AK Concrete Contractor Exam
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. Which of the following is the primary ingredient in concrete?
A. Sand
B. Cement
C. Gravel
D. Water
Answer: B. Cement
Rationale: Cement is the key binding agent in concrete that reacts with
water to form a hard matrix that binds the aggregates together.
2. What is the purpose of adding water to a concrete mix?
A. To increase weight
B. To reduce cement strength
C. To initiate hydration
D. To color the concrete
Answer: C. To initiate hydration
Rationale: Water reacts chemically with cement in a process called
hydration, which is essential for the concrete to harden and gain
strength.
3. Which type of cement is commonly used for general-purpose concrete?
A. Rapid-hardening cement
B. Sulfate-resistant cement
C. Ordinary Portland Cement (OPC)
D. White cement
Answer: C. Ordinary Portland Cement (OPC)
, Rationale: OPC is suitable for most general concrete construction and
provides adequate strength and durability.
4. What is the recommended water-cement ratio for normal concrete?
A. 0.2–0.3
B. 0.4–0.6
C. 0.45–0.6
D. 0.7–0.8
Answer: C. 0.45–0.6
Rationale: A water-cement ratio of 0.45–0.6 ensures sufficient
hydration without compromising strength or workability.
5. Which aggregate size is typically used for reinforced concrete beams?
A. 5 mm
B. 10 mm
C. 20 mm
D. 40 mm
Answer: C. 20 mm
Rationale: 20 mm coarse aggregate provides good strength and
workability for structural elements like beams.
6. What is slump test used to determine?
A. Compressive strength
B. Workability
C. Setting time
D. Water content
Answer: B. Workability
Rationale: The slump test measures the consistency and ease of
placement of fresh concrete.
7. Which admixture is used to accelerate concrete setting?
A. Air-entraining agent
B. Accelerator
C. Retarder
D. Water reducer
Answer: B. Accelerator
Rationale: Accelerators speed up the chemical reaction of cement with
water, reducing setting time.
8. Which admixture is used to improve concrete workability without
increasing water content?
A. Retarder
, B. Air-entraining agent
C. Plasticizer
D. Accelerator
Answer: C. Plasticizer
Rationale: Plasticizers increase workability by reducing the water
needed for the mix, improving flow without compromising strength.
9. What is the minimum compressive strength of structural concrete after
28 days?
A. 10 MPa
B. 20 MPa
C. 25 MPa
D. 50 MPa
Answer: C. 25 MPa
Rationale: Standard structural concrete is designed to achieve at least
25 MPa at 28 days to ensure adequate load-bearing capacity.
10. Which curing method involves keeping concrete moist using
water sprays or ponding?
A. Steam curing
B. Membrane curing
C. Wet curing
D. Dry curing
Answer: C. Wet curing
Rationale: Wet curing maintains moisture on the surface, which
ensures proper hydration and development of strength.
11. What is the function of reinforcement in concrete?
A. To reduce weight
B. To make it waterproof
C. To resist tensile forces
D. To accelerate setting
Answer: C. To resist tensile forces
Rationale: Concrete is strong in compression but weak in tension;
reinforcement (steel) provides tensile strength.
12. What type of concrete is best suited for heavy traffic pavements?
A. Lightweight concrete
B. High-strength concrete
C. Foam concrete
D. Decorative concrete
, Answer: B. High-strength concrete
Rationale: High-strength concrete can withstand higher loads and
abrasion, making it ideal for roads and pavements.
13. What is the main reason for using air-entrained concrete in cold
climates?
A. To reduce weight
B. To improve strength
C. To resist freeze-thaw cycles
D. To reduce setting time
Answer: C. To resist freeze-thaw cycles
Rationale: Entrained air provides small voids in the concrete, allowing
expansion of freezing water and preventing cracking.
14. Which test measures concrete resistance to axial loads?
A. Slump test
B. Flexural test
C. Compressive strength test
D. Split tensile test
Answer: C. Compressive strength test
Rationale: The compressive strength test determines how much load
concrete can bear without crushing.
15. What is the purpose of control joints in concrete slabs?
A. To strengthen the slab
B. To control cracking
C. To improve aesthetics
D. To resist water penetration
Answer: B. To control cracking
Rationale: Control joints create weakened planes, guiding cracks to
form along them rather than randomly.
16. Which type of concrete is used for underwater structures?
A. Lightweight concrete
B. Shotcrete or tremie concrete
C. Air-entrained concrete
D. Foam concrete
Answer: B. Shotcrete or tremie concrete
Rationale: Tremie concrete can be placed underwater without washing
out cement and aggregates.
