Soils and Aggregates Flashcards
7 cards from real NETTCP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Soils and Aggregates flashcards as text
According to AASHTO classification, a soil with a group index of 0 indicates:
Answer: Good subgrade material
A group index of 0 indicates a good subgrade material with minimal potential for poor performance.
Which sieve size is used to separate fine aggregate from coarse aggregate in AASHTO testing?
Answer: No. 4 (4.75 mm)
The No. 4 sieve (4.75 mm) is the standard dividing line between fine and coarse aggregate.
What does a high Los Angeles abrasion loss percentage indicate about aggregate quality?
Answer: Low resistance to wear and degradation
A high LA abrasion loss percentage means the aggregate breaks down easily under impact and abrasion, indicating poor durability.
The shrinkage limit of a soil is defined as the water content at which:
Answer: Further drying causes no additional volume change
The shrinkage limit is the water content below which no further volume change occurs as the soil dries.
In a sieve analysis, if 15% of aggregate passes the No. 200 sieve, this material is classified as:
Answer: Aggregate likely exceeding fines limits for base course
Most NETTCP base course specifications limit minus No. 200 material to around 8–12%, so 15% likely exceeds allowable fines.
Which laboratory test determines the maximum dry density and optimum moisture content of a soil?
Answer: Proctor compaction test
The Proctor compaction test (standard or modified) establishes the compaction curve to find maximum dry density and optimum moisture content.
Frost susceptibility in soils is most strongly associated with which soil type?
Answer: Silty soils with high capillary action
Silty soils are highly frost-susceptible because their fine pores promote strong capillary rise that feeds ice lens formation.