HPMC (Hydroxypropyl Methyl Cellulose) yog cov khoom siv polymer feem ntau siv hauv cov khoom siv hauv tsev, tshwj xeeb tshaj yog cov khoom siv cement thiab cov ntaub ntawv gypsum. Nws muaj dej solubility zoo, adhesion, dej tuav thiab thickening zog, yog li nws yog dav siv nyob rau hauv mortar, putty hmoov, pobzeb nplaum thiab lwm yam ntaub ntawv.
1. Ua rau shrinkage thiab tawg ntawm cov khoom siv hauv tsev
Thaum lub sij hawm hardening txheej txheem, cov ntaub ntawv hauv tsev feem ntau poob rau hauv ntim vim dej evaporation, tshuaj lom neeg cov tshuaj tiv thaiv thiab kev hloov nyob rau hauv ib puag ncig lwm yam, ua rau kev nyuaj siab concentration thiab tawg tsim. Lub ntsiab hom ntawm shrinkage muaj xws li:
Plastic shrinkage: Thaum cov khoom siv cement-based tseem tsis tau ua kom tawv, lub ntim ntim vim yog cov dej evaporation sai.
Qhuav shrinkage: Tom qab cov khoom hardens, nws raug rau huab cua ntev, thiab cov dej evaporates maj mam, ua rau lub ntim shrinkage.
Kub shrinkage: Volume hloov pauv los ntawm qhov kub thiab txias, tshwj xeeb tshaj yog nyob rau hauv ib puag ncig uas muaj qhov kub thiab txias sib txawv nruab hnub thiab hmo ntuj.
Autogenous shrinkage: Thaum lub sij hawm cov cement hydration txheej txheem, lub ntim sab hauv shrinks vim kev noj cov dej los ntawm cov tshuaj tiv thaiv hydration.
Cov shrinkages feem ntau ua rau muaj kev ntxhov siab hauv cov khoom siv, thaum kawg ua rau microcracks lossis tawg, uas cuam tshuam rau kev ua haujlwm ntev thiab kev zoo nkauj ntawm lub tsev. Txhawm rau zam qhov tshwm sim no, cov khoom siv ntxiv feem ntau xav tau los txhim kho kev ua haujlwm ntawm cov khoom, thiab HPMC yog ib qho ntawm lawv.
2. Mechanism ntawm kev ua ntawm HPMC
HPMC ua lub luag haujlwm tseem ceeb hauv kev txo qis qis thiab tawg ntawm cov khoom siv hauv tsev, uas yog ua tiav los ntawm cov txheej txheem hauv qab no:
Kev tuav dej: HPMC muaj lub peev xwm tuav dej ruaj khov thiab tuaj yeem tsim cov yeeb yaj kiab tso dej hauv mortar lossis putty hmoov kom qeeb cov dej evaporation. Txij li thaum cov evaporation sai ntawm cov dej hauv cov khoom yuav ua rau cov yas shrinkage, cov dej tuav cov nyhuv ntawm HPMC tuaj yeem txo qhov tshwm sim thaum ntxov shrinkage, khaws cov dej hauv cov khoom kom txaus, yog li txhawb nqa tag nrho cov tshuaj tiv thaiv dej ntawm cov cement thiab txo qis cov kab nrib pleb los ntawm dej poob thaum lub sij hawm ziab. Tsis tas li ntawd, HPMC tuaj yeem txhim kho kev ua haujlwm ntawm cov khoom siv nyob rau hauv cov dej ntub thiab qhuav thiab txo kev tawg los ntawm dej tsis zoo.
Thickening thiab ntxiv dag zog rau cov nyhuv: HPMC yog cov thickener uas tuaj yeem ua kom zoo sib xws thiab viscosity ntawm mortar thiab txhim kho tag nrho cov adhesion ntawm cov khoom. Thaum lub sij hawm tsim kho, yog tias cov khoom nyias nyias, nws yooj yim rau delaminate los yog sag, ua rau tsis sib xws ntawm qhov chaw lossis txawm tias tawg. Los ntawm kev siv HPMC, lub mortar tuaj yeem tswj cov viscosity tsim nyog, txhim khu lub zog thiab qhov ntom ntom ntawm cov khoom tom qab kev tsim kho, thiab txo qhov muaj peev xwm tawg. Tsis tas li ntawd, HPMC tseem tuaj yeem txhim kho cov shear tsis kam ntawm cov khoom siv thiab txhim kho nws cov kev ua haujlwm tawg.
Txhim kho qhov yooj yim ntawm cov khoom siv: HPMC molecules tuaj yeem ua lub luag haujlwm hauv kev txhim kho kev yooj yim ntawm cov ntaub ntawv cement lossis cov ntaub ntawv gypsum, kom cov khoom muaj zog tensile thiab khoov zoo dua tom qab kho. Txij li thaum cov ntaub ntawv hauv tsev feem ntau raug rau tensile los yog dabtsi yog khoov kev ntxhov siab nyob rau hauv ambient kub hloov thiab loads, tom qab ntxiv HPMC, qhov yooj ntawm cov khoom yuav nce, uas yuav zoo dua nqus sab nraud kev nyuaj siab thiab tsis txhob nkig tawg.
