Taw qhia
Cracking yog ib qho teeb meem zoo tshaj plaws nyob rau hauv precast qhob slabs. Txawm tias me me qhov tawg tuaj yeem cuam tshuam rau qhov zoo li, ua haujlwm ntev, thiab ua haujlwm ntev -. Vim li cas qee qhov precast slabs tawg nyob rau hauv tib lub sijhawm, thaum lwm tus nyob ruaj khov?
Qhob fibers muab kev daws teeb meem. Ua raws li micro- txhawb nqa lub network, cov fibers pab tswj kev shrinkage, disperse kev ntxhov siab sab hauv, thiab txwv kev tsim cov kab nrib pleb thaum ntxov. Piv nrog rau cov khoom siv dag zog steel, cov nyhuv ntawm cov fibers txuas mus thoob plaws tag nrho cov pob zeb ua ke, tsis yog txwv rau qhov chaw ruaj khov. Fiber reinforcement tau dhau los ua ib feem tseem ceeb ntawm niaj hnub precast slab ntau lawm.
Vim li cas Cracking tshwm sim hauv Precast Concrete Panels
Kev tawg hauv cov vaj huam sib luag precast tsis tshua muaj tshwm sim los ntawm ib qho. Feem ntau, nws tshwm sim los ntawm kev sib xyaw ua ke ntawm cov khoom shrinkage, qhov kub thiab txias variation, txwv tej yam kev mob, thiab thaum ntxov- hnub nyoog tuav loads ua nyob rau hauv ntau theem ntawm ntau lawm. Cov kev ntxhov siab no yuav sib sau ua ke thiab thaum kawg tso tawm ntawm qhov chaw tsis muaj zog.
Thaum Ntxov Yas Shrinkage
Cov pob zeb tshiab tuaj yeem plam cov av noo sai sai, tshwj xeeb tshaj yog nyob rau hauv qhov chaw kub, qhuav, lossis cua daj cua dub.
Thaum cov txheej txheej saum npoo pib ntsws thaum lub sab hauv tseem nyob hauv lub xeev yas, tensile kev ntxhov siab tsim, ua rau zoo, tsis xwm yeem "daim ntawv qhia" lossis "yas shrinkage" tawg.
Feem ntau pab txhawb muaj xws li:
Cov av noo sai sai poob vim qhov kub thiab txias, tsis tshua muaj av noo, cua muaj zog, lossis tshav ntuj ncaj qha
Kev poob qis dhau los lossis los ntshav tsis txaus, ua rau tsis muaj cov yeeb yaj kiab tiv thaiv dej
Ua tsis tau raws sij hawm los npog qhov chaw los yog huab cua kho
Drying Shrinkage Thaum Kho
Tom qab hardening, pob zeb tseem poob noo noo thiab undergoes volumetric shrinkage. Qhov teeb meem feem ntau tsis yog qhov shrinkage nws tus kheej, tab sis kev txwv ntawm qhov shrinkage.
Kev txhawb zog, cov khoom sib txuas, cov khoom sib txuas, kev sib txhuam formwork, thiab tsis sib xws sab hauv-sab nrauv tuaj yeem ua rau muaj kev ntxhov siab ntau ntxiv. Thaum qhov kev ntxhov siab no dhau ntawm lub zog tensile ntawm pob zeb, los ntawm - tawg los yog ib nrab - qhov tob yuav tshwm sim.
Hom cracking no feem ntau pom nyob rau hauv:
Ntev, slender phab ntsa panels los yog nyias panels, qhov twg shrinkage deformation yog ntau pronounced
Cov cheeb tsam uas tsis tshua muaj kev txhawb zog los yog kev hloov tam sim ntawd hauv kev nruj
Cov vaj huam sib luag ntsib cov dej noo loj lossis kub gradients ntawm lub hauv paus thiab saum npoo
Thermal Expansion, Contraction, thiab Temperature Stress
Thaum tshav kub kub yog generated thaum lub sij hawm cement hydration, ua rau sab hauv ntawm lub vaj huam sib luag kom siab tshaj qhov kub ntawm qhov chaw. Ua ke nrog kev hloov pauv nruab hnub- hmo ntuj los yog hloov pauv hauv chav kho mob, qhov no tuaj yeem tsim qhov kub thiab txias.
Thaum cov tub ntxhais thiab qhov chaw nthuav dav lossis cog lus ntawm cov nqi sib txawv, kev ntxhov siab thermal tsim. Qhov no yog ib qho tseem ceeb tshwj xeeb hauv cov vaj huam sib luag tuab, loj - hom ntawv, lossis thaum lub voj voog kho tsis zoo.
Cov cim qhia muaj xws li:
Thaum ntxov- muaj hnub nyoog tawg, tshwj xeeb tshaj yog nyob rau hauv qhov sib txawv kub loj
Txhaum propagation raws cov kab tsis muaj zog, nyob ib ncig ntawm qhov qhib, los yog ze ntawm cov npoo vaj huam sib luag
Thaum Ntxov -Kev Ua Haujlwm Hnub nyoog, Demolding, thiab Lifting Stress
Txhawm rau txhim kho kev ua tau zoo, cov vaj huam sib luag precast feem ntau yog demolded, qaij, thiab nqa thaum ntxov, thaum lub zog pob zeb tseem tab tom tsim.
Kev ntxhov siab hauv cheeb tsam lossis kev cuam tshuam tuaj yeem tshwm sim nyob ib puag ncig nqa cov ntsiab lus, npoo, kaum sab xis, thiab nruab nrab - thaj tsam deflection, ua rau cov kab plaub hau tawg, kaum sab xis, lossis ntug spalling.
Cov feem pheej pheej hmoo feem ntau suav nrog:
Premature demolding los yog tsis txaus kho
Cov lifting point layout tsis raug lossis tsis raug lifting ces kaum
Kev vibration thiab lwm yam cuam tshuam thaum lub sij hawm kev thauj mus los, tshwj xeeb tshaj yog nyob rau qhov ntev
Kev ntxhov siab ua rau muaj kev ntxhov siab los ntawm kev tsim cov ntsiab lus
Kev qhib, cov kaum ntse ntse, cov phiaj xwm kos, lub tes tsho, thiab nqa cov thauj tog rau nkoj hloov pauv txoj kev thauj khoom thiab kev sib tw nruj, tsim cov cheeb tsam kev ntxhov siab hauv cheeb tsam.
Piv nrog rau thaj chaw tiaj tus, tsis sib xws, cov chaw no muaj feem ntau yuav dhau los ua cov ntsiab lus tawg. Yog tias tsis muaj kev nthuav dav ntxiv lossis kev sib tsoo - tswj kev ntsuas, qhov kev pheej hmoo ntawm kev tawg yuav nce ntxiv.
Cov chaw muaj kev pheej hmoo siab - feem ntau suav nrog:
Corners ntawm lub qhov rooj thiab qhov rais qhib (classic stress concentration point)
Cov cheeb tsam nyob ib ncig ntawm embedded Cheebtsam los yog ntom ntxig layouts
Cov cheeb tsam ze ntawm nqa cov thauj tog rau nkoj thiab nyias ntug seem
Yuav Ua Li Cas Fibers Ua Haujlwm Hauv Precast Concrete
Fibers tsis tau txhais hais tias los hloov steel reinforcement. Hloov chaw, lawv ua zoo li peb lub - qhov kev nyab xeeb ntawm qhov sib kis thoob plaws hauv lub caij ua ntej, ua haujlwm ua ntej cov kab nrib pleb tshwm thiab txuas ntxiv ua txawm tias tom qab pib tawg. Raws li qhov sib txawv nyob rau hauv cov pob zeb, fibers tsim micro- txhawb nqa lub network uas txuas ntxiv kev txhawb nqa dhau qhov chaw rebar ruaj khov thiab mus rau tag nrho cov matrix. Thaum microcracks loj hlob vim shrinkage, kub hloov, los yog tswj, fibers txuas cov kab nrib pleb zoo li stitches, slowing lawv txoj kev loj hlob thiab txwv kev tawg dav. Nyob rau tib lub sijhawm, lawv pab rov faib cov kev ntxhov siab hauv cheeb tsam tensile, txo cov kev ntxhov siab vim los ntawm kev txwv kev ua haujlwm, cov khoom sib txuas, lossis tsis sib xws, thiab txo qhov kev pheej hmoo ntawm kev tawg ntawm cov fab thiab cov npoo. Rau cov tuam txhab precast, xaiv hom fiber ntau thiab siv cov tshuaj kom zoo feem ntau ua rau muaj kev rov ua haujlwm tsawg dua, huv si saum npoo tiav, thiab ua kom zoo dua tag nrho cov vaj huam sib luag zoo.
Hom Fibers Siv nyob rau hauv Precast Concrete Panels
Xaiv txoj caipob zeb fiber ntauyog tsawg txog "zoo tagnrho" thiab ntau ntxiv txog kev sib piv cov fiber ntau rau qhov tawg koj tab tom sim nres. Hauv kev tsim khoom precast, feem ntau cov fibers poob rau hauv ob peb pawg tswv yim.
Polypropylene Fiber rau pob zeb
Ua los ntawm 100% polyester hluavtaws cov ntaub ntawv thiab ua tiav siv cov txheej txheem tshwj xeeb, cov bundled monofilament hluavtaws fibers muaj qhov zoo xws li lub zog siab, corrosion resistance, kub tsis kam, muaj zog tshuaj stability, thiab muaj zog adhesion rau asphalt. Thaum ntxiv rau asphalt qhob thiab nplawm, lawv tuaj yeem tsim ntau yam ntawm peb - qhov sib txawv ntawm qhov sib txawv ntawm fiber ntau monofilaments, uas tuaj yeem ua lub luag haujlwm hauv kev txhawb nqa thiab kev sib txuas, yog li txhim kho cov cuab yeej cuab tam ntawm asphalt sib tov thiab tiv thaiv kev tawg ntawm asphalt pob zeb.
Hlau Fibers rau pob zeb
Steel fiber reinforced qhob yog ib qho tshiab multiphase composite cov khoom tsim los ntawm kev sib koom ua ke luv luv shear corrugated steel fibers rau hauv cov pob zeb zoo tib yam. Cov randomly faib shear corrugated steel fibers tuaj yeem cuam tshuam qhov kev nthuav tawm ntawm microcracks thiab tsim cov macrocracks hauv cov pob zeb, txhim kho tensile, flexural, thiab cuam tshuam cov khoom ntawm cov pob zeb, thiab nthuav tawm cov ductility zoo.
Polypropylene Twisted Fiber ntau
Ua los ntawm polypropylene los ntawm kev kos duab tshwj xeeb sib luag thiab sib tw molding txheej txheem thiab kev kho saum npoo, nws muaj lub zog tensile siab, zoo dispersibility hauv pob zeb, thiab muaj zog daim ntawv cog lus, ua rau nws tsim nyog rau kev sib tsoo ntawm cov cement pob zeb.
Polyacrylonitrile Fiber ntau
Polyacrylonitrile fiber ntau yog ib hom tshiab ntawm cov fiber ntau siv hauv asphalt pob zeb lossis cement pob zeb los txhim kho thiab tiv thaiv kev tawg. Nws yog cov khoom siv hluavtaws ua los ntawm polyacrylonitrile resin los ntawm cov txheej txheem tshwj xeeb.
Fibers thiab yas Shrinkage Crack Control
Piv txwv tias Fibers tuaj yeem hloov kho kom raug
Fibers pab txuas cov microcracks thiab qeeb tawg propagation, tab sis lawv tsis tuaj yeem nres qhov tensile stresses los ntawm thaum ntxov ya raws. Thaum cov vaj huam sib luag precast raug rau qhov kub thiab txias, cua muaj zog, lossis cov av noo tsawg, cov yas shrinkage tseem tuaj yeem tshwm sim -tshwj xeeb tshaj yog nyob rau qhov chaw loj, raug.
Kev noj fiber ntau tsis raug
Fibers pab tswj microcracks, tab sis lawv tsis tiv thaiv evaporation sai ntawm lawv tus kheej. Yog tsis muaj kev kho kom zoo, cov yas shrinkage cracking tseem tuaj yeem txhim kho. Kev kho kom zoo tseem yog thawj kab ntawm kev tiv thaiv, thaum fibers ua raws li kev ntsuas kev txhawb nqa.
Kev sib xyaw tsis zoo ua rau Fiber Balling
Kev siv cov fiber ntau tsawg dhau los ua rau muaj kev txwv tsis pub muaj kev sib tsoo, thaum cov ntsiab lus fiber ntau tuaj yeem txo qis kev ua haujlwm, ntxiab cua, thiab tsim teeb meem ntawm qhov chaw. Ib txwm ua raws li tus neeg muag khoom fiber ntau tau pom zoo ntau npaum li cas thiab kho raws li lub vaj huam sib luag thickness, qhov chaw raug, thiab tuav cov xwm txheej.
Siv cov qauv fibers qhov twg xav tau Microfibers
Ntau tus neeg tsim khoom tsom tsuas yog "siab dua- zog" cov qauv fibers. Txawm li cas los xij, thaum ntxov- lub hnub nyoog yas shrinkage thiab nplua nto tawg yog feem ntau tswj tau zoo dua los ntawm microfibers uas sai sai tsim ntom ntom- cov ntsiab lus txuas. Cov qauv fibers zoo dua rau kev cuam tshuam, tom qab-kawg toughness, thiab macro- tswj kev tawg. Kev tsis sib haum xeeb hauv kev xaiv fiber ntau feem ntau ua rau "cov fibers siv, tab sis cov kab nrib pleb tseem tshwm sim."
