CTQP Earthwork Construction Inspection 4 — Questions and Answers
Question 1: During earthwork inspection, a subgrade that pumps or deflects excessively under roller passes most likely indicates which condition?
- Adequate compaction has been achieved
- Subgrade has insufficient bearing capacity or is saturated (Correct answer)
- The roller is too heavy for the lift thickness
- Compaction is progressing normally and should continue
Correct answer: Subgrade has insufficient bearing capacity or is saturated
Pumping or excessive deflection under roller passes indicates the subgrade is saturated or lacks adequate bearing capacity, requiring remediation before paving.
Question 2: Which FDOT specification governs the acceptable limits for cleanliness and gradation of embankment material placed in Florida?
- FDOT Standard Specification Section 120 (Correct answer)
- FDOT Standard Specification Section 200
- FDOT Standard Specification Section 902
- FDOT Standard Specification Section 110
Correct answer: FDOT Standard Specification Section 120
FDOT Standard Specification Section 120 covers excavation and embankment, including material quality requirements for earthwork operations.
Question 3: When a fill area cannot drain naturally during compaction, the inspector should require the contractor to do what?
- Continue compaction regardless and test moisture afterward
- Install temporary drainage or pumping to remove standing water (Correct answer)
- Place a geotextile fabric over the wet area and compact on top
- Reduce lift thickness to half and increase roller passes by 50%
Correct answer: Install temporary drainage or pumping to remove standing water
Standing water must be removed via temporary drainage or pumping before compaction can proceed to avoid entrapping moisture in the fill.
Question 4: An inspector observes that the contractor is placing fill on a slope steeper than 3:1 without benching. What is the primary concern?
- Erosion will occur during the next rain event
- The new fill may slide along the interface with the existing slope (Correct answer)
- The fill material will segregate on the steep face
- Compaction equipment cannot safely operate at that angle
Correct answer: The new fill may slide along the interface with the existing slope
Without benching into an existing slope, new fill can slide along the slick interface, creating a failure plane at the original ground surface.
Question 5: Which test is most appropriate for determining in-place moisture-density of a granular fill material that contains large particles (>1.5 inch)?
- Standard Proctor laboratory test
- Nuclear density gauge directly on the surface
- One-point Proctor with field correction
- Sand cone test with oversized particle correction applied (Correct answer)
Correct answer: Sand cone test with oversized particle correction applied
The sand cone method with correction for oversized particles is used when materials contain large particles that exceed the limits of the nuclear gauge.
Question 6: In earthwork inspection, what does the term 'shrinkage factor' refer to?
- Reduction in material volume when soil moisture evaporates during drying
- Ratio of compacted fill volume to the bank (in-place) volume of the same material (Correct answer)
- Decrease in soil strength over time due to weathering
- Contraction of embankment slopes during seasonal temperature changes
Correct answer: Ratio of compacted fill volume to the bank (in-place) volume of the same material
Shrinkage factor compares compacted volume to bank volume; soils typically shrink when compacted because air voids are eliminated, requiring more bank measure to achieve a given fill volume.
Question 7: When inspecting a retaining wall backfill, what maximum lift thickness is typically specified before compaction with hand-operated tamping equipment near the wall?
- 12 inches loose
- 6 inches loose (Correct answer)
- 18 inches loose
- 24 inches loose
Correct answer: 6 inches loose
Near retaining walls and other structures, lift thickness is typically limited to 6 inches loose to prevent lateral pressure buildup and ensure adequate compaction with light equipment.
CTQP Earthwork Construction Inspection 4
During earthwork inspection, a subgrade that pumps or deflects excessively under roller passes most likely indicates which condition?