Concrete Mixture Evaluation and Acceptance for Air Field Pavements

by Richard C. Meininger, Natl Ready Mixed Concrete Assoc, Silver Spring, United States,
Norman R. Nelson, Natl Ready Mixed Concrete Assoc, Silver Spring, United States,

Document Type: Proceeding Paper

Part of: Aircraft/Pavement Interaction: An Integrated System


Evaluation of the strength of portland cement concrete using flexural strength and compressive strength tests is examined. Problems with the use of flexural testing in the field are discussed and alternative specification approaches to minimize testing problems and to provide an organized way of troubleshooting and settling low strength problems are covered. Data collected by the concrete industry and by a consultant for FAA projects show standard deviations for flexural strength from paving projects ranging from about 40 psi to 150 psi (coefficient of variation from 6 to 20 percent) with an average standard deviation of 75 psi. Specifications for concrete for air field pavements should recognize that an adequate strength overdesign as well as good testing practices are necessary to assure that a very high percentage of strength tests will meet requirements. Data are presented from case studies which show the effect of different specification strategies. Also, included are suggested quality control and trouble shooting protocols which should be included in specifications to improve data and information available and to handle low strength tests. It will help determine whether the concrete, as-placed, is truly substandard; whether the low strength is simply due to poor curing, handling, and testing; or whether it is due to an occasional low test from normal statistical variation. The procedure includes evaluation of the project data, as well as, the proper use of non-destructive tests and testing of cores when necessary. Specifications and testing can be improved to minimize on-the-job strength problems, and provide an organized way of investigating strength problems so that job delay and strength problems due to poor testing can be rapidly identified and minimized.

Subject Headings: Concrete pavements | Strength of materials | Field tests | Flexural strength | Mixtures | Compressive strength | Material tests | Structural strength

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