ACI Study Exam Real

Is the following statement true or false? According to ASTM C J 064, composite samples are required eve 1 if the only purpose 1or obtaining the sample is to determine temperature.

True

False

According to ASTM C 1064-86, the container must be larg e enoug h to provide at least ? Of concrete cover in all directions around the sensor of the temperature measuring device:

1 in. (25 mm)

2 in. (50 mm)

3 in. (75 mm)

5 in. (126 mm)

After the temperature measuring device is immersed in the sample:

The concrete around the device is remixed to release entrapped air

The concrete is gently pressed around the device at the surface so tt›at ambient air temperature does not affect the reading

Water is added to the tontainer a t the surface of the sample so tha t ambient air temperature does not affect the reading

The device is moved every 1 minute to a different location in the sample to insure an accurate reading

Temperature measurement of freshly mixed concrete must be completed within ? After obtaining the sample: [NOTE: Nominal maximum size of aggregate is less than 3 in. (75 mm)]

20 min

15 min

10 min

5 min

The temperature measurement of the concrete sample must be recorded to the nearest:

1° F (0.5° C)

2° F ( 1.0° C)

5° F (2.5° C)

10° F (5.5° C)

The maximum allowable time between obtaining the first and final portions o1 the composite sample is:

1 hr

15 min

1 min

30 min

The tests for slump or air content, or both must be started within ? After obtaining the final portion of the composite sample:

1 min

5 min

15 min

45 min

Start molding specimens for strength tests within ? After preparing the composite sample:

15 min

30 min

45 min

60 min

Is the following statement true or false? The samples to be used for strength tests must be a minimum of 1 ft 3 (28 L).

True

False

When sampling from a stationary mixer, except for a paving mixer, the technician can insure a representative sample by:

Obtaining samples from all parts of the batch — beginning, middle, and end

Reducing the gate opening

Passing a receptacle completely through the discharge stream

Placing a receptacle into the center of the discharge stream

Is the following statement true or false? When sampling from a paving mixer, it is permitted to sample the concrete after the contents of the mixer have been discharged.

True

False

Is the following statement true or false? When sampling from a revolving drum mixer or ag itator, the composite sample must be obtained before the addition of any water at the job site.

True

False

After removing the larger aggregate particles by wet-sieving, the batch is:

Passed through the sieve again to insure consistency

Remixed with a shovel

Left undisturbed until testing begins

Consolidated by rodding or vibrating

This test method is considered applicable to plastic concrete having coarse aggregate up to ? In size.

1 1/2 in. (37.5 mm)

2 in. (51 mm)

2 1/2 in. (63.5 mm)

3 in. (76 mm)

Is the following statement true or false? The slump test mold (cone) must be equipped with foot pieces (or clamps and a nonabsorbent base plate), and handles.

True

False

The slump test mold (cone) is filled in three layers of:

Equal height

Equal volume

Decreasing height

None of the above

Each layer of concrete in the slump test mold (cone) must be consolidated by:

Rodding 25 times, uniformly distributing the strokes over the entire cross section

Rodding 25 times around the perimeter only

Use of an internal vibrator

Tapping the mold lightly 10 to 15 times

The proper procedure to follow after the top surface is struck off is to:

Raise the mold (cone) in 10 ± 5 seconds with a vibratory motion

Raise the mold in 5 ± 2 seconds with a twisting motion

Tap the sides of the mold 10-15 times lightly before lifting

Raise the mold in 5 ± 2 seconds by a steady motion

Is the following statement true or false? After removal of the slump mold (cone) from the specimen, the specimen is allowed to settle 1 min. Before slump is measured.

True

False

If a decided falling -away or shearing -off of concrete from one side or a portion of the mass occurs after lifting the slump test mold (cone):

Use the remaining portion o I the mass to measure slump

Remix the concrete used in this test and repeat the procedures

Disregard the test and make a new test on another portion of the sample

Do not test for slump

If the concrete slump measures 45/15 in (110 mm), the recorded slump would be:

4 in. (102 mm)

4 1/4in (108 mm)

4 5/16in (110 mm)

4 1/2 in (114mm)

Is the following statement true or false? Yield is the volume of the concrete produced from a mixture of known quantities of component materials.

True

False

The minimum capacity of a "unit weight" measure (bucket) is always:

Determined by the nominal maximum size of coarse aggregate

0.5 ft3 (14 dm3)

1.0 ft3 (28 dm3)

3.5 ft3 (99dm3)

Is the following statement true or false? Measuring bowls of air meters are permitted to be used as the measure for this test as long as they conform to the requirements of Test Method C 231.

True

False

Initial strike-off is best accomplished by:

Pressing the plate across two-thirds of the concrete surface and withdrawing it with a sawing motion, then placing the plate over the original two-thirds and advancing it forward with a sawing motion

Pressing the plate across the entire concrete surface and withdrawing it with a sawing motion

Using the Camping rod and screeding the surface with a rolling motion

D. Using the edge of the plate and drawing it across the entire concrete surface

Calculate the "yield " (in cubic feet) of the following concrete batch: • The total weight of all materials batched: 27,600 lb • The unit weight of the concrete: 147 lb/ft3 • The design batch size: 7 yd3

1314.3 ft3 = (27,600/147) x 7

187.8 ft3 = 27,600/147

0.5 ft3 = (147/27,600) x 100

3942.9 ft3 = 27,600/7

Calculate the unit weigh t of concrete, given the following information: • Volume of measure: 0.504 ft3 • Net weight of measure (empty): 19.2 Ib • Weight of measure plus concrete: 92.7 Ib • Calibration factor: 1.98

