INFLUENCE OF AIR-VOID SYSTEM ON FREEZE-THAW DURABILITY OF CONCRETE. PDF Download
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Author: ZAFAR AHMED MALIK
Publisher:
ISBN:
Category :
Languages : en
Pages : 530
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Book Description
Two-way analysis of variance showed that type of air entraining agent, quality of aggregate, and content of condensed silica fume have a major effect on freeze-thaw durability of concrete.
Author: ZAFAR AHMED MALIK
Publisher:
ISBN:
Category :
Languages : en
Pages : 530
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Book Description
Two-way analysis of variance showed that type of air entraining agent, quality of aggregate, and content of condensed silica fume have a major effect on freeze-thaw durability of concrete.
Author: J. Marchand
Publisher: CRC Press
ISBN: 0203627091
Category : Architecture
Languages : en
Pages : 323
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Book Description
Concrete durability in climates where freezing and thawing occurs is a continuing problem. It is particularly acute for highway and bridge structures, where de-icing salts are used to combat the effects of frost, snow and ice. These salts can cause damage to concrete and accelerate corrosion of reinforcements. This book presents the latest international research on this area, with contributions from North America and Europe which were presented at an international RILEM workshop.
Author: David C. Stark
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 10
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Book Description
Author: Peter B. Makowichuk
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 0
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Book Description
Studies on the determination of air void parameters by microscopic analysis of polished concrete sections were correlated with freeze-thaw durability tests in order to compare the durability characteristics of concrete made using high early strength cement, normal Portland cement and normal portland cement with calcium chloride added a.s an accelerator. The results indicate that for a curing period of fourteen days the use of high early strength cement and the use of calcium chloride treated cement affects freeze-thaw durability in two ways. First, the increased rate of hydration proves beneficial as it provides the concrete with a higher strength at an earlier age. Second, the addition of calcium chloride and the use of high early strength cement results in an inferior air void system in the concrete which lowers the freeze-thaw durability. The change due to calcium chloride on the amount of hydration and on the air void system varies with the water cement ra.tio. Thus at high water cement ratios, the increases in the amount of hydration by the addition of calcium chloride or by the use of high early strength cement is great enough to offset the detrimental change in the air void system, and there is no significant change in durability. However at the lower water cement ratios the increase in amount of hydration is less and the detrimental effects on the air void system are more pronounced so that the durability is lowered considerably.
Author: M. Pigeon
Publisher: CRC Press
ISBN: 1482271443
Category : Technology & Engineering
Languages : en
Pages : 259
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Book Description
This book provides a comprehensive and authoritative review of durability of the frost resistance of concrete. It will enable both concrete materials specialists and practising engineers to better understand the deterioration processes which take place during freezing and thawing, and the effects of de-icing salts on concrete. It shows how test pro
Author: Alexandra Nicole Wehar
Publisher:
ISBN:
Category :
Languages : en
Pages : 141
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Book Description
"Over the past 60 years, pumping concrete has gained popularity due to the economic and technical benefits that typically accompanies it. However, boom configuration and flow rate can adversely affect freeze-thaw and scaling resistance of concrete due to the effects of pressure on the air-void system. Therefore, the objective of this research is to assess the influence of different pumping parameters on the durability of hardened self-consolidating concrete. Self-consolidating, flowable, and conventional concrete mixtures were tested during large scale pumping experiments positioning the pump boom in an 'A' and a flat shape as well as using different pumping speeds. In addition, the effect of adding a reducer and submerging the discharge hose into concrete to minimize the impact on the concrete air-void system was also explored. While pumping, the concrete fresh properties, including the air content were measured. The freeze-thaw durability and scaling resistance were tested for both pumped and non-pumped samples. Furthermore, the air-void size distribution in the hardened state was measured. During pumping, considerable changes in fresh air content were observed from sample to sample. Hardened results indicated that different pumping parameters induced different changes in the air-void system, most importantly the spacing factor. The most notable increases in spacing factor were observed when increasing the flow rate in the A configuration for self-consolidating and flowable mixtures and adding a reducer in the A configuration with self-consolidating concrete. The changes in air-void system corresponded to changes in the severity of scaling. A poor air-void system led to lower scaling resistance. Mixtures with higher air content showed fewer signs that pumping affects the freeze-thaw or scaling resistance"--Abstract, page iii.
