Dab tsi yog Kev faib tawm thiab cov txheej txheem ntawm cov neeg ua dej txo qis

Dej txo tus neeg saib xyuas yog hais txog cov xwm txheej uas cov pob zeb ua haujlwm thiab cov cement ntau npaum li cas tsis hloov, tuaj yeem txo cov dej sib tov, txhim kho lub zog ntawm cov pob zeb; Los yog nyob rau hauv cov xwm txheej ntawm kev ua haujlwm tsis tu ncua thiab lub zog, txuag tus nqi ntawm cov cement admixtures.

Lignosulfonate-based Water Reducers

Cov pawg no suav nrog calcium lignosulfonate (ntoo calcium), sodium lignosulfonate (ntoo sodium), thiab magnesium lignosulfonate (ntoo magnesium), nrog ntoo calcium uas feem ntau siv.

Ntoo calcium dej reducer yog tsim los ntawm residual cawv ntawm sulfite pulp los yog fiber ntau pulp. Nws yog ua tiav los ntawm neutralization nrog txiv qaub kua txiv, tom qab ntawd tshem tawm cov suab thaj los ntawm kev lom neeg fermentation, evaporation, concentration, thiab tshuaj tsuag kom qhuav los ua cov hmoov xim av-daj.

Qhov kev pom zoo ntawm cov ntoo calcium dej reducer feem ntau yog {{0}}.2% rau 0.3% ntawm cov cement loj. Nws tuaj yeem txo cov dej los ntawm 10% mus rau 15%, nce 28-hnub compressive zog ntawm pob zeb los ntawm 10% mus rau 20%; tsis txo cov dej, nws tuaj yeem ua kom cov pob zeb tawg los ntawm 80 mus rau 100mm; Yog tias tswj xyuas qhov qub compressive zog thiab poob qis, nws tuaj yeem txuag tau li 10% ntawm cov cement. Ntoo calcium dej reducer muaj cov nyhuv retarding ntawm pob zeb; ntau npaum li cas los yog siv nyob rau hauv qhov kub thiab txias yuav ua rau kom cov nyhuv no thiab tej zaum kuj yuav txo tau cov pob zeb, yog li yuav tsum tau ceev faj thaum siv.

Ntoo calcium dej reducer yog tsim rau cov kev ua vaj tse dav dav, tshwj xeeb tshaj yog siv rau cov ntim loj loj, kev tsim cov slipform, twj tso kua mis, thiab kev tsim kho lub caij ntuj sov. Nws tsis pom zoo kom siv ib leeg hauv kev tsim kho lub caij ntuj no; Nyob rau txhua hnub kub qis dua 5 degree, nws yuav tsum tau siv ua ke nrog cov neeg ua hauj lwm muaj zog thaum ntxov los yog cov tshuaj tiv thaiv kab mob. Nws kuj tseem tsis tsim nyog rau kev siv ib leeg hauv chav-kho pob zeb thiab cov pob zeb prestressed kom tsis txhob deg loosening tom qab chav kho.

Naphthalene Sulfonate Water Reducers

Naphthalene-raws li dej reducers yog tsim los ntawm naphthalene los yog nws homologues los ntawm sulfonation thiab methanol condensation. Tam sim no, nyob rau hauv Suav teb, feem ntau hom xws li NNO, NF, FDN, UNF, MF, thiab Jian Hom I yog cov tsis-cua-entraining dej reducers.

Cov tshuaj noj uas tsim nyog rau naphthalene-raws li dej reducers yog 0.5% rau 1.0% ntawm cov cement loj, txo cov dej los ntawm 10% mus rau 25%, thiab nce 28- hnub ua vaj tse. los ntawm ntau tshaj 20%. Naphthalene dej reducers txhim kho cov dej txo thiab lub zog zoo thiab hloov tau zoo rau ntau hom cement. Lawv tsim nyog rau kev npaj thaum ntxov-lub zog, siab-lub zog, kua dej, thiab chav-kho pob zeb.

Dej-soluble Resin Water Reducers

Hom dej reducer no yog tsim los ntawm cov dej-soluble resins, xws li melamine resin thiab gumalon resin, uas yog cov dej ua kom muaj txiaj ntsig zoo. Hauv Suav teb, SM resin dej reducer yog ib qho ntawm cov khoom lag luam.

