Consistency or Liquidity Index of Soil (LI) It is defined as the natural moisture content of the soil in excess of the FL expressed as a percentage of the PL, i.e., { (Natural moisture content—PL )/(Liquid limit—Plastic limit) }x 100 Percent and is a measure of the consistency of the soil. Its also called as water plasticity ratio. It can be defined as the maximum water content at which a reduction in water content will not cause a decrease in the volume of soil mass. The shrinkage limit is useful to estimate the expected settlements of structures due to drying of soils with change of seasons. Liquid State. 8. Thus, if the consistency index of a soil is equal to unity, it is at the plastic limit. The decrease in the volume of the soil with the decrease in the water content due to drying/evaporation is called as shrinkage. In all these cases, a high plasticity index is desirable for better workability and low permeability. 3. IS â 2720 (Part 5) â 1985 describes the procedure for the determination of plastic limit. The consistency limits have also been related to various other properties of soils. 5. It is relative ease with which a soil can be deformed. It is the lowest water content possible for the … 1. The shear strength of all soils is found to be the same, equal to about 27 g/cm2 or 0. The average water content out of three trials to the nearest whole number is reported as the plastic limit. Shrinkage limit is the water content at which the soil changes from the semi-solid state to the solid state. When this condition is reached, the water content of the pieces of soil thread is determined. The plasticity index is a useful measure to verify the suitability of clay for potteries, for the construction of the clay core in an earth dam, and for the construction of a clay liner to contain a polluted material. Soils with higher flow index (steeper flow curve) will have lower shear strength if the plasticity index is the same. It is the minimum water content at which the soil is still in the liquid state but possesses small shear strength against flow. 3.CONSISTENCY INDEX:- (Ic,CI) - Soil indicate hearness of water control of soil to its plastic limit. ; 6.78% 40.94~. The toughness index is a measure of the shear strength of the soil at its plastic limit and for soils with same plasticity index, the toughness is inversely proportional to flow index. standard liquid limit device, it is defined as the minimum water content at which a part of soil cut by a groove of standard dimension will flow together for a distance of 12mm (0.5ââ) under an impact of 25 blows in the device. 5. 10. (As shown in the fig.). The lower the shrinkage limit, the higher will be the possible settlements of structures. The apparatus consists of a flat square glass plate of minimum 45-cm size and 10-mm thickness, a rod of 3-mm diameter, oven, and containers for water content determination. Expansive soils also have low values of shrinkage limit. Hence these properties are generally used in the identification and classification of soils. In the semisolid state, the soil does not have plasticity and it will be brittle. A definite quantity of soil is dried in an electric oven (for 24 hrs at 105°C) and put in the top sieve. Consistency denotes the firmness of soil, which may be termed as soft,firm,stiff or hard. 13. The boundary water contents at which the soil undergoes a change from one state to another are called consistency limits. Soil consistency is also an important physical and dynamic property which varies with the variation of soil moisture and applied stress. Atterberg limits or consistency limits are the arbitrary limits of water content at which the soil mass passes from one state to another state. Liquid limit is the water content at which a soil changes from the liquid state to the plastic state. is a prerequisite. In 1911, Atterberg, a Swedish agricultural engineer, stated that a fine-grained soil can exist in four states, namely, liquid, plastic, semi-solid, or solid state, depending on its water content. Following is the procedure for the determination of plastic limit of the soil: i. The liquid limit is high for soils containing montmorillonite clay mineral, medium for soils containing illite, and minimum for soils containing kaolinite clay mineral. 1.About 120 gm of air-dried soil from thoroughly mixed portion of material passing425 micron I.S sieve is to be obtained. Where, V1 = vol. Through evaporation, crushing strength and Table 1. 1. Experimentally the plastic limit is defined as the water content at which a soil begins to crumble (forms cracks) when rolled into a thread of 3-mm diameter. loam, 24.18 and 30.50% for silty loam, 25.01 and 38.50% for … Soils with higher plasticity index have a higher dry strength and lower permeability compared to soils with lower plasticity index, although their liquid limit is the same. Published by: civilqa, Your email address will not be published. The index properties which are used are: Grain Size Distribution Consistency Limits Plasticity Index The sieves are arranged, keeping the finest below and the coarser above it. They are also used directly in specifications for controlling compaction used for the construction of embankments and Earth dams. They are of great significance in understanding the behaviour of clays. The liquid limit and the plasticity chart are used to classify fine-grained soils. Hard plastic consistency; E--F: Plastic limit; G-H: Friable-firm consistency; 1: Hard firm consistency. It is also the lowest water content at which a soil can still be completely saturated. 