Cellulose ether yuav ncua cov dej ntawm cov cement mus rau qhov sib txawv, uas yog tshwm sim hauv kev ncua kev tsim ntawm ettringite, CSH gel thiab calcium hydroxide. Tam sim no, cov txheej txheem ntawm cellulose ether ncua cov cement hydration feem ntau suav nrog qhov kev xav ntawm kev cuam tshuam ion txav, alkali degradation thiab adsorption.
1. Hypothesis ntawm hindered ion zog
Nws yog hypothesized tias cellulose ethers nce viscosity ntawm pore tov, cuam tshuam tus nqi ntawm ion zog, yog li ncua cov cement hydration. Txawm li cas los xij, hauv qhov kev sim no, cov cellulose ether nrog qis viscosity muaj peev xwm ua kom cov cement hydration, yog li qhov kev xav no tsis tuav. Qhov tseeb, lub sij hawm rau ion txav los yog tsiv teb tsaws yog luv heev, uas yog pom tseeb incomparable nrog lub sij hawm ntawm cement hydration ncua.
2. Alkaline degradation
Polysaccharides feem ntau yooj yim degraded nyob rau hauv alkaline tej yam kev mob los tsim hydroxycarboxylic acids uas ncua cov cement hydration. Yog li, yog vim li cas vim li cas cellulose ether ncua cov cement hydration tej zaum yuav yog tias nws degrades nyob rau hauv alkaline cement slurry los tsim hydroxycarboxylic acids, tab sis txoj kev tshawb no pom tias Cellulose ether yog ruaj khov nyob rau hauv alkaline tej yam kev mob, tsuas yog me ntsis degraded, thiab cov khoom degraded yuav luag tsis muaj kev cuam tshuam. ntawm kev ncua ntawm cement hydration.
3. Adsorption
Adsorption tej zaum yuav yog vim li cas tiag vim li cas cellulose ether ncua cov cement hydration. Ntau cov organic additives yuav adsorb rau cov cement hais thiab hydration cov khoom, tiv thaiv kev tawg ntawm cement hais thiab crystallization ntawm cov khoom hydration, yog li ncua lub hydration thiab teeb tsa ntawm cov cement. Nws tau pom tias cellulose ether yog yooj yim adsorbed rau calcium hydroxide, C. S. Qhov saum npoo ntawm hydration khoom xws li H gel thiab calcium aluminate hydrate, tab sis nws tsis yooj yim rau adsorbed los ntawm ettringite thiab unhydrated theem. Ntxiv mus, kom deb li deb ntawm cellulose ether muaj kev txhawj xeeb, lub peev xwm adsorption ntawm HEC muaj zog dua li ntawm MC, thiab qis dua cov ntsiab lus ntawm hydroxyethyl hauv HEC lossis hydroxypropyl hauv HPMC, qhov muaj zog adsorption muaj zog yog: nyob rau hauv cov nqe lus ntawm hydration khoom, hydrogen. Lub peev xwm adsorption ntawm calcium oxide C. S. Lub peev xwm adsorption ntawm H muaj zog dua. Kev tsom xam ntxiv kuj tseem qhia tau tias qhov muaj peev xwm adsorption ntawm cov khoom siv dej thiab cov cellulose ether muaj kev sib raug zoo nrog kev ncua ntawm cov cement hydration: qhov muaj zog dua qhov adsorption, qhov pom tseeb dua qhov ncua sij hawm, tab sis qhov adsorption ntawm ettringite rau cellulose ether tsis muaj zog, tab sis nws tsim. tau qeeb heev. Cov kev tshawb fawb kuj tau pom tias cellulose ether muaj qhov muaj zog adsorption ntawm tricalcium silicate thiab nws cov khoom hydration, yog li ua rau ncua sij hawm hydration ntawm silicate theem, thiab muaj ib tug tsawg adsorption rau ettringite, tab sis qhov tsim ntawm ettringite yog txwv. Pom tseeb qeeb, qhov no yog vim qhov ncua sij hawm tsim ntawm ettringite cuam tshuam los ntawm Ca2 + tshuav nyiaj li cas hauv cov tshuaj, uas yog qhov txuas ntxiv ntawm ncua sij hawm silicate hydration ntawm cellulose ether.
Hauv cov txiaj ntsig kev xeem, qhov muaj peev xwm rov qab los ntawm HEC muaj zog dua li ntawm MC, thiab lub peev xwm ntawm cellulose ether ncua kev tsim cov calcium hydroxide muaj zog dua li ntawm C. S. Lub peev xwm ntawm H gel thiab ettringite muaj zog, uas muaj kev sib raug zoo nrog lub peev xwm adsorption ntawm cellulose ether thiab cement hydration khoom. Nws tau lees paub ntxiv tias qhov adsorption yuav yog qhov laj thawj tiag tiag vim li cas cellulose ether qeeb cov cement hydration, thiab cellulose ether thiab cement hydration khoom muaj kev sib raug zoo. Lub zog muaj peev xwm adsorption ntawm cov khoom cement hydration, qhov pom tseeb ntawm kev tsim cov khoom lag luam qeeb hydration. Cov txiaj ntsig kev sim yav dhau los qhia tau hais tias cov cellulose ethers sib txawv muaj qhov sib txawv ntawm Portland cement hydration qeeb, thiab tib lub cellulose ether muaj qhov cuam tshuam qeeb ntawm cov khoom sib txawv, uas qhia tau hais tias Portland cement hydration cov khoom muaj qhov sib txawv ntawm fiber ntau. Lub adsorption ntawm cellulose ether yog xaiv, thiab cov adsorption ntawm cellulose ether rau cement hydration khoom kuj yog xaiv.
Post lub sij hawm: Feb-27-2023