ACI Tools, Equipment & Safety Procedures 2 — Questions and Answers
Question 1: Which type of float is used to bring moisture and fine particles to the surface during the first finishing pass?
- Steel trowel
- Bull float (Correct answer)
- Fresno trowel
- Edger
Correct answer: Bull float
A bull float is used immediately after screeding to embed aggregate and bring a thin layer of cement paste to the surface.
Question 2: What personal protective equipment is required when cutting concrete with a dry-cut saw?
- Only safety glasses
- Safety glasses and leather gloves
- Respirator, eye protection, and hearing protection (Correct answer)
- Face shield only
Correct answer: Respirator, eye protection, and hearing protection
Dry-cut concrete sawing generates silica dust and extreme noise, requiring respiratory, eye, and hearing protection.
Question 3: A power trowel blade set at a high positive pitch angle will produce what effect?
- Deeper cutting action
- More aggressive compaction and flatness
- A burnished, hard surface finish (Correct answer)
- Increased bleed water extraction
Correct answer: A burnished, hard surface finish
Increasing the blade pitch angle on a power trowel creates more friction and pressure, resulting in a denser, burnished surface.
Question 4: What is the purpose of a concrete vibrator during placement?
- To accelerate set time
- To consolidate concrete and remove entrapped air (Correct answer)
- To level the concrete surface
- To compact the subgrade
Correct answer: To consolidate concrete and remove entrapped air
Internal vibrators consolidate fresh concrete by eliminating air voids, improving strength and bond with reinforcement.
Question 5: Which OSHA standard specifically governs silica dust exposure limits for construction workers?
- 29 CFR 1926.1153 (Correct answer)
- 29 CFR 1910.1000
- 29 CFR 1926.50
- 29 CFR 1910.134
Correct answer: 29 CFR 1926.1153
OSHA 29 CFR 1926.1153 sets the permissible exposure limit (PEL) for respirable crystalline silica in construction.
Question 6: When using a laser screed, what does the rotating laser do?
- Controls concrete mix temperature
- Establishes a reference elevation plane for automatic grade control (Correct answer)
- Monitors vibration depth
- Measures air entrainment
Correct answer: Establishes a reference elevation plane for automatic grade control
The rotating laser transmits a level reference plane that the screed's receiver uses to automatically control grade.
Question 7: Before operating a ride-on power trowel, a finisher should inspect all of the following EXCEPT:
- Engine oil level
- Blade condition and torque
- Slab mix design water-cement ratio (Correct answer)
- Safety guards and shields
Correct answer: Slab mix design water-cement ratio
Water-cement ratio is a batch plant concern; pre-operation equipment inspection covers oil, blades, and safety guards.
ACI Tools, Equipment & Safety Procedures 2
Which type of float is used to bring moisture and fine particles to the surface during the first finishing pass?