Start molding specimens for strength tests within 30 minutes after fabricating the composite sample.
A. True
B. False - Answer- B. False
ASTM C172 -Para (4.1.2) - Start molding.
specimens for strength tests within 15 min after fabricating the
composite sample.
Q2. The maximum allowable ti...
ACI- Concrete Field -Testing Technician - Grade 1 graded A+ verified!!! 2024 130+ questions with 100% correct answers Q1. Start molding specimens for strength tests within 30 minutes after fabricating the composite sample. A. True B. False - Answer - B. False ASTM C172 -Para (4.1 .2) - Start molding. specimens for strength tests within 15 min after fabricating the composite sample. Q2. The maximum allowable time between obtaining the first and last portions of the composite sample may not exceed 5 minutes. A. True B. False - Answe r- B. False ASTM C172 - Para (4.1) - The elapsed time shall not exceed 15 min. between obtaining the first and final portions of the composite sample. According to ASTM C1064, what is one reason to take the temperature of concrete? - Answer - Verify conformance to a specified requirement for temperature of concrete A maximum temperature of freshly mixed concrete is specified in ASTM C1064 . True of False? - Answer - False The sample of concrete use d for temperature determination must be rodded 25 times. True or False? - Answer - False Sampling by this method is required when tests are to be made to determine _____ with specification requirements. - Answer - Compliance Q3. The composite concrete sample must be protected from sun, wind, contamination and rapid evaporation. A. True B. False - Answer - A. True ASTM C172 - Para (4.1.2) Q4. If the concrete contains aggregates larger than those that are appropriate for a size of mold or equipment used, the sample should be wet sieved before making the test. A. True B. False - Answer - A. True ASTM C172 - Para (6.1) Q5. The composite sample should not be remixed before beginning any tests. A. True B. False - Answer - B. False ASTM C172 -Para (4.1.1) -The sample shall be combined and remixed with a shovel the minimum amount necessary to ensure uniformity and compliance with the maximum time limits The concrete sample must be protected from c ontamination and _____. - Answer - Rapid evaporation The minimum size sample for making strength test specimens is _____. - Answer - 28 L (1ft^3) When sampling from a stationary mixer, the batch must be sampled at _____ or more regularly spaced intervals during discharge of the middle portion of the batch - Answer - 2 The composite sample for a paving mixer must represent a minimum of _____ differen t portions of the batch of concrete taken from the pile after discharge. - Answer - 5 When sampling from a revolving drum truck mixer, concrete must be sampled at a minimum of _____ regularly spaced intervals during discharge of the middle portion of this batch. - Answer - 2 Q6. Sampling should normally be performed, as the concrete is discharged from the mixer. A. True B. False - Answer - B. False ASTM C172 -Para (5). NOTE 2 —Sampling should normally be performe d as the concrete is delivered from the mixer. To the conveying vehicle used to transport the concrete to the forms; however, specifications may require other points of sampling, such as the discharge of a concrete pump. Q7. ASTM Method C172 includes sam pling from stationary mixers, paving mixers, truck mixers, agitators, and non -agitating equipment. A. True B. False - Answer - A. True ASTM C172 - Para (1.1) When the concrete contains aggregate larger than allowed for the slump test, the large aggregate must be _____. - Answer - Removed by wet sieving the sample over 1.5 in. [37.5 mm] sieve The mold for making the slump test is in the shape of _____. - Answer - The frustum of a cone The height of the slump mold is _____. - Answer - 12 in. [300 mm] Q8. After sampling is completed, start the tests for slump and air content within: A. 2 ½ minutes B. 10 minutes C. 15 minutes D. None of the above - Answer - D. None of the above ASTM C172 - Para (4.1.2) Start tests for slump, temperature, and air content within 5 min after obtaining the final portion of the composite sample. Q9. In any case, do not obt ain samples until: A. All the water and admixtures have been added to the concrete B. 200 revolutions of the drum have been obtained C. ½ of the water has been added D. None of the above - Answer - A. All the water and admixtures have been added to the conc rete. ASTM C172 - Para (5.2.3). In any case do not obtain samples until after all of the water has been added to the mixer. Q10. No samples shall be taken before_________ or after_________ of the batch has been discharged. A. 10% or after 90% B. 20% or af ter 90% C. 20% or after 80% D. None of the above - Answer - A. 10% or after 90% ASTM C172 - Para (5.2.1). NOTE 3 —No samples should be taken before 10 % or after 90 % o f the batch has been discharged Due to the difficulty of determining the actual quantity of concrete discharged, the intent is to provide samples that are representative of widely separated portions, but not the beginning and the end of the load. Q11. When strength tests are to be made, the minimum size of the composite sample shall be: A. ¼ cubic foot B. 1 cubic foot C. Any convenient size D. 1 Wheelbarrow - Answer - B. 1 cubic foot ASTM C172 - Para (5.1). Make the samples to be used for strength tests a minimum of 28 L (1 ft3).
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