Evaluation of Two Automated Methods for Determination of the Air Void System Parameters of Hardened Concrete PDF Download
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Author: Amir Mohammad Ramezanianpour Publisher: 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.
Author: Amir Mohammad Ramezanianpour Publisher: 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.
Author: A. M. Ramezanianpour Publisher: 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.
Author: Karl Peterson Publisher: 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.
Author: Publisher: ISBN: Category : Pavements, Concrete Languages : en Pages : 300
Book Description
In Phase I, the research team contacted each of 16 participating states to gather information about concrete and concrete material tests. A preliminary suite of tests to ensure long-term pavement performance was developed. The tests were selected to provide useful and easy-to-interpret results that can be performed reasonably and routinely in terms of time, expertise, training, and cost. The tests examine concrete pavement properties in five focal areas critical to the long life and durability of concrete pavements: (1) workability, (2) strength development, (3) air system, (4) permeability, and (5) shrinkage. The tests were relevant at three stages in the concrete paving process: mix design, preconstruction verification, and construction quality control. In Phase II, the research team conducted field testing in each participating state to evaluate the preliminary suite of tests and demonstrate the testing technologies and procedures using local materials.
Author: R. Pleau Publisher: ISBN: Category : Air voids Languages : en Pages : 9
Book Description
Many parameters affecting the quality of the air void characteristics measurement are reviewed and discussed. The difficulties more frequently encountered during the measurement process are described, and some simple rules are proposed in order to increase, as much as possible, the accuracy and reproducibility of the test. The influence of the sampling size is studied, and the variability of air content, specific surface, and spacing factor is estimated from a statistical analysis of about 600 different concrete mixtures. The influence of the operator's subjectivity is also investigated, and the effect produced by large air voids on the computation of the spacing factor is discussed.
Author: Publisher: ISBN: Category : Concrete Languages : en Pages : 230
Book Description
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: Amir Mohammad Ramezanianpour
Author: Amir Mohammad Ramezanianpour
Author: A. M. Ramezanianpour
Author: ASTM International
Author: Karl Peterson
Author: James Bayles
Author: 
Author: Marcia Jill Simon
Author: 
Author: R. Pleau
Author: