ACI Concrete Construction Inspection Questions and Answers

Question 1

An inspector is checking the placement of reinforcing steel in a 12-inch thick foundation wall prior to concrete placement.
The project specifications reference ACI 318 for concrete cast against and permanently exposed to earth.
What is the minimum required concrete cover over the reinforcing steel?

Accepted Answer

3 inches

Answer

3/4 inch

Answer

1 1/2 inches

Answer

2 inches

Question 2

According to ACI 347R, Guide to Formwork for Concrete, which of the following is the most critical factor in determining the safe stripping time for vertical formwork on walls and columns?

Accepted Answer

The ability of the concrete to support its own weight and resist surface damage.

Answer

The ambient air temperature at the time of stripping.

Answer

The specified 28-day compressive strength of the concrete.

Answer

The type of cement used in the concrete mix.

Question 3

An inspector is overseeing a concrete pour during hot weather conditions as defined by ACI 305R. Which of the following is a recommended measure to mitigate the adverse effects of high temperatures and wind on the fresh concrete?

Accepted Answer

Erecting sunshades and windbreaks around the placement area.

Answer

Adding calcium chloride to the mix to accelerate setting time.

Answer

Increasing the water-cement ratio at the job site to improve workability.

Answer

Delaying the start of curing procedures until the concrete has cooled.

Question 4

An inspector observes a worker repeatedly inserting an internal vibrator into the same location in a deep form for an extended period. The inspector notes a large amount of cement paste and fine aggregate collecting at the surface near the vibrator. This practice is most likely to cause which of the following issues?

Accepted Answer

Segregation of the concrete mixture.

Answer

Honeycombing due to insufficient consolidation.

Answer

Cold joints between concrete lifts.

Answer

Entrapment of excessive air voids.

Question 5

As part of a pre-placement inspection for a concrete slab-on-ground, which of the following items is most critical to verify is correct immediately before concrete discharge begins?

Accepted Answer

The subgrade is moist but free of standing water, and all formwork is clean.

Answer

The laboratory has submitted the 7-day strength results from a previous pour.

Answer

The finishing tools have been cleaned and staged.

Answer

The curing compound has been delivered and is stored in a shaded area.

Question 6

When using a liquid membrane-forming curing compound compliant with ASTM C309 on a freshly finished concrete surface, what is the most important application requirement for it to be effective?

Accepted Answer

The compound must be applied to achieve a continuous, uniform film.

Answer

The compound should be applied at double the manufacturer's recommended rate.

Answer

The application must be delayed for at least 12 hours after finishing.

Answer

The concrete surface should be lightly wetted with a fog spray just before application.

An inspector is checking the placement of reinforcing steel in a 12-inch thick foundation wall prior to concrete placement.The project specifications reference ACI 318 for concrete cast against and permanently exposed to earth.What is the minimum required concrete cover over the reinforcing steel?