ACI Technical Flashcards
A 6 by 12 in cylinder mold can be used for concrete containing aggregate with particles not exceeding
_____ in size, without the need for wet sieving the concrete.
2 inch
According to ASTM C1064, what is one reason to take the temperature of concrete?
Verify conformance to a specified requirement for temperature of concrete
After completing the strike-off procedure, what must be dont before weighing the measure and sample?
Clean off any excess concrete
After consolidation of the final layer, an excess of concrete ___ above the top of the measure is considered optimum.
1/8 inch
After molding test specimens, you should wait two hours before moving them to the location of initial storage. True or False?
False, the specimens must be moved within 15 minutes
After rodding each layer, what should be done to the measure before adding another layer of concrete?
Tap the sides of the measure smartly 10 to 15 times with the mallet
After final rodding, the sides of the slump mold should be tapped lightly with the tamping rod. True or False?
False
After the temperature of the concrete is read, what is required?
Reporting of temperature, record it, sun, wind, contamination
Air meter bowls used for this test must conform to ASTM ___ and be calibrated for volume according to ASTM ___.
C231, C29
The approximate concrete depth (in vertical distance) after placing the first layer is ___, and the second layer is ___.
2 5/8 inch, 6 1/8 inch
ASTM Method gives standardized requirements for ___, ___, ___, and ___, of test specimens.
making, curing, protecting, transporting
At the end of the procedure, the air meter is ___.
Disassembled and its contents examined
The composite sample for a paving mixer must represent a minimum of ___ different portions of the batch of concrete taken from the pile after discharge.
5
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 composite samples from a truck mixer must be obtained from the portion from the ___ portion of the batch
middle
Concrete mixtures with specified strengths of 6000 psi or greater shall have initial curing temperature between ___.
68 and 78 degress F
The concrete sample must be obtained in accordance with what ASTM method?
C172
The concrete sample must be protected from contamination and ___.
Rapid evaporation
Concrete samples from a truck mixer must be obtained before any water or admixture are added to the mixer at the job site. True or False?
False
The container for obtaining the concrete sample used in this procedure can be a ___, ___, or ___.
Metal pan, wheelbarrow, flat, clean nonabsorbent mixing board
Cylinders made for the purpose of determining when a structure may be put into service shall be removed from the mold ___.
At the time of the removal of formwork
Cylinders that are to be field cured are stored ___ and protected ___.
In or on the structure as near to the point of deposit of the concrete represented as possible; In as near as possible the same way as the formed work
The diameter of the tamping rod used in the test method is ___.
5/8 inch except 4” x 8” cylinders
The direct reading of the final liquid level in the neck of the air meter, is estimated to the nearest ___.
0.25 %
During transportation, test specimens must be protected from damage due to ___, ___, and ___.
Jarring, freezing temperatures, moisture loss
Each layer should fill approximately ___ the volume of the mold
One-third
Field Curing is the curing method used when test specimens are to be used for ___.
Determination of whether the structure is capable of being put into service; Comparison with standard cured specimens test results or with results from various in-place test methods; Adequacy of curing and protection of concrete in the Structure, or Form or shoring removal time requirements.
For a measure of 0.5 ft^3 [14 L], what is the required number of strokes of the tamping rof for consolidation of each layer?
25
For concrete with a slump less than 1 inch [25 mm], the test specimens must be consolidated by ___.
Vibration
For cylinders with a diameter of 6 inch [150 mm] or greater, the tamping rod must be a round, straight steel rod with diameter of ___.
5/8 +- 1/16 inch [16 mm +-2mm] 4 inch longer than cylinder. 24 inch maximum
For use in the slump test, the end of both ends of the tamping rod must be ___.
Rounded to a hemispherical tip
The height of the slump mold is ___.
12 inches [300 mm]
How deep should the tamping rod penetrate into each layer?
Rod each layer throughout its depth; on the second and final layers, the rod should penetrate into the previous layer approximately 1 inch [25 mm]
How long must the temperature measuring device remain in the freshly mixed concrete?
At least 2 minutes but not more than 5 minutes
How long should the air meter be inverted and agitated?
No more than five seconds at a time but must be repeated for a minimum of 45 seconds to free concrete from the base
How many times does the rolling operation occur?
