Standard Test Method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete PDF Download

Author: ASTM International
Publisher:
ISBN:
Category :
Languages : en
Pages : 15

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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: Anthony Torres
Publisher:
ISBN:
Category : Air-entrained concrete
Languages : en
Pages : 0

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The air void system in concrete provides a strong influence on the behavior of cementitious materials in both the fresh and hardened state, especially as it relates to freeze-thaw resistance and deicer scaling. The most common test procedure to characterize the air void system is ASTM C457 – Standard Test method for Microscopical Determination of Parameters of the Air-Void System in Hardened Concrete, which involves microscopic determination of the air content, paste content, air-void size distribution, and spatial dispersion of a sawn concrete sample. This procedure is reliant on the user to make hundreds of critical decisions per sample, which requires significant time, and is potentially subject to human error. Additionally, ASTM C457 provides minimal guidance regarding the exact steps and equipment necessary to prepare a sample for evaluation. The outcome of this research not only provides specific information regarding sample preparation for hardened concrete air void analysis, it also develops an alternative characterization technique that drastically minimizes evaluation time, human error, and increases reliability of key hardened air void characterization parameters. Specific results show on average air void difference of 0.5% and 0.7% between the alternative method versus ASTM C457 Procedure A and B, respectively. The results also show a significant reduction of analysis time from approximately 2 – 4 hours per sample to 15 minutes per sample when using the alternative method.

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: José Sena-Cruz
Publisher: Springer Nature
ISBN: 3030764656
Category : Technology & Engineering
Languages : en
Pages : 361

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This book gathers peer-reviewed contributions presented at the 3rd RILEM Spring Convention and Conference, held at Guimarães and hosted by the University of Minho, Portugal, on March 9-14, 2020. The theme of the Conference was “Ambitioning a Sustainable Future for Built Environment: comprehensive strategies for unprecedented challenges”, which was aimed at discussing current challenges and impacts of the built environment on sustainability. The present volume is dedicated to the topic “Service life extension of existing structures”, which covers the most recent scientific and technological developments in the understanding of the evolution and degradation of construction materials and structural systems. Analytical and numerical, as well as experimental approaches, aimed at characterizing, modelling and predicting the evolution of the physical, chemical and mechanical properties of construction materials and structural systems are regarded. Multiphysics models are also considered, as well as other strategies that contribute for an accurate characterization and prediction the service life and the evolution of existing and novel construction materials under normal or extreme environmental exposure or loading conditions. New strategies to promote the smart repairing or the recovery of material properties, as well as the service life extension, are also considered. The following subtopics are included: service life models and multiphysics approaches; smart structures, innovative monitoring and intervention strategies; management and optimized maintenance strategies; integrated rehabilitation and strengthening approaches.

Author: Lawrence J. Kaetzel
Publisher:
ISBN:
Category : Expert systems (Computer science)
Languages : en
Pages : 274

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Author: Peter C. Taylor
Publisher: Transportation Research Board
ISBN: 030909934X
Category : Aggregates (Building materials)
Languages : en
Pages : 96

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This report presents recommended changes to the cement specifications and test protocols contained in AASHTO Standard Specifications for Transportation Materials and Methods of Sampling and Testing (AASHTO M 85). These changes pertain to the amount of processing additions that can be incorporated in the cement and the tests required for evaluating acceptability of cements incorporating processing additions. The report also presents a recommended specification for evaluating processing additions that may be used in amounts exceeding those stipulated in the cement specification. These specifications will guide materials engineers and cement producers in evaluating cements and assuring that highway concrete is not deleteriously affected by the presence of such additions.

Author: Thomas John Van Dam
Publisher: Transportation Research Board
ISBN: 0309088356
Category : Technology & Engineering
Languages : en
Pages : 38

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Author: John P. Broomfield
Publisher: CRC Press
ISBN: 0203414608
Category : Architecture
Languages : en
Pages : 294

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Book Description
Corrosion of Steel in Concrete provides information on corrosion of steel in atmospherically exposed concrete structures and serves as a guide for those designing, constructing and maintaining buildings, bridges and all reinforced concrete structures. This new edition incorporates the new European standards as well as USA and other international standards. It also covers developments in galvanic and impressed current cathodic protection, new electrochemical techniques such as electro-osmosis, and stainless steel clad reinforcing bars. The corrosion of reinforcing steel in concrete is a major problem facing civil engineers and surveyors throughout the world today. There will always be a need to build structures in corrosive environments and it is therefore essential to address the problems that result. This is a book to educates about and forms a guide to the problems of corrosion, its causes and how to find solutions.

Author: Norb Delatte
Publisher: Elsevier
ISBN: 1845697030
Category : Technology & Engineering
Languages : en
Pages : 352

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Understanding and recognising failure mechanisms in concrete is a fundamental pre-requisite to determining the type of repair, or whether a repair is feasible. This title provides a review of concrete deterioration and damage, as well as looking at the problem of defects in concrete. It also discusses condition assessment and repair techniques.Part one discusses failure mechanisms in concrete and covers topics such as causes and mechanisms of deterioration in reinforced concrete, types of damage in concrete structures, types and causes of cracking and condition assessment of concrete structures. Part two reviews the repair of concrete structures with coverage of themes such as standards and guidelines for repairing concrete structures, methods of crack repair, repair materials, bonded concrete overlays, repairing and retrofitting concrete structures with fiber-reinforced polymers, patching deteriorated concrete structures and durability of repaired concrete.With its distinguished editor and international team of contributors, Failure and repair of concrete structures is a standard reference for civil engineers, architects and anyone working in the construction sector, as well as those concerned with ensuring the safety of concrete structures. - Provides a review of concrete deterioration and damage - Discusses condition assessment and repair techniques, standards and guidelines