Materials Sampling and Testing Flashcards
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Read the first 7 Materials Sampling and Testing flashcards as text
What are the two key values determined by the Standard Proctor compaction test (AASHTO T 99)?
Answer: Maximum dry density and optimum moisture content of a soil
The Standard Proctor test establishes the maximum dry density and the optimum moisture content, which serve as the compaction standard against which field results are compared.
What property does the Limerock Bearing Ratio (LBR) test measure for base course materials in Florida?
Answer: The bearing strength or load-bearing capacity of limerock and similar base course materials
The LBR test measures the bearing strength of limerock and stabilized materials used as base course, and the result is expressed as a percentage relative to a standard crushed stone.
What does the Los Angeles Abrasion test (AASHTO T 96) measure for coarse aggregates?
Answer: The resistance of coarse aggregate to degradation by abrasion and impact
The LA Abrasion test tumbles aggregate with steel balls in a rotating drum to measure the percent loss due to abrasion and impact, indicating aggregate hardness and durability.
What information does a sieve analysis (gradation test) provide about an aggregate sample?
Answer: The particle size distribution (gradation) of the aggregate
A sieve analysis separates aggregate particles by size using a series of nested sieves, producing a gradation curve that shows the percentage of material passing each sieve size.
When performing a concrete slump test per AASHTO T 119, what does a higher slump value indicate about the fresh concrete?
Answer: Greater workability and more fluid consistency of the fresh concrete
A higher slump indicates more workable, fluid concrete; this is usually due to higher water content, but can also result from water-reducing admixtures.
The Atterberg Limits test is used to determine which characteristics of fine-grained soils?
Answer: The Liquid Limit and Plastic Limit, which define the plasticity of fine-grained soils
Atterberg Limits define the moisture content boundaries between soil behavior states; the Liquid Limit and Plastic Limit are used to calculate the Plasticity Index, indicating expansive potential.
Why is it important to measure the air content of fresh concrete on Florida highway projects?
Answer: To verify that adequate air entrainment is present to ensure durability and resistance to distress
Air entrainment creates microscopic bubbles that improve concrete durability, workability, and resistance to distress; FDOT specifications require air content within defined limits.