A minimum of 2, a maximum of 3
How much time is allowed for lifting the slump mold?
5 +- 2 seconds
How much time is allowed to conduct the slump test from beginning to completion?
2 1/2 minutes
If, after consolidation of the final layer, the concrete level is 1/2 in. [13 mm] above the top of the measure, what should be done?
Remove a representative portion of the excess concrete with a trowel or scoop to 1/8” optimum
If less than 2.5 pints of alcohol are used, the air content is always indicated by the final meter reading. True or False?
False, if the air content is more than 9%, the number of calibrated cups of water introduced into the meter to bring the liquid level within the graduated range must be added
If more than 2.5 pints of alcohol are used, the final meter reading is always adjusted using ___.
A correction factor
If portions of undisturbed concrete are found in the air meter at the end of the test, ___.
The test is invalid
If rodding is the method of consolidation being used, the measure must be filled in how many layers?
3
If 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
if the concrete contains aggregate larger than the maximum allowed for this test, the sample must be
Wet sieved over a 1 1/2 inch [37.5 mm] sieve
If the concrete is to be consolidated by vibration, a standard 4 by 8 in. [100 mm by 200 mm] cylinder mold must be filled in ___ equal layers.
2
If the concrete sample contains aggregate larger than that allowed for this test, the sample must be ___.
Wet seived over a 1 in. [25 mm] sieve
If the concrete sample is to be consolidated by rodding, the measure is filled in ___ layers.
3 equal
If the concrete sample is to be consolidated by vibration, the measure is filled in ___ layers.
2 equal
If vibration is the method of consolidation, the measure must be filled in ___ approximately equal layers
2
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 air meter. True or false?
False; the funnel must be used
In order for an initial meter reading to be valid, the meter must not be leaking, the liquid level must stabilize within 6 minutes and the foam on the surface of the liquid must not be greater than 2 full percent divisions. True or false?
True
In rodding the sample, how deep should the rod penetrate each layer?
Rod bottom to full depth; rod second and final layer penetrating the previous layer about 1 in. [25 mm]
The interior surface of the slump mold is allowed to have minor irregularities. True or false?
False
It is necessary to tap the sides of the bowl after each layer has been rodded. True or false?
True
A mallet weighing ___ must be used to tap the sides of the bowl after rodding each layer.
1.25 +- 0.50 lb [600 +-200g]
The maximum allowable time between ontaining the first and final portions of the composite sample is ___ minutes.
15
The maximum elapsed time allowed between obtaining the final portion of the composite sample and the beginning of the test for slump, temperature, and air content is ___ minutes.
5
The maximum size aggregate allowed for this test method is ___.
2 in. [50 mm] in 6x12” cylinder
The maximum size aggregate allowed in this test method is ___.
1 1/2 in. [37.5 mm] in pressure meter
A maximum temperature of freshly mixed concrete is specified in ASTM C1064. True or false?
False
The measurement for slump is made from the top of the mold to what point of the concrete specimen?
The displaced original center of the top surface of the specimen
Measures other than air meter bowls used for this test must conform to ASTM ___.
C29
The minimum frequency of an internal vibrator used in this procedure is ___.
9000 vibrations per minute [150 Hz]
The minimum size sample for making strength test specimens is ___.
28 L [1 ft^3]
The mold for making the slump test is in the shape of ___.
The frustum of a cone
The molding of strength test specimens shall begin within ___ minutes after fabricating the composite samples.
15
The outside diameter or side dimension of the vibrating element must be at least ___ but not greater than ___.
0.75 in. [19 mm], 1.50 in. [38 mm]
A plastic container can be used for the measure in this method. True or false?
False, measure must be steel or another suitable metal
Portion of a composite sample shall be thoroughly remixed before beginning tests on the sample. True or false?
True
The pressure method of determining air content can be used on concrete containing ___ ___ aggregate.
Relatively Dense
Normal Weight
The pressure method of determining air content cannot be used on concrete containing the following types of aggregates, ___, ___, ___.
Lightweight, air-cooled blast furnace slag, or aggregates of high porosity
Prior to lifting the mold, concrete must be removed from ___.
