Arizona CR-9 Concrete Contractor Exam Practice
Questions And Correct Answers (Verified Answers) Plus
Rationale 2026 Q&A| Instant Download PDF
Section 1: Concrete Properties & Mix Design
1. Which AASHTO specification is most commonly referenced for concrete mix design in
Arizona CR-9 exams?
A. ASTM C94
B. AASHTO M157
C. ACI 301
D. ASTM C150
Correct Answer: B. AASHTO M157
Rationale: The AASHTO M157 standard is widely used as the basis for concrete mix design
procedures in many DOT specifications, including Arizona.
2. What is the primary purpose of slump testing concrete on a jobsite?
A. To measure compressive strength potential
B. To determine cement content
C. To assess workability of fresh concrete
D. To check aggregate gradation
Correct Answer: C. To assess workability of fresh concrete
Rationale: Slump testing provides a field measure of concrete workability and consistency,
not strength or material proportions.
3. In concrete terminology, “bleeding” refers to:
A. Loss of cement paste to evaporation
B. Cracking due to shrinkage
C. Water rising to the surface after placement
D. Corrosion of reinforcing steel
Correct Answer: C. Water rising to the surface after placement
Rationale: Bleeding is the separation of water that rises to the surface of freshly placed
concrete as heavier particles settle.
4. What is the minimum compressive strength required for structural concrete in most
residential applications?
,A. 2,000 psi
B. 3,000 psi
C. 4,500 psi
D. 5,000 psi
Correct Answer: B. 3,000 psi
Rationale: A minimum of 3,000 psi at 28 days is a typical requirement for general residential
structural concrete.
5. Which of the following admixtures reduces the water requirement while increasing
workability?
A. Retarder
B. Accelerator
C. Air-entraining agent
D. Superplasticizer
Correct Answer: D. Superplasticizer
Rationale: Superplasticizers are high-range water reducers that significantly improve
workability without adding water.
6. What is the primary concern addressed by air-entraining admixtures in concrete?
A. Higher compressive strength
B. Improved freeze-thaw durability
C. Faster set times
D. Reduced bleeding
Correct Answer: B. Improved freeze-thaw durability
Rationale: Air entrainment introduces microscopic air bubbles that improve resistance to
freeze–thaw cycles in environments like Arizona’s high altitude areas.
7. What is the maximum water-cement ratio for concrete exposed to freeze-thaw
conditions?
A. 0.30
B. 0.40
C. 0.50
D. 0.60
Correct Answer: C. 0.50
Rationale: A water-cement ratio of 0.50 or less is generally specified for concrete exposed to
freeze-thaw conditions and deicers to ensure durability.
8. Which type of cement is most suitable for construction in soils with high sulfate
content?
A. Type I
B. Type II
, C. Type III
D. Type V
Correct Answer: D. Type V
Rationale: Type V cement has the highest sulfate resistance, making it appropriate for
aggressive sulfate environments.
9. The unit weight of normal weight concrete is approximately:
A. 80 lb/ft³
B. 145 lb/ft³
C. 200 lb/ft³
D. 60 lb/ft³
Correct Answer: B. 145 lb/ft³
Rationale: Normal weight concrete weighs roughly 145 lb per cubic foot when cured.
10. The w/c ratio directly affects which property of hardened concrete?
A. Surface texture
B. Aggregate size
C. Strength and durability
D. Setting temperature
Correct Answer: C. Strength and durability
Rationale: Lower water-cement ratios produce higher strength and lower permeability,
enhancing durability.
11. Which of the following aggregates is most likely to cause alkali-silica reaction (ASR) in
concrete?
A. Granite
B. Limestone
C. Reactive chert
D. Quartzite
Correct Answer: C. Reactive chert
Rationale: Reactive chert contains silica that can react with alkalis in cement, causing
deleterious expansion.
12. A concrete mix that includes silica fume primarily aims to:
A. Increase slump
B. Reduce heat of hydration
C. Enhance durability and compressive strength
D. Accelerate setting time
Correct Answer: C. Enhance durability and compressive strength
Rationale: Silica fume is a pozzolanic material that refines the pore structure, increasing
strength and durability.
