Center for By-Products Utilization EVALUATION OF HIGH STRENGTH CONCRETE BY THE BREAK-OFF METHOD
نویسندگان
چکیده
The Break-Off method is the most recent development in in-place concrete strength testing. In this method, the force required to break-off an in-place concrete cylinder 2.17 in. (55 mm) in diameter and 2-2/4 in. (70 mm) long, is related to the compressive strength of the concrete from a predetermined calibration curve developed for this concrete mix. The reliability of the BreakOff method to test in-place high-strength concrete is investigated. The variables considered are aggregate shape, age of concrete, slab thickness, and method of obtaining cylindrical test specimens (either by inserting a plastic sleeve or by drilling a core). A total of 188 Break-Off tests and 30 standard cylinder tests are carried out for this project. Analysis of the results show that Break-Off test readings have a higher variability than the standard cylinder test readings. The accuracy of the Break-Off test method is not affected by the aggregate shape,, the slab thickness nor the type of specimen. Also, the aggregate shape and the slab thickness do not affect the Break-off test reading. However, the specimen type (sleeve or drilled) does affect the Breakoff reading. The results show that drilled specimen readings are on the average higher than sleeve specimen readings. Furthermore, this study confirms that the Break-Off test method is accurate for testing in-situ strength of concrete as reported by other researchers.
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