Soils Classification Testing

An overview of test procedures to classify soils according to the Uniform Soil

Classification System (ASTM D 4287)

John S. Landwermeyer, P.E.

Austin, Texas

ARIAS & ASSOCIATES, INC.Geotechnical  · Environmental  · Materials  Testing 

Sieve Analysis (ASTM D 421)Representative SampleDry Sample to get total dry weight (Night 1)Wash sample over the #200 SieveDry Sample (Night 2)Dry shake through sievesWeigh contents of each sieve% Retained = Wt Retained ÷Total Wt

Sieve Analysis – Possible ErrorsUn-representative Sample

SegregationInsufficient wash of sample over the #200 Sieve: use brush!Over-loading of sieve nestTare weights, human errors

Atterberg Limits (ASTM D 4318)

Liquid Limit Plastic Limit

Atterberg Limits – Soil Prep Representative Sample

Atterberg Limits – Soil PrepRepresentative SampleSoak for up to 12 hours (“slaking time”) (Night 1)Remove aggregate on #10 sieve

Atterberg Limits – Soil PrepRepresentative SampleSoak for up to 12 hours (“slaking time”) (Night 1)Remove aggregate on #10 sieveMechanical mixing

Atterberg Limits – Soil PrepRepresentative SampleSoak for up to 12 hours (“slaking time”) (Night 1)Remove aggregate on #10 sieveMechanical mixingPour thru #40 sieve, into lined absorbent bowlAllow soil to dry to below the Liquid Limit (Night 2)

Atterberg Limits – Liquid Limit Adjust moisture to the Liquid Limit

Atterberg Limits – Liquid LimitAdjust moisture to the Liquid LimitLL is reached when ½” of the grove closes after 25 blows

Atterberg Limits – Plastic LimitAdjust moisture to the Plastic LimitPL is reached when soil begins to break when rolled into 1/8” threads

Atterberg LimitsDetermine Moisture Contents at PL and LL (Night 3)

Atterberg Limits – Plasticity Index PI = LL – PL

“Fat Clay” = LL > 50 (ASTM D 2487)“Lean Clay” = LL < 50 (ASTM D 2487)“Expansive” = PI > 20 Non-cohesive = non-plastic = sand, silt or gravel

Atterberg Limits – Possible ErrorsUn-representative sample or sub-sampleDry preparation (ASTM D 4318) pulverization of soils containing rock decreases PI

Question & Answer

John S. Landwermeyer, P.E.

Thank you!