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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: 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: J. Ivan Escalante-Garcia Publisher: Springer Nature ISBN: 3031217357 Category : Technology & Engineering Languages : en Pages : 1029
Book Description
This volume gathers the latest advances, innovations and applications in the field of sustainable construction materials and structures, as presented by leading international researchers and engineers at the 75th RILEM Annual Week (75RW 2021), held in Merida, Mexico on August 29 – September 3, 2021. It covers topics such as supplementary cementitious materials, durability and Life Cycle assessment in urban and marine conditions, additive manufacturing of concrete in construction, structural performance and design, non-Portland cements and Alkali activated cementitious materials and eco-concrete, cultural heritage, non-destructive testing techniques, bituminous materials, and construction materials (polymers, timber, bamboo, recycling and masonry). The contributions, which were selected through a rigorous international peer-review process, share exciting ideas that will spur novel research directions and foster new multidisciplinary collaborations.
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: Stefan Bernard Publisher: CRC Press ISBN: 020384937X Category : Technology & Engineering Languages : en Pages : 310
Book Description
Over the last twenty years we have witnessed a revolution in ground stabilization in both underground and above-ground applications, thanks largely to the widespread adoption of shotcrete as a medium for support. Shotcrete technology continues to evolve and improve as its utilization increases. From relatively obscure and sporadic beginnings, it ha
Author: Mark G. Richardson Publisher: CRC Press ISBN: 1000968758 Category : Technology & Engineering Languages : en Pages : 407
Book Description
This new edition sets out the fundamental aspects of concrete durability with an emphasis on sustainability and carbon neutrality through performance-based methodologies. Global approaches to managing durability are explained from both a prescriptive and performance viewpoint. Achieving a balance between the interactive factors influencing durability and sustainability is supported by an explanation of the physical and chemical phenomena at play, determination of key performance parameters by mathematical modelling and physical testing, and current guidance for good practice. New chapters and sections examine the holistic approach to durability and significant aspects of traditional and new cementitious systems. The full range of threats to durability are covered in this single volume, including reinforcement corrosion, carbonation, chloride ingress, freeze-thaw effects, sulfate attack, acid and seawater attack, alkali-aggregate reaction, cracking, abrasion, erosion, cavitation, and weathering. The book presents a framework for specification through internationally adopted codes and standards and summarises the background to probabilistic approaches to durability design, providing a state-of-the-art review of mathematical modelling of deterioration mechanisms along with current directions in test methods for performance-based specifications. Fundamentals of Durable Reinforced Concrete is an essential reference on concrete durability for specifiers and researchers and is also accessible to undergraduate students.
Author: A. M. Ramezanianpour
Author: A. M. Ramezanianpour
Author: Chris Baumgart
Author: Basil Mark Harris
Author: J. Ivan Escalante-Garcia
Author: 
Author: Karl Peterson
Author: FIB – International Federation for Structural Concrete
Author: Joseph F. Lamond
Author: Stefan Bernard
Author: Mark G. Richardson