Ignoring Vaj Huam Sib Luag Geometry Thiab Restraint Conditions
Precast panels tsis yog ib qho kev nyuaj siab tiaj tus. Lub kaum sab xis, qhov rais thiab qhov rooj qhib, qhov chaw nyob ib ncig ntawm qhov chaw embedded, nqa cov ntsiab lus, thiab cov npoo nyias tag nrho tsim kom muaj kev ntxhov siab. Formwork restraint, uneven reinforcement tis, thiab sib txawv kom qhuav ntxiv amplify tensile stresses. Yog tias cov fibers ntxiv tsuas yog nyob rau theem sib xyaw xwb yam tsis muaj kev txhim kho kev tsim thiab kev tsim khoom hauv cov cheeb tsam tseem ceeb no, kev tawg yuav zoo li tseem nyob hauv tib qhov chaw.
FAQ
Q: Cov fibers puas tuaj yeem tiv thaiv kev tawg ntawm cov vaj huam sib luag precast?
A: Tsis yog. Fibers pab tswj thiab txo qhov tawg, tab sis lawv tsis tuaj yeem tshem tawm tag nrho. Lawv txwv kev pib tawg thiab tawg dav, thaum sib xyaw tsim, kho, thiab kev tsim kho tseem ceeb.
Q: Cov fibers puas tuaj yeem hloov cov khoom siv steel hlau?
A: Tsis yog. Fibers thiab steel reinforcement pab ntau lub hom phiaj. Steel reinforcement nqa cov qauv loads, thaum fibers txhim kho kev tswj kev tawg, toughness, thiab thaum ntxov - hnub nyoog kev ua tau zoo.
Q: Hom fiber ntau zoo tshaj rau precast phab ntsa panels?
A: Qhov no nyob ntawm qhov kev pheej hmoo tawg. PP microfibers muaj txiaj ntsig zoo hauv kev tswj cov yas shrinkage, PVA fibers muab kev tswj hwm microcrack zoo dua, thiab cov hlau fibers tau siv qhov twg yuav tsum muaj zog dua.
Q: Cov fibers puas cuam tshuam rau qhov chaw tiav lossis zoo li?
A: Thaum xaiv thiab sib xyaw kom zoo, fibers feem ntau txhim kho qhov zoo ntawm qhov pom los ntawm kev txo cov kab nrib pleb. Txawm li cas los xij, kev noj tshuaj tsis raug lossis tsis zoo dispersion tuaj yeem cuam tshuam rau qhov chaw tiav.
Q: Puas yog fibers haum rau nyias precast panels?
A: Yog. Cov vaj huam sib luag nyias tau txais txiaj ntsig zoo vim tias fibers pab tswj kev tawg nyob rau hauv cov cheeb tsam uas cov kev pab txhawb nqa ib txwm muaj tsawg.
Q: Puas yog fibers hloov kev sib xyaw ua ke lossis tso cov txheej txheem?
A: Tsuas yog me ntsis. Fibers yuav tsum tau ntxiv thiab dispersed kom raug, tab sis txheem precast qhob mixing thiab casting txheej txheem feem ntau nyob twj ywm unchanged.
Q: Puas yog fibers raug nqi -zoo rau precast qhob ntau lawm?
A: Feem ntau, yog. Kev txo qis rov ua dua, txo qis kev tsis lees paub, thiab txhim kho vaj huam sib luag zoo feem ntau offset tus nqi khoom ntxiv.
Xaus
Kev tswj kev tawg hauv cov pob zeb precast tsis tuaj yeem ua tiav los ntawm ib qho kev daws teeb meem. Fibers ua hauj lwm synergistically nrog kev sib xyaw ua ke tsim, kho, thiab kev txhawb zog los txhim kho kev ua tau zoo tag nrho. Los ntawm kev tswj cov shrinkage, dispersing nyob rau hauv kev ntxhov siab, thiab txwv tsis pub tawg tawm, fibers pab precast slabs tswj lawv kev ncaj ncees los ntawm casting mus rau installation. Rau cov tuam txhab tsim khoom precast uas tseem ceeb tshaj qhov zoo, zoo li, thiab ntev - lub sij hawm durability, xaiv hom fiber ntau thiab ntau npaum li cas yog ib txoj hauv kev ua tau zoo thiab muaj txiaj ntsig los txo qhov tsis xws luag, txo cov nqi rov ua dua, thiab txhim kho kev ntseeg siab ntau lawm.
