Image Analysis for Evaluating Air Void Parameters of Concrete PDF Download

Author: Scott Schlorholtz
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 62

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Author: A. M. Ramezanianpour
Publisher:
ISBN:
Category : Air-Void Characterization
Languages : en
Pages : 14

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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.

Author: J. Cahill
Publisher:
ISBN:
Category : Air entrainment
Languages : en
Pages : 14

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The use of ASTM C457 ("linear traverse" or "modified point-count methods") for microscopical determination of air-void content and parameters of the air-void system, in hardened concrete has become widespread in the prediction of the durability of concrete in freeze-thaw conditions, and in assessing concrete that has failed in service. More recently a new European Standard, based on linear traverse measurements has been adopted as an efficacy test for air entraining agents. The linear traverse method described in both standards involves identification, counting and, in the Euro Standard, measurement of air-voids. It is laborious, tedious and subjective and the error of the method has not been rigorously assessed. We have explored the possibility of using Image Analysis in conjunction with the linear traverse method to develop less laborious and subjective measurement methods. A number of methods of visualisation of air-voids have been applied to polished samples of hardened concrete which had previously been assessed by the standard linear traverse method. The quality of the surface preparation required for Image Analysis was found to be even more critical than for the standard manual method.

Author: Amir Mohammad Ramezanianpour
Publisher:
ISBN:
Category :
Languages : en
Pages : 192

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Determination of air void parameters of hardened concrete is usually performed according to ASTM C 457 standard. This standard process is tedious and the results depend on the skill of the operator. Several researchers have proposed alternative automated methods for performing the test. Two of these new methods are Rapid Air 457 and the scanner method. Rapid Air 457 collects images from the surface of concrete samples using a digital microscope whereas in the scanner method, the surface is scanned by a flat-bed scanner. Then, the captured images are analyzed by different computer software. In this thesis, 22 concrete samples were examined by these two methods and the air void parameters were compared to those obtained from the standard method. Moreover, different parameters influencing the results of the test were examined and the precision of the results were compared to the recommendations of ASTM standard.

Author: Mohamad Nagi
Publisher: Transportation Research Board
ISBN: 0309098890
Category : Air-entrained concrete
Languages : en
Pages : 60

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"This report presents a recommended procedure for evaluating air-entraining admixtures used in highway concrete. The procedure involves the testing of non-air-entrained concrete and concrete containing the air-entraining admixture under simulated field conditions. Criteria are proposed for acceptance of admixtures for use in either highway pavements or structures. The recommended procedure and acceptance criteria will guide materials engineers in evaluating and selecting air-entraining admixtures that should contribute to appropriate freeze-thaw durability and thus to good performance and long service life. The content of the report will be of immediate interest to materials engineers, researchers, and others concerned with the design of concrete mixtures for use in highway pavements and structures."--taken from Foreword, page [v].

Author: Paul Klieger
Publisher: ASTM International
ISBN: 0803120532
Category : Concrete
Languages : en
Pages : 621

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Author: Haizhu Lu
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Air void size and spatial distribution have long been regarded as critical parameters in the frost resistance of concrete. In cement-based materials, entrained air void systems play an important role in performance as related to durability, permeability, and heat transfer. Many efforts have been made to measure air void parameters in a more efficient and reliable manner in the past several decades. Standardized measurement techniques based on optical microscopy and stereology on flat cut and polished surfaces are widely used in research as well as in quality assurance and quality control applications. Other more automated methods using image processing have also been utilized, but still starting from flat cut and polished surfaces. The emergence of X-ray computed tomography (CT) techniques provides the capability of capturing the inner microstructure of materials at the micrometer and nanometer scale. X-ray CTâ s less demanding sample preparation and capability to measure 3D distributions of air voids directly provide ample prospects for its wider use in air void characterization in cement-based materials. However, due to the huge number of air voids that can exist within a limited volume, errors can easily arise in the absence of a formalized data processing procedure. In this study, air void parameters in selected types of cement-based materials (lightweight concrete, structural concrete elements, pavements, and laboratory mortars) have been measured using micro X-ray CT. The focus of this study is to propose a unified procedure for processing the data and to provide solutions to deal with common problems that arise when measuring air void parameters: primarily the reliable segmentation of objects of interest, uncertainty estimation of measured parameters, and the comparison of competing segmentation parameters.

Author:
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 230

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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.

Author: Marcia Jill Simon
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 404

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Author: Donald O. Thompson
Publisher: Springer Science & Business Media
ISBN: 1461559472
Category : Technology & Engineering
Languages : en
Pages : 2198

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These Proceedings, consisting of Parts A and B, contain the edited versions of most of the papers presented at the annual Review of Progress in Quantitative Nondestructive Evaluation held at Bowdoin College, Brunswick, Maine on July 28 to August 2, 1996. The Review was organized by the Center for NDE at Iowa State University, in cooperation with the American Society of Nondestructive Testing, the Ames Laboratory of the USDOE, the Federal Aviation Administration, the National Institute of Standardsand Technology, and the National Science Foundation Industry!University Cooperative Research Centers pro gram. This year's Review of Progress in QNDE was attended by approximately 400 participants from the U.S. and many foreign countries who presented over 350 papers. As usual, the meetingwas divided into 36 sessions, with as many as four sessions running concurrently. The Review covered all phases of NDE research and development from fundamental investigations to engineering applications or inspection systems, and it included many important methods of inspection techniques from acoustics to x-rays. In the last eight to ten years, the Review has stabilized at about its current size, which most participants seem to agree is large enough to permit a full-scale overview of the latest developments, but still small enough to retain the collegial atmosphere which has marked the Review since its inception.