Hydroxypropyl Methylcellulose (HPMC)yog ib qho cellulose ether uas tsis yog ionic siv dav hauv cov ntaub ntawv cement xws li cov tshuaj mortar, cov nplaum pobzeb, cov tshuaj mortar uas nws tus kheej leveling, thiab cov cement plaster. Nws lub luag haujlwm tseem ceeb yog los txhim kho kev ua haujlwm, kev khaws dej, thiab kev ruaj khov ntawm cov khoom sib xyaw. Txawm li cas los xij, ua ib qho khoom siv organic additive uas muaj molecular hnyav, HPMC kuj muaj feem cuam tshuam loj heev rau cov tshuaj tiv thaiv lub cev thiab tshuaj thaum lub sijhawm ua cov cement hydration.
1. Cov Khoom Siv Physicochemical ntawm HPMC
HPMC yog cov polymer yaj hauv dej uas tsim los ntawm cov cellulose ntuj los ntawm kev sib xyaw ua ke uas ua rau muaj methoxy thiab hydroxypropoxy pawg. Nws cov qauv molecular muaj ntau hydroxyl thiab ether bonds, ua rau nws tsim tau lub network hydrogen bond ruaj khov nrog cov dej molecules, ua rau muaj kev khaws cia dej zoo heev thiab cov khoom ua zaj duab xis. Nws cov kua dej ua rau pom cov yam ntxwv pseudoplastic kua, txhais tau tias nws cov viscosity txo qis hauv qab shear, uas yog qhov zoo rau kev ua haujlwm tsim kho. Vim nws cov khoom tsis-ionic, HPMC cuam tshuam me ntsis nrog cov khoom ionic hauv cement. Txawm li cas los xij, los ntawm kev nqus lub cev thiab cov teebmeem steric hindrance, nws tseem cuam tshuam rau cov txheej txheem hydration ntawm cov khoom cement.
2. Kev Cuam Tshuam ntawm HPMC rau theem pib ntawm Cement Hydration
Thaum pib ntawm kev ua kom cov cement hydration, cov molecule HPMC tuaj yeem nqus tau rau ntawm qhov chaw ntawm cov cement me me, tsim cov zaj duab xis polymeric. Cov zaj duab xis no cuam tshuam kev nkag mus ntawm cov dej rau hauv cov cement me me, ncua kev yaj ntawm C₃S (tricalcium silicate) thiab C₃A (tricalcium aluminate). Cov kev tshawb fawb tau qhia tias kev ntxiv HPMC ua rau lub sijhawm induction ntawm cement qeeb heev, hloov qhov exothermic peak ntawm lub system tom qab, ua rau txo qis ntawm tus nqi hydration.
Qhov kev ncua sij hawm no feem ntau yog los ntawm ob qho:
Kev cuam tshuam ntawm lub cev: Zaj duab xis HPMC txwv tsis pub dej sib kis thiab sib pauv ion, txo qhov tsim ntawm cov nuclei hydration thaum ntxov.
Kev sib tw nqus dej: HPMC muaj peev xwm nqus dej tau zoo, sib tw nrog cov cement rau dej dawb hauv lub kaw lus, ua rau qhov sib piv dej-cement qis dua, yog li ua rau qeeb qeeb ntawm cov tshuaj tiv thaiv dej.
Yog li ntawd, hauv cov tshuab mortar uas muaj HPMC, ob qho tib si thawj zaug thiab zaum kawg teeb tsa feem ntau ntev dua, tab sis qhov no yog qhov zoo rau kev txhim kho kev ua haujlwm.
3. Kev Cuam Tshuam ntawm HPMC rau Cov Khoom Siv Cement Hydration
Txawm hais tias HPMC thaum xub thawj tiv thaiv cov tshuaj tiv thaiv hydration, nws cov nyhuv qeeb tsis rhuav tshem qib kawg ntawm cov cement hydration. Raws li lub sijhawm, HPMC maj mam yaj lossis tawg hauv ib puag ncig alkaline, cuam tshuam cov txheej txheej thiab tso cai rau cov cement hydration txuas ntxiv mus.
