Concrete Admixtures: Hom, Functions, thiab Applications

Taw qhia

Pob zeb yog lub hauv paus ntawm cov txheej txheem niaj hnub no, tsim cov txheej txheem ntawm cov tsev, txoj kev, txuas hniav, tunnels, dams, thiab lwm yam. Nws txoj kev siv dav dav yog vim nws qhov siab compressive zog, versatility, thiab nqi-zoo. Cov khoom xyaw tseem ceeb ntawm pob zeb - cement, dej, thiab aggregates - feem ntau xav tau kev hloov kho kom tau raws li cov kev ua tau zoo thiab ib puag ncig. Qhov no yog qhov twgkev sib xyaw ua keua lub luag haujlwm tseem ceeb.

Kev sib xyaw ua keyog tej yam ntuj tso los yog tsim tshuaj los yog additives ntxiv rau cov pob zeb sib tov ua ntej los yog thaum lub sij hawm sib tov los hloov nws cov khoom nyob rau hauv lub tshiab los yog hardened xeev. Lawv siv los txhim kho kev ua haujlwm, teeb tsa lub sijhawm, lub zog, ua haujlwm ntev, ua haujlwm rau ib puag ncig raug, thiab txawm tias zoo nkauj. Cov ntawv sau no qhia txog kev faib tawm, cov txheej txheem, cov txiaj ntsig, thiab kev siv cov khoom sib xyaw, muab cov ncauj lus kom ntxaws txog lawv lub luag haujlwm tseem ceeb hauv kev tsim kho niaj hnub no.

Kev faib tawm ntawmQhob Admixtures

Admixtures feem ntau muab faib ua ob pawg loj:

1. Tshuaj lom neeg

Cov no yog cov dej-soluble tshuaj uas hloov cov cwj pwm ntawm cov pob zeb. Cov hom muaj xws li:

• Cov dej-txo cov khoom xyaw

• Retarding admixtures

• Accelerating admixtures

• Superplasticizers (High-range dej reducers)

• Huab cua-entrainingtus neeg sawv cev

• Corrosion inhibitors

• Shrinkage-txo admixtures

• Alkali-silica cov tshuaj tiv thaiv inhibitors

2. Mineral (los yog Supplementary Cementitious) Admixtures

Cov no yog cov ntaub ntawv zoo, feem ntau yog cov khoom lag luam, uas hloov ib feem ntawm Portland cement:

• ya tshauv

• Hauv av granulated blast furnace slag (GGBFS)

• Silica fume

• Metakaolin

• Rice husk tshauv

Chemical Admixtures thiab lawv cov haujlwm

1. Dej-txo cov khoom xyaw

Lub hom phiaj: Txhawm rau txo cov dej ntsiab lus hauv cov pob zeb sib tov tsis cuam tshuam rau kev ua haujlwm.

Hom:

• Ib txwm: Txo dej los ntawm 5-10%

• Nruab nrab: Txo dej los ntawm 6-12%

• Siab ntau (Superplasticizers): Txo dej kom txog li 30%

Common Compounds:

• Lignosulfonates

• Naphthalene sulfonates

• Polycarboxylate ethers (PCEs)

Daim ntawv thov:

• Npaj sib tov ua vaj tse

• Precast khoom

• High-kev ua tau zoo pob zeb

Cov txiaj ntsig:

• Ua kom muaj zog

• Tsawg permeability

• Txhim kho durability

2. Retarding Admixtures

Lub hom phiaj: Kom qeeb lub sij hawm teem ntawm pob zeb.

Siv hauv:

• Huab cua kub concreting

• Loj nchuav

• Complex formworks

Piv txwv:

• Qab Zib

• Phosphonates

• Hydroxycarboxylic acids

Qhov zoo:

• Tiv thaiv cov pob qij txha txias

• Txhim khu kev ua tiav

• Tso cai rau kev thauj mus los ntev

3. Accelerating Admixtures

Muaj nuj nqi: Txhim kho lub zog thaum ntxov.

Piv txwv:

• Calcium chloride (txawm tias siv tsawg vim muaj kev pheej hmoo corrosion)

• Calcium nitrate

• Sodium thiocyanate hmoov

Siv:

• Huab cua txias concreting

• Kev kho sai sai

• Precast qhob manufacturing

Nco tseg: Cov tshuaj chloride-free accelerators yog nyiam nyob rau hauv cov qhob reinforced los tiv thaiv corrosion steel.

