Dab tsi yog qhov cuam tshuam ntawm pob zeb dej-txo tus neeg saib xyuas ntawm pob zeb?

Ib qho yog qhov cuam tshuam ntawm kev txo dej.Qhov sib piv ntawm cov dej-cement tuaj yeem txo qis thaum lub fluidity yog tswj los ntawm kev ntxiv cov dej-txo cov neeg ua haujlwm siab rau hauv pob zeb. Cov dej txo tus nqi ntawm kev ua haujlwm siab dej txo tus neeg sawv cev tuaj yeem ncav cuag 10% mus rau 25%, thiab cov dej txo tus nqi ntawm cov dej zoo tib yam txo tus neeg sawv cev yog 5% mus rau 15%, thiab cov neeg ua haujlwm siab dej txo tus neeg saib xyuas kuj muaj npe. Qhov laj thawj ntawm cov dej txo cov nyhuv feem ntau yog vim qhov adsorption thiab dispersion ntawm pob zeb ntawm cov dej txo tus neeg sawv cev. Nyob rau hauv tus txheej txheem ntawm kev sib tov nrog dej thiab teeb thiab hardening, cement yuav tsim ib co flocculating lug. Muaj ntau qhov laj thawj rau kev tsim cov qauv zoo li cov tsiaj, uas tej zaum yuav yog vim muaj cov nqi sib txawv ntawm cov cement minerals (C3A, C4AF, C3S, C2S) thaum lub sij hawm hydration txheej txheem, thiab cov flocculation yog tshwm sim los ntawm cov attraction ntawm opposite nqi. Nws kuj tseem yuav yog vim lub thermal txav ntawm cov cement hais hauv kev daws teeb meem, cov cement particles sib tsoo nrog ib leeg, adsorb thiab nyiam ib leeg ntawm qee cov npoo thiab cov fab kom tsim cov qauv zoo li flocculation. Lub van der Waals gravitational kev sib cuam tshuam ntawm cov hais thiab thawj theem ntawm cov tshuaj tiv thaiv hydrolytic hydration kuj tuaj yeem ua rau flocculation. Hauv cov qauv zoo li flocculation no, ntau cov dej sib tov yog kaw, uas txo cov dej uas xav tau rau cov cement hydration thiab txo cov kev ua haujlwm ntawm kev sib tov tshiab. Yuav kom tswj tau qhov kev ua haujlwm ntawm cov huab cua sib xyaw ua ke tshiab hauv kev tsim kho, nws yog ib qho tsim nyog yuav tsum tau ua kom cov dej siv thaum sib xyaw kom haum, uas yuav txhawb kev tsim cov pores ntau dhau ntawm cov qauv pob zeb cement, uas cuam tshuam rau ntau lub cev. thiab mechanical zog ntawm hardened pob zeb. Yog tias cov dej ntau dhau tuaj yeem tso tawm, cov dej siv ntawm cov pob zeb sib xyaw tuaj yeem txo qis heev. Nyob rau hauv tus txheej txheem ntawm kev npaj ua vaj tse, ntxiv ib tug tsim nyog tus nqi ntawm cov dej txo tus neeg sawv cev yuav ua tau lub luag hauj lwm no zoo. Cov txiaj ntsig tau pom tias pawg hydrophobic ntawm superplasticizer yog ncaj qha adsorbed rau ntawm cov cement particle nto, thiab pawg hydrophilic taw qhia rau cov tshuaj aqueous los tsim ib zaj duab xis los yog ntau molecular adsorption. Vim yog cov kev taw qhia adsorption ntawm surfactant molecules, cov cement particle nto muaj tib lub cim ntawm tus nqi, yog li nyob rau hauv qhov kev txiav txim ntawm hluav taws xob repulsion, lub flocculation-zoo li qauv tsim los ntawm cov cement nyob rau hauv thawj cov dej ntxiv yog dispersed thiab disintegrated, thiaj li hais tias lub flocculation-zoo li tus qauv tsim los ntawm cov cement nyob rau hauv lub thawj dej ntxiv yog dispersed thiab disintegrated, thiaj li hais tias lub flocculation-zoo li tus qauv tsim los ntawm cov cement nyob rau hauv thawj zaug dej ntxiv yog dispersed thiab disintegrated, thiaj li hais tias lub flocculation-zoo li tus qauv tsim los ntawm cov cement nyob rau hauv thawj cov dej ntxiv yog dispersed thiab disintegrated. dej dawb nyob rau hauv lub flocculation-zoo li condensation lub cev yog tso tawm, thiaj li mus cuag lub hom phiaj ntawm dej txo.

