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20 Cards in this Set
- Front
- Back
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True or False. The method of determining air content of concrete containing lightweight aggregate is the pressure method. |
False. |
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True or False. When making a test cylinder from concrete being used in construction, the field technician must also measure the slump of the concrete. |
True |
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While the technician is checking the slump of the concrete, there is a decided falling away or shearing off of concrete from one side of the sample. What should the technician do? |
Disregard the test and retest another portion of the sample. |
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Preparation of the specimens for transport includes. |
Determination that at least 8 hours have elapsed since final set. |
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If the aggregate correction factor for a given source of fine and coarse aggregate is found to be 0.2% in a pressure air meter, and an air content value of 5.0% is read on the gage of the same air meter containing concrete with the same aggregate, what is the correct air content? |
4.8% |
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Strength test specimens transported from the field to the testing laboratory must be. |
Protected from jarring,moisture loss, freezing |
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Tests for the slump and air content must be started within ____ after obtaining the final portion of the composite sample. |
5 minutes |
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The minimum size for samples to be used for strength tests is. |
28L (1ft3) |
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True or False. After striking off of the measure used to determine density, a small quantity of concrete may be added to correct the deficiency. |
False |
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For normal strength concretes, what temperature range must be maintained for test cylinders during initial curing? |
60 -80*F |
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True or False. When concrete contains large aggregate, the testing technician should wet sieve the sample before making density (unit weight) test for use in yield computations. |
False |
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When determining the temperature of fresh concrete, what is the minimum amount of concrete cover in all directions around the sensor of the temperature measuring device? |
3 inches |
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True or False. The sides of the slump mold should be lightly tapped to consolidate the concrete in the mold. |
False |
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True or False. Unless specified otherwise, strength test specimens molded from concrete having a slump less than 1 inch must be consolidated by vibration. |
True |
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True or False. Test cylinders may be capped with a thin layer of Portland cement paste which is permitted to harden and cure with the specimen. |
True |
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Start molding strength test specimens within ____ after fabricating the composite sample. |
15 minutes |
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True or False. Representative samples are required for use in tests conducted for the purpose of determining compliance with the specifications for concrete quality. |
True |
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True or False. Test Method C172/C172M specifies a minimum time required for inverting and agitating the meter to free concrete from the base. |
True |
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True or False. It is acceptable to fabricate a test specimen from the same concrete used for the air content test. |
False. |
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According to test method C138, what is the air content (in percent) of the following concrete batch.
The theoretical density computed on air free basis is 168 lb/ft3
The density is 158 lb/ft3 |
6% = [(168-158)/168]×100 |
