Effect of Vibration on the Air Void Parameters and Freezing-thawing Resistance of Air-entrained Concrete PDF Download
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Author: J. E. Backstrom
Publisher:
ISBN:
Category :
Languages : en
Pages : 44
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Book Description
Author: J. E. Backstrom
Publisher:
ISBN:
Category :
Languages : en
Pages : 44
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Book Description
Author: Gilson Lomboy
Publisher:
ISBN:
Category : Air void
Languages : en
Pages : 20
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Book Description
The present research is aimed at investigating effects of concrete properties, particularly concrete rapid chloride permeability, strength, and air void parameters, on freezing-thawing (FT) resistance. In this study, concrete mixtures are made with different types of cement (Types I with 15 % class C fly ash and Type IP cements), different water-to-binder ratios (w/b=0.25, 0.35, 0.45, and 0.55), and with or without air entraining agent. The 28-day compressive strength, rapid chloride permeability, and FT durability of the concrete are determined according to ASTM C873, C1202, and C666A, respectively. The air void parameters of the concrete are measured with air void analyzer, Rapid Air, and porosity (ASTM C642) tests. The results indicate that although concrete made with a low w/b (≤0.35) has low rapid chloride permeability (≤1320 C), it generally still requires proper air entrainment for a desirable FT resistance (with a durability factor of ≥85 %), except for the concrete having very low rapid chloride permeability (520 C) and very high 28-day compressive strength (88 MPa or 12 760 psi). For the non-air-entrained concrete studied, there are clear relationships between FT durability and porosity, w/b, and permeability. However, such relationships do not exist for air-entrained concrete. The FT resistance of air-entrained concrete is largely dependent on the concrete air void characteristics.
Author: Ahmad A. Ghadban
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Pre-stressed concrete is used for manufacturing railroad ties. Air entrainment is used in concrete railroad ties to provide durability in freeze-thaw conditions commonly present in track. Vibration practices in pre-stressed concrete railroad tie plants could contribute to excessive air loss during manufacture and thus poor freeze-thaw resistance. Rheological properties of fresh concrete significantly influence the determination of how much air is lost during vibration. This research attempted to increase understanding of the effect of vibration on air bubble distribution and freeze-thaw resistance of concrete given certain compositions and rheological properties of concrete. The objective was achieved by examining the effect of different admixtures combinations, vibration parameters, and rheological properties on the air void system and freeze-thaw resistance of concrete. This research also proposed a method to measure rheological properties of concrete when vibrated and for concrete mixtures too stiff to measure using conventional rheology measurements. Results showed that delaying the initiation of vibration can cause significant air loss but does not necessarily decrease freeze-thaw performance of concrete. Results also showed that a majority of air loss occurs in the first 30 seconds of vibration. The types of admixtures used in the concrete mixture can significantly affect the air system and freeze-thaw durability of concrete; this effect was shown to be more pronounced in mixtures with low yield stress and plastic viscosity. While the peak vibration acceleration had a mild effect, the frequency and peak velocity of vibration did not seem to have a noticeable effect on the air system and freeze-thaw performance of concrete. Results also showed that rheological properties of stiff mixtures can be estimated by running the rheology test during vibration.
Author: Waterways Experiment Station (U.S.)
Publisher:
ISBN:
Category : Aggregates (Building materials).
Languages : en
Pages : 120
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Author: Lawrence J. Kaetzel
Publisher:
ISBN:
Category : Expert systems (Computer science)
Languages : en
Pages : 274
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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: Jussara Tanesi
Publisher:
ISBN:
Category : Air-entrained concrete
Languages : en
Pages : 96
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Book Description
Freeze-thaw resistance is a key durability factor for concrete pavements. Recommendations for the air void system parameters are normally: 6 ± 1 percent total air, and spacing factor less than 0.20 millimeters. However, it was observed that some concretes that did not possess these commonly accepted thresholds presented good freeze-thaw resistance in laboratory studies. This study evaluated the freeze-thaw resistance of several "marginal" air void mixes, with two different types of air-entraining admixtures (AEA)-a Vinsol resin and a synthetic admixture. This study used rapid cycles of freezing and thawing in plain water, in the absence of deicing salts. For the specific materials and concrete mixture proportions used in this project, the marginal air mixes (concretes with fresh air contents of 3.5 percent or higher) presented an adequate freeze-thaw performance when Vinsol resin based air-entraining admixture was used. The synthetic admixture used in this study did not show the same good performance as the Vinsol resin admixture
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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Book Description
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: 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.
