AZ L-64 Structural Concrete
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1. What is the primary ingredient that gives concrete its compressive
strength?
A. Water
B. Aggregate
C. Cement
D. Admixtures
Cement hydrates and forms calcium silicate hydrate (C-S-H), the
primary binder that provides compressive strength.
2. Which test measures the consistency (workability) of freshly mixed
concrete?
A. Air content test
B. Slump test
C. Compression test
D. Chloride test
The slump test provides a quick field measurement of concrete
workability and consistency.
3. Minimum required concrete cover for reinforcing bars in an exterior
slab exposed to weather is generally intended to protect against:
A. Thermal expansion
B. Load transfer
C. Corrosion
, D. Alkali-silica reaction
Adequate cover protects reinforcement from moisture and chlorides,
reducing corrosion risk.
4. Which admixture accelerates setting and early strength development?
A. Water-reducing admixture
B. Air-entraining admixture
C. Accelerating admixture
D. Retarding admixture
Accelerating admixtures speed up hydration, useful in cold weather
or when early strength is required.
5. What is the primary purpose of air-entraining admixtures in concrete?
A. Increase compressive strength
B. Reduce density
C. Improve freeze-thaw durability
D. Accelerate setting time
Entrained microscopic air voids provide space for freezing water,
improving freeze-thaw resistance.
6. The ACI document primarily used for structural concrete design and
construction is:
A. AASHTO LRFD
B. ASTM C150
C. ACI 318
D. ISO 9001
ACI 318 is the main standard that covers building code requirements
for structural concrete.
7. Which test is used to determine concrete compressive strength?
A. Slump test
B. Cylindrical compression test (28-day)
C. Flexural test
D. Chloride permeability test
Compression testing of standard cured cylinders at specified ages
(commonly 28 days) measures compressive strength.
8. What is the typical purpose of a water-reducing admixture?
A. Increase air content
B. Reduce water content while maintaining workability
C. Speed hydration
D. Increase set time
, Water reducers allow lower water-cement ratios for higher strength
or same strength with less cement.
9. For cast-in-place reinforced concrete beams, adequate consolidation is
achieved primarily by:
A. Hand-troweling
B. Surface vibrating only
C. Internal (needle) vibration and proper placement
D. Increasing slump to very high values
Internal vibration consolidates concrete around reinforcement and
within formwork, reducing voids.
10. Which aggregate property is most important for concrete
durability and strength?
A. Color
B. Gradation and cleanliness
C. Shape only
D. Magnetic susceptibility
Proper gradation and clean aggregates ensure good packing and
bonding with cement paste.
11. For cold-weather concrete placement, which practice is
recommended?
A. Use only frozen aggregates
B. Place concrete at subfreezing temperatures without protection
C. Maintain concrete temperature above specified minimum and
protect from freezing until safe strength achieved
D. Add extra water to mix
Preventing freezing during early hydration is essential; heaters,
insulated blankets, or accelerating admixtures are used.
12. ACI recommends curing concrete for adequate time primarily to:
A. Improve color uniformity
B. Allow continued hydration for strength and durability
C. Remove excess water
D. Harden formwork surfaces
Curing maintains moisture and temperature to promote hydration,
which increases strength and reduces permeability.
13. The lap splice length of reinforcing bars depends mainly on:
A. Bar color
B. Bar diameter and concrete strength
Contractor Exam Questions And
Correct Answers (Verified Answers) Plus
Rationale2026 Q&A| Instant Download
1. What is the primary ingredient that gives concrete its compressive
strength?
A. Water
B. Aggregate
C. Cement
D. Admixtures
Cement hydrates and forms calcium silicate hydrate (C-S-H), the
primary binder that provides compressive strength.
2. Which test measures the consistency (workability) of freshly mixed
concrete?
A. Air content test
B. Slump test
C. Compression test
D. Chloride test
The slump test provides a quick field measurement of concrete
workability and consistency.
3. Minimum required concrete cover for reinforcing bars in an exterior
slab exposed to weather is generally intended to protect against:
A. Thermal expansion
B. Load transfer
C. Corrosion
, D. Alkali-silica reaction
Adequate cover protects reinforcement from moisture and chlorides,
reducing corrosion risk.
4. Which admixture accelerates setting and early strength development?
A. Water-reducing admixture
B. Air-entraining admixture
C. Accelerating admixture
D. Retarding admixture
Accelerating admixtures speed up hydration, useful in cold weather
or when early strength is required.
5. What is the primary purpose of air-entraining admixtures in concrete?
A. Increase compressive strength
B. Reduce density
C. Improve freeze-thaw durability
D. Accelerate setting time
Entrained microscopic air voids provide space for freezing water,
improving freeze-thaw resistance.
6. The ACI document primarily used for structural concrete design and
construction is:
A. AASHTO LRFD
B. ASTM C150
C. ACI 318
D. ISO 9001
ACI 318 is the main standard that covers building code requirements
for structural concrete.
7. Which test is used to determine concrete compressive strength?
A. Slump test
B. Cylindrical compression test (28-day)
C. Flexural test
D. Chloride permeability test
Compression testing of standard cured cylinders at specified ages
(commonly 28 days) measures compressive strength.
8. What is the typical purpose of a water-reducing admixture?
A. Increase air content
B. Reduce water content while maintaining workability
C. Speed hydration
D. Increase set time
, Water reducers allow lower water-cement ratios for higher strength
or same strength with less cement.
9. For cast-in-place reinforced concrete beams, adequate consolidation is
achieved primarily by:
A. Hand-troweling
B. Surface vibrating only
C. Internal (needle) vibration and proper placement
D. Increasing slump to very high values
Internal vibration consolidates concrete around reinforcement and
within formwork, reducing voids.
10. Which aggregate property is most important for concrete
durability and strength?
A. Color
B. Gradation and cleanliness
C. Shape only
D. Magnetic susceptibility
Proper gradation and clean aggregates ensure good packing and
bonding with cement paste.
11. For cold-weather concrete placement, which practice is
recommended?
A. Use only frozen aggregates
B. Place concrete at subfreezing temperatures without protection
C. Maintain concrete temperature above specified minimum and
protect from freezing until safe strength achieved
D. Add extra water to mix
Preventing freezing during early hydration is essential; heaters,
insulated blankets, or accelerating admixtures are used.
12. ACI recommends curing concrete for adequate time primarily to:
A. Improve color uniformity
B. Allow continued hydration for strength and durability
C. Remove excess water
D. Harden formwork surfaces
Curing maintains moisture and temperature to promote hydration,
which increases strength and reduces permeability.
13. The lap splice length of reinforcing bars depends mainly on:
A. Bar color
B. Bar diameter and concrete strength