4. Superplasticizers

Txhais: High-range water reducers uas muab cov dej txo qis yam tsis muaj kev poob haujlwm.

Cov tshuaj:

• Polycarboxylate ethers

• Melamine-raws li admixtures

Daim ntawv thov:

• High-lub zog pob zeb

• Self-consolidating qhob (SCC)

• Pumped qhob

Qhov zoo:

• Ntxiv fluidity yam tsis muaj kev sib cais

• Enhanced nto tiav

• Cov pob zeb ntom ntom thiab ruaj khov

5. Cua-Entraining Admixtures

Lub hom phiaj: Qhia microscopic cua npuas rau hauv pob zeb.

Muaj nuj nqi:

• Txhim kho khov-thaw tsis kam

• Txhim khu kev ua haujlwm

• Txo los ntshav thiab cais tawm

Daim ntawv thov:

• Pavements

• Choj decks

• Exposed pob zeb nyob rau hauv cheeb tsam txias

Cov neeg sawv cev siv:

• Vinsol resin

• Cov roj ntsha

• Sulfonated hydrocarbons

6. Corrosion Inhibitors

Muaj nuj nqi: Tiv thaiv embedded steel reinforcement los ntawm corrosion.

Hom Hom:

• Calcium nitrite

• Zinc-based inhibitors

• Organic corrosion inhibitors

Daim ntawv thov:

• Marine structures

• Kev loj choj

• Chaw nres tsheb

7. Shrinkage-Reduction Admixtures (SRAs)

Muaj nuj nqi: Txo kom qhuav shrinkage thiab cuam tshuam tawg.

Mechanism: Txo qhov nro ntawm cov dej hauv capillaries.

Daim ntawv thov:

• Slabs ntawm qib

• Toppings

• Cov tswv cuab ntawm cov txheej txheem raug rau qhov ziab kom qhuav

8. Alkali-Silica Reaction (ASR) Inhibitors

Lub hom phiaj: Txo kev nthuav dav tshwm sim los ntawm cov tshuaj tiv thaiv ntawm alkalis hauv cement thiab reactive silica hauv aggregates.

Cov khoom xyaw:

• Lithium nitrate

• Pozzolanic cov ntaub ntawv uas khi alkalis

Mineral Admixtures (SCMs)

1. Fly Ash

Keeb kwm: By-product ntawm thee combustion nyob rau hauv fais fab nroj tsuag.

Cov chav kawm:

• Qib F: Tsawg calcium

• Qib C: Muaj calcium ntau

Cov txiaj ntsig:

• Txhim kho kev ua haujlwm

• Txhim kho durability

• Txo cov cua sov ntawm hydration

2. Silica Fume

Qhov chaw: By-product ntawm silicon hlau los yog ferrosilicon alloy ntau lawm.

Cov khoom:

• Zoo heev (100x finer tshaj li cement)

• Kev ua haujlwm siab pozzolanic

Siv:

• High-lub zog pob zeb

• Choj decks

• Marine structures

3. Av Granulated Blast Rauv Slag (GGBFS)

Keeb kwm: By-product ntawm hlau tsim.

Qhov zoo:

• High sulfate kuj

• Txhim kho lub zog mus ntev

• Lightens pob zeb xim (pab tau rau hauv daim ntawv thov architectural)

4. Metakaolin

Tsim los ntawm: Calcining kaolin av nplaum.

Cov txiaj ntsig:

• Siab reactivity

• Txhim kho lub zog thiab ua tiav

• Txo efflorescence

5. Rice Husk Tshauv

Qhov chaw: Agricultural pov tseg khoom

Siv:

• Eco-phooj ywg pob zeb

• Txhim kho impermeability

• Txo cov ntshav

Mechanisms ntawm Action

1. Pozzolanic Reaction: Silica nyob rau hauv cov ntxhia admixtures reacts nrog calcium hydroxide los tsim ntxiv CSH (calcium silicate hydrate), lub ntsiab lub zog-muab compound.

