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EFFECT OF FLY ASH ON THE FRESH AND HARDENED PROPERTIES OF CONCRETE

EFFECT OF FLY ASH ON THE FRESH AND HARDENED PROPERTIES OF CONCRETE. Asena SİVASLIOĞLU. Fly ash es are used in concrete technology for purposes of taking advantage of pozzolanic properties, providing economy and preventing environmental pollution. Workability and Water Demand.

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EFFECT OF FLY ASH ON THE FRESH AND HARDENED PROPERTIES OF CONCRETE

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  1. EFFECT OF FLY ASH ON THE FRESH AND HARDENED PROPERTIES OF CONCRETE Asena SİVASLIOĞLU

  2. Fly ashesare used in concrete technology for purposes of taking advantage of pozzolanic properties, providing economy and preventingenvironmental pollution.

  3. WorkabilityandWaterDemand • Fly ashimprovestheworkability of theconcreteandruduceswaterdemand but flyashmust not usedlike an additive, it has totaketheplace of cement. Theirparticlesarespherical. Fine-grainedoneshelpforworkability, coarsegrainedoneshelptoreducewater.

  4. Bleeding and Segregation Highly fine-grained fly ashes decreases the segregation by increasing the cohesion so prevent shrinkage.

  5. Setting Time • Fly ashneedsCa(OH)2 whichnascencyfromcement, sosetting time may be longer but somesituations can change it. Thesearelistedbelow; • High lime flyash can be self-binding • Fly ashes can be includesulphatewhichmayreactwithportlandcement.

  6. Heat of Hydration Air Content • Hydrationeffectsconcretebadly, it causescracks. Using flyashinstead of cementhelpstodecresetheharmfulheat of hydration. • Especially F typesflyashesincreaseneedforairentrainer in concrete.

  7. The Effect of Fly Ashes on The Strength of Concrete • Theeffect of flyashes on thestrength is lower in earlyages, thiseffectgraduallyincreasewhileconcretegettingolderbecausepozzolanicreactionstartslater.

  8. Fly asheswhichincludelowpercentage lime known as F typesflyashes, thistype of asheseffectthestrengthslowerthanothersfirst but afterthenbecomesfaster.

  9. Sulfate Attack Alkali-aggregateReaction • PozzolanspreventthereacitonwithsulfatebyusingCa(OH)2 somakesulfateresistance of concretehigherthanbefore. • Exceptmadebyligniteones. • Theflyashesincludelowpercentage lime helpstodecreasethe alkali aggregatereaction.

  10. Freeze-thaw Resistance • Therearetwoideasabout it; • Theconcreteinclude %20 flyash (high-lime) moredurable. • Fly ash has noeffect, theimportantone is airentrainer.

  11. Permeability Carbonation • Fly ashconcretes has morepermeability in earlyages but laterpermeabiltybecomeslower. It has noeffect on carbonation.

  12. REFERENCES • Effect of Fly ASH on Properties of Concrete • P. R. Wankhede V. A. Fulari AssistantProfessor • IBSS College of Engineering, Amravati • COIN Project report no 18 SigrunKjærBremseth (Norcem) Fly ash in concrete a literature study of the advantages and disadvantages • Semsi Yazici & Hasan SahanArel Department of Civil Engineering, Engineering Faculty, 35100 ˙Izmir, Turkey ―Effects of fly ash fineness on the mechanical properties of concrete‖. • Post GradueThesis, ITU • Emrah Gürbüz • C-TypeFlyAshes

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