Lub Mechanism Ntawm Kev Ua Ntawm Polycarboxylate Superplasticizer

Lub mechanism ntawm kev txiav txim ntawm polycarboxylate superplasticizer

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Dispersion: Tom qab cov cement yog tov nrog dej, vim yog hydration ntawm cov cement hais, ib qho hluav taws xob ob txheej txheej txheem yog tsim rau ntawm cov cement hais, uas tsim ib zaj duab xis dej solvated, thiab qhov saum npoo ntawm cov cement hais muaj ib qho kev sib cais ntawm cov cement. opposite nqi, uas ua rau muaj kev koom tes ntawm cov cement hais. , yog li cov cement slurry tsim cov qauv flocculation, kom 10 feem pua ​​​​rau 30 feem pua ​​​​ntawm cov dej sib xyaw yog qhwv hauv cov cement hais thiab tsis tuaj yeem koom nrog hauv kev khiav dawb thiab lubrication, yog li cuam tshuam cov fluidity ntawm cov pob zeb sib xyaw. Thaum cov dej txo tus neeg sawv cev ntxiv, vim tias cov dej txo tus neeg sawv cev molecules tuaj yeem raug coj mus rau adsorbed ntawm cov cement hais, qhov saum npoo ntawm cov cement hais muaj tib tus nqi (feem ntau yog tus nqi tsis zoo), tsim cov nyhuv electrostatic repulsion, uas. txhawb kev sib nrig sib dispersion ntawm cov cement hais thiab disintegration ntawm flocculation qauv. , tso cov qhwv ib feem ntawm cov dej thiab koom nrog hauv qhov ntws, yog li ua kom cov dej ntws zoo ntawm cov pob zeb sib xyaw.

Lubrication: Cov pab pawg hydrophilic nyob rau hauv cov dej-txo tus neeg saib xyuas yog heev polar, yog li cov adsorption zaj duab xis ntawm cov dej-txo tus neeg saib xyuas ntawm cov cement hais tuaj yeem tsim cov dej khov dej ruaj khov nrog cov dej molecules, uas muaj cov nyhuv lubricating zoo. , uas muaj peev xwm txo tau qhov zawv zawg tsis kam ntawm cov cement hais, yog li ntxiv txhim kho fluidity ntawm pob zeb.

Steric hindrance: lub hydrophilic branched saw nyob rau hauv cov qauv ntawm lub superplasticizer stretches nyob rau hauv lub aqueous tov, yog li tsim ib tug hydrophilic peb-dimensional adsorption txheej nrog ib tug tej thickness ntawm lub adsorbed cement hais. Thaum cov cement hais nyob ze rau ib leeg, txheej adsorption pib sib tshooj, uas yog, steric hindrance tshwm sim ntawm cov cement hais. Qhov sib tshooj ntau dua, qhov ntau dua qhov steric hindrance, thiab ntau dua qhov hindrance rau cohesion ntawm cov cement hais, uas ua rau cov pob zeb tawg. degree tseem zoo.

Sustained tso tawm cov nyhuv ntawm graft copolymerized branched chains: Thaum lub sij hawm kev npaj ntawm cov tshiab dej txo cov neeg ua hauj xws li polycarboxylate dej txo cov neeg ua hauj, ib co branched chains yog grafted rau cov molecules ntawm cov dej txo tus neeg sawv cev, uas yuav tsis tsuas muab steric qhov chaw nyob rau hauv tas li ntawd, nyob rau hauv lub Lub siab alkalinity ib puag ncig ntawm cov cement hydration, ceg saw tuaj yeem maj mam txiav tawm, yog li tso cov polycarboxylic acid nrog cov nyhuv dispersing, uas tuaj yeem txhim kho cov nyhuv dispersing ntawm cov cement hais thiab tswj cov slump. poob poob.