Summary Straighterline Introduction to Statistics

ACI Concrete Field Testing Technician- Grade I


The sensor of the temperature measuring device shall be submerged a minimum of
_____ in. [_____mm] into the freshly mixed concrete. - (correct Answer) - 3 in. [75
mm]
The temperature measuring device shall have a capacity of measuring temperature of
freshly mixed concrete to +- _____ degrees F [+- _____ C] throughout a range of
_____. - (correct Answer) - 1 degree F [0.5 C], 30 degrees F to 120 F [0 C to 50 C]
The temperature measuring device shall be calibrated _____, or whenever there is a
question of _____. - (correct Answer) - Annually, accuracy
The temperature of concrete may be measured in a wheelbarrow. True or False? -
(correct Answer) - True
The temperature of concrete may be measured in a wall form. True of False -
(correct Answer) - True
A composite sample of concrete is required even if the only purpose for obtaining
the sample is to determine temperature. True of False? - (correct Answer) - False
What must be done to the sample container prior to sampling the concrete? -
(correct Answer) - Dampen (with water)
What must be done to the concrete surrounding the temperature measuring device
after the device is submerged in the fresh concrete. - (correct Answer) - Gently
press the concrete around the temperature measuring device at the surface of the
concrete
How long must the temperature measuring device remain in the freshly mixed
concrete? - (correct Answer) - At least 2 minutes but not more than 5 minutes
After the temperature of the concrete is read, what is required? - (correct Answer)
- Reporting of temperature
The temperature of concrete is reported to the nearest _____ degrees F [_____ C] -
(correct Answer) - 1 degree F [0.5 C]
According to ASTM C1064, what is one reason to take the temperature of concrete? -
(correct 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? - (correct Answer) - False
The sample of concrete used for temperature determination must be rodded 25 times.
True or False? - (correct Answer) - False
Sampling by this method is required when tests are to be made to determine _____
with specification requirements. - (correct Answer) - Compliance
This method covers sampling from four types of mixtures which are _____, _____,
_____, and _____. - (correct Answer) - Stationary mixers, paving mixers, revolving
drum mixers, and open top mixers
The maximum allowable time between obtaining the first and final portions of a
composite sample is _____ minutes. - (correct Answer) - 15
Portions of a composite sample shall be thoroughly remixed bfore beginning tests on
the sample. True of False? - (correct Answer) - True
The maximum elapsed time allowed between obtaining the final portion of the
composite sample and beginning the tests for slump, temperature, and air content is
_____ minutes. - (correct Answer) - 5
The molding of strength test specimens shall begin within _____ minutes after
fabricating the composite sample. - (correct Answer) - 15
The concrete sample must be protected from contamination and _____. - (correct
Answer) - Rapid evaporation
The minimum size sample for making strength test specimens is _____. - (correct
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 -
(correct Answer) - 2
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. - (correct

, 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. - (correct Answer) - 2
Concrete samples from a truck mixer must be obtained before any water or admixtures
are added to the mixer at the job site. True or False? - (correct Answer) - False
The composite samples from a truck mixer must be obtained from the _____ portion of
the batch. - (correct Answer) - Middle
When the concrete contains aggregate larger than that permitted for a particular
test method, the sample of concrete must be _____ _____ before making the test. -
(correct Answer) - Wet sieved
The slump test is applicable to plastic concrete with a maximum size aggregate of
_____. - (correct Answer) - 1.5 in. [37.5 mm]
When the concrete contains aggregate larger than allowed for the slump test, the
large aggregate must be _____. - (correct 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 _____. - (correct Answer) -
The frustum of a cone
The height of the slump mold is _____. - (correct Answer) - 12 in. [300 mm]
The interior surface of the slump mold is allowed to have minor irregularities.
True or False? - (correct Answer) - False
For use in the slump test, the end or both ends of the tamping rod must be _____. -
(correct Answer) - Rounded to a hemispherical tip
The sample of concrete for use in making the slump test must be obained in
accordance with ASTM Standard _____. - (correct Answer) - C172, Standard Practice
for Sampling Freshly Mixed Concrete
The slump mold should be in a dry condition before beginning the test. True or
False? - (correct Answer) - False
The surface on which the slump mold will be placed must be _____. - (correct
Answer) - Flat, level, moist, nonabsorbent, and free of vibration
The slump mold is filled in _____ layers. - (correct Answer) - 3
Each layer should fill approximately _____ the volume of the mold. - (correct
Answer) - One-third
The approximate concrete depth (in verticle distance) after placing the first layer
is _____, and the second layer is _____. - (correct Answer) - 2 5/8 in. [70 mm], 6
1/8 in. [160 mm]
What is the specified number of roddings for each layer? - (correct Answer) - 25
How deep should the tamping rod penetrate into each layer? - (correct Answer) - Rod
each layer throughout its depth; on the second and final layers, the rod should
penetrate into the previous layer approximately 1 in. [25 mm]
When rodding the bottom layer, the tamping rod must be _____ to uniformly
distribute the strokes. - (correct Answer) - Slightly inclined
What must be done if the concrete drops below the top of the slump mold while the
top layer is being rodded? - (correct Answer) - Add additional concrete to keep an
excess of concrete above the top of the mold at all times
Prior to lifting the mold, concrete must be removed from _____. - (correct Answer)
- The area surrounding the base of the mold
After the final rodding, the sides of the slump mold should should be tapped
lightly with the tamping rod. True or False? - (correct Answer) - False
When raising the slump mold, it should not be rotated or twisted, True or False? -
(correct Answer) - True
How much time is allowed for lifting the slump mold? - (correct Answer) - 5 +- 2
seconds
The measurement for slump is made from the top of the mold to what point of the
concrete specimen? - (correct Answer) - The displaced original center of the top
surface of the specimen
The slump of the concrete is measured and reported to the nearest _____. - (correct
Answer) - 1/4 in. [5 mm]
How much time is allowed to conduct the slump test from beginning to completion? -