ACI Written Test 2024 Study Guide
The longest acceptable time for obtaining the first and final portions of a composite sample is 15
minutes.
Once all concrete samples arrive at the testing location, they should be combined and remixed using a
shovel to achieve uniformity.
Testing for tem...
ACI Written Test 2024 Study Guide
The longest acceptable time for obtaining the first and final portions of a composite sample is 15
minutes.
Once all concrete samples arrive at the testing location, they should be combined and remixed using a
shovel to achieve uniformity.
Testing for temperature, slump, and air content must begin within 5 minutes after obtaining the final
portion of the composite sample.
Molding strength specimens should start within 15 minutes after creating the composite sample.
After acquiring a concrete sample, it must be safeguarded against sunlight, wind, rapid evaporation,
contamination, and other sources of deterioration.
The minimum volume for a sample used in strength testing should be 1 cubic foot.
For sampling from a stationary mixer, two or more portions should be collected at regular intervals from
the middle of the batch. These portions are then combined into one composite sample for testing.
When sampling from a paving mixer, the contents should be emptied, and samples should be taken
from at least five different areas of the pile.
It is true that to prevent contamination or absorbent subgrades when discharging from a paving mixer,
three shallow pans can be placed on the subgrade to collect samples.
Concrete samples from a truck mixer should be taken before any water or admixtures are added at the
job site, which is false; samples must be obtained after additives have been introduced.
Two ways to obtain a sample from a revolving drum mixer include passing a receptacle through the
entire discharge stream or diverting the discharge stream into a sample container.
,At least two portions should be collected from the middle of the discharge at evenly spaced intervals
when sampling from a revolving drum truck mixer.
It is false that the discharge rate can be regulated by adjusting the size of the gate opening.
When sampling from a continuous mixer, concrete samples should not be taken until all mix proportion
adjustments have been completed and after at least five cubic feet of concrete has been discharged.
After combining sample portions from a continuous mixer into a composite sample, a minimum wait of
2 minutes and a maximum wait of 5 minutes is required before beginning tests.
Samples from open-top truck mixers should be collected using the most suitable method to ensure
representativity.
If the concrete contains aggregate larger than can be handled by the molds or equipment, the sample
must be wet-sieved.
When wet sieving occurs, any mortar stuck to the sides of the sieves should be scraped back into the
testing batch.
Post wet-sieving, the composite sample must be remixed with a shovel to ensure uniformity before
testing.
It is false that ASTM C 1064 specifies a maximum temperature for fresh concrete.
ASTM C 1064 may be used to verify ____________________________ with specifications.
✔️conformance
Concrete containing aggregate with a nominal maximum aggregate size greater than 3 inches may
require up to __________ minutes before the temperature stabilizes after mixing ✔️20
, The temperature measuring device shall be capable of measuring the temperature of fresh concrete to ±
________ °F and throughout the range of __________ °F to __________ °F. ✔️1, 30, 120
The temperature measuring device shall be calibrated ________________, or whenever there is a
question of _____________________. ✔️annually, accuracy
Reference thermometers must be accurate and readable to ± __________ ° F. ✔️0.5
The accuracy of TMD's must be verified at ________ temperatures at least ____________ apart ✔️2,
30 degrees F
The temperature of fresh concrete may be measured in the transporting equipment or forms providing
there is at least 3" of cover. True or False ✔️true
If transport equipment or forms are not used as the container, prior to sampling, you must
__________________ the sample container used for obtaining the temperature of fresh concrete
✔️dampen
A composite sample of concrete is required even if the only purpose for obtaining the sample is to
determine temperature. True or False ✔️False
The thermometer sensor should be immersed a minimum of __________ inches into the concrete and
have at least ___________ inches of concrete cover in all directions. ✔️3, 3
After inserting the thermometer, the concrete must be pressed around the temperature measuring
device to prevent the __________________ ___________ temperature from affecting the reading
✔️ambient air
Leave the temperature measuring device in the concrete for at least _________ minutes, but not more
than _________ minutes before reading ✔️2, 5
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