Author: R Auberg
Publisher: CRC Press
ISBN: 0203627326
Category : Architecture
Languages : en
Pages : 400
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Book Description
This book forms the proceedings of the international workshop to be held in Essen, Germany. This workshop summarises the conclusion of the technical committee's investigations into the resistance of concrete to freeze-thaw attack, specific in this to resistance with or without de-icing chemicals. It presents the RILEM recommendations on testing the freeze-thaw and de-icing salt resistance of concrete.
Author: Frederick Williamson
Publisher:
ISBN:
Category : Air-entrained concrete
Languages : en
Pages : 0
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Book Description
As a result of the knowledge that concrete freeze-thaw durability depends on the number, size, and spacing of air voids throughout the mass, rather than on the total volume of entrained air voids, study of the air void system of hardened concrete has become concentrated on the determination of significant air void parameters. This thesis presents the results of an investigation to determine relationships between freeze-thaw durability and air void parameters of hardened concrete. Specifically, the objective of this study was to establish the pattern of the relationships between concrete durability and both the void spacing factor and the specific surface of the voids. Eighteen concrete mixes, representing six air contents up to approximately nine per cent by volume, and three common cement contents, were prepared and tested during this program. Air void parameters of the hardened concrete, as determined by the lineal traverse method of microscopic examination (A.S.T.M. C 457 - 60T), were measured and related to freeze-thaw durability data obtained from tests performed in accordance with A.S.T.M. procedure C 290 - 57T. Compressive strength data were also obtained for all concrete mixes prepared. Compressive strength test results verified the well-known relationships involving strength, age, cement content, air content, and water-cement ratio. The most significant test results available from this investigation are those relating concrete freeze-thaw durability and air void parameters. It was found that air entrainment up to approximately six per cent air by volume improved the concrete freeze-thaw durability, by decreasing the air void size and spacing, and increasing the specific surface of the voids. At air contents greater than approximately six per cent, further air entrainment did not significantly improve the freeze-thaw durability. Freeze-thaw durability was found to be practically independent of both cement content and water-cement ratio, for air contents above approximately two per cent. Protection of concrete from freeze-thaw deterioration is thus more effectively realized by air entrainment, than by variations in cement content and/or water-cement ratio. Observed data showed that relationships between concrete durability and both specific surface and spacing factor are non-linear. A rapid increase in durability with decreasing void spacing indicates a critical void spacing factor of approximately 0.005 inch, for conditions of these tests.
Author: Mateusz Radlinski
Publisher:
ISBN:
Category : Air-Void Characterization
Languages : en
Pages : 14
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Book Description
This research was conducted to verify whether the semi-automatic method of air-void system characterization (using a flatbed scanner) could be used in lieu of the manual (ASTM C457) method. This research objective was accompanied by evaluating the critical air-void system parameters required to ensure freeze-thaw resistance of ternary concrete containing ordinary portland cement (OPC), 20 % of fly ash (FA), and 5 % of silica fume (SF). It was observed that, due to adverse effect of high superplasticizer dosage on air-void system quality (particularly on specific surface), the majority of high slump ternary mixtures exhibited poor freeze-thaw resistance, even if spacing factor was below the 0.20 mm recommended value. However, when the ternary mixtures were prepared with slump below the limit commonly specified for bridge deck applications (190 mm), the critical air-void system parameters of the OPC/FA/SF concrete were comparable to those typically associated with adequate quality air-void system in conventional concrete. Furthermore, since the critical value of specific surface was independent of slump (i.e., superplasticizer dosage), specific surface appeared to be more objective and reliable predictor of freeze-thaw resistance than spacing factor. When comparing the semi-automatic and manual methods of air-void system characterization, a reasonably strong agreement was obtained for such parameters as air content, void frequency, and spacing factor. Although the results of these methods did not match perfectly, the data suggested that the flatbed scanner technique could be efficiently used for discerning between freeze-thaw durable and non-durable concretes.
Author: J. E. Backstrom
Publisher:
ISBN:
Category :
Languages : en
Pages : 44
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Book Description
