CTQP Earthwork Construction Inspection 1 — Questions and Answers
Question 1: What does the term 'optimum moisture content' refer to in earthwork compaction?
- The moisture level at which soil achieves maximum dry density (Correct answer)
- The moisture level at which soil is too wet to compact
- The moisture level required for plant growth on embankments
- The moisture level at which soil becomes saturated
Correct answer: The moisture level at which soil achieves maximum dry density
Optimum moisture content is the moisture level at which a given soil achieves its maximum dry density under a specified compaction effort.
Question 2: Which FDOT test method is used to determine the field density of compacted embankment material?
- AASHTO T 99
- AASHTO T 180
- ASTM D 1556 or nuclear gauge method (Correct answer)
- ASTM D 2166
Correct answer: ASTM D 1556 or nuclear gauge method
FDOT uses the sand cone method (ASTM D 1556) or the nuclear density gauge to measure field compaction density of earthwork.
Question 3: What minimum percent compaction is typically required for embankment fill under Florida Department of Transportation specifications?
- 85%
- 90%
- 95% (Correct answer)
- 100%
Correct answer: 95%
FDOT specifications generally require embankment fill to be compacted to at least 95% of maximum dry density per AASHTO T 99 or T 180.
Question 4: What is a 'borrow pit' in the context of CTQP earthwork inspection?
- An excavation area where unsuitable material is disposed
- An off-site area from which suitable fill material is obtained (Correct answer)
- A temporary storage pond for stormwater
- A test pit used for soil classification
Correct answer: An off-site area from which suitable fill material is obtained
A borrow pit is an off-site excavation from which suitable embankment or fill material is obtained when sufficient on-site material is unavailable.
Question 5: During earthwork inspection, what is the maximum lift thickness typically allowed for general embankment before compaction?
- 6 inches loose measure
- 12 inches loose measure (Correct answer)
- 18 inches loose measure
- 24 inches loose measure
Correct answer: 12 inches loose measure
FDOT specifications typically limit loose lift thickness to 12 inches for general embankment to ensure adequate compaction throughout the layer.
Question 6: What does 'unsuitable material' mean in FDOT earthwork specifications?
- Material with a bearing capacity below 5 tons per square foot
- Material that cannot be adequately compacted or that will cause settlement (Correct answer)
- Any material that contains clay
- Material that fails the Atterberg limits test
Correct answer: Material that cannot be adequately compacted or that will cause settlement
Unsuitable material includes organic soils, muck, or any material that cannot be properly compacted or that will cause detrimental settlement under load.
CTQP Earthwork Construction Inspection 1
What does the term 'optimum moisture content' refer to in earthwork compaction?