Admixtures ua lub luag haujlwm tseem ceeb hauv kev txhim kho kev ua haujlwm ntawm lub tsev qhuav-sib xyaw mortar, tab sis qhov sib ntxiv ntawm cov tshuaj khib nyiab qhuav ua rau cov khoom siv ntawm cov khoom siv khib nyiab qhuav ntau dua li cov tshuaj mortar, uas suav txog ntau dua 40% ntawm cov khoom raug nqi nyob rau hauv qhuav-mixed mortar.
Raws li cov laj thawj saum toj no, daim ntawv no tshuaj xyuas thiab sib piv qee cov khoom siv ntawm cov khoom siv uas nquag siv, thiab ntawm lub hauv paus no, kawm txog kev ua haujlwm ntawm cov khoom siv khib nyiab qhuav uas siv cov khoom sib xyaw.
1. Tus neeg saib xyuas dej
Dej tuav tus neeg saib xyuas yog ib qho tseem ceeb admixture los txhim kho cov dej tuav kev ua tau zoo ntawm cov khoom sib xyaw qhuav, thiab nws kuj yog ib qho tseem ceeb ntawm cov khoom siv los txiav txim seb tus nqi ntawm cov khoom siv khib nyiab qhuav.
1.1 Cellulose ether
Cellulose ether yog cov ntsiab lus dav dav rau cov khoom lag luam uas tsim los ntawm cov tshuaj tiv thaiv ntawm alkali cellulose thiab etherifying tus neeg sawv cev nyob rau hauv qee yam mob. Alkali cellulose yog hloov los ntawm cov neeg ua haujlwm sib txawv kom tau txais cov cellulose ethers sib txawv. Raws li cov khoom ionization ntawm cov khoom hloov, cellulose ethers tuaj yeem muab faib ua ob pawg: ionic (xws li carboxymethyl cellulose) thiab non-ionic (xws li methyl cellulose). Raws li hom kev hloov pauv, cellulose ether tuaj yeem muab faib ua monoether (xws li methyl cellulose) thiab sib xyaw ether (xws li hydroxypropyl methyl cellulose). Raws li kev sib txawv solubility, nws tuaj yeem muab faib ua dej-soluble (xws li hydroxyethyl cellulose) thiab organic solvent-soluble (xws li ethyl cellulose), thiab lwm yam. Cov tshuaj khib nyiab qhuav yog dej-soluble cellulose, thiab dej-soluble cellulose yog muab faib ua hom instant thiab nto kho ncua sij hawm dissolution hom.
Lub mechanism ntawm kev txiav txim ntawm cellulose ether nyob rau hauv mortar yog raws li nram no:
(1) Tom qab cov cellulose ether nyob rau hauv lub mortar yog yaj nyob rau hauv dej, qhov zoo thiab niaj hnub faib ntawm cov cementitious cov ntaub ntawv nyob rau hauv lub system yog guaranteed vim lub nto nto, thiab cellulose ether, raws li ib tug tiv thaiv colloid, "wraps" cov khoom. hais thiab Ib txheej ntawm lubricating zaj duab xis yog tsim rau ntawm nws sab nrauv, uas ua rau cov mortar system ruaj khov, thiab kuj txhim kho cov fluidity ntawm mortar thaum lub sij hawm sib tov thiab smoothness ntawm kev tsim kho.
(2) Vim nws tus kheej cov qauv molecular, cov tshuaj cellulose ether ua rau cov dej hauv mortar tsis yooj yim ploj, thiab maj mam tso tawm rau lub sijhawm ntev, ua rau cov mortar nrog dej zoo thiab ua haujlwm tau zoo.
1.1.1 Molecular formula ntawm methyl cellulose (MC) [C6H7O2(OH)3-h(OCH3)n]x
Tom qab cov paj rwb refined yog kho nrog alkali, cellulose ether yog tsim los ntawm ib tug series ntawm cov tshuaj tiv thaiv nrog methane chloride ua etherification tus neeg sawv cev. Feem ntau, qhov degree ntawm kev hloov pauv yog 1.6 ~ 2.0, thiab cov solubility kuj txawv nrog ntau qib kev hloov pauv. Nws belongs rau non-ionic cellulose ether.
