Subbase Compaction Verification Flashcards
7 cards from real PIC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Subbase Compaction Verification flashcards as text
Which ASTM standard covers the sand cone method for field density testing of soil?
Answer: ASTM D1556
ASTM D1556 is the standard test method for density and unit weight of soil in place by the sand-cone method.
During a rubber balloon density test, the technician pumps water into the excavated hole. The test measures volume by:
Answer: Tracking the volume of water required to fill the hole via a calibrated cylinder
The balloon apparatus uses a graduated cylinder to measure exactly how much water fills the hole, giving the precise volume for density calculation.
Intelligent Compaction (IC) rollers equipped with GPS and accelerometers provide real-time data primarily for:
Answer: Mapping compaction uniformity across the entire subbase area
IC rollers generate color-coded stiffness maps showing where the subbase is uniformly compacted or where weak spots require additional passes.
What is the purpose of the 'check strip' or 'test strip' at the start of subbase compaction operations?
Answer: To determine the required number of roller passes to achieve specification density with the actual equipment and material
A test strip establishes the roller pattern (number of passes) needed to reach target density under actual field conditions before full production begins.
When compacting subbase material near a structure or retaining wall where a roller cannot operate, the preferred method is:
Answer: Plate compactor or jumping jack rammer in thin lifts
Plate compactors and jumping jack rammers achieve adequate compaction in confined areas that rollers cannot access, using reduced lift thicknesses for full depth effectiveness.
A laboratory CBR (California Bearing Ratio) value of 80% for a subbase material indicates:
Answer: The material's penetration resistance is 80% of that of a standard crushed stone reference
CBR compares the material's unit load resistance at a given penetration depth to that of a standard crushed stone, expressed as a percentage.
If a nuclear gauge is used within 10 feet of a metallic object such as a drainage pipe, the inspector should expect:
Answer: Potential interference causing inaccurate readings, requiring an alternative test method
Metal objects scatter gamma rays and reflect neutrons, distorting both density and moisture readings; alternative methods like sand cone should be used nearby.