Soils in Construction (Engineering)Douglas Kowalewski

SOIL PROPERTIESParticle Size Distribution

Gravel, Sand, Silt, Clay

Fi = (Ms-ΣMi) / Ms

Fi = Fraction of particles with diameter finer than “i”

ΣMi = summation of mass of particles with diameter finer

than “i”

SOIL PROPERTIES

Atterberg Limits: Soil Plasticity

Characterize the fine-grained fraction of soils

Measure the Following Water ContentPlastic Limit (PL)Liquid Limit (LL)Plastic Index (PI)

Plastic Index = LL – PL0: Nonplastic

1-5: Slightly Plastic5-10: Low Plasticity

10-20: Medium Plasticity20-40: High Plasticity

>40: Very High Plasticity

GEOTECHNICAL – Unified Soil Classification System

M = Silt (Plots below the A-line)C = Clay (Plots above the A-line)

CLAY

SILT

Grain Size Analysis: FINES

Plasticity: FINESGEOTECHNICAL – Unified Soil Classification System

H = High Liquid LimitL = Low Liquid Limit

LOW HIGH

Fine Soil

Plastic Index = LL – PL0: Nonplastic

1-5: Slightly Plastic5-10: Low Plasticity

10-20: Medium Plasticity20-40: High Plasticity

>40: Very High Plasticity

GEOTECHNICAL – Unified Soil Classification System

Reading: Appendix B USCS: pg 1-22

SOIL REPORTS

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GEOTECHNICAL