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Author: Leo P. H. (Leo Pieter H.) MeyerPublisher: National Library of Canada
ISBN: 9780315140820
Category :
Languages : en
Pages : 320
Book Description
Determination of Air Content of Hardened Concrete Using Image Analysis [microform]
![Determination of Air Content of Hardened Concrete Using Image Analysis [microform] PDF](https://books.google.com/books/content/images/frontcover/mAPywQEACAAJ?fife=w80-h100)
Author: Leo P. H. (Leo Pieter H.) MeyerPublisher: National Library of Canada
ISBN: 9780315140820
Category :
Languages : en
Pages : 320
Book Description
The Identification and Measurement of Entrained Air in Concrete Using Image Analysis
Author: J. CahillPublisher:
ISBN:
Category : Air entrainment
Languages : en
Pages : 14
Book Description
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.
The Image Analysis of Air-voids in Hardened Concrete
Author: Wallace Matthew MosherPublisher:
ISBN:
Category :
Languages : en
Pages : 318
Book Description
High-pressure Test for Determining Air Content of Hardened Concrete
Author: E. E. McCoy (Jr.)Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 80
Book Description
Evaluation 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.
Determination of Air Content in Hardened Concrete by Gamma-ray Transmission
Author: Microscopic Air Void Analysis of Hardened Portland Cement Concrete by the Isolated Shadow Technique
Author: Basil Mark HarrisDetermination of Air Void Content and Mixing Water Void Content of Hardened Concrete Using Electron Microscope Techniques
Author: Wesley Grigg MullenPublisher:
ISBN:
Category : Scanning electron microscopes
Languages : en
Pages :
Book Description
Canadiana
Author: Studying Air Properties in Hardened Portland Cement Concrete with Linear Traverse Method
Author: Lokman NgPublisher:
ISBN:
Category : Concrete
Languages : en
Pages : 88
Book Description
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.