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Comparison Of Air Void Content Measurements In Fresh Versus Hardened Concretes
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Book Synopsis Comparison of Air Void Content Measurements in Fresh Versus Hardened Concretes by : Hamdi Celik Ozyildirim
Download or read book Comparison of Air Void Content Measurements in Fresh Versus Hardened Concretes written by Hamdi Celik Ozyildirim and published by . This book was released on 1990 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study compares the air content of freshly mixed and hardened concretes. At the fresh stage, pressure meters (Types A and B) and a volumetric meter were used to determine the air content. At the hardened stage, the air content was calculated using the linear traverse method described in ASTM C 457, which is a microscopical procedure. The unit weight and compressive strength of the concretes were also determined. The results show that, at the ranges commonly used in the construction of pavements and bridges, the air content of fresh concrete measured by pressure meters and that determined by the microscopical method for essentially the same concrete after hardening are, for practical purposes, the same. The air content obtained by a volumetric meter as normally run in the field is generally lower than that obtained for the same hardened concretes by the microscopical method. The unit weight and compressive strength correlate well with the air content. It was also shown that adding water to concrete can significantly increase the air content, as well as the slump. Thus, a higher air content in hardened concretes than that indicated by initial measurements with a pressure meter is likely to be present if water is added during placement.
Book Synopsis Field Study of Air Content Stability in the Slipform Paving Process by :
Download or read book Field Study of Air Content Stability in the Slipform Paving Process written by and published by . This book was released on 2012 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study evaluated the impacts of construction on the air content and air-void system structure of Portland cement concrete pavements. The primary intent was to quantify the air content of fresh concrete before and after it has gone through the slipform paver. The air-void system parameters of hardened concrete were then assessed using cast and extracted core specimens. The results of the air content testing on fresh concrete and the concrete cylinder specimens cast in the field suggested that there is some loss of air as the concrete passes through the paver. Laboratory testing performed on cores extracted from the pavement did not provide any conclusive evidence that entrained air is lost during the slipform paving process. In fact, many of the extracted cores had measured air content values that were much higher than the specification requirement. If excessive, this could result in increased permeability and low-strength related issues. Although a rigorous statistical analysis was not performed, the results suggest that the air content testing on fresh concrete is not capturing the true air content of the concrete placed with a slipform paver. The fresh concrete air content is generally lower than the air content measured in the cores.
Book Synopsis Significance of Tests and Properties of Concrete and Concrete-making Materials by : Joseph F. Lamond
Download or read book Significance of Tests and Properties of Concrete and Concrete-making Materials written by Joseph F. Lamond and published by ASTM International. This book was released on 2006 with total page 661 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Studying Air Properties in Hardened Portland Cement Concrete with Linear Traverse Method by : Lokman Ng
Download or read book Studying Air Properties in Hardened Portland Cement Concrete with Linear Traverse Method written by Lokman Ng and published by . This book was released on 2010 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: Air void structure in hardened concrete is critical to its durability. This project mainly focuses on investigating the air void system in hardened concrete with the microscopic analysis Linear Traverse Method specified by ASTM Specification C457-08 (Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete). To understand the stability of the air void system in concrete, the same concrete mixes were examined with two other methods, pressure meter measurement and Air-Void Analyzer, under fresh state. The comparison of the results from the three methods for fresh and hardened concrete shows that properties of concrete vary in samples within the same batch with the same mix design, samples in different batches of the same mix design and samples with different mix designs. The measured air content from Linear Traverse Method and pressure meter are fairly close to each other, while Air-Void Analyzer measured air content is observed to be lower than that from Linear Traverse Method. The measured spacing factor from Air-Void Analyzer is observed to be higher than that from Linear Traverse Method, while the measured specific surface from Air-Void Analyzer is observed to be lower than that from Linear Traverse Method. However, no strong correlation in the measured air content and measured specific surface between Linear Traverse and Air-Void Analyzer is observed.
Book Synopsis Air Void Characterization in Fresh Cement Paste Through Ultrasonic Attenuation Using an Immersion Procedure by : Natalie Ainsworth Darraugh
Download or read book Air Void Characterization in Fresh Cement Paste Through Ultrasonic Attenuation Using an Immersion Procedure written by Natalie Ainsworth Darraugh and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The most prevalent method for the prevention of freeze-thaw and salt scaling damage in cement based materials is through the entrainment of air voids using air entraining chemical admixtures (AEA's). However, the common field methods for measuring air content in fresh concrete cannot distinguish between entrained and entrapped air voids, and the actual air content in the hardened concrete can vary from that determined by these tests due to a variety of factors such as workability, placing operations, consolidation efforts, and environmental conditions. Previous research has shown the ability of ultrasonic attenuation to distinguish between entrained and entrapped air voids in hardened cement paste, providing a foundation for an inversion procedure to calculate the size and volume content of the two scatterer sizes. While additional challenges are present with measurements in fresh paste, the use of an immersion setup can overcome the limitations of cement paste containment vessels and provide a means to measure air content from batching to placement. An immersion apparatus to monitor ultrasonic wave attributes including attenuation in fresh cement paste is designed and built. Results comparing air entrained and non-air entrained cement pastes are presented. Ultrasonic wave attributes are studied as a function of time and level of chemical air entrainer. Finally, recommendations are made to improve the accuracy of the immersion apparatus in order to develop an in situ, quality control procedure to quantify the air content of fresh cement paste from batching to placement.
Book Synopsis Significance of Tests and Properties of Concrete and Concrete-making Materials by : Paul Klieger
Download or read book Significance of Tests and Properties of Concrete and Concrete-making Materials written by Paul Klieger and published by ASTM International. This book was released on 1994 with total page 621 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Comparison of Properties of Fresh and Hardened Concrete in Bridge Decks by : Howard Newlon
Download or read book Comparison of Properties of Fresh and Hardened Concrete in Bridge Decks written by Howard Newlon and published by . This book was released on 1971 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was made on 17 bridge decks constructed in 1963 under regular construction procedures. The purpose was (1) to compare important properties of concrete as freshly placed in randomly selected bridge decks with those after hardening of the concrete, (2) to detect the influence, if any, of different screeding methods, and (3) to relate the performance of the decks to the observed properties of the fresh and hardened concrete. Some of the conclusions from this study were as follows: (1) The primary cause of variable or borderline performance of concrete in bridge decks is variable or borderline fresh concrete. Many of the deficiencies have been overcome by changes in specifications and procedures instituted since the construction of the bridges included in the study. (2) No influence of the screeding method on the properties of the concrete in place was found. (3) When viewed against the perfection desired by the engineer, the performance of these decks has been disappointing or borderline. When viewed against the performance that would be expected from concrete with the properties observed, the performance has been better than might be expected.
Book Synopsis Expert/knowledge-based Systems for Cement and Concrete by : Lawrence J. Kaetzel
Download or read book Expert/knowledge-based Systems for Cement and Concrete written by Lawrence J. Kaetzel and published by . This book was released on 1991 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Comparison of Air Contents in Fresh and Hardened Concretes Using Different Airmeters by : KH. Khayat
Download or read book Comparison of Air Contents in Fresh and Hardened Concretes Using Different Airmeters written by KH. Khayat and published by . This book was released on 1991 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The air contents of several concrete mixtures were measured while the material was in a plastic state, and the results were compared to corresponding values determined microscopically on the same hardened concretes. Two volumetric airmeters, a roller and a mini airmeter, as well as a pressure airmeter were employed for monitoring the air content in fresh concrete. The linear traverse method was used to determine the air content of hardened concrete. A total of 21 laboratory-prepared concrete mixtures were examined. Both 10 and 25-mm (3/8 and 1-in.) nominal size aggregates of different densities were used to produce normal-weight and lightweight concretes. The water-cementitious materials ratios for the concretes ranged between 0.23 and 0.53, and the cement content varied from 267 to 540 kg/m3 (450 to 910 lb/yd3), with silica fume incorporated in some concretes. An air-entraining agent was used to yield air contents between 0.5 and 12.5%.
Book Synopsis Distribution of Voids in Field Concrete by : Hamdi Celik Ozyildirim
Download or read book Distribution of Voids in Field Concrete written by Hamdi Celik Ozyildirim and published by . This book was released on 1978 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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).
Book Synopsis Expanded Study on the Effects of Aggregate Coating and Films on Concrete Performance by :
Download or read book Expanded Study on the Effects of Aggregate Coating and Films on Concrete Performance written by and published by . This book was released on 2007 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Strength, Shrinkage, Hardened Air Void Characteristics of Concrete Containing Slag Cement by : Ryan David Foley
Download or read book Strength, Shrinkage, Hardened Air Void Characteristics of Concrete Containing Slag Cement written by Ryan David Foley and published by . This book was released on 2006 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development and Application of a Method for Analyzing the Voids in Hardened Concrete by : Curtis Warren
Download or read book Development and Application of a Method for Analyzing the Voids in Hardened Concrete written by Curtis Warren and published by . This book was released on 1951 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Evaluation of Two Automated Methods for Air-Void Analysis of Hardened Concrete by : A. M. Ramezanianpour
Download or read book Evaluation of Two Automated Methods for Air-Void Analysis of Hardened Concrete written by A. M. Ramezanianpour and published by . This book was released on 2010 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Air-void analysis of hardened concrete is typically performed according to ASTM C457-09 ["Standard Test Method for Microscopical Determination of Parameters of Air-Void System in Hardened Concrete," Annual Book of ASTM Standards, Vol. 4.2, ASTM International, West Conshohocken, PA], which can be tedious to perform and is operator subjective. Several alternative automated methods have been proposed, two of which are the Rapid Air 457 and the scanner method developed at Michigan Technological University. In each of these methods, images are collected from contrast enhanced surfaces of polished concrete, and image analysis is performed to calculate air-void system parameters. In this research, 22 concrete samples were examined using these two methods, the air-void system parameters were compared to those obtained from the ASTM C457 standard, and the precision of the results was compared to the recommendations of ASTM standard. It was concluded that the total air content and the spacing factor of the air voids measured by Rapid Air 457 and the scanner method were comparable to the air content and the spacing factor measured according to the standard manual method. Considering the fact that the automated image systems could detect air voids smaller in diameter than those typically seen by an operator, it was found that if these small air voids are counted, calculated spacing factors are smaller than those calculated by the manual method. If small diameter air voids are removed from the analysis, then spacing factors agree fairly well with those calculated by ASTM C457 from stereo-optical microscopy.
Book Synopsis Techniques for Measuring Air Void Characteristics of Concrete by : Duane E. Amsler
Download or read book Techniques for Measuring Air Void Characteristics of Concrete written by Duane E. Amsler and published by . This book was released on 1973 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Enhanced Entrained Air Void System Characterization for Durable Highway Concrete by : Anthony Torres
Download or read book Enhanced Entrained Air Void System Characterization for Durable Highway Concrete written by Anthony Torres and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis High-pressure Test for Determining Air Content of Hardened Concrete by : E. E. McCoy (Jr.)
Download or read book High-pressure Test for Determining Air Content of Hardened Concrete written by E. E. McCoy (Jr.) and published by . This book was released on 1958 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
