AZ L-17 Plastering Contractor Exam
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the primary purpose of plaster in construction?
A. Structural support
B. Insulation
C. Surface finishing and protection
D. Load bearing
Rationale: Plaster is mainly used to create a smooth, protective, and
decorative finish on walls and ceilings, not for structural support.
2. Which type of plaster is commonly used for interior walls?
A. Cement plaster
B. Lime plaster
C. Gypsum plaster
D. Clay plaster
Rationale: Gypsum plaster is preferred for interior walls because it
sets quickly and provides a smooth finish.
3. What is the ideal mix ratio for cement plaster for exterior walls?
A. 1:2
B. 1:3
C. 1:4
D. 1:5
Rationale: A 1:4 cement-sand ratio provides durability for exterior
plastering while maintaining workability.
4. What is the main function of a bonding agent in plastering?
A. Speed up setting time
B. Increase thickness
C. Improve adhesion to the substrate
D. Provide color
, Rationale: Bonding agents are applied to help the plaster adhere
properly to smooth or non-porous surfaces.
5. Which tool is used to achieve a smooth plaster surface?
A. Trowel
B. Float
C. Plumb line
D. Level
Rationale: A float is used to smooth and level the plaster after it has
been applied.
6. When plastering, why is it important to dampen the wall beforehand?
A. To cool the wall
B. To prevent mold
C. To prevent the wall from absorbing water from the plaster too
quickly
D. To clean dust
Rationale: Dampening prevents the substrate from sucking water out
of the plaster, which could cause cracking or poor adhesion.
7. Which type of plaster is most suitable for creating decorative
moldings?
A. Cement plaster
B. Lime plaster
C. Gypsum plaster
D. Clay plaster
Rationale: Gypsum plaster is ideal for decorative work because it can
be easily molded and shaped.
8. What is the standard thickness of a single coat of interior gypsum
plaster?
A. 5–10 mm
B. 12–15 mm
C. 20–25 mm
D. 30–35 mm
Rationale: Interior gypsum plaster is usually applied in a coat of 12–
15 mm for durability and smooth finishing.
9. How long should cement plaster be cured?
A. 1 day
B. 3 days
C. 7 days
, D. 14 days
Rationale: Cement plaster should be cured for at least 7 days to
achieve strength and reduce cracking.
10. What is the main disadvantage of lime plaster?
A. Hard to apply
B. Slow setting time
C. Less durable than cement plaster
D. Not fire-resistant
Rationale: Lime plaster sets slowly and is softer, making it less
durable than cement-based plasters.
11. Which type of sand is preferred for plastering?
A. Coarse river sand
B. Crushed stone
C. Fine river sand
D. Gravel
Rationale: Fine sand ensures a smooth plaster finish and better
adhesion.
12. Why is it important to remove dust and loose particles before
plastering?
A. To reduce plaster thickness
B. To save plaster
C. To ensure proper adhesion of plaster
D. To prevent curing
Rationale: Loose particles prevent the plaster from bonding well to
the surface.
13. Which of the following accelerates the setting of plaster?
A. Cold water
B. Lime
C. Hot water
D. Sand
Rationale: Using warm or hot water speeds up the chemical reaction
in cement-based plaster, accelerating setting.
14. What is the main cause of plaster cracking?
A. Using fine sand
B. Rapid drying and shrinkage
C. Over-mixing
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the primary purpose of plaster in construction?
A. Structural support
B. Insulation
C. Surface finishing and protection
D. Load bearing
Rationale: Plaster is mainly used to create a smooth, protective, and
decorative finish on walls and ceilings, not for structural support.
2. Which type of plaster is commonly used for interior walls?
A. Cement plaster
B. Lime plaster
C. Gypsum plaster
D. Clay plaster
Rationale: Gypsum plaster is preferred for interior walls because it
sets quickly and provides a smooth finish.
3. What is the ideal mix ratio for cement plaster for exterior walls?
A. 1:2
B. 1:3
C. 1:4
D. 1:5
Rationale: A 1:4 cement-sand ratio provides durability for exterior
plastering while maintaining workability.
4. What is the main function of a bonding agent in plastering?
A. Speed up setting time
B. Increase thickness
C. Improve adhesion to the substrate
D. Provide color
, Rationale: Bonding agents are applied to help the plaster adhere
properly to smooth or non-porous surfaces.
5. Which tool is used to achieve a smooth plaster surface?
A. Trowel
B. Float
C. Plumb line
D. Level
Rationale: A float is used to smooth and level the plaster after it has
been applied.
6. When plastering, why is it important to dampen the wall beforehand?
A. To cool the wall
B. To prevent mold
C. To prevent the wall from absorbing water from the plaster too
quickly
D. To clean dust
Rationale: Dampening prevents the substrate from sucking water out
of the plaster, which could cause cracking or poor adhesion.
7. Which type of plaster is most suitable for creating decorative
moldings?
A. Cement plaster
B. Lime plaster
C. Gypsum plaster
D. Clay plaster
Rationale: Gypsum plaster is ideal for decorative work because it can
be easily molded and shaped.
8. What is the standard thickness of a single coat of interior gypsum
plaster?
A. 5–10 mm
B. 12–15 mm
C. 20–25 mm
D. 30–35 mm
Rationale: Interior gypsum plaster is usually applied in a coat of 12–
15 mm for durability and smooth finishing.
9. How long should cement plaster be cured?
A. 1 day
B. 3 days
C. 7 days
, D. 14 days
Rationale: Cement plaster should be cured for at least 7 days to
achieve strength and reduce cracking.
10. What is the main disadvantage of lime plaster?
A. Hard to apply
B. Slow setting time
C. Less durable than cement plaster
D. Not fire-resistant
Rationale: Lime plaster sets slowly and is softer, making it less
durable than cement-based plasters.
11. Which type of sand is preferred for plastering?
A. Coarse river sand
B. Crushed stone
C. Fine river sand
D. Gravel
Rationale: Fine sand ensures a smooth plaster finish and better
adhesion.
12. Why is it important to remove dust and loose particles before
plastering?
A. To reduce plaster thickness
B. To save plaster
C. To ensure proper adhesion of plaster
D. To prevent curing
Rationale: Loose particles prevent the plaster from bonding well to
the surface.
13. Which of the following accelerates the setting of plaster?
A. Cold water
B. Lime
C. Hot water
D. Sand
Rationale: Using warm or hot water speeds up the chemical reaction
in cement-based plaster, accelerating setting.
14. What is the main cause of plaster cracking?
A. Using fine sand
B. Rapid drying and shrinkage
C. Over-mixing
