CCIL Concrete Field Testing Procedures 2 — Questions and Answers
Question 1: When performing a slump test per ASTM C143, how many layers of concrete are used to fill the slump cone?
- One layer
- Two layers
- Three layers (Correct answer)
- Four layers
Correct answer: Three layers
The slump cone is filled in three equal layers, each rodded 25 times with the tamping rod.
Question 2: What is the minimum curing temperature specified for standard-cured concrete cylinders per ASTM C31?
- 10°C (50°F)
- 16°C (60°F) (Correct answer)
- 23°C (73°F)
- 27°C (80°F)
Correct answer: 16°C (60°F)
ASTM C31 requires standard curing between 16°C (60°F) and 27°C (80°F) for the initial curing period.
Question 3: Which instrument is used to measure the air content of fresh concrete using the pressure method?
- Hydrometer
- Type B air meter (Correct answer)
- Kelly ball apparatus
- Vicat needle
Correct answer: Type B air meter
The Type B pressure meter is the most common device used for air content measurement per ASTM C231.
Question 4: How long must a concrete cylinder remain undisturbed in its mold after casting before it can be transported to the lab?
- 2 hours
- 8 hours
- At least 8 to 48 hours depending on mix (Correct answer)
- 72 hours
Correct answer: At least 8 to 48 hours depending on mix
Per ASTM C31, cylinders must remain undisturbed for 8 to 48 hours depending on the set time of the concrete before being transported.
Question 5: In the volumetric method for air content (ASTM C173), which type of concrete is it specifically required for?
- Normal weight concrete only
- Lightweight or aggregate containing concrete (Correct answer)
- High-strength concrete
- Self-consolidating concrete
Correct answer: Lightweight or aggregate containing concrete
ASTM C173 volumetric method is required for lightweight concrete or concrete containing aggregates that react with the pressure method.
Question 6: What does a slump value of zero indicate about fresh concrete?
- The concrete is fully consolidated
- The concrete is too stiff or no workability (Correct answer)
- The mix lacks cement
- The water-cement ratio is too high
Correct answer: The concrete is too stiff or no workability
A zero slump indicates very stiff concrete with minimal workability, which may be intentional for specific placements like roller-compacted concrete.
Question 7: Per ASTM C138, what is the procedure called that measures the density of fresh concrete?
- Unit weight test (Correct answer)
- Compressive strength test
- Ball penetration test
- Bleeding rate test
Correct answer: Unit weight test
ASTM C138 covers the standard test method for density (unit weight), yield, and air content by the gravimetric method.
CCIL Concrete Field Testing Procedures 2
When performing a slump test per ASTM C143, how many layers of concrete are used to fill the slump cone?