AL CC Concrete Construction
Contractor Exam Questions And
Correct Answers (Verified Answers)
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1. What is the primary ingredient in concrete that provides compressive
strength?
A. Water
B. Cement
C. Sand
D. Aggregate
Answer: Cement
Rationale: Cement reacts with water through hydration to form a hard
matrix that binds aggregates together, providing compressive strength.
2. Which type of cement is most suitable for high early strength
applications?
A. Ordinary Portland Cement
B. Rapid Hardening Cement
C. Portland Pozzolana Cement
D. Sulphate Resisting Cement
Answer: Rapid Hardening Cement
Rationale: Rapid Hardening Cement achieves higher strength in a
shorter period due to finer grinding and higher C3S content.
3. What is the typical water-cement ratio for normal concrete?
A. 0.2–0.3
B. 0.4–0.6
C. 0.7–0.9
, D. 1.0–1.2
Answer: 0.4–0.6
Rationale: A water-cement ratio of 0.4–0.6 ensures proper workability
while maintaining strength.
4. What is the main purpose of admixtures in concrete?
A. Reduce aggregate size
B. Enhance workability, strength, or durability
C. Replace cement completely
D. Increase water content
Answer: Enhance workability, strength, or durability
Rationale: Admixtures modify concrete properties to improve
performance for specific construction needs.
5. Which aggregate size is typically used for structural concrete?
A. 5–10 mm
B. 10–20 mm
C. 20 mm nominal size
D. 50 mm nominal size
Answer: 20 mm nominal size
Rationale: 20 mm nominal size is standard for structural concrete,
balancing strength and workability.
6. What is the purpose of curing concrete?
A. Increase water content
B. Accelerate setting
C. Maintain moisture and temperature to allow proper hydration
D. Reduce cement content
Answer: Maintain moisture and temperature to allow proper hydration
Rationale: Curing ensures hydration continues, improving strength
and durability.
7. Which type of concrete is designed to withstand high sulphate
conditions?
A. Ordinary Portland Cement concrete
B. Rapid Hardening Concrete
C. Sulphate Resistant Concrete
D. Lightweight Concrete
Answer: Sulphate Resistant Concrete
Rationale: Sulphate Resistant Cement reduces the risk of chemical
attack from sulphates in soil or water.
, 8. What is the typical slump range for normal reinforced concrete?
A. 10–25 mm
B. 25–50 mm
C. 50–100 mm
D. 150–200 mm
Answer: 50–100 mm
Rationale: This slump provides adequate workability for placement
while preventing segregation.
9. Which type of test is used to determine the workability of fresh
concrete?
A. Compressive strength test
B. Slump test
C. Flexural test
D. Tensile test
Answer: Slump test
Rationale: The slump test measures consistency and ease of placement
of fresh concrete.
10. What is the minimum compressive strength for standard
residential concrete after 28 days?
A. 10 MPa
B. 15 MPa
C. 20 MPa
D. 30 MPa
Answer: 20 MPa
Rationale: 20 MPa is generally accepted as the minimum for
residential structural concrete.
11. Which factor primarily influences concrete durability?
A. Color of cement
B. Water-cement ratio
C. Aggregate shape
D. Mixing time
Answer: Water-cement ratio
Rationale: Lower water-cement ratios reduce porosity, increasing
durability and resistance to chemical attack.
12. What is the primary purpose of reinforcement in concrete?
A. Improve aesthetics
B. Carry tensile stresses
Contractor Exam Questions And
Correct Answers (Verified Answers)
Plus Rationale2026 Q&A| Instant
Download Pdf
1. What is the primary ingredient in concrete that provides compressive
strength?
A. Water
B. Cement
C. Sand
D. Aggregate
Answer: Cement
Rationale: Cement reacts with water through hydration to form a hard
matrix that binds aggregates together, providing compressive strength.
2. Which type of cement is most suitable for high early strength
applications?
A. Ordinary Portland Cement
B. Rapid Hardening Cement
C. Portland Pozzolana Cement
D. Sulphate Resisting Cement
Answer: Rapid Hardening Cement
Rationale: Rapid Hardening Cement achieves higher strength in a
shorter period due to finer grinding and higher C3S content.
3. What is the typical water-cement ratio for normal concrete?
A. 0.2–0.3
B. 0.4–0.6
C. 0.7–0.9
, D. 1.0–1.2
Answer: 0.4–0.6
Rationale: A water-cement ratio of 0.4–0.6 ensures proper workability
while maintaining strength.
4. What is the main purpose of admixtures in concrete?
A. Reduce aggregate size
B. Enhance workability, strength, or durability
C. Replace cement completely
D. Increase water content
Answer: Enhance workability, strength, or durability
Rationale: Admixtures modify concrete properties to improve
performance for specific construction needs.
5. Which aggregate size is typically used for structural concrete?
A. 5–10 mm
B. 10–20 mm
C. 20 mm nominal size
D. 50 mm nominal size
Answer: 20 mm nominal size
Rationale: 20 mm nominal size is standard for structural concrete,
balancing strength and workability.
6. What is the purpose of curing concrete?
A. Increase water content
B. Accelerate setting
C. Maintain moisture and temperature to allow proper hydration
D. Reduce cement content
Answer: Maintain moisture and temperature to allow proper hydration
Rationale: Curing ensures hydration continues, improving strength
and durability.
7. Which type of concrete is designed to withstand high sulphate
conditions?
A. Ordinary Portland Cement concrete
B. Rapid Hardening Concrete
C. Sulphate Resistant Concrete
D. Lightweight Concrete
Answer: Sulphate Resistant Concrete
Rationale: Sulphate Resistant Cement reduces the risk of chemical
attack from sulphates in soil or water.
, 8. What is the typical slump range for normal reinforced concrete?
A. 10–25 mm
B. 25–50 mm
C. 50–100 mm
D. 150–200 mm
Answer: 50–100 mm
Rationale: This slump provides adequate workability for placement
while preventing segregation.
9. Which type of test is used to determine the workability of fresh
concrete?
A. Compressive strength test
B. Slump test
C. Flexural test
D. Tensile test
Answer: Slump test
Rationale: The slump test measures consistency and ease of placement
of fresh concrete.
10. What is the minimum compressive strength for standard
residential concrete after 28 days?
A. 10 MPa
B. 15 MPa
C. 20 MPa
D. 30 MPa
Answer: 20 MPa
Rationale: 20 MPa is generally accepted as the minimum for
residential structural concrete.
11. Which factor primarily influences concrete durability?
A. Color of cement
B. Water-cement ratio
C. Aggregate shape
D. Mixing time
Answer: Water-cement ratio
Rationale: Lower water-cement ratios reduce porosity, increasing
durability and resistance to chemical attack.
12. What is the primary purpose of reinforcement in concrete?
A. Improve aesthetics
B. Carry tensile stresses