Questions And Correct Answers (Verified Answers) Plus
Rationale 2026 Q&A| Instant Download PDF
Section 1: Concrete Properties & Mix Design
1. Which AASHTO specification is most commonly referenced for concrete mix design in
Arizona CR-9 exams?
A. ASTM C94
B. AASHTO M157
C. ACI 301
D. ASTM C150
Correct Answer: B. AASHTO M157
Rationale: The AASHTO M157 standard is widely used as the basis for concrete mix design
procedures in many DOT specifications, including Arizona.
2. What is the primary purpose of slump testing concrete on a jobsite?
A. To measure compressive strength potential
B. To determine cement content
C. To assess workability of fresh concrete
D. To check aggregate gradation
Correct Answer: C. To assess workability of fresh concrete
Rationale: Slump testing provides a field measure of concrete workability and consistency,
not strength or material proportions.
3. In concrete terminology, “bleeding” refers to:
A. Loss of cement paste to evaporation
B. Cracking due to shrinkage
C. Water rising to the surface after placement
D. Corrosion of reinforcing steel
Correct Answer: C. Water rising to the surface after placement
Rationale: Bleeding is the separation of water that rises to the surface of freshly placed
concrete as heavier particles settle.
4. What is the minimum compressive strength required for structural concrete in most
residential applications?
,A. 2,000 psi
B. 3,000 psi
C. 4,500 psi
D. 5,000 psi
Correct Answer: B. 3,000 psi
Rationale: A minimum of 3,000 psi at 28 days is a typical requirement for general residential
structural concrete.
5. Which of the following admixtures reduces the water requirement while increasing
workability?
A. Retarder
B. Accelerator
C. Air-entraining agent
D. Superplasticizer
Correct Answer: D. Superplasticizer
Rationale: Superplasticizers are high-range water reducers that significantly improve
workability without adding water.
6. What is the primary concern addressed by air-entraining admixtures in concrete?
A. Higher compressive strength
B. Improved freeze-thaw durability
C. Faster set times
D. Reduced bleeding
Correct Answer: B. Improved freeze-thaw durability
Rationale: Air entrainment introduces microscopic air bubbles that improve resistance to
freeze–thaw cycles in environments like Arizona’s high altitude areas.
7. What is the maximum water-cement ratio for concrete exposed to freeze-thaw
conditions?
A. 0.30
B. 0.40
C. 0.50
D. 0.60
Correct Answer: C. 0.50
Rationale: A water-cement ratio of 0.50 or less is generally specified for concrete exposed to
freeze-thaw conditions and deicers to ensure durability.
8. Which type of cement is most suitable for construction in soils with high sulfate
content?
A. Type I
B. Type II
, C. Type III
D. Type V
Correct Answer: D. Type V
Rationale: Type V cement has the highest sulfate resistance, making it appropriate for
aggressive sulfate environments.
9. The unit weight of normal weight concrete is approximately:
A. 80 lb/ft³
B. 145 lb/ft³
C. 200 lb/ft³
D. 60 lb/ft³
Correct Answer: B. 145 lb/ft³
Rationale: Normal weight concrete weighs roughly 145 lb per cubic foot when cured.
10. The w/c ratio directly affects which property of hardened concrete?
A. Surface texture
B. Aggregate size
C. Strength and durability
D. Setting temperature
Correct Answer: C. Strength and durability
Rationale: Lower water-cement ratios produce higher strength and lower permeability,
enhancing durability.
11. Which of the following aggregates is most likely to cause alkali-silica reaction (ASR) in
concrete?
A. Granite
B. Limestone
C. Reactive chert
D. Quartzite
Correct Answer: C. Reactive chert
Rationale: Reactive chert contains silica that can react with alkalis in cement, causing
deleterious expansion.
12. A concrete mix that includes silica fume primarily aims to:
A. Increase slump
B. Reduce heat of hydration
C. Enhance durability and compressive strength
D. Accelerate setting time
Correct Answer: C. Enhance durability and compressive strength
Rationale: Silica fume is a pozzolanic material that refines the pore structure, increasing
strength and durability.