Thaum lub sijhawm tom qab hydration, cov qauv ntawm cov khoom xws li hydrated calcium silicate (CSH gel) thiab calcium hydroxide (CH3) tsim nyob rau hauv lub cev feem ntau yuav ua rau denser, thiab porosity txo qis. Cov dej-tuav cov nyhuv ntawm HPMC ua kom muaj kev sib txuas ntawm hydration hauv qhov chaw qhuav, yog li txhawb nqa tag nrho cov tshuaj tiv thaiv hydration thiab txo qhov tsim ntawm cov kab nrib pleb qhuav. Qee qhov kev tshawb fawb kuj qhia tau tias HPMC tuaj yeem txhawb nqa kev tsim cov CSH sib xws los ntawm kev tswj hwm ion migration thiab hauv zos pH, yog li ua rau kom muaj qhov ceev ntawm cov txheej interfacial.
4. Cov teebmeem ntawm HPMC rau Microstructure thiab Mechanical Properties
Qhov muaj HPMC hloov pauv qhov microstructure ntawm cov cement paste. Nws cov polymer network peb-seem pab khaws cov dej noo thaum lub sijhawm hardening, ua rau muaj kev faib tawm ntau dua ntawm cov khoom hydration thiab cov qauv pore zoo dua. Kev soj ntsuam scanning electron microscopy (SEM) qhia tau hais tias cov cement paste nrog ntxiv HPMC muaj tsawg dua qhov hws thiab cov denser CSH gel faib.
Txawm li cas los xij, cov khoom organic ntawm HPMC kuj tseem yuav ua rau lub zog thaum ntxov ntawm lub cev tawv tsis muaj zog rau qee qhov. Qhov no yog vim tias nyob rau theem pib, qee qhov chaw tsis tau hydrated tag nrho, thiab kev teeb tsa qeeb qeeb qeeb qeeb qeeb ntawm kev tsim lub zog. Txawm li cas los xij, thaum cov tshuaj tiv thaiv hydration txuas ntxiv mus, lub zog rov qab zoo thiab txawm tias me ntsis zoo dua tom qab. Tus qauv "kev txwv thaum ntxov, kev txhim kho tom qab" no tau pom tseeb tshwj xeeb hauv cov kab ke HPMC qis (<0.5%).
5. Kev Sib Npaug ntawm HPMC Dosage thiab Cov Teebmeem
Qhov ntau npaum li cas ntawm HPMC yog ib qho tseem ceeb uas cuam tshuam rau nws qhov ua tau zoo. Feem ntau, thaum HPMC koob tshuaj yog 0.1% -0.5% ntawm cov cement loj, nws tuaj yeem txhim kho kev khaws dej thiab kev ua haujlwm tau zoo yam tsis muaj kev txwv tsis pub cov txheej txheem hydration. Kev noj ntau dhau yuav ua rau lub sijhawm ntev hauv cov tshuaj tiv thaiv hydration, ua rau cov cement porosity ntau ntxiv, thiab thaum kawg, cuam tshuam tsis zoo rau cov khoom siv kho tshuab.
Qhov degree ntawm kev hloov pauv (DS), qib viscosity, thiab qhov hnyav molecular ntawm HPMC kuj cuam tshuam rau tus cwj pwm hydration. High-viscosity, high-substitution-degree HPMC muaj zog adsorption thiab barrier teebmeem, ua rau muaj kev ncua sijhawm ntau dua hauv hydration; thaum low-viscosity HPMC tuaj yeem sib npaug workability thiab hardening kev ua tau zoo.
HPMC ua lub luag haujlwm ob hauv cov txheej txheem hydration ntawm cov ntaub ntawv cement:
Theem Thaum Ntxov: Nws ncua qhov kev ua kom cov dej ntawm cov cement me me los ntawm kev nqus, tsim zaj duab xis, thiab nqus dej, ua kom lub sijhawm teeb tsa ntev dua.
theem nrab mus txog theem kawg: Nws txhawb nqa kev ua kom dej ntws tas mus li los ntawm kev khaws dej thiab kev tswj hwm kev sib cuam tshuam, txhim kho qhov ceev ntawm cov qauv thiab qhov ntim ruaj khov.
Cov tshuaj noj kom raug thiab cov qauv molecular tsim nyog ntawmHPMCTsis yog tsuas yog txhim kho kev ua haujlwm tau zoo xwb tab sis kuj tseem ua kom zoo dua qhov microstructure thiab kev ua haujlwm ntev ntawm cov cement paste rau qee qhov. Yog li ntawd, hauv kev tsim kho vaj tse, kev tswj hwm hom thiab koob tshuaj ntawm HPMC yog qhov tseem ceeb rau kev ua tiav qhov sib npaug thiab kev ua haujlwm zoo ntawm cov ntaub ntawv cement.
Lub sijhawm tshaj tawm: Kaum Ib Hlis-06-2025