DEVELOPMENT OF METHODS OF TESTING AGGREGATE LARGER THAN 1-1/2 INCH.
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS
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The investigation involved the study of concrete aggregate from seven different sources. The tests included petrographic analysis, sieve analysis, specific gravity, absorption, soft particles, Los Angeles abrasion, flat and elongated particles, magnesium sulfate soundness, and freezing and thawing in concrete. The objective of the study was to evaluate existing and new test methods and to determine if existing test methods for aggregates smaller than a 1-12-in. sieve. provide accurate data for use in evaluating aggregate larger than a 1-12-in. sieve. It was concluded from the physical tests that when the aggregates of larger than 1-12-in. size are crushed and then tested, the results give a better indication of actual behavior of the aggregates in concrete than do the results of similar tests of larger than 1-12-in. size material. It was concluded from the petrographic analyses that 1 for bedded rock, the maximum size of aggregate produced from a source should never be greater than the bedding thickness, 2 for material larger than 1-12-in., aggregate produced from bedded materials should be used in concrete before destructive weathering occurs or else it should be rescreened before using, and 3 chemical reactivity of the aggregate is more likely to be a problem with gravel aggregate than is particle size reduction during stockpile storage. Author
- Construction Equipment, Materials and Supplies
- Test Facilities, Equipment and Methods