Txoj Cai Ua Haujlwm Ntawm Polycarboxylate Superplasticizer hauv Cement -Raws li cov ntaub ntawv

1. Cov nyhuv Dispersion
Thaum cov dej ntxiv rau cov cement thiab nplawm, cov cement particles nyiam ib leeg, tsim cov qauv flocculated. Cov qauv flocculated no ntxiab 10%-30% ntawm cov dej nruab nrab ntawm cov cement, tiv thaiv cov dej molecules los ntawm kev ntws mus dawb thiab ua cov roj nplua nyeem. Flocculation cuam tshuam qhov fluidity ntawm cov cement paste. Polycarboxylic acid molecules adsorb rau ntawm qhov chaw ntawm cov cement hais, imparting tus nqi tsis zoo rau cov khoom. Qhov no electrostatic repulsion txhawb kev dispersion, cuam tshuam cov qauv flocculated thiab tso tawm cov dej twj tso kua mis molecules, cia lawv koom nyob rau hauv cov txheej txheem ntws. Qhov no yog vim li cas polycarboxylic acid superplasticizers muaj dej- txo cov nyhuv. Qhov no tuaj yeem nkag siab tias yog qhov nce kev siv cov dej molecules ntau dua li tsuas yog nce lossis txo qhov hnyav molecular ntawm dej. Tsis tas li ntawd, kev tsim cov complexes ntawm COO₂- thiab Ca₂+ ions txo cov calcium ion concentration hauv cov cement paste, ncua kev tsim ntawm Ca(OH)₂ crystals thiab txo qhov tsim ntawm C-S-H gels, yog li ua kom cov cement hydration qeeb. Yog li ntawd, polycarboxylic acid molecules kuj muaj qee yam cuam tshuam. Raws li ib sab, qhov nyuaj hauv kev txhim kho thaum ntxov- ntxiv dag zog rau polycarboxylic acid niam cawv tuaj yeem cuam tshuam rau lawv cov txiaj ntsig tsis zoo. Tam sim no, feem ntau cov khoom siv zog thaum ntxov ntawm kev ua lag luam cia siab rau kev sib xyaw nrog sodium nitrite thiab triethanolamine kom ua tiav lawv cov txiaj ntsig xav tau.

2. Lubrication
Lub sab chains ntawm polycarboxylate superplasticizer molecules muaj hydroxyl thiab ether pawg (-C-O-C-C), uas yog hydrophilic. Cov pab pawg no khi rau cov dej molecules los ntawm hydrogen bonds, ua ib zaj duab xis dej ntawm cov cement hais. Cov yeeb yaj kiab dej no muaj cov nyhuv lubricating zoo, txo qhov tsis kam ntawm cov cement hais thiab ua kom cov dej ntws ntawm cov pob zeb.

3. Steric Hindrance
Cov ceg ntoo uas muaj nyob hauv cov qauv polycarboxylate superplasticizer tsim cov qauv spatial ntawm qib microscopic, uas nws cov qauv spatial tiv thaiv kev sib cuag nrog cov cement hais. Qhov ze ntawm cov cement hais, qhov ntau dua qhov kev cuam tshuam steric hindrance. Cov nyhuv no ua rau cov pob zeb muaj peev xwm tswj tau qhov tawg tsis kam. Cement particles yog micron - loj, thaum polycarboxylate molecules yog nanometer- loj, qhov sib txawv ntawm kwv yees li peb qhov kev txiav txim ntawm qhov loj. Yog li ntawd, ib qho cement particle tuaj yeem nqus tau ob peb polycarboxylate molecules.

4. Adsorption
Polycarboxylate superplasticizers muaj ob pawg hydrophilic thiab hydrophobic hauv lawv cov qauv molecular, tsim cov txheej txheem adsorption zoo hauv pob zeb. Thaum lub sij hawm hydration txheej txheem, lawv ua raws li cov cement hais, tiv thaiv lawv cov aggregation thiab coagulation. Qhov no txo ​​cov cohesion thiab kev sib txhuam sab hauv ntawm cov pob zeb thiab ua rau nws cov fluidity.

5. Dej txo cov nyhuv
Polycarboxylate superplasticizers tsim ib txheej adsorption ntawm cov cement hais, tiv thaiv kev sib nrig adsorption thiab agglomeration ntawm cov khoom. Qhov no txo ​​cov kev sib txhuam ntawm cov cement hais, yog li txo cov cohesiveness ntawm pob zeb. Qhov no tso cai rau txo qis hauv cov ntsiab lus dej rau tib cov cement ntau npaum li cas, ua tiav cov dej - txo cov nyhuv. Qhov no txhim kho lub zog thiab durability ntawm pob zeb.

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