Dab tsi yog qhov kev txiav txim thiab cov txheej txheem ntawm dej txo tus neeg sawv cev?

Concrete water reducers tuaj yeem txo cov dej siv yam tsis muaj kev cuam tshuam rau kev tsim kho ntawm cov cement pob zeb. Thaum lub sij hawm hardening txheej txheem ntawm cov cement pob zeb, cov dej tsawg dua poob, ua rau cov voids sab hauv tsawg dua, uas tuaj yeem txhim kho cov pob zeb muaj zog.

Admixtures ntawm cov dej reducerstuaj yeem txhim kho kev ua haujlwm ntawm cov cement pob zeb, txo kev siv zog thaum siv thiab sib xyaw.

Cov dej txo qis tuaj yeem txo qis cov cement thiab dej siv yam tsis muaj kev txo qis kev ua haujlwm thiab cov khoom siv dag zog ntawm cov pob zeb, yog li txo cov nqi tsim kho.

CovCov qauv molecular ntawm cov dej reducer additivesmuaj hydrophilic kawg ntawm ob qho kawg, nrog hydrophobic kawg qhia rau cov roj los yog cov khoom sib txuas. Thaum siv, cov ntsiab lus hydrophilic kawg ntawm cov dej, thaum cov ntsiab lus hydrophobic kawg ntawm cov roj lossis cov khoom sib txuas. Qhov no txo ​​cov kev sib tshuam ntawm cov dej thiab roj los yog cov theem khoom, ua tiav cov nyhuv dispersing. Hauv kev tsim ua vaj tse thiab kev sib xyaw ua ke, ib zaug dej ntxiv rau cov cement, cov cement tam sim ntawd tsim cov qauv flocculent. Ntxiv cov dej reducers tuaj yeem ua raws li cov cement hais, thaiv kev sib cuag ntawm cov cement hais thiab dej. Tsis tas li ntawd, qhov kawg ntawm hydrophilic ntawm cov pob zeb ua dej reducers adsorbs ib tug npaum li cas ntawm cov dej molecules, lubricating cement hais kom yooj yim dispersion. Lub hydrophilic alkali yog tsis zoo them. Tom qab cov cement particles yog adsorbed rau saum npoo ntawm cov cement, lawv kuj muaj cov nqi tsis zoo tib yam, rov ua dua ib leeg thiab dispersing cov cement hais kom zoo dua, txo cov dej siv thiab txhim kho cov dej ntws ntawm cov cement pob zeb.

Dispersion: Tom qab cov cement sib tov nrog dej, hydration ntawm cov cement hais ua cov txheej txheem ob txheej ntawm cov cement hais, tsim kom muaj kev daws teeb meem dej. Tsis tas li ntawd, cov cement particles muaj qhov sib txawv ntawm lawv qhov chaw, ua rau agglomeration ntawm cov cement particles thiab tsim cov qauv flocculated, nrog 10% -30% ntawm cov dej sib tov tau ntim los ntawm cov cement particles thiab tsis koom nrog hauv cov dej ntws dawb thiab lubrication. Qhov no cuam tshuam cov fluidity ntawm pob zeb sib tov. Thaum cov dej reducers ntxiv, cov molecules ntawm cov pob zeb ua dej reducers tuaj yeem adsorb rau saum npoo ntawm cov cement hais, ua rau cov cement particles nqa tib tus nqi, tsim electrostatic repulsion. Qhov no txhawb kev sib nrig sib dispersion ntawm cement hais, tawg ntawm flocculated lug, tso ib co ntawm cov dej uas tau enveloped thiab koom nyob rau hauv ndlwg, zoo nce lub flowability ntawm qhob mix.

Lubrication: Cov pab pawg hydrophilic nyob rau hauv cov pob zeb dej reducers muaj cov polarity siab, yog li cov yeeb yaj kiab adsorption ntawm cov dej reducers ntawm cov cement hais tuaj yeem tsim cov dej khov dej ruaj khov nrog cov dej molecules. Cov yeeb yaj kiab dej no muaj lubrication zoo, txo cov zawv zawg tiv thaiv ntawm cov cement hais, ntxiv txhim kho cov dej ntws ntawm cov pob zeb.

Steric cuam tshuam: Lub hydrophilic sab chains nyob rau hauv cov qauv ntawm cov dej reducers stretch nyob rau hauv aqueous daws, tsim ib tug peb-dimensional hydrophilic adsorption txheej nyob rau saum npoo ntawm adsorbed cement hais. Thaum cov cement particles ze rau ib leeg, cov txheej txheem adsorption pib sib tshooj, tsim steric hindrance. Qhov sib tshooj ntau dua, qhov ntau dua qhov steric hindrance, uas ua rau kom muaj kev tiv thaiv rau kev sib txuas ntawm cov cement hais, yog li tswj cov slump ntawm pob zeb zoo.

Slow-tso nyhuv ntawm T-graft copolymer chains: Tshiab hom dej reducers xws li polycarboxylate qhob dej reducers muaj qee cov ceg cog rau hauv cov dej reducer molecules thaum npaj. Cov ceg ntoo no tsis tsuas yog muab kev cuam tshuam tsis zoo xwb tab sis kuj tuaj yeem maj mam degrade nyob rau hauv qhov chaw siab alkalinity ntawm cov cement hydration, tso cov khoom tawg, txhim kho cov dispersibility ntawm cov cement, thiab tswj kev poob qis.