CPII Construction Inspection Techniques 4 — Questions and Answers
Question 1: When inspecting reinforcing steel prior to concrete placement, which condition is acceptable per standard specifications?
- Rebar with mill scale and slight rust without pitting or loose flakes (Correct answer)
- Rebar coated with oil-based form release agent
- Rebar with mud and clay coating along its full length
- Rebar with significant section loss due to corrosion pitting
Correct answer: Rebar with mill scale and slight rust without pitting or loose flakes
Light rust and mill scale on rebar are generally acceptable and can actually improve bond to concrete, whereas oil, heavy mud, or corrosion pitting that reduces cross-section must be corrected.
Question 2: What is the minimum curing period typically specified for portland cement concrete flatwork exposed to moderate temperatures to achieve adequate strength development?
- 24 hours
- 3 days
- 7 days (Correct answer)
- 28 days
Correct answer: 7 days
A minimum curing period of 7 days is commonly specified for portland cement concrete to ensure adequate strength gain and durability through continued cement hydration.
Question 3: An inspector observes formwork for a concrete retaining wall being stripped after only 18 hours, while the specification requires 72-hour minimum. What should the inspector do?
- Allow stripping since the concrete appears solid and has set
- Issue a stop-work notice for that activity and document the violation (Correct answer)
- Notify the contractor verbally and continue the inspection
- Consult the weather conditions and allow stripping if temperatures were above 70°F
Correct answer: Issue a stop-work notice for that activity and document the violation
Premature formwork removal is a specification violation that can compromise concrete strength and structural integrity, requiring a formal stop-work action and documentation.
Question 4: When inspecting asphalt pavement during placement, the inspector notes the mat temperature has dropped below the minimum specified compaction temperature before rolling is complete. What is the likely consequence?
- The pavement will have excessive bleeding and flushing
- The asphalt will be over-compacted, reducing air voids below specification
- Inadequate compaction will result in an in-place density below specification (Correct answer)
- The aggregate will segregate, causing surface raveling immediately after placement
Correct answer: Inadequate compaction will result in an in-place density below specification
Cold asphalt is stiffer and resists compaction, resulting in insufficient density that leads to premature pavement distress, rutting, and reduced service life.
Question 5: During a storm drain inspection, an inspector uses a laser level to check pipe slope. The measured slope is 0.45% where 0.50% minimum is specified. What is the appropriate response?
- Accept the pipe since 0.45% will still drain by gravity
- Reject the pipe installation and require re-grading to meet the minimum specified slope (Correct answer)
- Document the deficiency and allow the contractor to compensate with a steeper slope on the next section
- Request a hydraulic analysis from the contractor to demonstrate 0.45% is adequate
Correct answer: Reject the pipe installation and require re-grading to meet the minimum specified slope
Pipe slope below the specified minimum is a nonconformance that must be corrected before backfill, as insufficient slope can cause sediment deposition and reduced system capacity.
Question 6: What is the purpose of performing a sand cone density test on a completed fill layer?
- To determine the shear strength of the compacted soil
- To measure in-place dry density and compare it to the maximum dry density from lab testing (Correct answer)
- To classify the type of soil being compacted
- To measure the permeability of the compacted layer
Correct answer: To measure in-place dry density and compare it to the maximum dry density from lab testing
The sand cone test measures in-place soil density, which is then compared to the laboratory-determined maximum dry density to calculate percent compaction achieved in the field.
Question 7: Which condition would cause an inspector to reject a concrete test cylinder result even if the 28-day break strength meets the minimum requirement?
- The cylinder was cured in a standard fog room at 73°F
- The cylinder broke in a cone-and-shear pattern
- The cylinder was improperly capped with sulfur capping compound after transport damage to the ends (Correct answer)
- The cylinder was tested within 24 hours of its 28-day cure date
Correct answer: The cylinder was improperly capped with sulfur capping compound after transport damage to the ends
Damaged cylinder ends that require remedial capping introduce testing variability, and results from improperly prepared specimens may not accurately represent the concrete's actual strength.
CPII Construction Inspection Techniques 4
When inspecting reinforcing steel prior to concrete placement, which condition is acceptable per standard specifications?