(1) Methylcellulose yog soluble hauv dej txias, thiab nws yuav nyuaj rau yaj hauv dej kub. Nws cov tshuaj aqueous yog ruaj khov nyob rau hauv thaj tsam ntawm pH = 3 ~ 12. Nws muaj kev sib raug zoo nrog cov hmoov txhuv nplej siab, cov pos hniav, thiab lwm yam thiab ntau surfactants. Thaum qhov kub nce mus txog qhov kub thiab txias, gelation tshwm sim.
(2) Cov dej tuav ntawm methyl cellulose nyob ntawm nws cov nyiaj ntxiv, viscosity, particle fineness thiab dissolution tus nqi. Feem ntau, yog tias qhov sib ntxiv yog qhov loj, qhov zoo me me, thiab cov viscosity loj, cov dej tuav tau siab. Ntawm lawv, qhov sib ntxiv muaj qhov cuam tshuam loj tshaj plaws ntawm cov dej tuav tus nqi, thiab qib ntawm viscosity tsis ncaj qha mus rau theem ntawm cov dej tuav tus nqi. Tus nqi dissolution feem ntau yog nyob ntawm qhov kev hloov kho saum npoo ntawm cellulose hais thiab particle fineness. Ntawm cov cellulose ethers saum toj no, methyl cellulose thiab hydroxypropyl methyl cellulose muaj cov dej tuav ntau dua.
(3) Kev hloov ntawm qhov kub thiab txias yuav cuam tshuam rau cov dej tuav tus nqi ntawm methyl cellulose. Feem ntau, qhov kub thiab txias dua, qhov dej khaws cia tsis zoo. Yog hais tias lub mortar kub siab tshaj 40 ° C, cov dej tuav ntawm methyl cellulose yuav txo qis, cuam tshuam rau kev tsim kho ntawm mortar.
(4) Methyl cellulose muaj qhov cuam tshuam loj rau kev tsim kho thiab adhesion ntawm mortar. Qhov "adhesion" ntawm no yog hais txog cov nplaum nplaum ntawm tus neeg ua haujlwm cov cuab yeej siv thiab cov phab ntsa substrate, uas yog, shear resistance ntawm lub mortar. Lub adhesiveness yog siab, shear resistance ntawm lub mortar yog loj, thiab lub zog yuav tsum tau los ntawm cov neeg ua hauj lwm nyob rau hauv tus txheej txheem ntawm kev siv kuj loj, thiab kev tsim kho ntawm lub mortar yog tsis zoo. Methyl cellulose adhesion yog nyob rau theem nrab hauv cellulose ether cov khoom.
1.1.2 Cov mis molecular ntawm hydroxypropyl methylcellulose (HPMC) yog [C6H7O2(OH)3-mn(OCH3)m, OCH2CH(OH)CH3]n]x
Hydroxypropyl methylcellulose yog ib hom cellulose uas nws cov zis thiab kev noj tau nce zuj zus nyob rau xyoo tas los no. Nws yog non-ionic cellulose tov ether ua los ntawm refined paj rwb tom qab alkalization, siv propylene oxide thiab methyl chloride ua etherification tus neeg sawv cev, los ntawm ib tug series ntawm cov tshuaj tiv thaiv. Qhov kev hloov pauv feem ntau yog 1.2 ~ 2.0. Nws cov khoom sib txawv vim qhov sib txawv ntawm cov ntsiab lus methoxyl thiab hydroxypropyl cov ntsiab lus.
(1) Hydroxypropyl methylcellulose yog yooj yim soluble nyob rau hauv dej txias, thiab nws yuav ntsib teeb meem nyob rau hauv dissolving nyob rau hauv dej kub. Tab sis nws qhov kub thiab txias hauv dej kub yog siab dua li ntawm methyl cellulose. Lub solubility hauv dej txias kuj zoo heev piv nrog methyl cellulose.
(2) Lub viscosity ntawm hydroxypropyl methylcellulose muaj feem xyuam rau nws qhov hnyav molecular, thiab qhov loj dua qhov hnyav molecular, qhov viscosity siab dua. Kub kuj cuam tshuam rau nws cov viscosity, thaum kub nce, viscosity txo. Txawm li cas los xij, nws cov viscosity siab muaj qhov kub qis dua li methyl cellulose. Nws cov tshuaj yog ruaj khov thaum khaws cia ntawm chav tsev kub.
(3) Cov dej tuav ntawm hydroxypropyl methylcellulose nyob ntawm nws qhov sib ntxiv, viscosity, thiab lwm yam, thiab nws cov dej tuav tus nqi nyob rau hauv tib qhov sib ntxiv yog siab dua li ntawm methyl cellulose.
