ACI CERTIFICATION

Collecting a representative sample of concrete to be testes is as important as executing the test methods to obtain

Accurate Results

This practice covers sample from four types of equipment, which are ___________, _______________, ______________, __________

Stationary mixers, paving mixers, revolving truck mixers, continuous mixers

The elapsed time between obtaining the first and final portions of a composite sample shall not exceed

15 minutes

Portions of a composite sample shall be thoroughly remixed before beginning tests on the sample? True or False

True

Start tests for slump, temperature, and air content within ___________ after obtaining the final portion of the composite sample

5 minutes

Start molding specimens for strength test withing _______________ after fabricating the composite sample

15 minutes

The concrete sample must be protected from contamination and ______________

Evaporation

The minimum size sample for making strength test speciment is ___________

1 ft³

When sampling from a stationary mixer, the batch must be sampled at _______________ or more regularly intervals during discharge of the middle portion of the batch

2

When sampling from a paving mixer, obtain samples from at least ___________ different portions of the pile and combine them into one composite sample for test purposes

5

When sampling from a revolving truck mixer, sample the concrete by collecting ___________ or more portions take at regularly spaced intervals during discharge of the middle portion of the batch

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

False

When the concrete contains aggregate larger than that permitted for a particular test method, the sample of concrete must be ___________ before making the test

Wet Screened

The stem of the thermometer is submerged a minimum of _________ into the freshly mixed concrete

3 inches

The thermometer shall be capable of accurately measuring the temperature of freshly mixed concrete to ___________ throughout a range of ______

1 degree Fahrenheit, 30 to 120 degree Fahrenheit

The thermometer shall be verified within ____________

1 year of current use

The temperature of concrete may be measured in a wheelbarrow. True or False?

True

The temperature of concrete may be measured in a wall form. True or False?

True

A composite sample of concrete is required even if the only purpose of obtaining the sample is to determine the temperature. True or False?

False

What must be done to the sample container prior to sampling the concrete?

Dampened with water

What must be done to the concrete surrounding the thermometer after the device is submerge in the fresh concrete?

Push concrete around the stem to ensure the concrete is in full contact with the stem

How long must the thermometer remain in the freshly mixed concrete?

2 - 5 minutes

After the temperature of the concrete is read, what is then required?

Record the temperature

The temperature of the concrete is recorded to the nearest

1 degree Fahrenheit

There is a specified maximum temperature of freshly mixed concrete. True or False?

False

The sample of concrete used for temperature determination must be rodded 25 times. True or False?

False

When the concrete contains aggregate larger than allowed for the slump test, the large aggregate must be _________

Wet screened over 1.5 inch sieve

The mold for making the slump test is in the shape of a

The frustum cone

The height of the slump mold is

12 inches

The interior surface of the slump mold is allowed to have minor irregularities. True or False?

False

For use in the slump test, the tamping end or both ends of the tamping rod must be _________

Rounded to a hemispherical tip

The slump mold should be in a dry condition before beginning the test. True or False?

False

The surface on which the slump mold will be placed must be _____________

Flat, level, damp, nonabsorbent, and rigid

The slump mold is filled in __________ layers

Three

Each layer should fill approximately _________ the volume of the mold

1/3

Rod each layer _________ times uniformly over the cross section with the rounded end of the rod

25

How deep should the tamping rod penetrate into each layer?

Rod each layer throughout its depth on the second and final layer rod should penetrate into previous layer about 1 inch

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

Prior to lifting the mold, concrete must be removed from

The area surrounding the base of the mold

After the final rodding, the sides of the slump mold should be tapped lightly with the tamping rod. True or False

False

When raising the slump mold, it should not be rotated or twisted. True or False?

True

How much time is allowed for lifting the slump mold?

5 (+ or -) 2 seconds

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

The slump of the concrete is measured and reported to the nearest?

¼ inch

How much time is allowed to conduct the slump test from beginning to completion?

2.5 minutes

The length of the tamping rod used in this test method is

At least 4 inches taller than the height of the measure but no more than 24 inches in overall length

What is the required shape of the tamping end of the rod?

Rounded to a hemispherical tip

What is the required minimum frequency of the vibrator used in this test method?

9000 vibrations per minute (150 Hz)

The outside diameter or side dimension of the vibrating element must be at least _________ but not greater than ______

0.75 inch, 1.5 inch

What material is the measure made of?

Typically Metal

What is the minimum thickness of a metal strike off plate?

¼ inch

What is the minimum thickness for a glass or acrylic strike off plate?

½ inch

What is the specified weight of the mallet used on measures that are ½ ft³ or smaller?

1 ¼ (+ or -) ½ lb

What method of consolidation must be used when the slump is greater than 3 inches?

Rodding

What method of consolidation must be used when the slump is less than 1 inch?

