CO Masonry Contractor Exam Questions
and Correct Answers (Verified Answers)
Plus Rationale 2027 Q&A| Instant
Download Pdf
1. Which property of masonry units is most important for resisting
compressive loads in a structural wall?
A. Color
B. Surface texture
C. Compressive strength
D. Water absorption
Answer: C. Compressive strength
Rationale: Compressive strength indicates the ability of a masonry
unit to resist loads that push or compress the material. Structural
masonry walls depend heavily on adequate compressive strength to
safely carry vertical and other imposed loads.
, 2. What is the primary purpose of mortar in masonry construction?
A. To replace reinforcement
B. To bond masonry units and distribute loads
C. To waterproof the wall completely
D. To increase the weight of the wall
Answer: B. To bond masonry units and distribute loads
Rationale: Mortar bonds individual masonry units together and helps
distribute stresses across the contact surfaces. Although mortar can
contribute to weather resistance, it should not be considered a
complete waterproofing system.
3. Which mortar type generally provides the highest compressive
strength among common ASTM mortar types?
A. Type O
B. Type N
C. Type S
D. Type M
Answer: D. Type M
Rationale: Type M mortar has the highest compressive strength of the
commonly specified mortar types. It is typically used where high
compressive strength is needed, such as certain below-grade or
heavily loaded masonry applications.
, 4. What is the main function of mortar joints in a masonry wall?
A. To eliminate all thermal movement
B. To provide bonding and accommodate minor dimensional
variations
C. To replace flashing
D. To prevent all cracking
Answer: B. To provide bonding and accommodate minor dimensional
variations
Rationale: Mortar joints create a relatively uniform bedding surface
between masonry units and allow for small dimensional differences.
Proper joints also contribute to bond, alignment, durability, and
weather resistance.
5. Which tool is commonly used to finish and compact mortar joints
after the mortar has partially set?
A. Brick hammer
B. Jointing tool
C. Plumb bob
D. Mason's line
Answer: B. Jointing tool
Rationale: A jointing tool is used to compress and shape mortar joints
after the mortar has reached an appropriate consistency. Proper
, jointing improves the appearance and can improve resistance to
water penetration.
6. What is the primary purpose of a masonry bond pattern?
A. To determine the color of the wall
B. To arrange units so the wall acts as an integrated assembly
C. To eliminate the need for mortar
D. To reduce the number of courses
Answer: B. To arrange units so the wall acts as an integrated assembly
Rationale: Bond patterns determine how masonry units overlap and
interact from course to course. Proper bonding helps distribute loads
and provides structural continuity within the masonry assembly.
7. In running bond brickwork, vertical joints are generally:
A. Aligned continuously
B. Staggered from one course to the next
C. Filled with concrete only
D. Left completely open
Answer: B. Staggered from one course to the next
Rationale: Running bond normally places each brick so that its vertical
joint is offset from the joints in adjacent courses. This arrangement
improves the continuity and integrity of the wall.
and Correct Answers (Verified Answers)
Plus Rationale 2027 Q&A| Instant
Download Pdf
1. Which property of masonry units is most important for resisting
compressive loads in a structural wall?
A. Color
B. Surface texture
C. Compressive strength
D. Water absorption
Answer: C. Compressive strength
Rationale: Compressive strength indicates the ability of a masonry
unit to resist loads that push or compress the material. Structural
masonry walls depend heavily on adequate compressive strength to
safely carry vertical and other imposed loads.
, 2. What is the primary purpose of mortar in masonry construction?
A. To replace reinforcement
B. To bond masonry units and distribute loads
C. To waterproof the wall completely
D. To increase the weight of the wall
Answer: B. To bond masonry units and distribute loads
Rationale: Mortar bonds individual masonry units together and helps
distribute stresses across the contact surfaces. Although mortar can
contribute to weather resistance, it should not be considered a
complete waterproofing system.
3. Which mortar type generally provides the highest compressive
strength among common ASTM mortar types?
A. Type O
B. Type N
C. Type S
D. Type M
Answer: D. Type M
Rationale: Type M mortar has the highest compressive strength of the
commonly specified mortar types. It is typically used where high
compressive strength is needed, such as certain below-grade or
heavily loaded masonry applications.
, 4. What is the main function of mortar joints in a masonry wall?
A. To eliminate all thermal movement
B. To provide bonding and accommodate minor dimensional
variations
C. To replace flashing
D. To prevent all cracking
Answer: B. To provide bonding and accommodate minor dimensional
variations
Rationale: Mortar joints create a relatively uniform bedding surface
between masonry units and allow for small dimensional differences.
Proper joints also contribute to bond, alignment, durability, and
weather resistance.
5. Which tool is commonly used to finish and compact mortar joints
after the mortar has partially set?
A. Brick hammer
B. Jointing tool
C. Plumb bob
D. Mason's line
Answer: B. Jointing tool
Rationale: A jointing tool is used to compress and shape mortar joints
after the mortar has reached an appropriate consistency. Proper
, jointing improves the appearance and can improve resistance to
water penetration.
6. What is the primary purpose of a masonry bond pattern?
A. To determine the color of the wall
B. To arrange units so the wall acts as an integrated assembly
C. To eliminate the need for mortar
D. To reduce the number of courses
Answer: B. To arrange units so the wall acts as an integrated assembly
Rationale: Bond patterns determine how masonry units overlap and
interact from course to course. Proper bonding helps distribute loads
and provides structural continuity within the masonry assembly.
7. In running bond brickwork, vertical joints are generally:
A. Aligned continuously
B. Staggered from one course to the next
C. Filled with concrete only
D. Left completely open
Answer: B. Staggered from one course to the next
Rationale: Running bond normally places each brick so that its vertical
joint is offset from the joints in adjacent courses. This arrangement
improves the continuity and integrity of the wall.
