Air Content by the Volumetric Method
The initial quantity of water and alcohol added to the air meter can be poured directly into the neck of the top section of the meter. True or False
False. The funnel must be used.
When strength specimens are to be made, what three other tests must be done?
slump, air content, and temperature
During transportation, test specimens must be protected from damage due to?
Jarring, freezing temperatures and moisture loss
Calculate the reported density of the concrete
Mass of empty measure: 7.80 lb
Mass of full measure: 45.64
Reported Volume of measure: 0.251 ft3
Net mass of concrete 37.84 lb
Reported Density (unit weight):150.76
The minimum frequency of an internal vibrator for making cylinders or beams is what?
150 Hz, 9000 vibrations per minute
How many times does the rolling operation occur?
A minimum of two and maximum of three
If the concrete is to be consolidated by vibration, a standard 4x8 cylinder mold but be filled in how many layers?
2 layers
Transportation time shall not exceed
4 hours
Calculate the reported air content (pressure meter) of the concrete
Measure air content: 8.0%
Aggregate Correction Factor: 0.4%
Reported air content: 7.6%
How long do you have until you have to start making the strength test specimens?
15 minutes
What happens when the air content is greater than the 9% range of the meter?
Calibrated cups of water are added to bring the liquid level within the graduated range.
What is the minimum frequency of an internal vibrator used to make specimens?
150 Hz, 9000 vibrations per minute
Cylinders that are to be field cured are stored where and protected how?
Stored in or on the structure as near to the point of deposit of the concrete represented as possible
Protected in as near as possible the same way as the formed work
Calculate the reported air content (volumeter) of the concrete
Initial meter reading:6.50
Final meter reading:6.75
Pints of alcohol used: 2
Calibrated cups of water added: 0
Reported Air Content: 6.75
When determining unit weight, what method of consolidation must be used when the slump is greater than 3 inches? What if the slump is less than 1 inch?
3 inches- rodding
less than 1 inch- vibration
When large amounts of alcohol are used, the direct reading will tend to indicate what?
A higher air content
A 6x12 cylinder mold can be used for concrete containing aggregate with particles not exceeding what size, without the need for wet sieving?
2 inches
The temperature and moisture environment for field cured cylinders must be?
the same as the structural work
The total mass of all materials in a batch is 38,600 lb. If the density of the concrete is 148.5 lb/ft3, determine the yield.
Y=M/Dx27
9.63yd3
What is the minimum allowable capacity of the measuring bowl for testing air content by the pressure method?
0.20ft3
Calculate the reported air content of the concrete.
Initial meter reading: 8.0
Final meter reading: 8.25
Pints of alcohol used: 4
Calibrated cups of water added: 2
Alcohol content correction is 0.50
Final reading - alcohol correction +calibrated cups=air content
=9.75
Concrete mixtures with specified strengths of 6000PSI or greater shall have an initial curing temperature between?
68-78 F
Field curing is the curing method used when test specimens are to be used for what?
Determination of whether the structure is capable of being put into service, comparison with standard curing specimens test results or with various in-place test methods, adequacy of curing and protection of concrete, and form or shoring removal time requirements
A theoretical density for a concrete mixture is 151.2lb/ft3. If the density of the concrete being produced at the jobsite is 141.7lb/ft3, calculate the air content of the concrete.
((151.2-141.7)/151.2)x100=6.28%
What should you always do when you bring cylinders into the lab?
Check them in so Chloe doesn't have too.
Write clearly and put them away in the curing room properly so Chloe doesn't get confused.
Clean up after yourself so Chloe doesn't have too.
Thank you!!