Tswj cov cement hydration cov tshuaj tiv thaiv: Hauv cov khoom siv cement, qhov ceev ntawm cov tshuaj tiv thaiv dej ncaj qha cuam tshuam rau kev ua haujlwm ntawm cov khoom. Yog tias cov tshuaj tiv thaiv hydration sai dhau, qhov kev ntxhov siab hauv cov khoom tsis tuaj yeem tso tawm raws sijhawm, ua rau tawg. HPMC tuaj yeem txo qis tus nqi ntawm cov dej tshuaj tiv thaiv los ntawm nws cov dej tuav thiab kev tiv thaiv zaj duab xis, tiv thaiv cov cement los ntawm kev poob dej sai heev thaum ntxov, thiab yog li zam qhov tshwm sim ntawm spontaneous shrinkage thiab tawg thaum lub sij hawm hardening txheej txheem ntawm cov khoom.
Txhim kho kev tsim kho kev ua haujlwm: HPMC tuaj yeem txhim kho kev tsim kho ntawm cov khoom siv hauv tsev, feem ntau tshwm sim hauv nws cov dej ntws zoo, tuav dej thiab lubricity, ua kom cov khoom sib xws, thiab txo cov kab nrib pleb los ntawm kev tsim kho tsis raug. Nws tuaj yeem ua tshuaj cug, ua kom muaj hmoov, ua kom yooj yim dua thiab muaj zog ntawm cov ntaub ntawv, thiab txo cov kev pheej hmoo ntawm cov khoom tawg hauv zos los ntawm kev tsim kho tsis sib xws.
3. Kev siv HPMC hauv cov khoom siv hauv tsev tshwj xeeb
Pobzeb nplaum: HPMC tuaj yeem txhim kho qhov kev ua haujlwm zoo ntawm cov nplais nplaum nplaum, xyuas kom cov vuas tuaj yeem sib npaug ntawm cov substrate thaum lub sijhawm teeb tsa, thiab txo qis los yog tawg los ntawm kev ntxhov siab lossis kev poob qis. Tsis tas li ntawd, qhov thickening thiab dej tuav cov teebmeem ntawm HPMC kuj ua rau cov pobzeb nplaum tuav lub sijhawm qhib ntev dua tom qab kev tsim kho, txhim kho kev tsim kho, thiab txo cov kab nrib pleb los ntawm kev kho tsis sib xws.
Putty hmoov: Hauv cov hmoov putty, cov dej tuav cov cuab yeej ntawm HPMC tuaj yeem tiv thaiv cov putty los ntawm kev poob dej sai heev thaum lub sij hawm ziab, thiab txo qhov shrinkage thiab tawg los ntawm dej poob. Nyob rau tib lub sijhawm, cov nyhuv thickening ntawm HPMC tuaj yeem txhim kho kev tsim kho ntawm putty, ua kom yooj yim rau kev thov sib npaug ntawm phab ntsa, thiab txo cov kab nrib pleb uas tshwm sim los ntawm daim ntawv thov tsis sib xws.
mortar: Ntxiv HPMC rau mortar tuaj yeem txhim kho nws txoj haujlwm ua haujlwm tau zoo, ua kom lub mortar smoother thaum lub sij hawm tsim kho, txo kev sib cais thiab stratification, thiab yog li txhim kho cov uniformity thiab adhesion ntawm mortar. Nyob rau tib lub sijhawm, cov dej tuav cov nyhuv ntawm HPMC tuaj yeem ua rau cov dej evaporate qeeb dua thaum lub sij hawm hardening txheej txheem ntawm mortar, tsis txhob shrinkage thiab cracking tshwm sim los ntawm thaum ntxov dej poob.
4. Kev ceev faj rau kev siv HPMC
Kev tswj kev noj tshuaj: Tus nqi ntawm HPMC ntxiv muaj qhov cuam tshuam ncaj qha rau nws cov txiaj ntsig, thiab nws feem ntau yuav tsum tau hloov kho raws li cov khoom sib piv thiab cov ntawv thov tshwj xeeb. HPMC ntau dhau yuav ua rau cov khoom muaj qhov sib xws, cuam tshuam rau kev tsim kho; thaum HPMC tsis txaus yuav tsis tuaj yeem ua lub luag haujlwm ntawm kev tuav dej thiab ua kom tuab raws li nws yuav tsum tau ua.
Siv nrog lwm cov tshuaj ntxiv: HPMC feem ntau yog siv ua ke nrog lwm cov tshuaj ntxiv (xws li dej reducers, air entraining agents, plasticizers, etc.) kom ua tiav cov txiaj ntsig zoo dua. Thaum siv, nws yog ib qho tsim nyog yuav tau xav txog kev sib cuam tshuam ntawm cov khoom sib txawv kom tsis txhob muaj kev cuam tshuam rau kev ua haujlwm ntawm cov khoom siv.
Ua ib qho tseem ceeb hauv tsev ntxiv, HPMC muaj qhov cuam tshuam tseem ceeb hauv kev txo qis qis thiab tawg ntawm cov khoom siv hauv tsev. Nws zoo txo cov kab nrib pleb los ntawm dej poob thiab kev ntxhov siab los ntawm kev txhim kho cov dej tuav, thickening, yooj ntawm cov khoom thiab txhim kho cov cement hydration cov tshuaj tiv thaiv. Kev siv HPMC tsim nyog tuaj yeem tsis tsuas yog txhim kho kev tsim kho ntawm cov khoom siv, tab sis kuj tseem txuas ntxiv lub neej kev pab cuam ntawm lub tsev qauv thiab txo tus nqi ntawm kev kho tom qab. Nrog rau kev nce qib ntawm cov khoom siv thev naus laus zis txuas ntxiv mus, daim ntawv thov ntawm HPMC hauv kev tsim kho yuav ua kom dav thiab tob.
Post lub sij hawm: Sep-21-2024