Materials Sampling and Testing Flashcards
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Read the first 7 Materials Sampling and Testing flashcards as text
When computing the average of two companion concrete cylinder breaks, if one result deviates more than what percentage from the average, additional cylinders must be tested?
Answer: 15%
Per ASTM C39, if individual cylinder strength deviates more than 8% of the average, ASTM C39 recommends investigating; many agency specs use a 10% threshold for triggering additional testing.
The Atterberg limits test is used to characterize which property of fine-grained soils?
Answer: Plasticity and moisture sensitivity
Atterberg limits (liquid limit, plastic limit, plasticity index) classify fine-grained soil plasticity and its sensitivity to moisture changes.
The purpose of the Los Angeles Abrasion test (AASHTO T 96) is to measure:
Answer: Resistance of aggregate to degradation by impact and abrasion
The LA Abrasion test measures the percentage of material lost when aggregate is subjected to impact and grinding inside a rotating steel drum with steel balls.
A volumetric flask used in specific gravity testing of fine aggregate must be calibrated at what temperature?
Answer: 73.4°F (23°C)
AASHTO T 84 requires calibration of the pycnometer or volumetric flask at 73.4°F (23°C) to ensure accurate volume measurements.
When obtaining a core sample from an asphalt pavement for thickness verification, the minimum core diameter recommended by FDOT specifications is:
Answer: 4 inches
A minimum 4-inch diameter core is typically required for asphalt thickness and density testing to ensure a representative sample with adequate material for testing.
The sand equivalent test (AASHTO T 176) measures the relative proportion of which two components in fine aggregate?
Answer: Clay-like fines and sand-size particles
The sand equivalent test separates clay-like or plastic fines from sand-size particles to assess the cleanliness and quality of fine aggregate used in pavements.
During a proctor compaction test, if the soil is too wet and the moisture-density curve shows density decreasing, the technician should:
Answer: Air-dry the soil and retest at lower moisture contents
When the curve descends on the wet side of optimum, the soil must be air-dried to lower moisture content points to properly define the full compaction curve and identify the true maximum dry density.