7. Materials Flashcards
What is the shear strength of a soil?
Its resistance to shearing stresses.
What is shear strength a function of?
cohesion, angle of internal friction, and normal stress on the failure plan.
How are the parameters, “c” and “phi” determined?
Directly from standard field vane shear test or indirectly through lab test ( direct shear test, triaxial test).
What are three ways soils are compressed?
- Compression of solid particles and water in the voids
- Compression and expulsion of air in the voids
- Expulsion of water in the voids
What is the compressibility of a soil mass dependent upon?
The rigidity of the soil skeleton which in turn is dependent on the structural arrangement of the particles (e.g., loose, dense, honeycombed).
What does compaction do to a soil?
improves strength and reduces compressibility.
What is the coefficient of permeability, k depended upon?
soil particle size, shape, structure, void ratio, degree of saturation, and void connectivity.
What is specific discharge (v)?
the discharge per unit x-sectional area, AKA Darcy velocity or discharge velocity (average velocity over an area)
What is seepage velocity (Vv)?
velocity through the pore space only.
How is hydraulic conductivity determined?
Constant head test or Falling head test.
What is frost heave?
When temperature in the a soil mass drops below water’s freezing point, water in the void freezes and therefore expands, causing the soil mass to move upward.
What is compaction?
the process of increasing the bulk density of a soil or aggregate by removing air.
What is achieve with optimum water content exists?
Maximum dry density.
What are the factors affecting field compaction?
besides soil type and moisture content,
- thickness of the lift
- intensity of pressure applied by the compacting equp.
- area over which the pressure is applied.
What is the Liquid Limit?
the moisture content at which the cohesive soil passes from liquid state to plastic state.
What is Plastic Limit?
the moisture content at which the cohesive soil passes from plastic state to semisolid state.
What does the area under a stress-strain diagram represent?
the amount of the strain energy per unit volume absorbed by the material.
What is the Modulus of Resilience?
the strain energy absorbed up to the yield point .
What is the Modulus of Toughness?
the total area under the diagram up to fracture.
What is ductility?
it corresponds to the amount of energy absorbed at failure. Thus toughness can be representative of ductility.
How does the increase of Carbon affect steel?
- Increases yield strength
- Reduces fracture strain and toughness
- Does not affect modulus of elasticity
What is the purpose of the Torsion Test (Shear Test)?
to calculate the Shear Modulus (G) and thus obtain the Poisson’s Ratio.
What is the purpose of the Charpy V-Notch Test?
to measure toughness.
How to protect steel material from corrosion?
- Barrier coating using zinc (galvanization) or epoxy (rebar).
- Cathodic protection
