EFFECTS OF AIR ENTRAINMENT ON PROPERTIES OF CONCRETE
A THESIS SUBMITTED TO
: ' ..: C RADUATE SCHOOL OF NATURAL AND APPLIED SCIENCES OF
THE MIDDLE EAST TECHNICAL UNIVERSITY
BY
BAHADIR HALIM USLU
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE IN
THE DEPARTMENT OF CIVIL ENGINEERING
DECEMBER 1998
ABSTRACT
EFFECTS OF AIR ENTRAINMENT ON PROPERTIES OF CON RETE
Uslu, Bahadlr Halim
M.Sc., Departmenl of Civil Engineering Supervisor: Dr. Lutfullah Turanll
December 1998, 135 pages
The process of alf entrainment, vvhereby many small al(
bubbles are introduced into concrete and become part of the matrix, provides a significant improvement in the durability of concrete to freezing and thawing exposure. Moreover, intentionally entrained air improves the
workability and consistency of plastic concrete and reduces its bleeding and segregation. However, the most serious drawback is the considerable
reduction in the property of strength when an air-entraining admixture is used for the purpose of producing an air-entrained concrete.
In this study, the effects of air entrainment on properties of fresh concrete; and on mechanical properties, compressive and flexural strength, and modulus of elasticity; and also freeze-thaw resistance, In
other words durability, of hardened concrete was investigated.
Moreover, a statistical study was performed to get an empirical
formula Ihat has given the direct relation between the modulus of elasticity and compressive strength values of the specimens and also to prove the
reliability and accuracy of the modulus of elastiCity and compressive
'"
strength tests. Thereafter, an estimated study based on the pulse velocity test results was made to evaluate the modulus of elasticity values of the concretes, exposed to accelerated freeze-thaw cycles, for the confirmation of the results.
For these purposes, twelve different concrete mixes were prepared by the consideration of slump and air content values as the parameters, by using three different slump values as 4cm, 8cm, and 12cm, and also four different air contents as 1.3%, 4%, 6%, and 8% for
the mixes mentioned previously. All of the tests were performed according to the related ASTM Standards throughout this study.
The interpretation of the results of tests, and the performed statistical and estimated study revealed that air-entrained concretes
having the minimum possible slump value with an optimum air content can either be used in applications such as mass concrete, pavements,
foundations and so on where the durability of concrete is primarily important or for general purposes safely since they also have the required strength property besides their good durability.
Keywords: Air Entrainment, Air-Entrained Concrete, Durability, Strength, Freezing and Thawing Exposure, Freeze-Thaw Resistance
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HAVA SURUKLEMENiN BETONUN bZELlKLERi UZERiNDEKi ETKiLERi
Uslu, Bailadrr Halim
Yuksek Lisans, In, aat Muhendisligi Balumu Tez Yaneticisi: Dr. Lutfullah Turanll
Arallk 1998, 135 sayla
Betonun igerisinde gok say Ida kuguk hava kabarclgmln yeralmaslnm sagianmasl ve beton harclnln bir paryasl haline getiriJmesi i,lemi olan hava suruklemesi, betonun donma gazulmeye kar,1 dayanlkllilglnda anemli miktarda artl, saglamaktadlr. Aynca, istemli olarak sOrOklenmi!j hava, taze betonun i~lenebilirligini ve klvamlnl arttmrken, betonun kusma ve aYrI§lmaslnl ise azaltlr. Ne var ki, hava suruklenmi, beton uretmek igin hava surukleyici bir katkl kullanlidrglnda, betonun dayanlmlnda meydana gel en yadslnamaz miktardaki azalma, kar,lia,lian en anemli dezavantaj olarak ortaya glkmaktadrr.
Bu t;alliima ile, hava sOrOkleme iiileminin taze betonun bazi 6zelikleri, ve sert!e¥mi~ betonun mekanik ozeEkleri alan basI ny, egilmede yekme ve elastik modulO ve aYfica betonun donma-yazOlme direnci;
ba,ka bir deyi,le, betonun donma ve gazulme etkilerine kar,1 dayanlkllllgi Ozerindeki etkileri incelendi.
v
Bunlann yanlslra, bela nun elaslik modulO ve basin\, dayanlml degerleri araslnda dogrudan bir ili~ki oldugunu gosteren, deneysel verilere dayali, bir formOI elde edebilmek ve aynca numuneler Ozerinde yapllan elastisite modulO ve basin\, dayanlml deneylerinin gOvenilirligini ve dogruluk derecesini kanltlayabilmek amaelyla istatistiksel bir ,ali~ma ger\,ekle~tirildi. Daha sonra, hlzlandlnlml~ tekrarlanan donma~6z0lme
etkisine maruz blrakllan beton numunelerin ultrasonik dalga hlzl sonu\,lan kullamlarak bu betonlann elastik modulO degerleri hesaplandl. Veriler ineelendiginde, ultrasonik h,z ve hesaplanan elastik modOIO degerlerinden aynl sonuylara vanldlgl, iki 1'211~manln birbirini dogruladlgl gorOldO.
Bu ,ali~malar i\,in, \,okme ve hava miktan degerleri degi~ken
parametreler olmak ko~ulu ile, 4 em, 8 em, ve 12 em \,okme degerlerine ve
%1.3, %4, %6, ve %8 oramnda dart degi§ik hava miktanna sahip oniki degi§ik beton kan§lml hazlrlandl. Bu deneysel ,all§ma sOresince ger\,ekle§tirilen tOm deneyler ASTM Standardlan'na uygun olarak yaplldl.
Ger\,ekle§tirilen bOtOn ,ali§malar; mOmkOn alan en dO§Ok
\,okme degerine sahip ve il'Brisinde uygun miktarda sOrOklenmi§ hava bulunduran bir betonun, dayanlkillik ozeliginin birinei derecede onem kazand,g, kOtie betonu, kaldlnmlar, beton yollar ve temel betonlan gibi uygulamalannda ozellikle tereih edilmesi gerekligini gostermi~tir. Boyle bir beton, dayamkllllgmm yamslra, yeterli dOzeyde dayamm ozeligine de
sahip olacagmdan hemen her alanda gOvenli bir §ekilde kuliamlabilir.
Anahtar Kelimeler: Hava SOrOkleme, Hava SOrOklenmi§ Beton, Dayamkillik, Dayamm, Donma ve C;;ozOlme Etkisi, Donma-C;;ozOlme Direnei
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