ACI Tools, Equipment & Safety Procedures 3 — Questions and Answers
Question 1: What is the primary function of a concrete edger tool?
- Remove laitance from the surface
- Create a rounded, finished edge along forms (Correct answer)
- Score control joints
- Compact concrete near formwork
Correct answer: Create a rounded, finished edge along forms
An edger is run along form edges to create a smooth, rounded profile that resists chipping when forms are stripped.
Question 2: Lockout/tagout (LOTO) procedures must be followed when:
- Adjusting power trowel blade pitch during normal operation
- Servicing or cleaning equipment with potential stored energy (Correct answer)
- Operating a portable concrete vibrator
- Checking oil levels with the engine running
Correct answer: Servicing or cleaning equipment with potential stored energy
LOTO is required before any servicing or maintenance to prevent unexpected energization of equipment.
Question 3: Which screed type uses mechanical vibration to consolidate concrete while striking it off to grade?
- Roller screed
- Vibratory screed (Correct answer)
- Straight-edge screed
- Laser screed
Correct answer: Vibratory screed
A vibratory screed combines a strike-off action with vibration to consolidate concrete and produce a uniform surface.
Question 4: What hazard is associated with operating power finishing equipment near electrical conduit embedded in a slab?
- Accelerated concrete curing
- Electrocution if conduit is nicked and energized (Correct answer)
- Reduced surface flatness
- Premature blade wear
Correct answer: Electrocution if conduit is nicked and energized
Cutting into energized embedded conduit with metal trowel blades creates a serious electrocution hazard.
Question 5: A groover (jointing tool) is used to:
- Smooth aggregate below the surface
- Create a weakened plane that controls crack location (Correct answer)
- Apply curing compound
- Test concrete hardness
Correct answer: Create a weakened plane that controls crack location
A groover cuts a groove into fresh concrete to create a weakened plane where shrinkage cracks will occur in a controlled location.
Question 6: When must a concrete finisher wear chemical-resistant gloves and boots?
- Only when mixing concrete by hand
- Whenever in prolonged contact with fresh concrete (Correct answer)
- Only during hot weather pours
- When using a bull float only
Correct answer: Whenever in prolonged contact with fresh concrete
Fresh concrete is highly alkaline and prolonged skin contact causes chemical burns; protective gloves and boots are required.
Question 7: What is the recommended insertion spacing for an internal vibrator to ensure full consolidation?
- Random, wherever air pockets appear
- 1.5 times the vibrator's radius of action (Correct answer)
- At every rebar intersection
- One insertion per cubic yard
Correct answer: 1.5 times the vibrator's radius of action
ACI 309R recommends spacing vibrator insertions at 1.5 times the radius of action to ensure overlapping consolidation coverage.
ACI Tools, Equipment & Safety Procedures 3
What is the primary function of a concrete edger tool?