Mechanical Properties thiab Failure Mechanisms of Fiber-Reinforced Concrete: Influence of Fiber Type and Content
Qhob yog siv dav tshaj plaws Kev tsim kho khoom. Nws muaj ntau qhov zoo, suav nrog nws qhov muaj ntau, txheej txheem tsim khoom yooj yim, tus nqi qis, thiab kev siv yooj yim. Nws yog dav siv nyob rau hauv ntau yam xws li vaj tse, txoj kev, txuas hniav, tunnels, thiab hydraulic engineering. Raws li ib tug loj tus naj npawb ntawm engineering tej yaam num tau tsim, cov kev xav tau ntawm cov pob zeb ua tau zoo kuj maj mam nce. Yog li ntawd, qhov tsis txaus ntawm cov pob zeb ib txwm muaj, xws li lub zog tensile tsis txaus, kev ua haujlwm tsis zoo, thiab qhov ntim tsis ruaj khov, tau dhau los ua pom tseeb. Yog li ntawd, kev txhim kho kev ua tau zoo ntawm cov pob zeb ua tau zoo ib yam yog ib qho ntawm cov kev tshawb fawb tseem ceeb hauv kev tsim vaj tsev engineering.
Txhawm rau txhim kho pob zeb kev ua tau zoo, fibers feem ntau yog ntxiv los txhim kho nws cov khoom siv dag zog thiab toughness. Piv txwv suav nrog Hlau Fibers (SF), hluavtaws fibers (xws li polypropylene fibers), ntxhia fibers (xws li basalt fibers - BF), thiab carbon fibers (CF). Txoj hauv kev no tau txhawb nqa qhov kev ua tau zoo ntawm cov pob zeb ua haujlwm siab (HPC) thiab cov pob zeb ua haujlwm siab (UHPC).
Fibers tuaj yeem, rau qee qhov, txhim kho cov khoom siv dag zog ntawm pob zeb. Txawm li cas los xij, ntau hom fiber ntau thiab cov ntsiab lus inevitably ua rau muaj kev hloov pauv loj hauv lawv cov kev cuam tshuam rau cov pob zeb ua haujlwm. Tam sim no, cov ntsiab lus fiber ntau zoo, qhov kev sib raug zoo ntawm cov tsis muaj feem cuam tshuam thiab cov khoom siv kho tshuab, thiab cov txheej txheem hauv qab ntawm cov khoom siv fiber ntau tseem xav tau kev qhia ntxiv. Txoj kev tshawb no tshawb xyuas carbon fibers (CF), basalt fibers (BF), thiab steel fibers (SF) raws li kev tshawb fawb, npaj cov qauv ua vaj tse nrog cov ntsiab lus fiber ntau sib txawv. Cov fibers no tau raug xaiv vim lawv cov ntaub ntawv ua tau zoo txhim kho hauv kev ua vaj tse thiab kev siv dav. Los ntawm kev tswj cov kev sim sib txawv, qhov cuam tshuam ntawm fiber ntau hom thiab cov ntsiab lus ntawm lub zog compressive, elastic modulus, thiab tsis ua hauj lwm hom kev ua vaj tse raug soj ntsuam. Kev sib txuas cov duab digital thiab scanning electron microscopy (SEM) cov txheej txheem kev soj ntsuam, qhov kev hloov pauv hloov pauv tus cwj pwm ntawm fiber ntau ntxiv pob zeb thaum lub sij hawm sim tau pom, ua rau cov lus xaus hauv qab no:
1.Piv rau cov pob zeb zoo tib yam (PC), kev koom ua ke ntawm steel fibers (SF), carbon fibers (CF), thiab basalt fibers (BF) tau txhim kho cov cuab yeej cuab tam ntawm fiber ntau pob zeb (FRC) thiab hloov kho nws hom tsis ua haujlwm. Cov fibers no tau hloov lub pob zeb compactness thiab thawj qhov pore compression yam ntxwv. Raws li cov ntsiab lus fiber ntau nce, hom tsis ua hauj lwm hloov ntawm nkig mus rau ductile. Qhov kev hloov pauv tseem ceeb yog 0.5% rau steel fiber ntau pob zeb (SFC) thiab 1.0% rau carbon fiber ntau pob zeb (CFC) thiab basalt fiber ntau pob zeb (BFC). Txhawm rau ua kom muaj txiaj ntsig zoo tshaj plaws, cov ntsiab lus zoo rau steel fibers yog 2.0%, carbon fibers 1.0%, thiab basalt fibers 0.5%.
2.Txawm hais tias cov ntsiab lus fiber ntau tuaj yeem txhim kho lub compactness thiab bearing peev xwm ntawm cov pob zeb, cov ntsiab lus siab heev tuaj yeem ua rau "saturation" tshwm sim, ua rau fiber ntau "agglomeration." Qhov no cuam tshuam tsis zoo rau cov pob zeb ntawm lub cev, lub zog, thiab deformation yam ntxwv. Steel fiber ntau ua tiav qhov kev ua tau zoo ntawm cov fiber ntau feem ntawm 2.0%, thaum carbon fiber pob zeb thiab basalt fiber ntau tau mus txog lawv qhov kev ua tau zoo ntawm 1.0% thiab 0.5%, feem. Tshaj li cov ntsiab lus zoo, kev ua haujlwm tau poob qis.
3.Scanning Electron Microscopy (SEM) kev soj ntsuam tau qhia tias qhov sib cuam tshuam ntawm cov fibers thiab cov cementitious matrix ho cuam tshuam rau macroscopic mechanical zog ntawm pob zeb. Qhov tsim nyog tus nqi ntawm fibers tsim ib tug ntom peb-dimensional network qauv nyob rau hauv lub pob zeb, txhim khu lub matrix kev sib txuas thiab tag nrho cov kev ua tau zoo. Txawm li cas los xij, cov ntsiab lus fiber ntau ntau ua rau muaj fiber ntau agglomeration, tsim kom tsis muaj zog interfacial cheeb tsam thiab txo cov pob zeb ceev thiab lub zog. Cov kev hloov hauv microstructure tau zoo ib yam nrog cov evolution ntawm macroscopic mechanical zog.
4.Qhov sib ntxiv ntawm fibers tau hloov pauv qhov tsis ua haujlwm ntawm cov pob zeb. Piv nrog rau cov pob zeb dawb, fiber ntau cov pob zeb ua kom pom kev zoo dua tom qab ua tsis tiav, nrog tsawg dua thiab cov kab nrib pleb, thiab txhim kho toughness. Cov hlau fibers tau zoo tshaj plaws hauv kev ua kom tawg, ua raws li carbon fibers thiab basalt fibers. Cov "bridging effect" ntawm fibers tau ua lub luag haujlwm tseem ceeb hauv kev tawm tsam kev tawm tsam tawg, thaum "cov nyhuv cuam tshuam tsis muaj zog" muaj qhov cuam tshuam tsis zoo rau cov khoom siv kho tshuab.