The area surrounding the base of the mold
The sample of concrete for use in making the slump test must be obtained in accordance with ASTM Standard ___.
C172, Standard practice for sampling freshly mixed concrete
The sample of concrete used for temperature determination must be rodded 25 times. True or false?
False
The sample of concrete used for this test is to be obtained in accordance with what ASTM standard?
C172
The sample of concrete used in molding test specimens must be obtained in accordance with what ASTM standard?
C172
The sample of concrete used in this test method must be obtained in accordance with what ASTM Standard?
C172
Sampling by this method is required when tests are to be made to determine ___ with specification requirements.
Compliance
The sensor of the temperature measuring device shall be submerged a minimum of ___ in. [___ mm] into the freshly mixed concrete.
3 inches [75 mm]
The slump mold is filled in ___ layers.
3
The slump mold should be in a dry condition before beginning the test. True or False?
False
The slump of the concrete is measured and reported to the nearest ___.
1/4 in [5 mm]
The slump test is applicable to plastic concrete with a maximum size aggregate of ___.
1.5 in. (37.5 mm]
Specimens shall not be transported until ___ after final set.
8h
Standard Curing is the curing method used when test specimens are to be used for ___.
Acceptance testing for specified strength, checking the adequacy of mixture proportions for strength, quality control
The supporting surface on which specimens are stored shall be level within ___.
1/4 in. per ft. [20 mm per m]
The surface on which the slump mold will be placed must be ___.
Flat, level, moist, nonabsorbent, and free of vibration
The temperature and moisture environment for field cured cylinders must be ___.
The same as the structural work
The temperature measuring device shall be calibrated ___, or whenever there is a question of ___.
Annually, accuracy
The temperature measuring device shall have a capacity of measuring temperature of freshly mixed concrete to +- ___ degrees F [+- ___C] throughout a range of ___.
1 degree F [0.2 C], 30 degrees F to 120 F [0 C to 50 C]
The temperature of concrete is reported to the nearest ___ degrees F [___ C].
1 degree F [0.5 C]
The temperature of concrete may be measured in a wall form. True or False
True
The temperature of concrete may be measured in a wheelbarrow. True or False?
True
This method covers sampling from five types of mixtures which are ___, ___, ___, and ___.
Stationary mixers, paving mixers, revolving drum mixers, open top mixers, and continuous mixers
Transportation time shall not exceed ___. minutes
4 hours
Upon completion of initial curing, the test specimens may be left in their molds and sealed in plastic bags. True or False?
False; specimens are to be demolded and placed in water storage tanks or moist rooms with free water at a temperature of 73.5 +- 3.5 degrees F [23 +- 2.0 C]
Upon final filling of the air meter with water, what part of the liquid level should be adjusted to the zero mark on meter?
Bottom of the meniscus
Up to 48 hours after molding, test specimens that are to be standard cured shall be stored in a temperature range between ___ to ___.
60 and 80 degrees F [16 to 27 C]
Vibration of the concrete sample is not allowed when the slump of concrete exceeds ___.
3 in. [75 mm] Except for cylinders and beams
The volumetric method of determining air content of concrete can be used on concrete containing what types of aggregate?
All types of aggregate
What are the required characteristics of the tamping rod used in this test method?
Round, straight steel rod, with a 16 mm [5/8 in/] +/- mm [1/16 in.] diameter, length at least 100 mm [4 in.] greater than the depth of the measuring bowl, but not greater than 600 mm [24 in.] in overall length, with the tamping end rounded to a hemispherical tip of the same diameter as the rod. (All but 4x8” cylinder)
What are the requirements for the strike-off bar used in this test method?
Flat, straight steel bar at least 1/8 by 3/4 by 12 in. [3 by 20 by 300 mm] or a flat, straight high-density polyethylene bar, or other plastic of equal or greater abrasion resistance, at least 1/4 by 3/4 by 23in. [6 by 30 by 300mm]
What are the requirements for the tampinf rod used in the test method?
Round, straight 5/8 [16 mm] +- 1/16 in. [2 mm] diameter rod at least 5 in. [300 mm] greater in length than the depth of the bowl being used, with the tamping end rounded to a hemispherical tip of the same diameter, made of steel, high-density polyethylene, or other plastic of equal or greater abrasion resistance. (At volumetric meter only.)
