Aechitectural Graphic Standards Ch 1 Flashcards
Clay
determined by the size for particles and composition.
inorganic and have grains less than 0.0002” in diameter.
charged particles and affinity for water.
cohesion and plasticity.
stiff, medium, or soft.
satisfactory bearing material.
Silt
inorganic particles less than 0.003” and 0.0002” in diameter.
found at bottom of lakes and river deltas.
Sand
0.003” - 0.079” in diameter.
compacted = ideal bearing material
coarse and fine.
Gravel
fine to coarse. 0.003” - 0.079” in diameter. fragments range from 0.75” ~ 3”.
good foundation material
Cobbles
3”-10”.
reliable foundation-bearing, difficult to compact when used for fill.
Boulders
rock fragments greater than 10”.
fill mass of voids between boulders are filled with finer-grained sands and silts.
not good for direct foundation support.
Bedrock
Unbroken hard rock.
desirable for extremely high bearing pressure and loads.
Residuum
soils derived from the in-place decomposition of bedrock materials.
more weathered near the surface and rocklike with depth.
Alluvial Soils
loose and saturated. not good for support of structures or pavements.
Colluvial Soils
irregular and loose in composition. Improvement required prior to being used to support buildings or pavements.
Aeolian Soils
silt or sand-sized soils. Component in place but loses strength when disturbed or recompacted.
Till
Mixture of clay, silt, sand, gravel, and boulders deposited by glaciers.
well graded = excellent foundation strata
Loam
humus and sand, silt, or clay
agriculture not foundations
Cohesionless Soils
cobbles, gravels, sands, and nonplastic silts.
formed by mechanical weathering
strength caused by interparticle friction
Cohesive Soils
clay minerals with unbalanced chemical charge.
attracts water = bonds
Consolidation
soils subjected to loads, water within the void spaces supports the change in stress through an increase in pressure.
the resulting reduction in volume over time = consolidation
Underconsolidated Soils
Soils deposited in a very loose state. Never experienced stresses equal to or greater than current overburden stresses.
Foundations can expect large short- and long-term settlement.
Overconsolidated Soils
Not elastic. Soils that have previously been loaded to stresses above those created by the current soil overburden.
Foundations can expect less short- and long-term settlements.
Desiccation
When soils are dried, capillary tension pulls the soil grains together = soils shrinks and lose volume.