ACI Certification Concrete Construction Inspection 2

Question 1

During concrete placement, what is the maximum free-fall height typically permitted for concrete without causing segregation?

Accepted Answer

5 feet (1.5 m)

Answer

15 feet (4.5 m)

Answer

20 feet (6 m)

Answer

25 feet (7.5 m)

Question 2

What is the primary purpose of consolidating concrete using internal vibration during placement?

Accepted Answer

To remove entrapped air and ensure the concrete completely fills the form without voids

Answer

To increase the water-cement ratio

Answer

To accelerate the initial set time

Answer

To increase the slump of stiff concrete mixtures

Question 3

When inspecting reinforcing bar placement, the ACI concrete construction special inspector checks that cover to reinforcement meets the specified minimum. What is the typical minimum clear cover for cast-in-place concrete exposed to weather (bars #6 and larger)?

Accepted Answer

2 inches (50 mm)

Answer

1 inch (25 mm)

Answer

3/4 inch (19 mm)

Answer

1.5 inches (38 mm)

Question 4

An inspector observes that the concrete delivered to the site has a slump 3 inches higher than specified. What is the correct course of action?

Accepted Answer

Reject the load and notify the contractor and engineer of record before placement

Answer

Add dry cement to the truck to stiffen the mix

Answer

Allow placement if the surface appears workable

Answer

Add superplasticizer to normalize the measured value

Question 5

What does 'honeycombing' in hardened concrete indicate, and what is its primary cause?

Accepted Answer

Voids in the concrete matrix caused by inadequate consolidation or segregation, leaving coarse aggregate exposed

Answer

Surface cracking from rapid drying of the surface

Answer

Delamination of the surface mortar layer from thermal cycling

Answer

Alkali-silica reaction gel pockets within the paste

Question 6

According to ACI 305R, what is the maximum concrete temperature at point of discharge permitted without special hot-weather precautions?

Accepted Answer

95°F (35°C)

Answer

75°F (24°C) ambient air temperature

Answer

85°F (29°C) ambient air temperature

Answer

100°F (38°C)