Page 159 - Trenchless Technology Piping Installation and Inspection

Pipe and Pipe Installation Considerations 125

Group
Main Divisions Symbol Typical Names
Gravels Well-graded gravels and gravel-
GW
50% or sand mixtures, little or no fines
Clean
more of
gravels
course GP Poorly graded gravels and gravel-
fraction sand mixtures, little or no fines
Course- retained Silty gravels, gravel-sand-silt
grained on the Gravels GM mixtures
soils 4.75 mm with
More (No. 4) fines GC Clayey gravels, gravel-sand-clay
than 50% sieve mixtures
retained Sands Well-graded sands and gravelly
on the 50% or SW sands, little or no fines
0.075 mm more of Clean
(No. 200) course sands Poorly graded sands and gravelly
sieve fraction SP sands, little or no fines
passes
SM Silty sands, sand-silt mixtures
the 4.75 Sands
mm with
(No. 4) fines SC Clayey sands, sand-clay mixtures
sieve
Inorganic silts, very fine sands,
ML rock four, silty or clayey fine
sands
Silts and clays
Inorganic clays of low to medium
Fine- Liquid limit 50% CL plasticity, gravelly/sandy/silty/
grained or less lean clays
soils
More OL Organic silts and organic silty
than 50% clays of low plasticity
passes the Inorganic silts, micaceous or
0.075 mm MH diatomaceous fine sands or
(No. 200) silts, elastic silts
Silts and clays
sieve
Liquid limit greater Inorganic clays or high plasticity,
CH
than 50% fat clays
Organic clays of medium to high
OH
plasticity
Peat, muck, and other highly
Highly organic soils PT
organic soils

Source: ASTM D2487
TABLE 4.3 Unified Soil Classification System (USCS)