AGGREGATE GRADING AND THE INTERNAL STRUCTURE OF CONCRETE
It is shown that there are many gradings for concrete aggregate that can be considered as optimum for one purpose or another. In addition to the behavior of the concrete in the frash as well as in the hardened state, visual inspection of the internal structure of concrete reveals whether the grading used is close enough to the desired optimum. A method, adopted from a procedure used in petrography, is presented for such evaluation of the structure of concrete. This is based on the measurement of the intercepts of mortar layers among coarse aggregate particles in the finished concrete. Various kinds of concretes are analyzed by this method. The results indicate that there exists a needed minimum value for the average mortar layer intercept below which the workability of the concrete is inadequate; this needed minimum mortar intercept is dependent on several factors such as the method of compaction and the grading of the sand; and the minimum value seems to be independent of the particle shape of the coarse aggregate. The effect of the particle shape of coarse aggregate on the grading optimum is also discussed. Based on this, two methods for measuring the angularity of the particles are recommended. Finally, internal structures of concretes made with continuous gradings and comparable gap gradings are contrasted.
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Supplemental Notes:
- Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
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Authors:
- Popovics, Sandor
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Discussers:
- Mather, B
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Conference:
- 52nd Annual Meeting of the Highway Research Board
- Location: Washington District of Columbia, United States
- Date: 1973-1-22 to 1973-1-26
- Publication Date: 1973
Media Info
- Media Type: Digital/other
- Features: Figures; References; Tables;
- Pagination: pp 56-64
- Monograph Title: Grading of concrete aggregates
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Serial:
- Highway Research Record
- Issue Number: 441
- Publisher: Highway Research Board
Subject/Index Terms
- TRT Terms: Aggregate gradation; Aggregates by shape and surface texture; Concrete aggregates; Design; Gap grading; Mix design; Optimization; Workability
- Uncontrolled Terms: Aggregate shape; Internal structure
- Old TRIS Terms: Optimum design
- Subject Areas: Design; Highways; Materials;
Filing Info
- Accession Number: 00159547
- Record Type: Publication
- ISBN: 0309021723
- Files: TRIS, TRB
- Created Date: Sep 20 1977 12:00AM