145.53 Ib/ft3 = (92.7 — 19.2) x 1.98

183.93 Ib/ft3 = 92.7/0.504

37.04 lb/ft3 = (92.7 — 19.2) x 0.504

46.82 lb/ft3 = 92.7/1.98

Relative yield is defined as:

The percentage of surplus in a batch, in reference to the projected volume

The ratio of the actual volume of concrete obtained to the volume as designed for the batch

The ratio of the total absolute volume of the component ingredients to the volume of air

The volume of concrete produced per batch, computed on an air-free basis

What is the air content (in percent) of the following concrete batch? • The theoretical weight computed on an air-free basis is 152 Ib/ft3 • The unit weight is 145 lb/ft3

4.6% = [(152 — 145)/152] x 100

4.8% = [(152 — 145)/145] x 100

0.46% = [(152 — 145)/152] x 10

0.48% = [(152 — 145)/145] x 10

This ASTM Test Method is intended for use on concrete made with:

Relatively dense aggregate only

Lightweight aggregate only

Air cooled blast-furnace slag only

Any type of aggregate

Is the following statement true or false? The aggregate correction factor must be determined in order to accurately calculate air content.

True

False

If the concrete sample contains aggregate particles that would be retained on a 2 in. (50 mm) sieve, before beg inning the test for air content the sample:

Should be discarded and another sample taken

May be used regardless of the aggregate size

Must be wet-sieved over a 1 1/2 in. (37.5 mm) sieve

Must be wet-sieved over a 2 in. (50 mm) sieve

Is the following statement true or false? According to ASTM C 231, the flanges or rims of the bowl and cover must be thoroughly cleaned prior to assembly.

True

False

When the slump of the concrete is 4 in. (102 mm), consolidation is accomplished by:

When vibration is used to consolidate concrete in the measuring bowl, it shouId be continued until:

The coarse aggregate no longer protrudes

The surface becomes relatively smooth and glazed in appearance

Froth escapes from the sample

The larger bubbles stop rising

According to ASTM C 231, vibrating longer than necessary to consolidate the sample:

May cause segregation and loss of entrained air

May cause inaccuracies in the aggregate correction factor

May cause an increase in air content

Is a good idea if time permits

Is the following statement true or false? Water which has collected in the air chamber of a Type B meter must be bled or subsequent tests will be inaccurate.

True

False

Is the following statement true or false? According to ASTM C 23 1, if the measure contains a great excess of concrete after consolidation, a representative portion must be removed with a scoop or trowel before strike-off.

True

False

Calculate the air content of a concrete sample, based upon the following information: • A Type B meter is used • Aggregate correction factor: 0.2 • Reading on the pressure gage: 6.8%

1.4% = 6.8 x 0.2

6.6% = 6.8 - 0.2

7.0% = 6.8 + 0.2

34.0% = 6.8 / 0.2

This ASTM Test Method is appropriate for concrete containing:

Only dense aggregate

Only cellular aggregate

Any type of aggregate

Only uniformly sized aggregate

Which one of the following tools is not used in this ASTM Test Method?

A small concrete vibrator

A mallet

A funnel

A tamping rod

The capacity of the top section of the airmeter must be at least

Equal to the bottom section

20% larger than the bottom section

50% larger than the bottom section

100% larger than the bottom section

Is the following statemen I true or false? The graduations on the neck of the top section of the airmeter represent percentages of the volume of the bottom section of the airmeter.

True

False

Immediately after water is added and the screw cap tightened, the next step is:

Rock and roll the unit until air appears to have been removed from the concrete

Tap the sides of the air meter 15—20 times smartly with the mallet

Invert and agitate the unit until the concrete settles free from the base

Allow the unit to stand until the air rises to the top

The procedure of rocking and rolling the meter with the neck elevated must be repeated:

For 15 minutes

Until no further drop in the water column is observed

Twice

Until the water level drops below the graduations on the neck

Is the following statement true or false? After the alcohol has been added and the foam has been dispelled, a direct reading of the liquid in the top of the neck is taken from the top of the meniscus and estimated to the nearest 1.0% .

True

False

What is the air content of the following concrete sample? • Direct reading of the liquid in the neck after alcohol is added was 3.4% • Amount of alcohol added was 3 cups

3.4%

3.0%

0.4% = (3.4 — 3)

6.4% = (3.4 + 3)

Molds used when performing procedures according to ASTM C 31 must be watertight as judged by:

Their ability to hold water poured into them

Their ability to hold water under high pressure

The manufacturer’s rating

Their ability to hold mineral oil or release material

Is the following statement true or false? Flexural strength specimens can be molded cylinders or beams.

True

False

Is the following statement true or false? Concrete used to determine air content may be removed from the airmeter, remixed, and used for fabricating strength specimens

True

False

When rodding is the method of consolidation, fill the standard 6 x 12 compressive strength mold in:

Three layers of equal volume

Two layers of equal volume

One layer

None of the above

When consolidating the concrete in flexural strength specimens by vibration, insert the vibrator at intervals not exceeding:

1 in. (25 mm)

2 in. (50 mm)

4 in. (100 mm)

6 in. (150 mm)

After striking off compressive strength specimens, they must be moved to the location o1 initial storage:

After 2 hr

Within 30 min

Immediately

After initial set has occurred

Is the following statement true or false? The curing procedures for specimens used to determine form removal time or when a structure may be put into service are the same as for a specimen to be used as the basis for acceptance

True

False

Is the following statement true or false? Specimens that are to be transported to a laboratory 48 hr or later after molding are to be demolded 24 ± 8 hr after molding and placed in standard curing until transported.

True

False

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