Vibration

If rodding is the method of consolidation being used, the measure must be filled in how many layers?

Three

For a measure of ½ ft³, what is the required number of strokes of the tamping rod for consolidation of each layer?

25

When rodding the middle and the top layers, the tamping rod should penetrate into the layer below approximately

1 inch

If vibration is the method of consolidation, the measure must be filled in ____ approximately equal layers

Two

If, after consolidation of the final layer, the concrete level is ½ inch above the top of the measure, what should be done?

Remove enough concrete to ensure you have over filled the measure approximately 1/8 inch above the top of the measure

After completing the strike off procedure, what must be done before weighing the measure and sample?

Clean off any excess concrete

The pressure method of determining air content can be used on concrete containing ___________, and ___________ aggregate.

Normal weight; Heavyweight

The pressure method of determining air content cannot be used on concrete containing the following _____________ or _________

Lightweight aggregates; aggregates of high porosity

What is the specified size of mallet required for a typical air meter?

1 ¼ (+ or -) ½ lb

Wet screening may be necessary when the mixture contains aggregate with a nominal maximum size greater than?

1.5 inches

If the concrete sample is to be consolidated by rodding, the measure is filled in _________ layers

3 equal

If the concrete is to be consolidated by vibration, the measure is filled in _________ layers

2 equal

When rodding the concrete sample, what is the specified number of strokes required for each layer?

25

Vibration of the concrete sample is not allowed when the slump of the concrete exceeds __________

3 inches

In rodding the sample, how deep should the rod penetrate each layer?

Rod bottom layer through full depth; rod second and final layer penetrating the previous layer about 1 inch

After rodding each layer what should be done to the measure before adding another layer of concrete?

Tap sides of the measure 10 to 15 times with mallet

What tools may be used to strike off the top surface of the concrete following consolidation of the final layer?

A strike off bar or plate

The volumetric method of determining air content of concrete can be used on concrete containing what types of aggregate?

All types of aggregates

What are the requirement for the tamping rod used in this test method?

Steel or plastic, with a hemispherical tip on onr or both ends, at least 4 inches taller than measure but no more than 24 inches in overall length

What are the requirements for the strike off bar used in this test method?

Metal or plastic flat bar at least ¾ inch in width and 12 inches in length. If using a meter made of metal, the thickness must be at least 1/8 inch and if using a meter made of plastic the thickness must be at least ¼ inch.

What is the minimum capacity of the measuring cup used to add alcohol to the air meter?

1 pt

What type of alcohol and concentration must be used in this test method?

Isopropyl, 70% by volume

A mallet weighing _________ must be used to tap the sides of the bowl after rodding each layer

1.25(+ or -) .5 lb

If the concrete contains aggregate that would be retained on the ____________ sieve, you must wet screen a representative portion of the concrete sample over an ____________ sieve

1 ½ inch; 1 inch

When filling the measuring bowl of the air meter, the concrete must be placed in ______ layers of equal volume

2

What is the required number of strokes required when rodding each layer of concrete?

25

It is necessary to tap the sides of the measuring bowl after each layer has been rodded. True or False?

True

The initial quality 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

Upon final filling of the air meter with water what part of the liquid level should be adjusted to the zero mark on the meter?

Bottom of the meniscus

How long should the air meter be inverted and agitated?

No more than 5 seconds at a time, but must be repeated for a minimum of 45 seconds to free concrete from base

How many times does the rolling operation occur?

A minimum of 2, a maximum of 3

Why is the isopropyl alcohol added to the meter?

To dispel any foam

The direct reading of the final liquid level in the neck of the air meter, is estimated to the nearest ______

0.25%

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

In order for an initial meter reading to be valid, the meter must not be leaking, the liquid level must stabilize within 6 min, and the foam on the surface of the liquid must not be greater than 2 full percent divisions. True or False

true

If less than 2.5 pt of alcohol are used, the air content is always indicated by the final meter reading. True or False?

False

If more than 2.5 pt of alcohol are used, the final meter reading is always adjusted using

A correction factor

At the end of the procedure the air meter is ____________

Disassembled and its contents examined

If portions of undisturbed concrete are found in the air meter at the end of the test, _________

The test is invalid

For cylinders with a diameter of 6 inches or greater the tamping rod must have a diameter of _______

5/8 inch

The minimum frequency of an internal vibrator used in this procedure is _____

150 Hz (9000 vibrations per minute)

Concrete containing aggregate with particles not exceeding _______ can be used to cast specimens without the need for wet screening.

2 inches

For concrete with a slump of less than 1 inch, the test specimens must be consolidated by ________

Vibration

If the concrete is to be consolidated by vibration, a standard 4 by 8 inch cylinder mold must be filled in _______ equal layers

2

When rodding a standard 6 by 12 inch cylinder, each layer must be rodded ______ times.

25