Qhov thib ob yog plasticization.Ntxiv cov dej-txo tus neeg sawv cev rau pob zeb tuaj yeem ua kom muaj dej ntau ntxiv thaum ua kom cov dej-cement piv tsis hloov. Tus neeg saib xyuas dej-txo tuaj yeem ua rau cov pob zeb tshiab sib xyaw ua ke ntau dua 10cm thaum ua kom cov cement tsis hloov, thiab cov dej-txo cov neeg ua haujlwm siab tuaj yeem npaj cov pob zeb nrog slump ntawm 25cm. Ntxiv nrog rau cov teebmeem tshwm sim los ntawm kev nqus dej dispersion tau hais ua ntej, plasticization kuj muaj cov teebmeem ntub dej thiab lubricating.

Qhov thib peb yog cov nyhuv wetting: Tom qab cov cement yog tov nrog dej, qhov saum npoo ntawm cov khoom yog ntub los ntawm dej, thiab cov dej ntub dej muaj kev cuam tshuam zoo rau kev ua haujlwm ntawm cov coagulants tshiab. Thaum zoo li no diffusion wetting tshwm sim lawm, tus nqi ntawm qhov chaw dawb lub zog txo yuav raug xam los ntawm cov kab zauv uas tau hais los ntawm Glbbs.

Qhov thib plaub yog cov nyhuv lubrication: pawg polar hydrophilic nyob rau hauv cov dej-txo tus neeg saib xyuas yog directionally adsorbed rau saum npoo ntawm cov cement hais thiab yooj yim txuam nrog dej molecules nyob rau hauv daim ntawv ntawm hydrogen bonds. Lub zog ntawm lub koom haum hydrogen bond yog ntau dua li qhov kev nyiam ntawm molecular ntawm cov dej molecules thiab cov cement hais. Thaum cov cement particles adsorb txaus dej-txo tus neeg sawv cev, los ntawm kev koom tes ntawm R-SO30 thiab hydrogen bonds nyob rau hauv dej molecules, ua ke nrog hydrogen daim ntawv cog lus ntawm cov dej molecules, ib tug ruaj khov txheej ntawm solvated dej zaj duab xis yog tsim nyob rau saum npoo ntawm cov dej molecules. cov cement hais, uas ua lub luag haujlwm tiv thaiv peb sab, tiv thaiv kev sib cuag ncaj qha ntawm cov cement hais, thiab plays lub luag haujlwm lubricating ntawm cov khoom. Qhov sib ntxiv ntawm cov dej txo tus neeg sawv cev yog nrog los ntawm kev qhia txog qee yam ntawm cov npuas dej (txawm tias yog hom dej uas tsis muaj cov neeg ua haujlwm txo qis, cov npuas me me yuav raug qhia). Cov npuas zoo no nyob ib puag ncig los ntawm cov yeeb yaj kiab molecular directionally adsorbed los ntawm cov dej txo cov neeg ua haujlwm, thiab muaj tib lub cim tus nqi raws li cov cement particle adsorption zaj duab xis, yog li cov cement particles yog dispersed ntawm npuas thiab cov cement hais vim hluav taws xob repulsion, yog li ua kom cov zawv zawg. muaj peev xwm ntawm cov cement hais (xws li pob bearing). Cov nyhuv no yog pom tseeb dua rau cov pob zeb sib xyaw nrog huab cua-entrained dej-txo tus neeg sawv cev. Vim tias cov nyhuv adsorption thiab dispersion, cov nyhuv ntub dej thiab cov nyhuv lubrication ntawm cov dej reducer, tsuav yog siv cov dej me me, cov pob zeb tuaj yeem sib xyaw tau yooj yim sib npaug, yog li txhim kho kev ua haujlwm ntawm cov pob zeb sib xyaw tshiab.