2. Dispersion ntawm Cement Particles: Superplasticizers txo flocculation, ua kom thaj chaw saum npoo thiab dej.

3. Entrained Air Pockets: Tsim micro-chamber uas nqus qhov nthuav dav los ntawm cov dej khov.

4. Tshuaj cuam tshuam: Qee cov khoom siv cuam tshuam los yog ua kom cov dej ntws tawm los hloov cov cwj pwm.

Qhov zoo ntawm kev siv Admixtures

• Txhim khokev ua haujlwm

• Zoo duadurabilitythiabtsis kammus rau ib puag ncig hnyav

• Txodej-cement ratio(ua kom muaj zog)

• Kev tswj lub sijhawm(setting thiab hardening)

• Nqi efficiency los ntawmcement txo

• Environmentally Friendly Alternatives (kev tsim kho kom ruaj khov)

Cov kev sib tw thiab kev txwv

• Compatibility teeb meemnruab nrab ntawm cov khoom sib xyaw thiab cov cement

• Overdosage txaus ntshai(tuaj yeem txo lub zog los yog ua rau ncua sij hawm)

• Tus nqi cuam tshuam, tshwj xeeb tshaj yog nrog advanced additives

• Kev txhawj xeeb txog ib puag ncignrog qee cov khoom siv hluavtaws

• Kev tswj kom zoothiab xav tau kev sib xyaw tsim nyog

Cov kev siv hauv kev xyaum

1. Kev tsim kho vaj tse

• Dams, tunnels, txoj kev loj, thiab lub tshav dav hlau runways siv cov khoom sib xyaw kom ruaj khov, tswj kev tawg, thiab kev ua haujlwm ntev.

2. Cov tsev siab

• Superplasticizers thiab retarders pab txhawb qhov kev tso kawm ntawm pob zeb ntawm qhov siab zoo thiab txo cov pob qij txha.

3. Marine thiab Coastal Structures

• Corrosion inhibitors thiab air-entraining agents pab tiv thaiv chloride-laden ib puag ncig.

4. Precast pob zeb

• Accelerators thiab dej reducers ua kom lub voj voog ntau lawm thiab txhim kho qhov zoo.

5. Cov pob zeb loj

• Retarders thiab ntxhia admixtures txo thermal gradients thiab shrinkage-induced cracks.

Sustainability thiab Green Construction

Cov khoom siv sib xyaw ua ke muaj txiaj ntsig zoo raukev tsim kho kom ruaj khov:

• Txokev siv cov cement, txo qis carbon emissions.

• Txhim kholub neej, txo qhov xav tau kev kho.

• Tso cai siv ntawmindustrial by-products(eg, ya tshauv, slag).

• Txhawb kev loj hlob ntawmlow-carbon qhob.

Admixtures dlhos nrog ntsuab tsev ntawv pov thawj zoo liLEEDthiabBREEAM.

Yav tom ntej Trends thiab Innovations

1. Kev Kho Tus Kheej Admixtures

• Muab cov microcapsules los yog cov kab mob uas ua rau cov kab nrib pleb thiab kaw lawv tus kheej.

2. Nano-Admixtures

• Siv nanoparticles zoo li nano-silica los txhim kho microstructure thiab mechanical zog.

3. Ntse Admixtures

• Sensors embedded nyob rau hauv admixtures uas tuaj yeem tshaj tawm cov ntaub ntawv hauv lub sijhawm ntawm kev ntxhov siab, lim, thiab kub.

4. 3D Printing Qhob

• Yuav tsum tau muaj dej txaus thiab ceev-tsim admixtures rau precision txheej.

5. Carbon-Capturing Admixtures

• Kev txhim kho tab tom ua rau ntxiab CO₂ hauv pob zeb thaum kho, txo cov pa tawm.

Kev sib xyaw ua ketau revolutionized niaj hnub kev tsim kho los ntawm enabling zus tau tej cov muaj zog, ntau ruaj, thiab ntau sustainable pob zeb. Los ntawm kev txhim kho kev ua haujlwm yooj yim mus rau kev kho tus kheej zoo tshaj plaws, kev sib xyaw ua ke ntawm cov pob zeb ua kom tau raws li cov qauv tsim thiab ib puag ncig xav tau. Raws li kev lag luam hauv nroog loj zuj zus ntxiv thiab kev hu xov tooj rau kev tsim kho kom ruaj khov loj zuj zus, lub luag haujlwm ntawm cov khoom siv hauv kev tsim kom muaj kev ua tau zoo, eco-friendly pob zeb yuav tsuas yog qhov tseem ceeb dua.

Engineers, architects, thiab kev tsim kho cov tub txawg yuav tsum nyob twj ywm abreast ntawm admixture technology, xaiv thiab siv cov ntaub ntawv no ntse kom qhib lub peev xwm ntawm pob zeb nyob rau hauv lub xyoo pua 21st.