AFt makhiristo, ndi kusintha zinthu kaphatikizidwe yokumba akhoza kusintha morphology wa AFt makhiristo. Chifukwa chake, chiŵerengero cha makhiristo a AFt mu slurry wamba wa simenti pakati pa awiriwo atha kuyambitsidwa ndi chinthu chimodzi chokha chakumwa madzi poyambira hydration ya simenti. Komabe, kusiyana kwa AFt crystal morphology chifukwa cha HEMC ndi MC kuyenera kukhala makamaka chifukwa cha njira yawo yapadera yosungiramo madzi. Hemcs ndi MCS amapanga “njira yotsekeka” ya kayendedwe ka madzi mkati mwa microzone ya matope atsopano a simenti, zomwe zimalola “kanthaŵi kochepa” kumene madzi “amakhala osavuta kuloŵa ndi ovuta kutuluka.” Komabe, panthawiyi, chilengedwe chamadzimadzi mkati ndi pafupi ndi microzone chimasinthidwanso. Zinthu monga ndende ya ion, pH, ndi zina zambiri, Kusintha kwa malo okulirapo kumawonekeranso mu mawonekedwe a morphological a AFt makhiristo. "Loop yotsekedwa" iyi yoyendetsa madzi ndi yofanana ndi njira yomwe imafotokozedwa ndi Pourchez et al. HPMC ikugwira ntchito yosunga madzi.

3. Mapeto

(1) Kuwonjezera kwa hydroxyethyl methyl cellulose ether (HEMC) ndi methyl cellulose ether (MC) kungasinthe kwambiri morphology ya ettringite kumayambiriro (tsiku limodzi) slurry wamba wa simenti.

(2) kutalika ndi awiri a ettringite kristalo mu HEMC kusinthidwa simenti slurry ndi ang'onoang'ono ndodo mawonekedwe; Kutalika ndi m'mimba mwake kwa makhiristo a ettringite mu MC wosinthidwa simenti slurry ndi yayikulu, yomwe ndi mawonekedwe a singano. Ma kristalo a ettringite mu slurries wamba simenti ali ndi gawo pakati pa awiriwa.

(3) Zotsatira zosiyana za ma cellulose ethers pa morphology ya ettringite makamaka chifukwa cha kusiyana kwa kulemera kwa maselo.