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Colorado Concrete Contractor
Examination — Local Jurisdiction
Practice Exam 2026 | 100 Questions &
Answers with Detailed Rationales |
Complete Exam Prep & Study Guide
1. What is the primary purpose of a concrete mix design?
A. To eliminate curing
B. To determine proportions needed to achieve required performance
C. To increase finishing time
D. To eliminate reinforcement
Answer: To determine proportions needed to achieve required performance
Rationale: A concrete mix design establishes the proportions of cementitious
materials, water, aggregates, and admixtures needed to meet strength,
durability, workability, and other project requirements.
2. What is the water-cement ratio?
A. The ratio of aggregate to cement
B. The ratio of water to cementitious material by weight
C. The ratio of cement to sand by volume
D. The ratio of water to aggregate
,Answer: The ratio of water to cementitious material by weight
Rationale: The water-cementitious materials ratio is a major factor affecting
concrete strength, permeability, and durability.
3. What generally happens to concrete strength when excess mixing water is
added?
A. Strength increases
B. Strength remains unchanged
C. Strength generally decreases
D. Cement hydration stops
Answer: Strength generally decreases
Rationale: Excess water increases the water-cement ratio and leaves additional
capillary pore space after evaporation, generally reducing strength and
durability.
4. What is the purpose of aggregate in concrete?
A. To provide the only source of hydration
B. To provide bulk, stability, and dimensional structure
C. To replace curing
D. To prevent cement hydration
Answer: To provide bulk, stability, and dimensional structure
Rationale: Aggregates make up most of concrete volume and provide structural
skeleton, economy, and dimensional stability.
5. Which aggregate is normally considered fine aggregate?
A. Gravel
B. Crushed stone retained on large screens
C. Sand
D. Reinforcing steel
,Answer: Sand
Rationale: Fine aggregate generally consists of particles passing the applicable
fine-aggregate sieve and is commonly natural or manufactured sand.
6. What is the main function of cement in concrete?
A. To act as reinforcement
B. To bind the aggregate together
C. To prevent all cracking
D. To replace water
Answer: To bind the aggregate together
Rationale: Cement reacts chemically with water through hydration and forms
cement paste that binds the aggregates into a hardened mass.
7. What is concrete slump primarily used to measure?
A. Hardened strength
B. Air content
C. Consistency or workability
D. Cement fineness
Answer: Consistency or workability
Rationale: The slump test provides an indication of the consistency of fresh
concrete and is commonly used to evaluate workability and uniformity.
8. What should a contractor do if concrete slump is below the specified
requirement?
A. Automatically add unlimited water
B. Follow the approved project procedure for adjustment
C. Add soil
D. Remove all aggregate
Answer: Follow the approved project procedure for adjustment
, Rationale: Concrete adjustments must comply with the approved mix design,
project specifications, and applicable requirements rather than arbitrary
addition of water.
9. What is concrete curing?
A. Removing reinforcement
B. Maintaining conditions needed for cement hydration and strength
development
C. Drying concrete as quickly as possible
D. Grinding hardened concrete
Answer: Maintaining conditions needed for cement hydration and strength
development
Rationale: Proper curing maintains adequate moisture and temperature so
hydration can continue and the concrete can develop intended properties.
10.Why is curing especially important during hot, dry weather?
A. Concrete cannot hydrate in summer
B. Rapid moisture loss can cause cracking and reduced strength
C. Aggregate disappears
D. Cement becomes reinforcement
Answer: Rapid moisture loss can cause cracking and reduced strength
Rationale: Hot, dry, and windy conditions can accelerate evaporation, increasing
plastic-shrinkage risk and interfering with proper strength development.
11.What is the purpose of reinforcing steel in reinforced concrete?
