ETC ETC Construction Methods & Equipment 1 — Questions and Answers
Question 1: What is the primary purpose of shoring in an excavation?
- To support the walls of an excavation and prevent cave-in (Correct answer)
- To pump groundwater from the trench
- To compact the subgrade before pipe installation
- To mark the limits of the excavation
Correct answer: To support the walls of an excavation and prevent cave-in
Shoring systems such as trench boxes, sheet piling, or timber shoring support excavation walls to protect workers from cave-in hazards.
Question 2: What type of pile derives its bearing capacity primarily from friction along its length?
- Friction pile (Correct answer)
- End-bearing pile
- Batter pile
- Sheet pile
Correct answer: Friction pile
A friction pile transfers structural load to the soil through skin friction along the pile shaft rather than bearing on a hard stratum.
Question 3: What equipment is commonly used to compact granular fill material in lifts during earthwork?
- Vibratory roller (Correct answer)
- Backhoe
- Grader
- Scraper
Correct answer: Vibratory roller
A vibratory roller combines static weight and vibration to densify granular soils and base materials effectively.
Question 4: What is the minimum concrete cover for reinforcing steel in a slab not exposed to weather per ACI 318?
- 0.75 inch (three-quarters inch) (Correct answer)
- 1.5 inches
- 3 inches
- 4 inches
Correct answer: 0.75 inch (three-quarters inch)
ACI 318 requires a minimum three-quarters-inch cover for non-prestressed bars in slabs not exposed to weather when cast against stay-in-place forms.
Question 5: What is the function of a motor grader on a construction site?
- To fine-grade and level earthwork surfaces to precise elevations (Correct answer)
- To excavate rock and hard soil
- To compact subgrade material
- To haul fill material from borrow areas
Correct answer: To fine-grade and level earthwork surfaces to precise elevations
A motor grader uses a long adjustable blade to cut, spread, and finish earthwork surfaces to specified grades and cross-slopes.
Question 6: What does the slump test evaluate for fresh concrete?
- The consistency and workability of the concrete mix (Correct answer)
- The compressive strength of hardened concrete
- The air content of the mix
- The water-cement ratio
Correct answer: The consistency and workability of the concrete mix
The slump test measures how much fresh concrete settles after removing a standard cone mold, indicating its consistency and water content.
ETC ETC Construction Methods & Equipment 1
What is the primary purpose of shoring in an excavation?