Author: Karl PetersonPublisher:
ISBN:
Category :
Languages : en
Pages : 78
Book Description
Air Void Analysis of Hardened Concrete Via Flatbed Scanner
Author: Karl PetersonAdvancement on the Application of a Flat-bed Scanner for Hardened Portland Cement Concrete Air Void Analysis
Author: Jeremy CarlsonThe Practical Application of a Flatbed Scanner for Air-Void Characterization of Hardened Concrete
Author: Karl PetersonPublisher:
ISBN:
Category : Air-Void Characterization
Languages : en
Pages : 23
Book Description
Over the past 30 years, with the advent of computers and digital imaging, many automated systems have been introduced for the purpose of air-void characterization. The majority of the systems employs a contrast-enhancement procedure where a polished cross-section of concrete is darkened with paint, and white powder is forced into the depressions left by air-voids. The system described here follows the same approach and uses a flatbed scanner to collect a single digital image of the entire sample. For all of the systems based on contrast enhancement, the first step is to select a threshold level. Image pixels brighter than the threshold level represent air and image pixels darker than the threshold level represent non-air (i.e., paste or aggregate). Further digital processing steps may be employed but the initial selection of threshold level exerts a strong influence on whether a pixel in the final data set is classified as air or non-air. A systematic approach for threshold determination has been proposed based on an iterative procedure that compares automatically determined air-void parameters to manually determined air-void parameters from a set of training specimens. The calibration procedure finds a single optimum threshold level for the automated system that is to be used for all subsequent analyses. The approach was tested on a population of 88 specimens with manually determined air-void parameters, with the goal of determining an appropriate value for the number of training specimens.
Automated Air-void System Characterization of Hardened Concrete
Author: Karl W. PetersonEvaluation of Two Automated Methods for Air-Void Analysis of Hardened Concrete
Author: A. M. RamezanianpourPublisher:
ISBN:
Category : Air-Void Characterization
Languages : en
Pages : 14
Book Description
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.
Evaluation of Two Automated Methods for Determination of the Air Void System Parameters of Hardened Concrete
Author: Amir Mohammad RamezanianpourPublisher:
ISBN:
Category :
Languages : en
Pages : 192
Book Description
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.
Significance of Tests and Properties of Concrete and Concrete-making Materials
Author: Joseph F. LamondPublisher: ASTM International
ISBN: 0803133677
Category : Technology & Engineering
Languages : en
Pages : 661
Book Description
Microscopic Air Void Analysis of Hardened Portland Cement Concrete by the Isolated Shadow Technique
Author: Basil Mark HarrisPore Structure of Cement-Based Materials
Author: Kalliopi K. AligizakiPublisher: CRC Press
ISBN: 9780419228004
Category : Science
Languages : en
Pages : 442
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.
Author: