Hnub Kawg: 20 Lub Ib Hlis, 2022

3. Lub tshuab ua haujlwm ntawm superplasticizers

Lub mechanism ntawm dej txo tus neeg sawv cev los txhim kho fluidity ntawm qhob sib tov mas muaj xws li dispersing nyhuv thiab lubricating nyhuv. Cov dej txo tus neeg sawv cev yog qhov tseeb surfactant, ib kawg ntawm cov saw hlau ntev molecular yog yooj yim soluble hauv dej - hydrophilic pawg, thiab lwm qhov kawg yog insoluble hauv dej - hydrophobic pawg.

ib. Dispersion: Tom qab cov cement yog tov nrog dej, vim lub molecular attraction ntawm cov cement hais, cov cement slurry tsim cov qauv flocculation, kom 10% mus rau 30% ntawm cov dej sib tov yog qhwv hauv cov cement thiab tsis tuaj yeem koom nrog dawb. ntws thiab lubrication. cov nyhuv, yog li cuam tshuam cov fluidity ntawm cov pob zeb sib tov. 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 tawg ntawm cov cement hais thiab kev puas tsuaj ntawm cov qauv flocculation. , 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.

b. Lubrication: pawg hydrophilic nyob rau hauv lub superplasticizer yog heev polar, yog li cov adsorption zaj duab xis ntawm lub superplasticizer nyob rau saum npoo ntawm cov cement hais tuaj yeem tsim cov dej khov dej ruaj khov nrog cov dej molecules, thiab cov yeeb yaj kiab dej no muaj lub lubrication zoo tuaj yeem txo cov zawv zawg. tsis kam ntawm cov cement hais, yog li ntxiv kev txhim kho fluidity ntawm pob zeb.

Cov nyhuv ntawm dej reducer rau pob zeb, thiab lwm yam:

ib. Teem sijhawm. Superplasticizers feem ntau tsis muaj qhov cuam tshuam, thiab tseem tuaj yeem txhawb nqa dej thiab tawv ntawm cov cement. Retarded superplasticizer yog ib qho kev sib xyaw ntawm superplasticizer thiab retarder. Nyob rau hauv ib txwm muaj xwm txheej, thiaj li yuav ncua lub hydration ntawm cement thiab txo qhov poob ntawm slump, ib tug npaum li cas ntawm retarder yog ntxiv rau cov dej txo tus neeg sawv cev.

b. Cov ntsiab lus roj. Tam sim no, feem ntau siv polycarboxylate dej reducer muaj cov ntsiab lus huab cua, thiab cov ntsiab lus cua ntawm cov pob zeb yuav tsum tsis txhob siab dhau, txwv tsis pub cov pob zeb ua kom muaj zog yuav raug txo kom tsawg.

c. Kev tuav dej.

Superplasticizers tsis pab ntau los txo cov ntshav ntawm cov pob zeb, thiab tej zaum yuav ua rau kom cov ntshav. Cov ntshav pob zeb nce ntxiv thaum noj ntau dhau.