NEVADA C-5 CONCRETE CONTRACTOR
EXAM BANK | ACTUAL ACCURATE
CURRENTLY TESTING EXAM QUESTIONS
AND ANSWERS | EXPERT VERIFIED FOR
GUARANTEED PASS | LATEST UPDATE
1. What is the primary purpose of using air-entraining admixtures in
concrete?
A. Increase compressive strength
B. Improve pumpability
C. Increase resistance to freeze–thaw cycles
D. Reduce shrinkage cracking
Correct Answer: C
Rationale: Air-entrained concrete contains microscopic air bubbles that
relieve internal pressure when water freezes, improving durability in
freeze–thaw environments. Compressive strength slightly decreases, so A
is incorrect.
2. Rebar placed in a slab-on-grade must have a minimum concrete
cover of:
A. ¾ inch
B. 1 inch
,C. 2 inches
D. 3 inches
Correct Answer: C
Rationale: ACI 318 requires 2 inches of cover for reinforcement in
concrete cast directly against the ground.
3. Which slump measurement indicates a stiff, low-workability
concrete mix?
A. 1 inch
B. 4 inches
C. 6 inches
D. 9 inches
Correct Answer: A
Rationale: Lower slump values indicate lower workability. A 1-inch slump
is common for pavement or structural mixes requiring low deformation.
4. What is the maximum allowable moisture content variation in
aggregates before mix proportions should be adjusted?
A. ±0.5%
B. ±1%
C. ±2%
D. ±5%
Correct Answer: B
Rationale: A general rule in concrete production is that variations above
±1% moisture in aggregates require mix-water adjustments to maintain
correct water-cement ratio.
,5. What is the main function of vapor barriers under concrete slabs?
A. Increase curing rate
B. Prevent water migration into the slab
C. Improve concrete strength
D. Reduce finishing time
Correct Answer: B
Rationale: Vapor barriers stop moisture from migrating upward,
preventing issues like blistering, delamination, and flooring failure.
6. What is the recommended minimum curing period for standard
concrete at 70°F?
A. 12 hours
B. 24 hours
C. 3 days
D. 7 days
Correct Answer: D
Rationale: ACI guidelines recommend 7 days for standard curing to
ensure adequate hydration and strength development.
7. Which type of formwork material is BEST suited for curved concrete
walls?
A. Steel forms
B. Modular aluminum forms
C. Plywood and lumber
D. Foam forms
, Correct Answer: C
Rationale: Plywood/lumber formwork is flexible and can be shaped to
curves, unlike rigid metal systems.
8. A contractor notices honeycombing after removing formwork. The
likely cause is:
A. Excessive curing
B. Poor consolidation
C. Too much cement
D. Over-vibration
Correct Answer: B
Rationale: Honeycombing occurs when the concrete is not adequately
consolidated, leaving voids and exposed aggregate.
9. What is the main purpose of control joints in a concrete slab?
A. Increase compressive strength
B. Control the location of shrinkage cracks
C. Improve surface finish
D. Increase durability
Correct Answer: B
Rationale: Control joints create weakened planes so shrinkage cracks
occur at predetermined locations.
10. Which tool is used to measure the air content of fresh concrete?
EXAM BANK | ACTUAL ACCURATE
CURRENTLY TESTING EXAM QUESTIONS
AND ANSWERS | EXPERT VERIFIED FOR
GUARANTEED PASS | LATEST UPDATE
1. What is the primary purpose of using air-entraining admixtures in
concrete?
A. Increase compressive strength
B. Improve pumpability
C. Increase resistance to freeze–thaw cycles
D. Reduce shrinkage cracking
Correct Answer: C
Rationale: Air-entrained concrete contains microscopic air bubbles that
relieve internal pressure when water freezes, improving durability in
freeze–thaw environments. Compressive strength slightly decreases, so A
is incorrect.
2. Rebar placed in a slab-on-grade must have a minimum concrete
cover of:
A. ¾ inch
B. 1 inch
,C. 2 inches
D. 3 inches
Correct Answer: C
Rationale: ACI 318 requires 2 inches of cover for reinforcement in
concrete cast directly against the ground.
3. Which slump measurement indicates a stiff, low-workability
concrete mix?
A. 1 inch
B. 4 inches
C. 6 inches
D. 9 inches
Correct Answer: A
Rationale: Lower slump values indicate lower workability. A 1-inch slump
is common for pavement or structural mixes requiring low deformation.
4. What is the maximum allowable moisture content variation in
aggregates before mix proportions should be adjusted?
A. ±0.5%
B. ±1%
C. ±2%
D. ±5%
Correct Answer: B
Rationale: A general rule in concrete production is that variations above
±1% moisture in aggregates require mix-water adjustments to maintain
correct water-cement ratio.
,5. What is the main function of vapor barriers under concrete slabs?
A. Increase curing rate
B. Prevent water migration into the slab
C. Improve concrete strength
D. Reduce finishing time
Correct Answer: B
Rationale: Vapor barriers stop moisture from migrating upward,
preventing issues like blistering, delamination, and flooring failure.
6. What is the recommended minimum curing period for standard
concrete at 70°F?
A. 12 hours
B. 24 hours
C. 3 days
D. 7 days
Correct Answer: D
Rationale: ACI guidelines recommend 7 days for standard curing to
ensure adequate hydration and strength development.
7. Which type of formwork material is BEST suited for curved concrete
walls?
A. Steel forms
B. Modular aluminum forms
C. Plywood and lumber
D. Foam forms
, Correct Answer: C
Rationale: Plywood/lumber formwork is flexible and can be shaped to
curves, unlike rigid metal systems.
8. A contractor notices honeycombing after removing formwork. The
likely cause is:
A. Excessive curing
B. Poor consolidation
C. Too much cement
D. Over-vibration
Correct Answer: B
Rationale: Honeycombing occurs when the concrete is not adequately
consolidated, leaving voids and exposed aggregate.
9. What is the main purpose of control joints in a concrete slab?
A. Increase compressive strength
B. Control the location of shrinkage cracks
C. Improve surface finish
D. Increase durability
Correct Answer: B
Rationale: Control joints create weakened planes so shrinkage cracks
occur at predetermined locations.
10. Which tool is used to measure the air content of fresh concrete?
