CA C8 Concrete Contractor Exam

CA C8 Concrete Contractor Exam Questions And Correct Answers (Verified Answers) Plus Rationale2026 Q&A| Instant Download Pdf

• What is the primary purpose of reinforcing steel (rebar) in concrete?
• To increase durability
• To resist tensile forces
• To prevent shrinkage
• To reduce weight

Rationale: Rebar is used in concrete primarily to resist tensile

stresses, as concrete is weak in tension but strong in compression.

• What is the typical water-cement ratio for normal-strength concrete?

A) 0.2–0.3

B) 0.4–0.6

C) 0.7–0.9

D) 1.0–1.2

Rationale: A water-cement ratio of 0.4–0.6 provides adequate

workability while maintaining strength.

• Which type of cement is best suited for concrete exposed to sulfate

soils?

• Ordinary Portland Cement
• Rapid Hardening Cement
• Sulphate-Resisting Cement
• White Cement

Rationale: Sulphate-resisting cement is specifically formulated to

resist sulfate attack in aggressive soils. 1 / 3

• What is the minimum curing period recommended for most concrete

mixes?

• 3 days
• 5 days
• 7 days
• 14 days

Rationale: Standard curing for most concrete mixes is at least 7 days

to allow sufficient strength development.

• Which concrete test measures the consistency of freshly mixed

concrete?

• Slump Test
• Slump Test
• Compressive Strength Test
• Air Content Test

Rationale: The slump test measures workability and consistency of

fresh concrete.

• What is the maximum aggregate size typically used in reinforced

concrete slabs?

• 10 mm
• 20 mm
• 40 mm
• 50 mm

Rationale: 20 mm maximum aggregate size is commonly used to

ensure proper compaction around reinforcement.

• Which admixture is used to accelerate concrete setting in cold weather?
• Retarder
• Accelerator
• Air-entraining agent
• Superplasticizer

Rationale: Accelerators reduce setting time, allowing concrete to gain

strength faster in cold conditions.

• What is the primary reason for using air-entraining agents in concrete?
• Increase density
• Improve freeze-thaw resistance
• Reduce workability
• Reduce strength 2 / 3

Rationale: Air-entraining agents create microscopic air bubbles that

improve resistance to freeze-thaw cycles.

• What is the ideal temperature range for placing concrete?

A) 0–5°C

B) 5–15°C

C) 10–30°C

D) 30–45°C

Rationale: Concrete placed between 10–30°C sets properly and avoids

thermal cracking or slow hydration.

• What is the standard compressive strength test duration for

concrete cylinders?

• 1 day
• 3 days
• 28 days
• 90 days

Rationale: Concrete is typically tested for compressive strength after

28 days, the standard curing period.

• What is “bleeding” in concrete?
• Cracking due to shrinkage
• Separation of water from the mix
• Air entrapment
• Corrosion of reinforcement

Rationale: Bleeding occurs when water rises to the surface of freshly

placed concrete, which can weaken the surface if excessive.

• Which type of concrete finish provides a non-slip surface for

sidewalks?

• Trowel finish
• Broom finish
• Float finish
• Exposed aggregate

Rationale: Broom finish creates texture on the concrete surface to

improve traction.

• What is the effect of using too much water in a concrete mix?
• Increases strength
• Improves durability
• Reduces strength and durability
• Speeds setting
• / 3