qhia
Hydroxypropyl methylcellulose (HPMC) yog ib qho cellulose ether uas tau siv dav hauv ntau yam lag luam xws li zaub mov, tshuaj, thiab kev tsim kho ua cov thickener, emulsifier, thiab stabilizer. Hauv kev tsim kho kev lag luam, HPMC feem ntau yog siv los ua cov khoom ntxiv rau cov khoom siv cement kom ua tiav cov khoom xav tau xws li kev ua haujlwm, dej tuav thiab kav ntev. Cov kev tshawb fawb tau pom tias ntxiv HPMC rau cov ntaub ntawv cement-based ncua cov txheej txheem dej ntawm cov cement, thaum kawg cuam tshuam rau kev txhim kho lub zog ntawm cov khoom siv cement.
Qhov cuam tshuam ntawm HPMC rau cement hydration
Cement hydration yog ib qho tshuaj lom neeg cov tshuaj tiv thaiv uas cuam tshuam nrog cov tshuaj tiv thaiv dej nrog cov cement qhuav. Thaum lub sij hawm hydration txheej txheem, cov cement particles reacts nrog dej los tsim ntau yam khoom hydration, uas pab txhim kho lub zog ntawm cement-based cov ntaub ntawv. Cov kev tshawb fawb tau pom tias qhov sib ntxiv ntawm HPMC rau cov khoom siv cement tuaj yeem ncua cov cement hydration, yog li hloov tus nqi thiab qhov loj ntawm lub zog.
Ib qho ntawm cov laj thawj tseem ceeb rau ncua sij hawm cov cement hydration yog cov dej tuav cov khoom ntawm HPMC. HPMC yog hydrophilic polymer uas absorbs dej thiab swells los tsim ib tug zoo li gel. Thaum HPMC ntxiv rau cov khoom siv cement, nws nqus dej los ntawm qhov sib tov, yog li txo cov dej dawb uas xav tau los ua kom cov cement. Qhov no nyob rau hauv lem slows down lub hydration txheej txheem, raws li cov tshuaj tiv thaiv ntawm cement nrog dej yuav tsum tau ib tug txaus cov dej.
Lwm qhov tseem ceeb uas ua rau ncua sij hawm cov cement hydration yog qhov adsorption ntawm HPMC rau ntawm cov cement hais. HPMC muaj affinity siab rau cov cement hais vim nws polarity. Nws tuaj yeem raug adsorbed rau saum npoo ntawm cov cement particles thiab tsim lub cev tiv thaiv kom tsis txhob muaj kev sib cuag ntawm cov dej molecules thiab cov cement hais. Qhov no nyob rau hauv lem slows down cov tshuaj tiv thaiv ntawm cement nrog dej, uas ua rau ncua sij hawm cement hydration.
Qhov sib ntxiv ntawm HPMC rau cov ntaub ntawv cement-based kuj tseem cuam tshuam rau nucleation thiab crystal kev loj hlob txheej txheem ntawm cov khoom hydration. Kev ywg dej ntawm cov cement cuam tshuam nrog kev tsim ntawm ntau theem crystalline, xws li calcium silicate hydrate (CSH) thiab calcium hydroxide (CH). HPMC tuaj yeem cuam tshuam cov nucleation thiab siv lead ua kev loj hlob ntawm qee qhov ntawm cov theem no, ua rau cov cement hydration qeeb ntxiv.
Lub mechanism ntawm cement hydration ncua
Lub luag haujlwm tseem ceeb uas HPMC ncua sijhawm cov cement hydration yog tsim los ntawm kev thaiv lub cev ntawm cov cement thiab dej. Thaum HPMC tau tawg mus rau hauv dej, nws tsim cov gel zoo li matrix uas tuaj yeem ntim cov khoom cement thiab txo qhov muaj dej dawb rau cov cement hydration. Qhov no nyob rau hauv lem slows down cov tshuaj tiv thaiv ntawm cement nrog dej, ua rau ncua sij hawm nyob rau hauv lub zog ntawm kev loj hlob ntawm cement-based cov ntaub ntawv.
Lwm lub tswv yim yog qhov adsorption ntawm HPMC rau saum npoo ntawm cov cement hais. HPMC muaj affinity siab rau cov cement hais vim nws polarity. Nws tuaj yeem raug adsorbed rau saum npoo ntawm cov cement particles thiab tsim lub cev tiv thaiv kom tsis txhob muaj kev sib cuag ntawm cov dej molecules thiab cov cement hais. Qhov no ntxiv qeeb cov tshuaj tiv thaiv ntawm cement nrog dej.
HPMC tuaj yeem cuam tshuam nrog ntau yam ntawm cov cement, xws li calcium ions, yog li cuam tshuam rau cov nucleation thiab crystal kev loj hlob txheej txheem ntawm hydration khoom. HPMC tuaj yeem cuam tshuam cov nucleation thiab siv lead ua kev loj hlob ntawm qee qhov ntawm cov theem no, ua rau cov cement hydration qeeb ntxiv.
nyob rau hauv xaus
Qhov sib ntxiv ntawm HPMC rau cov khoom siv cementitious tuaj yeem ncua cov cement hydration, yog li hloov tus nqi thiab qhov loj ntawm kev txhim kho lub zog. Cov txheej txheem ntawm ncua sij hawm cement hydration yog vim qhov tsim ntawm lub cev barrier ntawm cov cement hais thiab dej, uas yog adsorbed rau saum npoo ntawm cov cement hais thiab inhibits cov nucleation thiab crystal kev loj hlob txheej txheem ntawm hydration khoom. Kev nkag siab txog cov txheej txheem los ntawm HPMC retards cement hydration tuaj yeem ua rau peb ua kom zoo dua kev siv HPMC hauv cov ntaub ntawv cementitious kom tau txais cov khoom xav tau thaum tswj kev txhim kho lub zog ntawm cov ntaub ntawv cementitious.
Post lub sij hawm: Oct-24-2023