Cellulose ether akan ilimin halittar jiki na farkon etringite

Sakamakon hydroxyethyl methyl cellulose ether da methyl cellulose ether a kan ilimin halittar jiki na ettringite a farkon siminti slurry an yi nazari ta hanyar duban microscopy na lantarki (SEM). Sakamakon ya nuna cewa tsawon-diamita rabo na ettringite lu'ulu'u a hydroxyethyl methyl cellulose ether modified slurry ne karami fiye da cewa a cikin talakawa slurry, da kuma ilimin halittar jiki na ettringite lu'ulu'u ne gajere sanda-kamar. Tsawon diamita rabo na ettringite lu'ulu'u a cikin methyl cellulose ether modified slurry ya fi girma fiye da cewa a cikin talakawa slurry, da kuma ilimin halittar jiki na ettringite lu'ulu'u ne allura-sanda. Lu'ulu'u na ettringite a cikin slurries na siminti na yau da kullun suna da rabon al'amari a wani wuri tsakanin. Ta hanyar binciken gwajin da ke sama, ya kara bayyana cewa bambancin nauyin kwayoyin halitta na nau'in ether na cellulose guda biyu shine mafi mahimmancin abin da ya shafi ilimin halittar ettringite.

Mabuɗin kalmomi:ettingite; Tsawon diamita; Methyl cellulose ether; Hydroxyethyl methyl cellulose ether; ilimin halittar jiki

Ettringite, a matsayin samfurin hydration ɗan ƙaramin faɗaɗa, yana da tasiri mai mahimmanci akan aikin siminti, kuma koyaushe shine wurin bincike na kayan tushen siminti. Ettringite wani nau'in trisulfide ne na calcium aluminate hydrate, tsarin sinadaransa shine [Ca3Al (OH) 6 · 12H2O] 2 · (SO4) 3 · 2H2O, ko kuma ana iya rubuta shi da 3CaO · Al2O3 · 3CaSO4 · 32H2O, sau da yawa ana rage shi da AFt. . A cikin tsarin siminti na Portland, ettringite yana samuwa ne ta hanyar amsawar gypsum tare da aluminate ko ferric aluminate ma'adanai, wanda ke taka rawa na jinkirta hydration da farkon ƙarfin siminti. Samuwar da ilimin halittar jiki na ettringite yana shafar abubuwa da yawa kamar zafin jiki, ƙimar pH da ƙaddamarwar ion. Tun farkon 1976, Metha et al. An yi amfani da sikanin microscopy na lantarki don nazarin yanayin yanayin halittar AFt, kuma ya gano cewa yanayin halittar irin waɗannan samfuran hydration da aka faɗaɗa kaɗan sun ɗan bambanta lokacin da girman sararin samaniya ya isa kuma lokacin da sarari ya iyakance. Na farko ya kasance siriri siriri mai siffar allura-sanda, yayin da na karshen ya kasance gajeriyar siffa mai siffar sanda. Binciken Yang Wenyan ya gano cewa siffofin AFt sun bambanta da yanayin warkewa daban-daban. Yanayin rigar zai jinkirta haɓakar AFt a cikin simintin faɗaɗa-doped kuma yana ƙara yuwuwar kumburin kankare da fashewa. Yanayin daban-daban yana shafar ba kawai samuwar da microstructure na AFt ba, har ma da kwanciyar hankali. Chen Huxing et al. gano cewa kwanciyar hankali na dogon lokaci na AFt ya ragu tare da karuwar abun ciki na C3A. Clark da Monteiro et al. gano cewa tare da karuwar matsa lamba na muhalli, AFt crystal tsarin ya canza daga tsari zuwa rashin lafiya. Balonis da Glasser sun sake nazarin sauye-sauye masu yawa na AFm da AFt. Renaudin et al. yayi nazarin canje-canjen tsarin AFt kafin da kuma bayan nutsewa cikin bayani da sigogin tsarin AFt a cikin bakan Raman. Kunther et al. yayi nazarin tasirin hulɗar tsakanin CSH gel calcium-silicon rabo da sulfate ion akan AFt crystallization pressure by NMR. A lokaci guda, dangane da aikace-aikacen AFt a cikin kayan da aka yi da siminti, Wenk et al. nazarin AFt crystal fuskantarwa na kankare sashe ta hard synchrotron radiation X-ray diffraction gama fasahar. An bincika samuwar AFt a cikin siminti mai gauraya da wurin bincike na ettringite. Dangane da jinkirin amsawar ettringite, wasu malamai sun gudanar da bincike mai yawa akan dalilin AFt.

