Lub mechanism ntawm kev txiav txim ntawm cov dej txo tus neeg sawv cev

Dispersion: Tom qab cov cement yog tov nrog dej, vim yog hydration ntawm cov cement hais, ob chav hluav taws xob txheej txheej txheem yog tsim nyob rau saum npoo ntawm cov cement hais, ua rau ib tug solvated dej zaj duab xis, thiab cov opposite nqi nyob rau saum npoo. cov cement particles ua rau muaj kev sib raug zoo ntawm cov cement hais. , ua rau cov cement slurry tsim cov qauv flocculation, ua rau 10% mus rau 30% ntawm cov dej sib tov tau 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 tov. Thaum ntxiv cov dej-txo tus neeg sawv cev, cov dej-txo cov tshuaj molecules tuaj yeem raug adsorbed rau saum npoo ntawm cov cement hais, kom cov npoo ntawm cov cement hais muaj tib tus nqi (feem ntau tsis zoo), tsim electrostatic repulsion, uas. txhawb kev sib nrig sib dispersion ntawm cov cement hais thiab disintegration ntawm flocculation qauv. , tso ib feem ntawm cov ntaub qhwv dej los koom rau hauv qhov ntws, yog li ua kom cov dej ntws zoo ntawm cov pob zeb sib xyaw.
Lubricant nyhuv: 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 tias yuav tsim ib tug ruaj khov solvated dej zaj duab xis nrog dej molecules. Cov yeeb yaj kiab dej no muaj cov nyhuv lubrication zoo. , tuaj yeem txo qhov zawv zawg tsis kam ntawm cov cement hais, yog li ntxiv txhim kho cov dej ntws ntawm cov pob zeb.
Steric hindrance: Lub hydrophilic branched chains nyob rau hauv lub superplasticizer qauv txuas mus 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, cov txheej txheem adsorption pib sib tshooj, uas yog, steric hindrance tshwm sim ntawm cov cement hais. Qhov sib tshooj ntau dua, qhov ntau dua qhov steric repulsion, thiab ntau dua qhov cuam tshuam rau kev sib koom ua ke ntawm cov cement hais, ua rau cov pob zeb tawg. Qhov kub tseem nyob zoo.
Slow-tso cov nyhuv ntawm grafted copolymer branched chains: Thaum lub sij hawm npaj cov txheej txheem ntawm cov tshiab dej-txo cov neeg ua hauj xws li polycarboxylate dej-txo cov neeg sawv cev, ib co ceg yog grafted rau lub molecules ntawm dej-txo tus neeg saib xyuas. Cov saw caj dab no tsis tuaj yeem muab qhov chaw xwb Ntxiv mus, nyob rau hauv qhov chaw siab alkalinity 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 dispersion ntawm cov cement hais thiab tswj slump. poob poob.