What is the approximate volume of the measuring cup used to add water to the air meter, in relation to the volume of the air meter bowl?
1.00% +- 0.04%
What is the minimum allowable capacity of the measuring bowl used in this test method?
6 L [0.20 ft^3]
What is the minimum thickness for a glass or acrylic strike-off plate?
1/2in. [12mm]
What is the minimum thickness of a metal strike-off plate?
1/4 in. [6 mm]
What is the required minimum frequency of the vibrator used in this test method?
9000 vibrations per minute
What is the required shape of the tamping end of the rod?
Rounded to a hemispherical tip
What is the specified number of rodding’s for each layer?
25
What is the specified number of strokes required when rodding each layer of concrete?
25
What is the specified weight of the mallet required for this test method when the measuring bowl has the capacity of 1 ft^3 or less?
2.25 +-0.50 lb.
What is the specified weight of the mallet used on measures that are 0.5 ft^3 [14 L] or smaller?
1.25 +-0.50 lb. [600 +- 200g]
What method of consolidation must be used when the slump is greater than 3 in. [75 mm]
Rodding
What method of consolidation must be used when the slump is less than 1 in. (25 mm)?
Vibration
What must be done if the concrete drops below the top of the slump mold while the top layer is being rodded?
Add additional concrete to keep an excess of concrete above the top of the mold at all times
What must be done if there is an excessive amount of concrete in measure following consolidation of the final layer?
Remove a representative quantity of concrete with the scoop or trowel before the strike off
What must be done if there is a slight deficiency in the quantity of concrete in the measure of consolidation of final layer?
Add a quantity of representative concrete before strike off
What must be done to the concrete surrounding the temperature measuring device after the device is submerged in the fresh concrete.
Gently press the concrete around the temperature measuring device at the surface of the concrete
What must be done to the sample container prior to sampling the concrete?
Dampen (with water)
What tools may be used to strike off the top surface of the concrete following consolidation of the final layer?
A strike-off bar; a metal, glass, or acrylic plate. (Air pressure only)
What type of alcohol and concentration must be used in this test method?
Isopropyl, 70% by volume (65% by weight)
When consolidating a flexural strength test specimen by rodding, rod one stroke for each ___ of top surface area
2 in^2 [14 cm^2]
When consolidating the concrete by vibration, how many times should the vibrator be inserted into each layer?
3
When filling the bowl of the air meter, the concrete must be placed in ___ layers of equal depth.
2 when vibrating
When internal vibration is used to be consolidate a standard flexural strength test specimen, the technician should insert the vibrator at intervals not exceeding ___ along the center line of the beam.
6 in. [150 mm]
When large amounts of alcohol are used, the direct reading will tend to indicate a ___ air content.
Higher
When raising the slump mold, it should not be rotated or twisted. True or False?
True
When rodding a standard 6 by 12 in [150 mm by 300 mm] cylinder, each layer must be rodded ___ times.
25
When rodding a standard 6 by 12 in. [150 mm by 300 mm] cylinder, the tamping rod should penetrate into the underlying layer by about ___.
1 in. [25 mm]
When rodding the bottom layer, the tamping rod must be ___ to uniformly distribute the strokes.
Slightly inclined for slump
When rodding the concrete sample, what is the specified number of strokes required for each layer?
25
When rodding the middle and the top layers, the tamping rod should penetrate into the layer below approximately ___.
1 in. [25 mm]
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.
2
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.
2
When strength specimens are to be made, what three other tests must be made?
Slump, air content, temperature
When the concrete contains aggregate larger than the allowed for the slump test, the large aggregate must be ___.
Removed by wet sieving the sample over 1.5 in [37.5 mm] sieve
When thee concrete contains aggregate larger than that permitted for a particular test method, the sample of concrete must be ___, ___ before making the test.
Wet seived
When using an internal vibrator to consolidate a 6 by 12 in. [150 mm by 300 mm] compressive strength test specimen, the vibrator must be inserted at ___ different points for each layer.
2
Why is the isopropyl alcohol added to the water?
To dispel any foam that may be on the surface of the water