Ƙarar haɓakar haɓakar haɓakar ettringite wani lokaci yana da kyau, kuma yana iya aiki a matsayin "fadada" mai kama da ma'adinin fadada magnesium oxide don kula da kwanciyar hankali na kayan da ke da siminti. Bugu da kari na polymer emulsion da redispersible emulsion foda canza macroscopic Properties na tushen siminti kayan saboda su gagarumin tasiri a kan microstructure na tushen ciminti kayan. Duk da haka, sabanin redispersible emulsion foda wanda yafi kara habaka bonding dukiya na taurare turmi, da ruwa-soluble polymer cellulose ether (CE) yana ba da sabon gauraye turmi mai kyau ruwa riƙe da thickening sakamako, don haka inganta aiki yi. Ana amfani da ba-ionic CE ba, gami da methyl cellulose (MC), hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (HPMC),hydroxyethyl methyl cellulose (HEMC), da sauransu, kuma CE tana taka rawa a cikin sabon gauraye turmi amma kuma yana shafar tsarin samar da ruwa na siminti. Nazarin ya nuna cewa HEMC yana canza adadin AFt da aka samar azaman samfurin hydration. Duk da haka, babu wani binciken da ya yi daidai da tsarin da aka kwatanta da tasirin CE akan ƙananan ƙwayoyin cuta na AFt, don haka wannan takarda ya bincika bambancin tasirin HEMC da MC akan ƙananan ƙwayoyin cuta na ettringham a farkon (1-day) siminti slurry ta hanyar nazarin hoto kwatanta.

1. Gwaji

1.1 Raw Materials

P·II 52.5R Portland ciminti da Anhui Conch Cement Co., LTD aka zaba a matsayin siminti a cikin gwaji. The biyu cellulose ethers ne hydroxyethyl methylcellulose (HEMC) da methylcellulose (methylcellulose, Shanghai Sinopath Group) bi da bi. MC); Ruwan da ake hadawa shine ruwan famfo.

1.2 Hanyoyin gwaji

Matsakaicin ruwa-ciminti samfurin manna siminti shine 0.4 (yawan rabon ruwa zuwa siminti), kuma abun ciki na ether cellulose shine 1% na yawan siminti. An gudanar da shirye-shiryen samfurin bisa ga GB1346-2011 "Hanyar Gwaji don Amfani da Ruwa, Saitin Lokaci da Ƙarfin Ƙarfafa Ƙarfafa Ƙwararrun Ciminti". Bayan da aka samar da samfurin, an rufe fim ɗin filastik a saman ƙirar don hana ƙawancewar ruwa da carbonization, kuma an sanya samfurin a cikin ɗakin da aka kwantar da zafin jiki na (20 ± 2) ℃ da yanayin zafi na (60 ± 5). ) %. Bayan kwana 1, sai a cire gyalen, sannan a fasa samfurin, sannan a dauko dan karamin samfurin daga tsakiya a jika a cikin sinadarin ethanol mai gurbataccen ruwa, sannan a fitar da samfurin a bushe kafin a yi gwajin. An manne busassun samfuran a teburin samfurin tare da manne mai gefe biyu, kuma an fesa wani fim ɗin zinare a saman ta Cressington 108auto atomatik ion sputtering kayan aiki. A halin yanzu sputtering shine 20mA kuma lokacin sputtering shine 60s. An yi amfani da FEI QUANTAFEG 650 Mahalli Scanning Electroscope Microscope (ESEM) don lura da halayen halittar AFt akan sashin samfurin. An yi amfani da babban yanayin lantarki na biyu don kiyaye AFT. Ƙarfin hanzari ya kasance 15 kV, diamita na tabo ya kasance 3.0 nm, kuma an sarrafa nisan aiki a kusan 10 mm.

2. Sakamako da tattaunawa

Hotunan SEM na ettringite a cikin slurry mai ƙarfi HEMC-gyara siminti sun nuna cewa haɓakar haɓakar Layered Ca (OH) 2 (CH) a bayyane yake, kuma AFt ya nuna tarin gajeriyar sanda mai kama da AFt, kuma an rufe wasu gajerun sanda-kamar AFT. tare da tsarin membrane HEMC. Zhang Dongfang et al. Hakanan ya sami ɗan gajeren sanda-kamar AFt lokacin lura da canje-canjen microstructure na HEMC da aka canza siminti ta hanyar ESEM. Sun yi imani da cewa talakawa ciminti slurry amsa da sauri bayan cin karo da ruwa, don haka AFt crystal kasance siririn, da kuma tsawo na hydration shekaru ya haifar da ci gaba da karuwa na tsawon-diamita rabo. Duk da haka, HEMC ya karu danko na maganin, rage yawan adadin ions a cikin maganin kuma ya jinkirta isowar ruwa a saman sassan clinker, don haka tsawon tsayin diamita na AFt ya karu a cikin rashin ƙarfi kuma halayen halayensa sun nuna. gajeriyar siffa mai kama da sanda. Idan aka kwatanta da AFt a cikin slurry na siminti na yau da kullun na shekaru iri ɗaya, an tabbatar da wannan ka'idar a wani yanki, amma bai dace ba don bayyana canje-canjen morphological na AFt a cikin slurry na MC da aka gyara. Hotunan SEM na ettridite a cikin 1-day taurare MC modified siminti slurry kuma ya nuna daidaitacce girma na Layered Ca (OH) 2, wasu AFt saman an kuma rufe da fim tsarin MC, kuma AFt nuna morphological halaye na tari girma. Koyaya, idan aka kwatanta, AFt crystal a cikin MC slurry da aka gyara na siminti yana da girman tsayin diamita da ƙarin siriri ilimin halittar jiki, yana nuna nau'in halittar acicular na yau da kullun.