A. To provide resistance primarily to tensile stresses
B. To replace cement
C. To eliminate curing
D. To make concrete waterproof
Answer: To provide resistance primarily to tensile stresses
Colorado Concrete Contractor
Examination — Local Jurisdiction
Practice Exam 2026 | 100 Questions &
Answers with Detailed Rationales |
Complete Exam Prep & Study Guide
1. What is the primary purpose of a concrete mix design?
A. To eliminate curing
B. To determine proportions needed to achieve required performance
C. To increase finishing time
D. To eliminate reinforcement
Answer: To determine proportions needed to achieve required performance
Rationale: A concrete mix design establishes the proportions of cementitious
materials, water, aggregates, and admixtures needed to meet strength,
durability, workability, and other project requirements.
2. What is the water-cement ratio?
A. The ratio of aggregate to cement
B. The ratio of water to cementitious material by weight
C. The ratio of cement to sand by volume
D. The ratio of water to aggregate
,Answer: The ratio of water to cementitious material by weight
Rationale: The water-cementitious materials ratio is a major factor affecting
concrete strength, permeability, and durability.
3. What generally happens to concrete strength when excess mixing water is
added?
A. Strength increases
B. Strength remains unchanged
C. Strength generally decreases
D. Cement hydration stops
Answer: Strength generally decreases
Rationale: Excess water increases the water-cement ratio and leaves additional
capillary pore space after evaporation, generally reducing strength and
durability.
4. What is the purpose of aggregate in concrete?
A. To provide the only source of hydration
B. To provide bulk, stability, and dimensional structure
C. To replace curing
D. To prevent cement hydration
Answer: To provide bulk, stability, and dimensional structure
Rationale: Aggregates make up most of concrete volume and provide structural
skeleton, economy, and dimensional stability.
5. Which aggregate is normally considered fine aggregate?
A. Gravel
B. Crushed stone retained on large screens
C. Sand
D. Reinforcing steel
,Answer: Sand
Rationale: Fine aggregate generally consists of particles passing the applicable
fine-aggregate sieve and is commonly natural or manufactured sand.
6. What is the main function of cement in concrete?
A. To act as reinforcement
B. To bind the aggregate together
C. To prevent all cracking
D. To replace water
Answer: To bind the aggregate together
Rationale: Cement reacts chemically with water through hydration and forms
cement paste that binds the aggregates into a hardened mass.
7. What is concrete slump primarily used to measure?
A. Hardened strength
B. Air content
C. Consistency or workability
D. Cement fineness
Answer: Consistency or workability
Rationale: The slump test provides an indication of the consistency of fresh
concrete and is commonly used to evaluate workability and uniformity.
8. What should a contractor do if concrete slump is below the specified
requirement?
A. Automatically add unlimited water
B. Follow the approved project procedure for adjustment
C. Add soil
D. Remove all aggregate
Answer: Follow the approved project procedure for adjustment
, Rationale: Concrete adjustments must comply with the approved mix design,
project specifications, and applicable requirements rather than arbitrary
addition of water.
9. What is concrete curing?
A. Removing reinforcement
B. Maintaining conditions needed for cement hydration and strength
development
C. Drying concrete as quickly as possible
D. Grinding hardened concrete
Answer: Maintaining conditions needed for cement hydration and strength
development
Rationale: Proper curing maintains adequate moisture and temperature so
hydration can continue and the concrete can develop intended properties.
10.Why is curing especially important during hot, dry weather?
A. Concrete cannot hydrate in summer
B. Rapid moisture loss can cause cracking and reduced strength
C. Aggregate disappears
D. Cement becomes reinforcement
Answer: Rapid moisture loss can cause cracking and reduced strength
Rationale: Hot, dry, and windy conditions can accelerate evaporation, increasing
plastic-shrinkage risk and interfering with proper strength development.
11.What is the purpose of reinforcing steel in reinforced concrete?
A. To provide resistance primarily to tensile stresses
B. To replace cement
C. To eliminate curing
D. To make concrete waterproof
Answer: To provide resistance primarily to tensile stresses
