CALIFORNIA CONTRACTORS STATE LICENSE
BOARD (CSLB) C-8 CONCRETE CONTRACTOR
EXAM, QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) PLUS RATIONALES 2026
Q&A | INSTANT DOWNLOAD PDF.
1. Which type of concrete is most commonly used for residential
driveways?
A. High-strength concrete
B. Lightweight concrete
C. Ordinary Portland cement concrete
D. Fiber-reinforced concrete
Ordinary Portland cement concrete is standard for residential driveways
due to its durability and cost-effectiveness.
2. What is the primary purpose of reinforcing steel in concrete?
A. To reduce water content
B. To accelerate curing
C. To increase tensile strength
D. To reduce shrinkage
Concrete is strong in compression but weak in tension; reinforcing steel
provides the tensile strength needed.
3. What is the minimum compressive strength required for most
concrete sidewalks?
A. 2,500 psi
B. 3,500 psi
C. 2,500–3,000 psi
,D. 5,000 psi
Typical concrete sidewalks are designed to withstand everyday foot and
light vehicle traffic, usually 2,500–3,000 psi.
4. What is the effect of adding too much water to a concrete mix?
A. Increases strength
B. Reduces strength
C. Speeds up curing
D. Improves bonding
Excess water dilutes cement paste and increases porosity, which lowers
strength.
5. What is the purpose of a slump test?
A. Determine water content
B. Measure aggregate size
C. Measure workability
D. Check curing rate
The slump test indicates the consistency and workability of fresh
concrete.
6. Which of the following is considered an air-entraining admixture?
A. Fly ash
B. Silica fume
C. Detergent-based chemical
D. Superplasticizer
Air-entraining admixtures introduce tiny air bubbles to improve freeze-
thaw resistance.
7. How long should concrete typically cure before heavy traffic is
allowed?
A. 1 day
B. 3 days
C. 7 days
, D. 28 days
Concrete reaches adequate strength for light loads in about 7 days; full
strength develops over 28 days.
8. What is the main reason for using control joints in concrete slabs?
A. Decoration
B. To reinforce the slab
C. To control cracking
D. To increase compressive strength
Control joints create weakened planes where cracks can form in a
controlled manner.
9. Which aggregate size is typically used for residential concrete slabs?
A. 1 inch
B. 3/4 inch
C. 1 1/2 inch
D. 2 inches
3/4 inch is commonly used for slabs less than 6 inches thick to ensure
proper consolidation and finish.
10. When placing concrete in cold weather, what is a common
practice?
A. Use ice instead of water
B. Cure in direct sun only
C. Use heated materials
D. Reduce cement content
Heated water or aggregates help maintain proper curing temperatures
in cold conditions.
11. What is the main advantage of fiber-reinforced concrete?
A. Increases curing time
B. Reduces compressive strength
C. Controls cracking
BOARD (CSLB) C-8 CONCRETE CONTRACTOR
EXAM, QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) PLUS RATIONALES 2026
Q&A | INSTANT DOWNLOAD PDF.
1. Which type of concrete is most commonly used for residential
driveways?
A. High-strength concrete
B. Lightweight concrete
C. Ordinary Portland cement concrete
D. Fiber-reinforced concrete
Ordinary Portland cement concrete is standard for residential driveways
due to its durability and cost-effectiveness.
2. What is the primary purpose of reinforcing steel in concrete?
A. To reduce water content
B. To accelerate curing
C. To increase tensile strength
D. To reduce shrinkage
Concrete is strong in compression but weak in tension; reinforcing steel
provides the tensile strength needed.
3. What is the minimum compressive strength required for most
concrete sidewalks?
A. 2,500 psi
B. 3,500 psi
C. 2,500–3,000 psi
,D. 5,000 psi
Typical concrete sidewalks are designed to withstand everyday foot and
light vehicle traffic, usually 2,500–3,000 psi.
4. What is the effect of adding too much water to a concrete mix?
A. Increases strength
B. Reduces strength
C. Speeds up curing
D. Improves bonding
Excess water dilutes cement paste and increases porosity, which lowers
strength.
5. What is the purpose of a slump test?
A. Determine water content
B. Measure aggregate size
C. Measure workability
D. Check curing rate
The slump test indicates the consistency and workability of fresh
concrete.
6. Which of the following is considered an air-entraining admixture?
A. Fly ash
B. Silica fume
C. Detergent-based chemical
D. Superplasticizer
Air-entraining admixtures introduce tiny air bubbles to improve freeze-
thaw resistance.
7. How long should concrete typically cure before heavy traffic is
allowed?
A. 1 day
B. 3 days
C. 7 days
, D. 28 days
Concrete reaches adequate strength for light loads in about 7 days; full
strength develops over 28 days.
8. What is the main reason for using control joints in concrete slabs?
A. Decoration
B. To reinforce the slab
C. To control cracking
D. To increase compressive strength
Control joints create weakened planes where cracks can form in a
controlled manner.
9. Which aggregate size is typically used for residential concrete slabs?
A. 1 inch
B. 3/4 inch
C. 1 1/2 inch
D. 2 inches
3/4 inch is commonly used for slabs less than 6 inches thick to ensure
proper consolidation and finish.
10. When placing concrete in cold weather, what is a common
practice?
A. Use ice instead of water
B. Cure in direct sun only
C. Use heated materials
D. Reduce cement content
Heated water or aggregates help maintain proper curing temperatures
in cold conditions.
11. What is the main advantage of fiber-reinforced concrete?
A. Increases curing time
B. Reduces compressive strength
C. Controls cracking
