Table 2. Unified soil classification system (ASTM D-2487). 



Group 

 Major Divisions ^Symbols 



Typical Names 



Laboratory C'astilication Catena 



o _ 



5 1 



£ 2 " 



Well-graded g'avels. gravel-sand 

 lures, i tt lie O' no fines 



c o 



Poorly graded g'avels. gravel-sand r 

 lures. Utile or no fines 



Siiiy gravels, gravel-sand-silt mixtures 



w to 



Clayey gravels, gravel-sand-clay 



lUfCS 



E I 



Well-graded sands, gravelly sands, little 

 or no fines 



Poorly graded sands, gravelly sands, 

 little or no fines 



S E. 



■5 S ° 



n a 



to a 



Silty sands, sand-silt mixtures 



Clayey sands, sand-clay mixtures 



o o jS 



£ C ;, 



a o 5 ' 

 ceo 



|| s' 



2 a ^ 



C„ - — greater tha« 4. C c • 



D,n * D„i. 



Not meeting all gradation requirements (or GVV 



Atterberg limits below "A" 

 hne or P.I. less than 4 



Atterberg limits below "A" 

 line with P.I. greater than 7 



Above "A" ime with P.I. 

 between 4 and 7 are border- 

 line cases requiring use of 

 dual symbols 



I IDjo>" 



■ greater than 6: C^ ■ between 1 and 3 



Not meeting all gradation requir 



Atterberg limits above "A" 

 line or P.I. less than 4 



Atterberg limits above "A" 

 hne with P.I. greater than 7 



Limns plotting m hatched 

 /one with P.I. between 4 

 and 7 are borderline cases 

 requiring use of dual sym- 

 bols 



Inorganic silts and very line sands, 

 rock flour, silty or clayey fine sands, 

 or clayey silts with slight plasticity 



*o — 



c _ 



Z i 



Inorganic clays of low to medium 

 plasticity, gravelly clays, sandy clays, 

 silty clays, lean clays 



Plasticity Chart 



Organic silts and organic silty clays of 

 low piastictly 



Inorganic silts, micaceous or diatorna- 

 ceous fine sandy or silty soils, elastic 



SiltS 



Inorganic clays of high plasticity, fat 

 clays 



Organic clays of medium to high 

 plasticity, organic silts 



« 40 



= :o 



10 

 



































CH 



/ 



















A\ 















^/ 



r i 



OH and 



1 



MH 









CL 



/ 



V 















"CL ML 



7^ 















^M» 





V 



< 



DL 



10 20 30 40 SO 60 70 80 90 100 

 Liquid limit 



Peal and other highly organic soils 



Division of CM and SM groups Into subdivisions of d and u are for roads ond airfields only. Subdivision is based on Atterberg 

 limitsl suffix d used when L.L. is 28 or less and the P.I. is 6 or less; the sdf fix u used -when L.L. is greater than 23. 

 Borderline classifications, used for soils possessing characteristics of two groups, ore designated by combinations of 

 group symbols. For example! OvV-QC, well -graded grave I -so nd mixture with clay binder. 



52 



