Concrete Contractor Exam Practice Test
Questions And Correct Answers
(Verified Answers) Plus Rationales
2025|2026 Q&A | Instant Download Pdf
1. What is the minimum compressive strength typically required for
structural concrete at 28 days?
a) 1500 psi
b) 2000 psi
c) 3000 psi
d) 4000 psi
Concrete used for structural applications usually requires a
compressive strength of at least 3000 psi at 28 days for adequate
performance.
2. What does the slump test primarily measure?
a) Strength
b) Workability
, c) Durability
d) Air content
The slump test is used to determine the workability or consistency of
fresh concrete.
3. Which cement type provides high early strength?
a) Type I
b) Type III
c) Type II
d) Type V
Type III cement is designed for high early strength, often reaching 70%
of its strength in just 7 days.
4. What is the maximum allowable water-cement ratio for durable
concrete exposed to severe weathering?
a) 0.65
b) 0.60
c) 0.45
d) 0.75
A lower water-cement ratio, such as 0.45, reduces permeability and
increases durability.
5. Which admixture is commonly used to improve workability without
adding water?
a) Retarder
b) Plasticizer (water reducer)
, c) Accelerator
d) Pozzolan
Plasticizers or water-reducing admixtures improve workability while
maintaining strength.
6. What is the main purpose of using air-entraining admixtures?
a) Increase strength
b) Improve freeze-thaw resistance
c) Reduce shrinkage
d) Accelerate setting
Air-entrainment improves concrete’s durability against freeze-thaw
cycles by providing tiny air bubbles.
7. Which aggregate size is commonly used for slabs on grade?
a) 2 in.
b) 1 1/2 in.
c) 3/4 in.
d) 3 in.
3/4 in. aggregate is a common maximum size for slabs on grade,
balancing strength and workability.
8. What tool is used to compact concrete in narrow forms or around
reinforcement?
a) Float
b) Trowel
c) Vibrator
, d) Edger
Internal vibrators are essential for consolidating concrete around
reinforcement and within forms.
9. Which test is commonly used to determine compressive strength of
concrete?
a) Slump test
b) Cylinder test
c) Air content test
d) Flexural test
Cylinders are cast, cured, and tested to measure compressive strength.
10. What is the primary cause of segregation in concrete?
a) Low slump
b) Proper compaction
c) Excess water
d) Adequate mixing
Excess water causes aggregates to separate from mortar, leading to
segregation.
11. When finishing a concrete slab, which tool is used immediately
after screeding?
a) Trowel
b) Joiner
c) Bull float
d) Edger
Questions And Correct Answers
(Verified Answers) Plus Rationales
2025|2026 Q&A | Instant Download Pdf
1. What is the minimum compressive strength typically required for
structural concrete at 28 days?
a) 1500 psi
b) 2000 psi
c) 3000 psi
d) 4000 psi
Concrete used for structural applications usually requires a
compressive strength of at least 3000 psi at 28 days for adequate
performance.
2. What does the slump test primarily measure?
a) Strength
b) Workability
, c) Durability
d) Air content
The slump test is used to determine the workability or consistency of
fresh concrete.
3. Which cement type provides high early strength?
a) Type I
b) Type III
c) Type II
d) Type V
Type III cement is designed for high early strength, often reaching 70%
of its strength in just 7 days.
4. What is the maximum allowable water-cement ratio for durable
concrete exposed to severe weathering?
a) 0.65
b) 0.60
c) 0.45
d) 0.75
A lower water-cement ratio, such as 0.45, reduces permeability and
increases durability.
5. Which admixture is commonly used to improve workability without
adding water?
a) Retarder
b) Plasticizer (water reducer)
, c) Accelerator
d) Pozzolan
Plasticizers or water-reducing admixtures improve workability while
maintaining strength.
6. What is the main purpose of using air-entraining admixtures?
a) Increase strength
b) Improve freeze-thaw resistance
c) Reduce shrinkage
d) Accelerate setting
Air-entrainment improves concrete’s durability against freeze-thaw
cycles by providing tiny air bubbles.
7. Which aggregate size is commonly used for slabs on grade?
a) 2 in.
b) 1 1/2 in.
c) 3/4 in.
d) 3 in.
3/4 in. aggregate is a common maximum size for slabs on grade,
balancing strength and workability.
8. What tool is used to compact concrete in narrow forms or around
reinforcement?
a) Float
b) Trowel
c) Vibrator
, d) Edger
Internal vibrators are essential for consolidating concrete around
reinforcement and within forms.
9. Which test is commonly used to determine compressive strength of
concrete?
a) Slump test
b) Cylinder test
c) Air content test
d) Flexural test
Cylinders are cast, cured, and tested to measure compressive strength.
10. What is the primary cause of segregation in concrete?
a) Low slump
b) Proper compaction
c) Excess water
d) Adequate mixing
Excess water causes aggregates to separate from mortar, leading to
segregation.
11. When finishing a concrete slab, which tool is used immediately
after screeding?
a) Trowel
b) Joiner
c) Bull float
d) Edger
