Kesatuan sistem klasifikasi tanah di adopsi oleh ASTM D-2487-98 dan IS: 1498-1970 yang digunakan dengan maksud untuk klasifikasi dan identifikasi tanah secara keteknikan umum.
Klasifikasi Tanah dibagi 3 bagian :
Klasifikasi Tanah dibagi 3 bagian :
In these soils, 50% or more of the total material by weight is larger than 75micron IS sieve size. (artinya jika jenis material yang ada 50% atau lebih atau selain material berukuran clay hingga very fine sand, dan atau dari fine sand ke cobble disebut Coarse grained soils).
Coarse grained soils, dibagi menjadi dua sub divisi:
Gravel (G) dan Sands (S)
Fine grained soils:
In these soils, 50% or more of the total material by weight is smaller than 75 micron IS sieve size. (Artinya jika materialnya berupa 50% atau lebih dan terdiri dari material berukuran clay hingga very fine sand, disebut Fine grained soils).
Fine grained soils, dibadi menjadi 3 sub divisi :
a Inorganic silts dan very fine sands: M
b Inorganic clays: C
c Organic silts and clays dan organic matter: O.
The fine grained soils are further divided into the following groups on the basis of the following arbitrarily selected values of liquid limit which is a good index of compressibility:
i) Silts and clays of low compressibility:
Having a liquid limit less than 35 and represented by symbol L.
ii) Silts and clays of medium compressibility:
Having a liquid limit greater than 35 and less than 50 and represented by symbol I.
iii) Silts and clays of high compressibility:
Having a liquid limit greater than 50 and represented by a symbol H.
Combination of these symbols indicates the type of fine grained soil. For example, ML means inorganic silt with low to medium compressibility.
Unified Soil Classification System and Symbol Chart:
Pada gambar di bawah akan ditampilkan klasifikasi yang membedakan Coarse grained soils, Fine grained soils dan Plasticity Chart.
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| Fig 1: Unified soil classification system for coarse grained soils |
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| Fig 2: Unified soil classification system for fine grained soils |
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| Fig 3: Soil Plasticity chart as per Unified soil classification system |
Highly organic soils and other miscellaneous soil materials:
These soils contain large percentage of fibrous organic matter, such as peat, and the particles of decomposed vegetation. In addition, certain soils containing shells, cinders and other non-soil materials in sufficient quantities are also grouped in this division.(Tanah ini mengandung persentase besar dari bahan fibrous organik, seperti gambut, dan dekomposisi tanaman. Beberapa kondisi, akan ditemukan cangkang, sisa arang dan non soil yang terakumulasi bersama lapisan ini).
Untuk melengkapi bahan bacaan para Geotech. Di bawah ini akan tersedia link untuk mengunduh ASTM D 2487-98 Standart Practise For Classification Of Soils For Engineering Purpose (Unified Soil Classification System or USCS).
Ref : http://theconstructor.org/