SM water reducer ntau npaum li cas ntawm {{0}}.5% mus rau 2.0% ntawm cov cement loj, txo cov dej los ntawm 15% mus rau 27%, nce 3- hnub ua vaj tse zog los ntawm 30% mus rau 100%, thiab 28-hnub lub zog los ntawm 20% mus rau 30%. SM water reducer yog tsim rau kev npaj cov pob zeb ua kom muaj zog, ua kom muaj zog thaum ntxov, cov pob zeb ua dej, thiab cov pob zeb ua kom zoo.

Kev Ua Haujlwm thiab Mechanisms ntawm Dej Reducers

Cov dej reducers feem ntau cuam tshuam cov pob zeb sib xyaw tshiab hauv ntau txoj hauv kev:

Dej txo

Cov txheej txheem ntawm kev txo cov dej yog feem ntau vim yog adsorption ntawm cov dej reducer molecules ntawm cov cement hais thiab dispersal ntawm cov khoom no. Thaum ntxiv rau pob zeb, cov dej reducers dissociate rau hauv loj anionic molecules thiab hlau cations (xws li Na+, Ca2+). Cov anionic molecules, uas muaj cov khoom muaj zog surfactant, ua raws li cov cement hais, imparting ib tug tsis zoo nqi thiab ua rau dispersion vim electrostatic repulsion. Tsis tas li ntawd, vim tias cov dej reducers yog hydrophilic, cov txheej txheem adsorption tsim ib zaj duab xis nyob ib ncig ntawm cov cement hais, tseem cuam tshuam cov cement agglomeration (qhov chaw-stabilizing nyhuv). Qhov no dispersal ntawm cement hais thiab theem nrab agglomerates tso dej thiab huab cua los ntawm cov flocculated aggregates, ua tiav cov dej txo.

Plasticizing nyhuv

Kev sib koom ua ke ntawm cov dej txo hauv cov pob zeb tuaj yeem txhim kho nws cov fluidity thaum tswj cov dej-rau-cement piv, qhov tshwm sim hu ua plasticizing. Dhau li ntawm cov nyhuv adsorptive dispersal, cov dej reducers kuj ua haujlwm los ntawm kev ntub dej thiab lubricating. Nrog rau cov khoom no, tsuas yog ib qho me me ntawm cov dej yuav tsum tau ua kom yooj yim sib tov cov pob zeb sib xyaw, txhim kho kev ua haujlwm ntawm cov pob zeb tshiab.

Teeb Retarding

Cov ions raug tso tawm los ntawm cov dej reducers nyob rau hauv cov cement-dej system tuaj yeem adsorb rau saum npoo ntawm cov cement hais, ua rau lawv cov ζ-muaj peev xwm, yog li txuas ntxiv rau qhov system stability. Ntxiv mus, anionic adsorption txheej thiab dej zaj duab xis tsim los ntawm hydrogen bonding kuj cuam tshuam kev sib cuag ntawm cov cement hais thiab dej, slowing down hydration thiab yog li ua raws li ib tug retarder.

Mechanism of Action of Water Reducers

Cov dej reducers yog cov surfactants ib txwm, nrog rau txhua hom muaj cov qauv molecular muaj ob ntu: pawg polar thiab pawg tsis-polar. Cov pawg polar txuas mus rau saum npoo ntawm cov cement hais, feem ntau txiav txim siab qhov kev sib raug zoo ntawm cov dej reducer molecules rau cov ntxhia hauv cov cement. Qhov no cuam tshuam rau cov tshuaj thiab lub cev ntawm tag nrho cov dej reducer molecule lossis ion. Thaum cov dej reducer molecules (los yog ions) adsorb rau saum npoo ntawm cov cement pob zeb hauv av nrog cov pab pawg tsis-polar tig mus rau sab nraud, txheej txheej hydrophobic yog tsim, yog li cuam tshuam nws cov khoom siv hydrophobic. Tsis tas li ntawd, pawg tsis-polar cuam tshuam rau lub zog adhesion ntawm cov cement hais thiab adsorptive muaj peev xwm ntawm pawg polar.