Classification of soil
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This document discusses different methods for classifying soils, including particle size classification, textural classification, Highway Research Board (HRB) classification, Unified Soil Classification System (USCS), and Indian Standard Classification System (ISCS). The key points are: 1) Soils can be classified based on their particle size, texture, engineering properties for pavement or other uses, plasticity characteristics, and percentage of sand, silt and clay. 2) Classification systems group soils with similar properties together to describe and understand their engineering behavior. 3) The ISCS system is based on the USCS but further subdivides fine-grained soils into low, intermediate and high plasticity groups based on
![CLASSIFICATION OF SOILS
CREATED BY :-
ALAY MEHTA 141080106011
SHIVANI PATEL 141080106021
KAVIN RAVAL 141080106026
KUNTAL SONI 141080106028
by
PranameshChakraborty
GEOTECHNICS AND APPLIED GEOLOGY
[G.T.A.G.]](https://image.slidesharecdn.com/classificationofsoil-151105043115-lva1-app6891/85/Classification-of-soil-1-320.jpg)
Classification of soil
- 1. CLASSIFICATION OF SOILS CREATED BY :- ALAY MEHTA 141080106011 SHIVANI PATEL 141080106021 KAVIN RAVAL 141080106026 KUNTAL SONI 141080106028 by PranameshChakraborty GEOTECHNICS AND APPLIED GEOLOGY [G.T.A.G.]
- 2. Purpose
- 3. Purpose Arrange various types of soils into groups according to their engineering or various other characteristics. Soil possessing similar characteristics can be placed in the same group. 3
- 4. CLASSIFICATION OF SOIL 1. Particle Size Classification 2. Textural Classification 3. Highway Research Board (HRB) Classification 4. Unified Soil Classification System (USCS) 5. Indian Standard Classification System (ISCS)
- 6. Soils arranged according to grain sizes. Terms such as gravel, sand, silt and clay are used to indicate grain sizes. These terms are used only as designation of particle sizes. They do not signify naturally occurring soil types. Naturally occurring soil are mixture of particles of different sizes. Introduction 6
- 7. IS Classification of Grain Size 7
- 9. Soil classification of composite soils exclusively based on Particle Size Distribution. Most popular is the Triangular Classification of U.S. Public Roads Administration. Classification based on % of sand, silt and clay size. More suitable for describing coarse grained soil. Clay soil properties are less dependent on particle size distribution. Introduction 9
- 11. HIGHWAY RESEARCH BOARD (HRB) CLASSIFICATION
- 12. Based on both particle-size composition as well as plasticity characteristics. Mostly used for pavement construction. 7 primary groups (A-1, A-2,…., A-7). A-1 subdivided into 2 subgroups. A-2 subdivided into 4 subgroups. Introduction
- 13. Used to describe performance of soil when used for pavement construction. Not used to place a soil in a particular group. It means rating the value of soil as a subgrade material within its own group. Higher the value of GI, poorer is the quality of material. Group Index (GI)
- 14. Group Index of a soil depends on: 1. Amount of material passing 75 micron IS sieve. 2. Liquid Limit. 3. Plastic Limit. GROUP INDEX (GI) DETERMINATION
- 15. Classification Group Symbols Main Soil Type Prefix Subgroup Suffix Classification Group symbols Gravel G Well-graded Poorly-graded Silty Clayey W P M C GW GP GM GC Sand S Well-graded Poorly-graded Silty Clayey W P M C SW SP SM SC Silt M LL < 50% LL > 50% L H ML MH Clay C LL < 50% LL > 50% L H CL CH Organic O LL < 50% LL > 50% L H OL OH Peat Pt Pt
- 16. Group Symbols and Group Names Group Symbol Typical Name GW Well-graded gravels. GP Poorly-graded gravels. GM Silty gravels. GC Clayey gravels SW Well-graded sands. SP Poorly-graded sands. SM Silty sands. SC Clayey sands.
- 17. Group Symbol Typical Name CL Inorganic clays of low plasticity. ML Inorganic silts with slight plasticity. OL Organic soil of low plasticity. CH Inorganic clays of high plasticity. MH Inorganic silts with high plasticity. OH Organic soil of high plasticity. Pt Peat. Group Symbols and Group Names
- 18. INDIAN STANDARD CLASSIFICATION SYSTEM (ISCS) IS:1498-1970
- 19. Introduction Based on USCS system Modifications are: Fine grained soils subdivided into 3 groups (low, intermediate and high plasticity) as against two groups(low and high) in USCS. wL <35=L, 35<wL <5o=I, wL >50=H Thus, soil classified into 18 groups as against 15 in USCS. 19
- 20. Classification Group Symbols Main Soil Type Prefix Subgroup Suffix Classification Group symbols Gravel G Well-graded Poorly-graded Silty Clayey W P M C GW GP GM GC Sand S Well-graded Poorly-graded Silty Clayey W P M C SW SP SM SC Silt M LL < 35% 35<LL<>50 LL > 50% L I H ML MI MH Clay C LL < 35% 35<LL<>50 LL > 50% L I H CL CI CH Organic O LL < 35% 35<LL<>50 LL > 50% L I H OL OI OH Peat Pt Pt 20
- 21. Plasticity Chart High Plasticity use H - wL >50 Intermediate Plasticity use I – 35< wL >50 Low Plasticity use L - wL <35 Below A-line, use M (Silt) or O (Organic) Above A-line, use C - Clay