A Method for Analyzing Void Distribution in Air-Entrained Concrete PDF Download
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Author: RE. Philleo
Publisher:
ISBN:
Category : Air entrainment
Languages : en
Pages : 3
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Book Description
A method is derived that makes possible the determination of the fraction of hardened cement paste within any stipulated distance of the nearest air void as a means of determining the extent to which the paste is protected from the damaging effects of freezing. The required input consists of the total air content and the number of air voids per unit volume. Both can be determined from a Rosiwal linear traverse performed by microscope on a polished section of concrete. Determining the void density requires a count of chord intercepts in two or three small size groups.
Author: RE. Philleo
Publisher:
ISBN:
Category : Air entrainment
Languages : en
Pages : 3
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Book Description
A method is derived that makes possible the determination of the fraction of hardened cement paste within any stipulated distance of the nearest air void as a means of determining the extent to which the paste is protected from the damaging effects of freezing. The required input consists of the total air content and the number of air voids per unit volume. Both can be determined from a Rosiwal linear traverse performed by microscope on a polished section of concrete. Determining the void density requires a count of chord intercepts in two or three small size groups.
Author: Hamdi Celik Ozyildirim
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 36
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Book Description
This study was intended to evaluate the air void characteristics of concrete in an attempt to identify, quantitatively or semi-quantitatively, different types of voids and to predict their influence on strength and durability. At the outset, it was anticipated that total air contents and water-- cement ratios of concrete mixtures would reflect the presence of excess water or air voids. However, because it is difficult to determine the water-cement ratio of hardened concrete, an attempt was made to relate the water-cement ratio and the air content, taken as independent variables, to the parameters of the void system that are .readily determined from the hardened concrete. The parameters of the void system considered were 1. The specific surface and the spacing factor calculated from linear traverse data. 2. The constants of a continuous chord frequency distribution curve derived from a probability density function. 3. The mean diameters and the number of bubbles per unit volume determined by a graphical method. The concrete samples were prepared in the laboratory, and the variables included the amount of air entrainment, the water cement ratio, the mixing time, and the mixture temperature. The data on the void system were obtained by utilizing the chord lengths of voids determined by the linear traverse analysis of concrete specimens. Within the framework of the study it was not possible to correlate the combined effect of water and air content with the above mentioned void parameters. A good correlation was obtained between the air contents of fresh and hardened concretes that were properly measured. Satisfactory relationships were established between the measures of resistance to freezing and thawing (weight loss, relative dynamic modulus of elasticity, and the surface rating), and certain parameters-of the void system (the spacing factor, the specific surface, and the diameter of the bubbles).
Author: Koji Sakai
Publisher: Taylor & Francis US
ISBN: 9780419198505
Category : Concrete
Languages : en
Pages : 908
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Book Description
Author: Anthony Torres
Publisher:
ISBN:
Category : Air-entrained concrete
Languages : en
Pages : 0
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Book Description
The air void system in concrete provides a strong influence on the behavior of cementitious materials in both the fresh and hardened state, especially as it relates to freeze-thaw resistance and deicer scaling. The most common test procedure to characterize the air void system is ASTM C457 – Standard Test method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete, which involves microscopic determination of the air content, paste content, air-void size distribution, and spatial dispersion of a sawn concrete sample. This procedure is reliant on the user to make hundreds of critical decisions per sample, which requires significant time, and is potentially subject to human error. Additionally, ASTM C457 provides minimal guidance regarding the exact steps and equipment necessary to prepare a sample for evaluation. The outcome of this research not only provides specific information regarding sample preparation for hardened concrete air void analysis, it also develops an alternative characterization technique that drastically minimizes evaluation time, human error, and increases reliability of key hardened air void characterization parameters. Specific results show on average air void difference of 0.5% and 0.7% between the alternative method versus ASTM C457 Procedure A and B, respectively. The results also show a significant reduction of analysis time from approximately 2 – 4 hours per sample to 15 minutes per sample when using the alternative method.
Author: Donald J. Janssen
Publisher: RILEM Publications
ISBN: 9782912143310
Category : Concrete
Languages : en
Pages : 318
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Book Description
Author: Basil Mark Harris
Publisher:
ISBN:
Category :
Languages : en
Pages : 634
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Book Description
Author: V.S. Ramachandran
Publisher: William Andrew
ISBN: 0815516541
Category : Technology & Engineering
Languages : en
Pages : 1183
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Book Description
Since the publication of the first edition ten years ago, significant developments have occurred in the use of admixtures in concrete. Eight new chapters and a full update of the preceding ten chapters bring this book up to date; reflecting the relative advances made in the science and technology of different groups of admixtures. The increased role and development of admixtures in concrete technology is evidenced by a number of conferences, publications, and novel admixtures available in the market place. These developments in the field caused the modification of many chapters in the first edition in order to reflect the advances. Although individual chapters refer to standards and specifications of admixtures, those only interested in the standards or techniques used in investigating admixtures will find the second chapter (Research Technologies, Standards, and Specifications) useful. Admixtures are not as inert as may be presumed. They may chemically interact with the constituents of concrete and affect the properties of the fresh and hardened concrete and its durability. The third chapter deals with these aspects. It was important to devote a chapter to recent attempts in developing new admixtures.
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: Odd E. Gjørv
Publisher: CRC Press
ISBN: 9780419238805
Category : Concrete
Languages : en
Pages : 874
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Book Description
Author: Kalliopi K. Aligizaki
Publisher: CRC Press
ISBN: 9780419228004
Category : Science
Languages : en
Pages : 442
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Book Description
Pore Structure of Cement-Based Materials provides a thorough treatment of the experimental techniques used to characterize the pore structure of materials. The text presents the principles and practical applications of the techniques used, organized in an easy-to-follow and uncomplicated manner, providing the theoretical background, the way to analyze experimental data, and the factors affecting the results. The book is the single comprehensive source of the techniques most commonly used for pore structure analysis, covering simple techniques like mercury intrusion porosimetry and water absorption, to the more sophisticated small-angle scattering and nuclear magnetic resonance. The book is an essential reference text for researchers, users, and students in materials science, applied physics, and civil engineering, who seek a deep understanding of the principles and limitations of the techniques used for pore structure analysis of cement-based materials.
