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Free ACI Practice Questions

10 free, exam-style ACI Concrete Field Testing Technician Grade I (ACI) practice questions with answers and explanations. No signup required. Work through them below, then take the full free ACI practice test to study every exam domain.

The ACI exam has 55 questions and runs 1 hour.

These 10 free ACI questions are organized by exam domain, so you can see how each part of the ACI Concrete Field Testing Technician Grade I blueprint is tested. Reveal the answer and explanation under each question.

Domain 2: ASTM C172/C172M - Sampling Freshly Mixed Concrete

Question 1

A technician obtains the final composite portion at 2:30 PM. Temperature is measured at 2:31 PM. Slump test begins at 2:33 PM. Air content test begins at 2:34 PM. Cylinder molding begins at 2:48 PM. Which ASTM C172 time limit was violated?

  1. The 5-minute limit for starting the slump test was exceeded by 3 minutes
  2. The 5-minute limit for starting the air content test was exceeded by 4 minutes
  3. No time limits were violated - all testing activities are within C172 requirements
  4. The 15-minute limit for starting to mold strength specimens was exceeded
Show answer & explanation

Correct answer: D - The 15-minute limit for starting to mold strength specimens was exceeded

Domain 3: ASTM C143/C143M - Slump of Hydraulic-Cement Concrete

Question 2

During the slump test per ASTM C143, should the sides of the slump cone be tapped with a mallet after each layer?

  1. Yes - tap the sides 10 to 15 times with a rubber mallet after rodding each layer
  2. No - do NOT tap the sides of the slump cone at any point during the test
  3. Yes - lightly tap the sides 5 times after completing all three layers
  4. Yes - tap the sides only when the expected slump is less than 3 inches
Show answer & explanation

Correct answer: B - No - do NOT tap the sides of the slump cone at any point during the test

Domain 4: ASTM C138/C138M - Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete

Question 3

Concrete has a measured slump of 3/4 inch. A technician decides to rod the density measure per ASTM C138. This decision is:

  1. Not acceptable - slump below 1 inch must be vibrated
  2. Acceptable - rodding is the default consolidation method for all slump ranges
  3. Acceptable - but the technician must increase to 50 rod strokes per layer
  4. Not acceptable - concrete with slump below 1 inch does not require consolidation
Show answer & explanation

Correct answer: A - Not acceptable - slump below 1 inch must be vibrated

Question 4

The theoretical (air-free) density of a concrete mix is 150.0 lb/ft³. The measured density per ASTM C138 is 144.0 lb/ft³. What is the gravimetric air content?

  1. 2.0%
  2. 4.0%
  3. 6.0%
  4. 8.0%
Show answer & explanation

Correct answer: B - 4.0%

Domain 5: ASTM C231/C231M - Air Content of Freshly Mixed Concrete by the Pressure Method

Question 5

Concrete made with lightweight aggregate requires an air content test. Which test method MUST be used?

  1. ASTM C231 - the pressure method using a Type B meter
  2. ASTM C138 - the gravimetric method based on density
  3. ASTM C173 - the volumetric method
  4. Any standardized air content method may be used regardless of aggregate type
Show answer & explanation

Correct answer: C - ASTM C173 - the volumetric method

Domain 6: ASTM C173/C173M - Air Content of Freshly Mixed Concrete by the Volumetric Method

Question 6

After completing the ASTM C173 volumetric air content test, the technician removes the top section and finds undisturbed portions of concrete remaining in the bowl. The test result is:

  1. Valid - undisturbed concrete at the bottom of the bowl does not affect accuracy
  2. Valid - but the technician should adjust the reading upward by 0.5% to compensate
  3. Invalid - undisturbed concrete means not all air was displaced; must retest
  4. Valid - record the reading as-is with a notation about the remaining concrete
Show answer & explanation

Correct answer: C - Invalid - undisturbed concrete means not all air was displaced; must retest

Domain 7: ASTM C31/C31M - Making and Curing Concrete Test Specimens in the Field

Question 7

Per ASTM C31, the correct rodding parameters (layers / strokes per layer) for each cylinder size are:

  1. 4×8: 2 layers, 25 strokes | 6×12: 3 layers, 25 strokes | 9×18: 4 layers, 50 strokes
  2. 4×8: 3 layers, 25 strokes | 6×12: 3 layers, 25 strokes | 9×18: 3 layers, 50 strokes
  3. 4×8: 2 layers, 25 strokes | 6×12: 2 layers, 25 strokes | 9×18: 2 layers, 50 strokes
  4. 4×8: 2 layers, 50 strokes | 6×12: 3 layers, 50 strokes | 9×18: 4 layers, 50 strokes
Show answer & explanation

Correct answer: A - 4×8: 2 layers, 25 strokes | 6×12: 3 layers, 25 strokes | 9×18: 4 layers, 50 strokes

Question 8

A technician uses a 5/8-inch (16 mm) diameter tamping rod to consolidate a 4×8 inch test cylinder. Per ASTM C31, this is:

  1. Correct - the 5/8-inch rod is the standard tamping rod for all cylinder mold sizes
  2. Correct - rod diameter has no significant effect on consolidation of small specimens
  3. Incorrect - a 4-inch diameter mold requires a 3/4-inch (19 mm) diameter tamping rod
  4. Incorrect - a 4-inch diameter mold requires the 3/8-inch (10 mm) rod
Show answer & explanation

Correct answer: D - Incorrect - a 4-inch diameter mold requires the 3/8-inch (10 mm) rod

Question 9

How does the initial curing temperature requirement for high-strength concrete (≥ 6,000 psi) differ from standard concrete (< 6,000 psi) per ASTM C31?

  1. High-strength requires a higher range of 80-100°F to accelerate early strength gain
  2. High-strength requires a narrower range: 68-78°F versus 60-80°F for standard
  3. There is no difference - both use the same 60-80°F initial curing temperature range
  4. High-strength requires a wider range of 50-90°F to accommodate specialty admixtures
Show answer & explanation

Correct answer: B - High-strength requires a narrower range: 68-78°F versus 60-80°F for standard

Question 10

To pass the ACI Concrete Field Testing Technician - Grade I written examination, a candidate must achieve:

  1. At least 60% on each ASTM section AND at least 70% overall
  2. A minimum overall score of 70% with no individual section requirement
  3. A minimum overall score of 80% across all 55 questions combined
  4. At least 50% on each ASTM section AND at least 60% overall
Show answer & explanation

Correct answer: A - At least 60% on each ASTM section AND at least 70% overall

The rest of the ACI blueprint

The ACI exam also covers these domains. Drill them in the full free practice test:

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