AZ L-87 Shotcrete Contractor Exam
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. Which type of cement is most commonly used in shotcrete
applications?
A) Type I
B) Type II
C) Type III
D) Type IV
Rationale: Type III cement is high early-strength cement, which is
preferred in shotcrete to allow rapid setting and strength gain.
2. What is the primary advantage of wet-mix shotcrete over dry-mix?
A) Less water control required
B) Better quality control and uniformity
C) Lower initial cost
D) Easier on-site adjustments
Rationale: Wet-mix allows better control of water-cement ratio,
reducing rebound and improving consistency.
3. Rebound in shotcrete refers to:
A) The curing time
B) Material that bounces off the surface during application
C) The strength gain
D) Water loss during spraying
Rationale: Rebound is the portion of shotcrete that does not adhere
and falls off during spraying.
4. The nozzleman in shotcrete operations is responsible for:
A) Mixing concrete
, B) Directing the shotcrete stream onto the substrate
C) Curing the surface
D) Testing compressive strength
Rationale: The nozzleman controls placement, ensuring proper
thickness and compaction.
5. What is a typical water-cement ratio for shotcrete?
A) 0.30–0.35
B) 0.35–0.45
C) 0.50–0.60
D) 0.60–0.70
Rationale: A lower water-cement ratio ensures higher strength and
reduces rebound.
6. Which ACI guideline specifically addresses shotcrete?
A) ACI 318
B) ACI 506
C) ACI 301
D) ACI 211
Rationale: ACI 506 provides detailed standards for materials,
equipment, and procedures for shotcrete.
7. Accelerators in shotcrete are used to:
A) Reduce rebound
B) Speed up setting time
C) Increase slump
D) Reduce water content
Rationale: Chemical accelerators help the shotcrete set quickly,
especially in overhead applications.
8. The maximum aggregate size recommended for dry-mix shotcrete is:
A) 3/8 inch (9.5 mm)
B) 1/2 inch (12.5 mm)
C) 3/4 inch (19 mm)
D) 1 inch (25 mm)
Rationale: Larger aggregates can block the nozzle or reduce adhesion
in dry-mix shotcrete.
9. Overhead shotcrete applications require special attention to:
A) Aggregate grading
B) Rebound and sagging prevention
C) Water-cement ratio only
, D) Pump length
Rationale: Overhead placement is prone to sag and rebound, requiring
careful technique and possibly accelerators.
10. Curing of shotcrete should begin:
A) Immediately after spraying
B) As soon as possible to prevent moisture loss
C) After 24 hours
D) Only if ambient temperature is low
Rationale: Proper curing ensures strength gain and reduces cracking
due to drying shrinkage.
11. Which nozzle type is recommended for dry-mix shotcrete?
A) Long straight
B) Diverging tip with a central orifice
C) Short open tip
D) Fan-shaped nozzle
Rationale: This type allows proper mixing at the nozzle and consistent
material flow.
12. Rebound can be minimized by:
A) Increasing water content
B) Reducing nozzle distance and adjusting spray angle
C) Using larger aggregate
D) Spraying faster
Rationale: Closer nozzle distance and proper angle reduce the amount
of material that bounces off.
13. What is the typical thickness per lift in shotcrete placement?
A) 1–2 inches
B) 2–4 inches
C) 4–6 inches
D) 6–8 inches
Rationale: Multiple lifts are required to build up thickness and ensure
proper compaction.
14. Which factor most affects shotcrete adhesion?
A) Aggregate color
B) Substrate preparation and moisture
C) Curing method
D) Pump type
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. Which type of cement is most commonly used in shotcrete
applications?
A) Type I
B) Type II
C) Type III
D) Type IV
Rationale: Type III cement is high early-strength cement, which is
preferred in shotcrete to allow rapid setting and strength gain.
2. What is the primary advantage of wet-mix shotcrete over dry-mix?
A) Less water control required
B) Better quality control and uniformity
C) Lower initial cost
D) Easier on-site adjustments
Rationale: Wet-mix allows better control of water-cement ratio,
reducing rebound and improving consistency.
3. Rebound in shotcrete refers to:
A) The curing time
B) Material that bounces off the surface during application
C) The strength gain
D) Water loss during spraying
Rationale: Rebound is the portion of shotcrete that does not adhere
and falls off during spraying.
4. The nozzleman in shotcrete operations is responsible for:
A) Mixing concrete
, B) Directing the shotcrete stream onto the substrate
C) Curing the surface
D) Testing compressive strength
Rationale: The nozzleman controls placement, ensuring proper
thickness and compaction.
5. What is a typical water-cement ratio for shotcrete?
A) 0.30–0.35
B) 0.35–0.45
C) 0.50–0.60
D) 0.60–0.70
Rationale: A lower water-cement ratio ensures higher strength and
reduces rebound.
6. Which ACI guideline specifically addresses shotcrete?
A) ACI 318
B) ACI 506
C) ACI 301
D) ACI 211
Rationale: ACI 506 provides detailed standards for materials,
equipment, and procedures for shotcrete.
7. Accelerators in shotcrete are used to:
A) Reduce rebound
B) Speed up setting time
C) Increase slump
D) Reduce water content
Rationale: Chemical accelerators help the shotcrete set quickly,
especially in overhead applications.
8. The maximum aggregate size recommended for dry-mix shotcrete is:
A) 3/8 inch (9.5 mm)
B) 1/2 inch (12.5 mm)
C) 3/4 inch (19 mm)
D) 1 inch (25 mm)
Rationale: Larger aggregates can block the nozzle or reduce adhesion
in dry-mix shotcrete.
9. Overhead shotcrete applications require special attention to:
A) Aggregate grading
B) Rebound and sagging prevention
C) Water-cement ratio only
, D) Pump length
Rationale: Overhead placement is prone to sag and rebound, requiring
careful technique and possibly accelerators.
10. Curing of shotcrete should begin:
A) Immediately after spraying
B) As soon as possible to prevent moisture loss
C) After 24 hours
D) Only if ambient temperature is low
Rationale: Proper curing ensures strength gain and reduces cracking
due to drying shrinkage.
11. Which nozzle type is recommended for dry-mix shotcrete?
A) Long straight
B) Diverging tip with a central orifice
C) Short open tip
D) Fan-shaped nozzle
Rationale: This type allows proper mixing at the nozzle and consistent
material flow.
12. Rebound can be minimized by:
A) Increasing water content
B) Reducing nozzle distance and adjusting spray angle
C) Using larger aggregate
D) Spraying faster
Rationale: Closer nozzle distance and proper angle reduce the amount
of material that bounces off.
13. What is the typical thickness per lift in shotcrete placement?
A) 1–2 inches
B) 2–4 inches
C) 4–6 inches
D) 6–8 inches
Rationale: Multiple lifts are required to build up thickness and ensure
proper compaction.
14. Which factor most affects shotcrete adhesion?
A) Aggregate color
B) Substrate preparation and moisture
C) Curing method
D) Pump type
