Investigation Into the Effect of Water-cement Ratio on the Freezing-thawing Resistance of Non-air and Air-entrained Concrete PDF Download
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Author:
Publisher:
ISBN:
Category : Air-entrained concrete
Languages : en
Pages : 22
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Author:
Publisher:
ISBN:
Category : Air-entrained concrete
Languages : en
Pages : 22
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Author: Kejin Wang
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 52
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The aim of the present study is to investigate the effect of low-permeability concrete, made with reduced water-to-binder ratios (w/b) and/or supplementary cementitious materials (SCMs), on the need for air entrainment to achieve freezing-thawing (F-T) durability. In the present study, concrete mixes were made with different types of cement (Type I and IP), with or without fly ash replacement (15%), with different water-to-binder ratios (w/b=0.25, 0.35, 0.45 and 0.55), and with or without air entraining agent (AEA). All concrete mixtures were controlled to have a similar slump by using different dosages of superplasticizer. The rapid chloride permeability and F-T durability of the concrete samples were determined according to ASTM C1202 and ASTM C666A, respectively. The air void structure of the concrete was studied using the Air Void Analyzer, Rapid Air, and porosity tests (ASTM C642). In addition, the general concrete properties, such as slump, air content, unit weight, and 28-day compressive strength, were evaluated. The results indicate that all concrete mixes with proper air entrainment (ASTM C23 air content greater than or equal to 6%) showed good F-T resistance (durability factor greater than or equal to 86%). All concrete mixes without AEA showed poor F-T resistance (durability factor less than 40%), except for one mix that had very low permeability and high strength. This was the concrete made with Type IP cement and with a w/b of 0.25, which had a permeability of 520 coulombs and a compressive strength of 12,760 psi (88 MPa). There were clear relationships between the F-T durability and hardened concrete properties of non-air entrained concrete. However, such relationships did not exist in concrete with AEA. For concrete with AEA, good F-T durability was associated with an air void spacing factor less than or equal to 0.28 mm (by AVA) or less than or equal to 0.22 mm (by RapidAir).
Author: Waterways Experiment Station (U.S.)
Publisher:
ISBN:
Category : Aggregates (Building materials).
Languages : en
Pages : 120
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Author: Robert E. Philleo
Publisher:
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 48
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Recent developments have made a new generation of high-strength concrete a viable material for routine construction. The two principal developments are high-range water-reducing admixtures, which permit the placement of concrete of very low water-cement ratio, and silica fume, a pozzolan of extremely high fineness. The advent of this high- strength concrete has put requirements for strength and durability in conflict. Because entrained air reduces the strength of concrete, builders seek to eliminate or limit the use of entrained air. There are those who argue that high-strength concrete is of such a quality that entrained air is unnecessary. Much of the high-strength concrete currently being used is in buildings, where the question of durability is minor. The question, however, cannot be avoided in exposed highway structures. Service records of non-air-entrained high-strength concrete exposed to freezing are not conclusive. Hence, this report synthesizes the available knowledge on the subject. Its aim is to provide guidance to those who wish to use high-strength concrete in typical highway applications and to indicate where further information is needed.
Author: Waterways Experiment Station (U.S.)
Publisher:
ISBN:
Category : Aggregates (Building materials).
Languages : en
Pages : 64
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Author: National Research Council (U.S.). Highway Research Board
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 68
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In the first report adequate resistance to freezing and thawing was obtained when the air content of the mortar fraction was in the range of 9 plus or minus 1 per cent. The report also includes information on the effect of entrained air on strength, resistance to salt scaling, volume change and absorption of these concretes. The second report is a resume to date of investigations conducted to test materials and procedures for protecting concrete pavements against scaling and disintegration caused by calcium chloride and other thawing agents used for ice removal.
Author: National Research Council (U.S.). Highway Research Board
Publisher:
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 80
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Book Description
Author: David J. Varnes and George Kiersch
Publisher: Geological Society of America
ISBN: 0813741025
Category :
Languages : en
Pages : 394
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Author: Richard A. Walls
Publisher:
ISBN:
Category :
Languages : en
Pages : 310
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Author: H. Sommer
Publisher: RILEM Publications
ISBN: 9782912143037
Category : Concrete
Languages : en
Pages : 316
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