(4) Hydroxypropyl methylcellulose ruaj khov rau cov kua qaub thiab alkali, thiab nws cov tshuaj aqueous yog ruaj khov nyob rau hauv thaj tsam ntawm pH = 2 ~ 12. Caustic dej qab zib thiab txiv qaub dej tsis tshua muaj txiaj ntsig rau nws qhov kev ua tau zoo, tab sis alkali tuaj yeem ua kom nws tawg thiab ua kom nws cov viscosity. Hydroxypropyl methylcellulose yog ruaj khov rau cov ntsev ntau, tab sis thaum lub concentration ntawm ntsev tov yog siab, lub viscosity ntawm hydroxypropyl methylcellulose tov nyhav nce.
(5) Hydroxypropyl methylcellulose tuaj yeem sib xyaw nrog cov dej-soluble polymer compounds los ua ib qho kev daws teeb meem thiab siab dua viscosity. Xws li polyvinyl cawv, starch ether, zaub pos hniav, thiab lwm yam.
(6) Hydroxypropyl methylcellulose muaj enzyme zoo dua li methylcellulose, thiab nws cov tshuaj tsis tshua muaj peev xwm degraded los ntawm enzymes dua methylcellulose.
(7) Qhov adhesion ntawm hydroxypropyl methylcellulose rau mortar siv yog siab dua li ntawm methylcellulose.
1.1.3 Hydroxyethylcellulose (HEC)
Nws yog tsim los ntawm refined paj rwb kho nrog alkali, thiab reacted nrog ethylene oxide raws li etherification tus neeg sawv cev nyob rau hauv lub xub ntiag ntawm acetone. Qhov kev hloov pauv feem ntau yog 1.5 ~ 2.0. Nws muaj zog hydrophilicity thiab yooj yim rau nqus noo noo.
(1) Hydroxyethyl cellulose yog soluble hauv dej txias, tab sis nws nyuaj rau yaj hauv dej kub. Nws cov tshuaj yog ruaj khov ntawm qhov kub thiab txias yam tsis muaj gelling. Nws tuaj yeem siv tau ntev hauv qhov kub thiab txias hauv mortar, tab sis nws cov dej tuav qis dua li ntawm methyl cellulose.
(2) Hydroxyethyl cellulose ruaj khov rau cov kua qaub thiab alkali. Alkali tuaj yeem ua kom nrawm nrawm rau nws qhov kev sib cais thiab ua kom nws cov viscosity me ntsis. Nws dispersibility hauv dej yog me ntsis phem dua li ntawm methyl cellulose thiab hydroxypropyl methyl cellulose. .
(3) Hydroxyethyl cellulose muaj kev ua haujlwm zoo los tiv thaiv mortar, tab sis nws muaj sijhawm ntev dua rau cov cement.
1.1.4 Carboxymethylcellulose (CMC) [C6H7O2(OH)2och2COONa]n
Ionic cellulose ether yog tsim los ntawm ntuj fibers (paj rwb, thiab lwm yam) tom qab kev kho alkali, siv sodium monochloroacetate ua tus neeg sawv cev etherification, thiab tau txais kev kho cov tshuaj tiv thaiv. Qib ntawm kev hloov pauv feem ntau yog 0.4 ~ 1.4, thiab nws qhov kev ua tau zoo cuam tshuam los ntawm qib hloov pauv.
(1) Carboxymethyl cellulose yog hygroscopic ntau dua, thiab nws yuav muaj dej ntau dua thaum khaws cia rau hauv cov xwm txheej.
(2) Carboxymethyl cellulose aqueous tov yuav tsis tsim gel, thiab viscosity yuav txo nrog qhov kub thiab txias. Thaum qhov kub siab tshaj 50 ° C, viscosity yog irreversible.
(3) Nws ruaj khov heev cuam tshuam los ntawm pH. Feem ntau, nws tuaj yeem siv rau hauv gypsum-raws li mortar, tab sis tsis yog hauv cov cement-based mortar. Thaum alkaline heev, nws poob viscosity.
(4) Nws cov dej tuav tau qis dua li ntawm methyl cellulose. Nws muaj cov nyhuv retarding ntawm gypsum-raws li mortar thiab txo nws lub zog. Txawm li cas los xij, tus nqi ntawm carboxymethyl cellulose yog qis dua li ntawm methyl cellulose.
Post lub sij hawm: Mar-23-2023