CT Concrete Contractor Exam
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A| Instant Download Pdf
1. What is the primary purpose of reinforcing steel in concrete?
a) To make the concrete heavier
b) To increase concrete’s tensile strength
c) To improve workability
d) To reduce curing time
b) To increase concrete’s tensile strength
Rationale: Reinforcing steel (rebar) provides tensile strength, which
concrete alone lacks.
2. What is the typical water-cement ratio range for most structural
concrete?
a) 0.1–0.2
b) 0.3–0.5
c) 0.6–0.8
d) 1.0–1.2
b) 0.3–0.5
Rationale: A water-cement ratio of 0.3–0.5 provides optimal strength
and workability.
3. Which type of cement is most commonly used for general
construction?
a) Portland cement
b) Rapid-hardening cement
c) Sulfate-resisting cement
d) White cement
a) Portland cement
, Rationale: Ordinary Portland Cement (OPC) is widely used for
general structural and non-structural concrete.
4. What is the minimum compressive strength for structural concrete in
most building codes?
a) 10 MPa
b) 20 MPa
c) 25 MPa
d) 40 MPa
c) 25 MPa
Rationale: Many codes specify 25 MPa as the minimum for
reinforced concrete structural members.
5. Which factor primarily affects concrete workability?
a) Cement type
b) Water content
c) Aggregate size
d) Temperature
b) Water content
Rationale: The water content relative to cement is the main factor
affecting slump and workability.
6. How long should freshly placed concrete be cured under normal
conditions?
a) 1–2 days
b) 3–7 days
c) 7–28 days
d) 30–60 days
c) 7–28 days
Rationale: Proper curing for at least 7 days (28 days preferred)
ensures adequate strength development.
7. Which admixture is used to accelerate concrete setting?
a) Air-entraining agent
b) Superplasticizer
c) Calcium chloride
d) Water-reducing agent
c) Calcium chloride
Rationale: Calcium chloride speeds up the hydration process,
reducing setting time.
, 8. What is the standard slump range for general reinforced concrete?
a) 10–25 mm
b) 50–100 mm
c) 125–175 mm
d) 200–250 mm
b) 50–100 mm
Rationale: A slump of 50–100 mm is typical for reinforced concrete,
balancing workability and stability.
9. What is the main cause of plastic shrinkage cracks?
a) Over-reinforcement
b) Rapid evaporation of water from the surface
c) Low cement content
d) Excessive vibration
b) Rapid evaporation of water from the surface
Rationale: Fast drying before setting causes surface shrinkage
cracks.
10. Which test measures concrete’s compressive strength?
a) Slump test
b) Vebe test
c) Cylinder or cube compression test
d) Rebound hammer test
c) Cylinder or cube compression test
Rationale: Standard test involves crushing concrete specimens after
curing to determine strength.
11. What is the purpose of air-entraining agents in concrete?
a) Increase density
b) Improve resistance to freezing and thawing
c) Reduce curing time
d) Increase compressive strength
b) Improve resistance to freezing and thawing
Rationale: Entrained air pockets reduce damage from freeze-thaw
cycles.
12. Which aggregate size is recommended for heavily reinforced
sections?
a) 5–10 mm
b) 10–20 mm
c) 20–40 mm
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A| Instant Download Pdf
1. What is the primary purpose of reinforcing steel in concrete?
a) To make the concrete heavier
b) To increase concrete’s tensile strength
c) To improve workability
d) To reduce curing time
b) To increase concrete’s tensile strength
Rationale: Reinforcing steel (rebar) provides tensile strength, which
concrete alone lacks.
2. What is the typical water-cement ratio range for most structural
concrete?
a) 0.1–0.2
b) 0.3–0.5
c) 0.6–0.8
d) 1.0–1.2
b) 0.3–0.5
Rationale: A water-cement ratio of 0.3–0.5 provides optimal strength
and workability.
3. Which type of cement is most commonly used for general
construction?
a) Portland cement
b) Rapid-hardening cement
c) Sulfate-resisting cement
d) White cement
a) Portland cement
, Rationale: Ordinary Portland Cement (OPC) is widely used for
general structural and non-structural concrete.
4. What is the minimum compressive strength for structural concrete in
most building codes?
a) 10 MPa
b) 20 MPa
c) 25 MPa
d) 40 MPa
c) 25 MPa
Rationale: Many codes specify 25 MPa as the minimum for
reinforced concrete structural members.
5. Which factor primarily affects concrete workability?
a) Cement type
b) Water content
c) Aggregate size
d) Temperature
b) Water content
Rationale: The water content relative to cement is the main factor
affecting slump and workability.
6. How long should freshly placed concrete be cured under normal
conditions?
a) 1–2 days
b) 3–7 days
c) 7–28 days
d) 30–60 days
c) 7–28 days
Rationale: Proper curing for at least 7 days (28 days preferred)
ensures adequate strength development.
7. Which admixture is used to accelerate concrete setting?
a) Air-entraining agent
b) Superplasticizer
c) Calcium chloride
d) Water-reducing agent
c) Calcium chloride
Rationale: Calcium chloride speeds up the hydration process,
reducing setting time.
, 8. What is the standard slump range for general reinforced concrete?
a) 10–25 mm
b) 50–100 mm
c) 125–175 mm
d) 200–250 mm
b) 50–100 mm
Rationale: A slump of 50–100 mm is typical for reinforced concrete,
balancing workability and stability.
9. What is the main cause of plastic shrinkage cracks?
a) Over-reinforcement
b) Rapid evaporation of water from the surface
c) Low cement content
d) Excessive vibration
b) Rapid evaporation of water from the surface
Rationale: Fast drying before setting causes surface shrinkage
cracks.
10. Which test measures concrete’s compressive strength?
a) Slump test
b) Vebe test
c) Cylinder or cube compression test
d) Rebound hammer test
c) Cylinder or cube compression test
Rationale: Standard test involves crushing concrete specimens after
curing to determine strength.
11. What is the purpose of air-entraining agents in concrete?
a) Increase density
b) Improve resistance to freezing and thawing
c) Reduce curing time
d) Increase compressive strength
b) Improve resistance to freezing and thawing
Rationale: Entrained air pockets reduce damage from freeze-thaw
cycles.
12. Which aggregate size is recommended for heavily reinforced
sections?
a) 5–10 mm
b) 10–20 mm
c) 20–40 mm
