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Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.
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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Determination of the Air-Void System Parameters in Hardened Concrete--An Error Analysis
Author(s): B. W. Langan and M. A. Ward
Publication: Journal Proceedings
Appears on pages(s): 943-952
Keywords: air-entrained concretes; air entrainment; concrete durability; errors; hardened concretes; measurement; standard deviation; tests.
Abstract:ASTM Standard Practice C 457, "The Microscopial Determination of Air-Void Content and Parameters of the Air-Void System in Hardened Concrete," is extensively used in the assessment of the potential durability of concrete, particularly in the assessment of concrete that has failed in service. Unfortunately, little information is available concerning the accuracy of the air-void parameters obtained using this test method. In the current standard, the expected maximum single operator standard deviation is given for air content only and is based solely on theoretical calculations. To obtain an estimate of the magnitude of the total error, normal error analysis is applied to the equations used to determine the air-void parameters by the modified point count method. It is shown that the expected errors in the average chord intercept, specific surface, and spacing factor can be estimated if the errors in estimating the air and paste contents and number of voids per unit length can be established. Two methods are presented to predict the maximum theoretical errors in specific surface and spacing factor. Repetitive testing of standard surfaces is used to compare theoretical and measured errors for within-laboratory and interlaboratory data. It is shown that significant differences can exist between the air-void parameters determined, particularly in the interlaboratory data.
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