Nevada C-5 Concrete Contractor Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which of the following is the primary purpose of reinforcing steel in
concrete?
A. To increase the concrete’s compressive strength
B. To reduce the weight of the concrete
C. To improve the concrete’s tensile strength
D. To accelerate curing time
Reinforcing steel, such as rebar, is embedded in concrete to enhance
its tensile strength, as concrete alone is weak in tension.
2. What is the standard slump range for concrete used in most
residential slabs?
A. 6–8 inches
B. 3–4 inches
C. 1–2 inches
D. 5–6 inches
A slump of 3–4 inches provides workable concrete that maintains
adequate strength and minimizes excessive water content.
3. Which type of cement is most commonly used for general-purpose
concrete?
A. Rapid hardening cement
B. Sulfate-resisting cement
C. Ordinary Portland Cement (OPC)
D. High-alumina cement
Ordinary Portland Cement is widely used for general construction
due to its balance of cost, strength, and availability.
,4. What is the primary function of admixtures in concrete?
A. To increase aggregate size
B. To modify properties such as workability, setting time, or
durability
C. To replace cement entirely
D. To increase water absorption
Admixtures are chemicals or materials added to concrete to alter its
physical properties for specific construction needs.
5. Which test is used to determine the consistency of fresh concrete?
A. Compressive strength test
B. Flexural strength test
C. Slump test
D. Water absorption test
The slump test measures the workability and consistency of freshly
mixed concrete before it sets.
6. When placing concrete in hot weather, which practice helps reduce
the risk of thermal cracking?
A. Using less water
B. Placing concrete slowly
C. Cooling the ingredients and using retarders
D. Using only coarse aggregate
High temperatures accelerate hydration and increase cracking risk;
cooling ingredients and adding retarders slows the set.
7. What is the minimum concrete cover required for reinforcing steel in a
slab-on-grade exposed to weather?
A. 1 inch
B. 1.5 inches
C. 2 inches
D. 2.5 inches
Concrete cover protects steel from corrosion, particularly when
exposed to moisture or chemicals.
8. How long should concrete typically cure before it reaches
approximately 70% of its design strength?
A. 1 day
B. 3 days
, C. 7 days
D. 28 days
Concrete gains roughly 70% of its strength in the first 7 days under
proper curing conditions.
9. Which aggregate is generally used for high-strength concrete?
A. Crushed stone with sharp edges
B. Well-graded, clean, hard aggregates
C. Rounded river gravel only
D. Lightweight expanded shale exclusively
Well-graded, durable aggregates improve the density and strength
of concrete.
10. In concrete mix design, what effect does increasing the water-
cement ratio have?
A. Increases strength
B. Reduces workability
C. Reduces strength and increases porosity
D. Reduces setting time
Higher water content increases porosity, lowering compressive
strength and durability.
11. What is the primary reason for using expansion joints in
concrete pavements?
A. To reduce weight
B. To increase tensile strength
C. To accommodate thermal expansion and contraction
D. To improve surface finish
Expansion joints prevent cracking caused by temperature changes by
allowing controlled movement.
12. Which type of concrete finish is achieved by using a steel
trowel?
A. Broom finish
B. Exposed aggregate
C. Smooth, hard finish
D. Stamped finish
Steel troweling produces a dense, smooth surface suitable for floors
and interior slabs.
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which of the following is the primary purpose of reinforcing steel in
concrete?
A. To increase the concrete’s compressive strength
B. To reduce the weight of the concrete
C. To improve the concrete’s tensile strength
D. To accelerate curing time
Reinforcing steel, such as rebar, is embedded in concrete to enhance
its tensile strength, as concrete alone is weak in tension.
2. What is the standard slump range for concrete used in most
residential slabs?
A. 6–8 inches
B. 3–4 inches
C. 1–2 inches
D. 5–6 inches
A slump of 3–4 inches provides workable concrete that maintains
adequate strength and minimizes excessive water content.
3. Which type of cement is most commonly used for general-purpose
concrete?
A. Rapid hardening cement
B. Sulfate-resisting cement
C. Ordinary Portland Cement (OPC)
D. High-alumina cement
Ordinary Portland Cement is widely used for general construction
due to its balance of cost, strength, and availability.
,4. What is the primary function of admixtures in concrete?
A. To increase aggregate size
B. To modify properties such as workability, setting time, or
durability
C. To replace cement entirely
D. To increase water absorption
Admixtures are chemicals or materials added to concrete to alter its
physical properties for specific construction needs.
5. Which test is used to determine the consistency of fresh concrete?
A. Compressive strength test
B. Flexural strength test
C. Slump test
D. Water absorption test
The slump test measures the workability and consistency of freshly
mixed concrete before it sets.
6. When placing concrete in hot weather, which practice helps reduce
the risk of thermal cracking?
A. Using less water
B. Placing concrete slowly
C. Cooling the ingredients and using retarders
D. Using only coarse aggregate
High temperatures accelerate hydration and increase cracking risk;
cooling ingredients and adding retarders slows the set.
7. What is the minimum concrete cover required for reinforcing steel in a
slab-on-grade exposed to weather?
A. 1 inch
B. 1.5 inches
C. 2 inches
D. 2.5 inches
Concrete cover protects steel from corrosion, particularly when
exposed to moisture or chemicals.
8. How long should concrete typically cure before it reaches
approximately 70% of its design strength?
A. 1 day
B. 3 days
, C. 7 days
D. 28 days
Concrete gains roughly 70% of its strength in the first 7 days under
proper curing conditions.
9. Which aggregate is generally used for high-strength concrete?
A. Crushed stone with sharp edges
B. Well-graded, clean, hard aggregates
C. Rounded river gravel only
D. Lightweight expanded shale exclusively
Well-graded, durable aggregates improve the density and strength
of concrete.
10. In concrete mix design, what effect does increasing the water-
cement ratio have?
A. Increases strength
B. Reduces workability
C. Reduces strength and increases porosity
D. Reduces setting time
Higher water content increases porosity, lowering compressive
strength and durability.
11. What is the primary reason for using expansion joints in
concrete pavements?
A. To reduce weight
B. To increase tensile strength
C. To accommodate thermal expansion and contraction
D. To improve surface finish
Expansion joints prevent cracking caused by temperature changes by
allowing controlled movement.
12. Which type of concrete finish is achieved by using a steel
trowel?
A. Broom finish
B. Exposed aggregate
C. Smooth, hard finish
D. Stamped finish
Steel troweling produces a dense, smooth surface suitable for floors
and interior slabs.
