Cawv mechanism ntawm superplasticizer ntawm qhob zog
Superplasticizer yog qhov tseem ceeb ntawm cov khoom siv hauv tsev, siv cov npuas dej thiab npuas thiab lwm cov npuas, thiab lawv muaj cov yam ntxwv sib txawv thiab tsim qauv, yog tshwm sim los ntawm ionic superplasticizer. Tom qab ntxiv cov superplasticizer hauv cov pob zeb ua kev sib tov, superplasticizer yuav adsorb rau ntawm cov nplais cement. Feem ntau, kwv yees li 80% ntawm cov superplasticizer yuav raug adsorbed los ntawm cov nplais pob khoom, kom lawv muaj peev xwm tswj kev sib sau ua ke ntev ntev yam tsis muaj qhov tsis txawv. Thaum tsis ntxiv cov superplasticizer, pob zeb yuav muaj qhov nqi ntawm cov pa roj (li 2%), tsim los ntawm qhov loj me ntawm npuas tsis sib npaug, thiab kev faib tawm tsis sib xws heev. Tom qab ntxiv cov superplasticizer rau pob zeb ua kev, kev faib tawm ntawm cov qhob tsis tuaj yeem tuaj yeem tswj cov khoom zoo thiab txhim kho kev ua haujlwm ntawm kev ua vaj tse, xws li lub zog tensile ntawm qhob. Dhau li ntawm, ntxiv cov superplasticizer hauv kev ua vaj tse sib tov yuav pab txo kev siv dej hauv kev ua vaj tse sib tov. Cov huab cua huab cua me me uas tsim tawm yuav pab sau cov micro-qhov hws hauv pob zeb, txhim kho pob zeb tiv thaiv kev cuam tshuam ntawm cov pob zeb ua kom ruaj khov, thiab txhim kho nws cov tshuaj tiv thaiv ua rau xeb thiab kev tiv thaiv kev laus. Lub superplasticizer tuaj yeem ua ke rau qhov dej pub dawb ntawm kev ua haujlwm sab hauv, uas pab txo qhov ntsuas hluav taws xob zoo li qub thiab txhim kho qhov tsis kam ntawm cov pob zeb ua kom rov ua khov khov. Superplasticizer tuaj yeem ua rau qeeb ntawm cov tshuaj tiv thaiv hydration ceev ntawm cov cement nyob nruab nrab thiab qib theem, txhim kho lub zog ntawm cov cement thiab txhim kho nws qhov kev ua haujlwm tiv thaiv kev nthuav dav. Yog li no, thaum tov cov pob zeb ua ke, ntxiv rau kev txiav txim siab cov xuab zeb, pob zeb, cov cement thiab lwm yam khoom siv yooj yim, ntxiv qhov tsim nyog ntawm qee qhov nyiaj ntawm superplasticizer txhawm rau txhim kho kev siv cov pob zeb ua haujlwm.
1) Cuam tshuam ntawm superplasticizer rau ntawm qhov poob ntawm cov pob zeb ua haujlwm tshiab
Thaum txheeb xyuas qhov ua haujlwm tau thiab fluidity ntawm cov pob zeb ua, cov ntsiab lus tseem ceeb heev yog ib qho poob qis. Qhov loj dua tus nqi, qhov zoo dua fluidity ntawm qhob. Kev poob qis yog hais txog qhov sib txawv ntawm cov pob zeb pob zeb ntsuas rov qab ntxiv tom qab lub sijhawm tshwj xeeb thiab nws txoj kev poob qis. Cov yam ntxwv cuam tshuam suav nrog cov cement, cov yam ntxwv sib xyaws thiab cov piv ntawm dej-cement, thiab lwm yam. Hom superplasticizer kuj yog qhov tseem ceeb muaj feem xyuam. Thaum ntxov 30min, naphthalene series superplasticizer muaj qhov ntau qhov pob zeb poob, suav txog 60%, tom qab ntawm melamine series superplasticizer tus neeg sawv cev (30%) thiab polycarboxylic acid series superplasticizer (20%), uas qhia tau tias polycarboxylic acid series superplasticizer tau muaj qhov zoo tshaj plaws pob zeb ua kev tiv thaiv. Los ntawm nws cov txheej txheem tsim, chav haujlwm ntawm polycarboxylic acid superplasticizer hauv cov khoom siv pob zeb yuav muab adsorbed rau saum npoo ntawm cov cement, raws li txoj kev sib tw tso cai ua cov cement molecular polymer adsorption txheej tsim los ntawm electrostatic repulsion ntau dispersive nyhuv, txhim kho nws ruaj khov, yog li cov pob zeb ua kev ntxiv polycarboxylic acid system tom qab superplasticizer, tuaj yeem txo qhov kev poob qis.
(2) Cuam tshuam ntawm superplasticizer ntawm kev ua kom muaj zog ntawm cov pob zeb ua ke tshiab.
Lub zog ntawm cov pob zeb ua tiav ntawm cov khoom sib txawv ntawm cov neeg sab nraud muaj qhov sib txawv. Los ntawm kev thov cov superplasticizer, tuaj yeem txo qhov sib xyaw ntawm cov pob zeb sib tov sib xyaw ua kom dej haus, txhim kho qib dej ntawm cov cement, txhim kho pob zeb txhua lub hnub nyoog (3 d, 7 d thiab 28 d) siv, tuaj yeem yog los ntawm peb muaj kev ua haujlwm siab superplasticizer ntawm qhob compressive lub zog tau nce siab tshaj li qhov ntawm cov qhob qhob compressive zog, 3 d, 7 d, thiab 28 d compressive zog nce tus nqi yog npaum li 15%, 20%, thiab 30% feem. Dhau li, hom qhob nrog lub zog tshaj plaws hauv lub zog thaum ntxov yog cov pob zeb ua kev sib xyaw nrog polyhydroxy acid superplasticizer, thiab nws lub zog compressive lub zog tseem yog qhov siab tshaj plaws tom qab 28 hnub. Txawm li cas los xij, cov pob zeb ua ke ntawm naphthalene series superplasticizer muaj qhov qis qis tsis muaj zog thaum ntxov, uas qhia tau tias nws lub zog thaum ntxov ua haujlwm tsis zoo.