Dukansu HEMC da MC sun jinkirta farkon tsarin hydration na ciminti kuma suna haɓaka danko na maganin, amma bambance-bambance a cikin halayen halayen AFt da suka haifar da su har yanzu suna da mahimmanci. Abubuwan al'amuran da ke sama za a iya ƙara haɓakawa ta fuskar tsarin kwayoyin halitta na ether cellulose da AFt crystal tsarin. Renaudin et al. soaked da hada AFt a cikin shirye alkali bayani don samun "rigar AFt", da kuma partially cire shi da kuma bushe shi a saman saman CaCl2 cikakken bayani (35% dangi zafi) don samun "bushe AFt". Bayan nazarin gyaran tsarin da Raman spectroscopy da X-ray foda diffraction, an gano cewa babu wani bambanci tsakanin tsarin biyu, kawai shugabanci na crystal samuwar sel canza a cikin bushewa tsari, wato, a cikin aiwatar da muhalli. canza daga "rigar" zuwa "bushe", AFt lu'ulu'u sun kafa sel tare da al'ada na al'ada na karuwa a hankali. Lu'ulu'u na AFt tare da c al'ada shugabanci sun zama ƙasa da ƙasa. Mafi mahimmancin sashin sararin samaniya mai girma uku ya ƙunshi layi na al'ada, b na al'ada da layin al'ada c waɗanda suke daidai da juna. A cikin yanayin da aka gyara b na al'ada, AFt lu'ulu'u sun taru tare da na yau da kullun, wanda ya haifar da wani ɓangaren giciye tantanin halitta a cikin jirgin ab normals. Don haka, idan HEMC ya "ajiye" ruwa fiye da MC, yanayin "bushe" zai iya faruwa a cikin wani yanki na yanki, yana ƙarfafa haɗin kai da haɓakar lu'ulu'u na AFt. Patural et al. ya gano cewa ga CE kanta, mafi girman matakin polymerization (ko mafi girman nauyin kwayoyin), mafi girman dankon CE kuma mafi kyawun aikin riƙe ruwa. Tsarin kwayoyin halitta na HEMCs da MCS suna goyan bayan wannan hasashe, tare da ƙungiyar hydroxyethyl suna da nauyin kwayoyin da ya fi girma fiye da ƙungiyar hydrogen.

Gabaɗaya, lu'ulu'u na AFt za su yi girma kuma za su yi hazo ne kawai lokacin da ions masu dacewa suka kai wani jikewa a cikin tsarin mafita. Saboda haka, abubuwa kamar ion maida hankali, zafin jiki, pH darajar da samuwar sarari a cikin dauki bayani iya muhimmanci rinjayar da ilimin halittar jiki na AFt lu'ulu'u, da kuma canje-canje a cikin wucin gadi kira yanayi na iya canza ilimin halittar jiki na AFt lu'ulu'u. Saboda haka, rabo daga AFt lu'ulu'u a cikin talakawa ciminti slurry tsakanin biyu na iya zama lalacewa ta hanyar guda factor na ruwa amfani a farkon hydration na siminti. Koyaya, bambance-bambance a cikin ilimin halittar jini na AFt crystal wanda HEMC da MC ke haifarwa yakamata su kasance galibi saboda tsarin riƙe ruwa na musamman. Hemcs da MCS suna haifar da "rufe madauki" na jigilar ruwa a cikin microzone na sabobin siminti slurry, yana ba da izinin " ɗan gajeren lokaci" wanda ruwa ke "sauƙi don shiga kuma yana da wahala a fita." Koyaya, a wannan lokacin, yanayin yanayin lokacin ruwa a ciki da kusa da microzone shima ana canza shi. Abubuwa kamar ion maida hankali, pH, da dai sauransu, Canjin yanayin girma yana kara nunawa a cikin halayen halayen halayen halayen AFt. Wannan "rufe madauki" na jigilar ruwa yana kama da tsarin aikin da Pourchez et al ya bayyana. HPMC tana taka rawa wajen kiyaye ruwa.

3. Kammalawa

(1) Bugu da kari na hydroxyethyl methyl cellulose ether (HEMC) da kuma methyl cellulose ether (MC) iya muhimmanci canza ilimin halittar jiki na ettringite a farkon (1 rana) talakawa ciminti slurry.

(2) Tsawon da diamita na ettringite crystal a cikin HEMC da aka gyara siminti slurry ƙanana ne da gajeren siffar sanda; Tsawon da diamita rabo na ettringite lu'ulu'u a MC gyara siminti slurry ne babba, wanda shi ne allura-sanda siffar. Lu'ulu'u na ettringite a cikin slurries na siminti na yau da kullun suna da rabo tsakanin waɗannan biyun.

(3) Sakamakon daban-daban na ethers cellulose guda biyu akan ilimin halittar ettringite shine ainihin saboda bambancin nauyin kwayoyin halitta.