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. Which of the following is the primary ingredient in concrete?
A. Sand
B. Cement
C. Gravel
D. Water
Answer: B. Cement
Rationale: Cement is the key binding agent in concrete that reacts with
water to form a hard matrix that binds the aggregates together.
2. What is the purpose of adding water to a concrete mix?
A. To increase weight
B. To reduce cement strength
C. To initiate hydration
D. To color the concrete
Answer: C. To initiate hydration
Rationale: Water reacts chemically with cement in a process called
hydration, which is essential for the concrete to harden and gain
strength.
3. Which type of cement is commonly used for general-purpose concrete?
A. Rapid-hardening cement
B. Sulfate-resistant cement
C. Ordinary Portland Cement (OPC)
D. White cement
Answer: C. Ordinary Portland Cement (OPC)
, Rationale: OPC is suitable for most general concrete construction and
provides adequate strength and durability.
4. What is the recommended water-cement ratio for normal concrete?
A. 0.2–0.3
B. 0.4–0.6
C. 0.45–0.6
D. 0.7–0.8
Answer: C. 0.45–0.6
Rationale: A water-cement ratio of 0.45–0.6 ensures sufficient
hydration without compromising strength or workability.
5. Which aggregate size is typically used for reinforced concrete beams?
A. 5 mm
B. 10 mm
C. 20 mm
D. 40 mm
Answer: C. 20 mm
Rationale: 20 mm coarse aggregate provides good strength and
workability for structural elements like beams.
6. What is slump test used to determine?
A. Compressive strength
B. Workability
C. Setting time
D. Water content
Answer: B. Workability
Rationale: The slump test measures the consistency and ease of
placement of fresh concrete.
7. Which admixture is used to accelerate concrete setting?
A. Air-entraining agent
B. Accelerator
C. Retarder
D. Water reducer
Answer: B. Accelerator
Rationale: Accelerators speed up the chemical reaction of cement with
water, reducing setting time.
8. Which admixture is used to improve concrete workability without
increasing water content?
A. Retarder
, B. Air-entraining agent
C. Plasticizer
D. Accelerator
Answer: C. Plasticizer
Rationale: Plasticizers increase workability by reducing the water
needed for the mix, improving flow without compromising strength.
9. What is the minimum compressive strength of structural concrete after
28 days?
A. 10 MPa
B. 20 MPa
C. 25 MPa
D. 50 MPa
Answer: C. 25 MPa
Rationale: Standard structural concrete is designed to achieve at least
25 MPa at 28 days to ensure adequate load-bearing capacity.
10. Which curing method involves keeping concrete moist using
water sprays or ponding?
A. Steam curing
B. Membrane curing
C. Wet curing
D. Dry curing
Answer: C. Wet curing
Rationale: Wet curing maintains moisture on the surface, which
ensures proper hydration and development of strength.
11. What is the function of reinforcement in concrete?
A. To reduce weight
B. To make it waterproof
C. To resist tensile forces
D. To accelerate setting
Answer: C. To resist tensile forces
Rationale: Concrete is strong in compression but weak in tension;
reinforcement (steel) provides tensile strength.
12. What type of concrete is best suited for heavy traffic pavements?
A. Lightweight concrete
B. High-strength concrete
C. Foam concrete
D. Decorative concrete
, Answer: B. High-strength concrete
Rationale: High-strength concrete can withstand higher loads and
abrasion, making it ideal for roads and pavements.
13. What is the main reason for using air-entrained concrete in cold
climates?
A. To reduce weight
B. To improve strength
C. To resist freeze-thaw cycles
D. To reduce setting time
Answer: C. To resist freeze-thaw cycles
Rationale: Entrained air provides small voids in the concrete, allowing
expansion of freezing water and preventing cracking.
14. Which test measures concrete resistance to axial loads?
A. Slump test
B. Flexural test
C. Compressive strength test
D. Split tensile test
Answer: C. Compressive strength test
Rationale: The compressive strength test determines how much load
concrete can bear without crushing.
15. What is the purpose of control joints in concrete slabs?
A. To strengthen the slab
B. To control cracking
C. To improve aesthetics
D. To resist water penetration
Answer: B. To control cracking
Rationale: Control joints create weakened planes, guiding cracks to
form along them rather than randomly.
16. Which type of concrete is used for underwater structures?
A. Lightweight concrete
B. Shotcrete or tremie concrete
C. Air-entrained concrete
D. Foam concrete
Answer: B. Shotcrete or tremie concrete
Rationale: Tremie concrete can be placed underwater without washing
out cement and aggregates.