3.A portion of the paste is placed in the cup ofLIQUID LIMIT device and spread intoportion with few strokes of spatula. The plastic 1i mit is that water content at which a 1/8 in. This specific water contents are known as consistency limits. Introduction The physical analysis of soil tilth is one of the … The Plastic Limit (PL or w PL), also known as the lower plastic limit, is the water content at which a soil changes from the plastic state to a semisolid state. - Ic is zero at liquid limit. About 60 g of air-dried soil passing through 425 pm IS sieve is taken and mixed with sufficient water such that its water content is more than the estimated plastic limit and such that the soil becomes plastic enough to be easily molded with fingers. The consistency of soils according to Atterberg limits gives the following diagram. iii. Soil can no longer behave as plastic; any change in shape will cause the soil to show visible cracks. Semi Solid . Soil has different different states depending upon its water content such as - 1. Depending on its water content, a soil may appear in one of four states: solid, semi-solid, plastic and liquid.In each state, the consistency and behavior of a soil is different and consequently so are its engineering properties. The test is repeated taking another portion of the soil paste; a total of three trials are made and the corresponding water contents are determined. Thus, when the water content of a given soil is more than its liquid limit, the soil will be in liquid state and has negligible shear strength. Defination Soil consistency is the strength with which soil materials are held together or the resistance of soils to deformation and rupture. v. The procedure of rolling into a thread of uniform diameter of 3 mm and kneading back into a ball is repeated until cracks appear on the surface of the soil thread, which begins to crumble. As per laboratory concern, w.r.t. Skempton gave an equation for compression index in the terms of liquid limit. 1) Liquid limit The higher the liquid limit and plasticity index, the more severe will be the anticipated problems due to compressibility, swelling, and shrinkage to the foundations and to the structure located in such soils. The water content at which the soil changes from one state to other is known as the Consistency limit. A negative consistency index indicates that the soil has a natural water content greater than the liquid limit and hence behaves just like a liquid. Consistency index is a measure of the shear strength of the soils. A soil cutting test rig Keywords: was developed to perform soil cutting at three consistency limits (sticky limit, plastic limit and liquid Sticky limit limit) and the sticky point of soil, three rake angles (158, 308 and 458), and three operating depths Sticky point Flat triangular shaped tool (30 mm, 50 mm and 70 mm). diameter thread of soil begins to crack and crumble under continued rolling by hand. 11. In general, the higher the liquid limit, the higher will be the swelling of the soil on wetting. When the water content is between the liquid limit and the plastic limit, the soil exhibits plasticity, that is, the soil can be molded to any shape without rupture. Skempton related compression index of soils to the liquid limit. The higher the consistency index, the higher will be the unconfined compressive strength of the soil. Representative of our own empirical and pragmatic genius are the well-known Michigan method and also the more or … The liquid limit and plasticity index are extremely useful for the classification of soils. The liquid limit is an important index property of fine-grained soils and helps predict its swelling and compressibility behavior under loads. - Ic is 100% When soil is relatively strong, as it is in semi solid stage. The shrinkage limit is the water content below which the soil does not undergo any shrinkage and is in solid state. the plastic limit is one of the limits of atterberg limits. The soil properties on which their classification and identification are based are known as index properties. consistency for agricultural purposes to get a clear concept of the range of water contents of a soil in the plastic state (Atterberg, 1911). These limits are liquid limit, plastic limit and shrinkage limit. The boundary water content between plastic state and semisolid state of consistency of soil is called plastic limit. weight of mercury)/W0]*100 PLASTIC LIMIT: The crushed soil sample is taken and passed through 425µ m IS sieve. •Liquid Limit(LL) is defined as the moisture content at which soil begins to behave as a liquid material and begins to flow. iv. The water contents at which the soil changes from one state to the other are known as consistency limit. The Atterberg limits which are most useful for engineering purpose are the liquid limit, plastic limit and shrinkage limits. of soil mass at water content w2 %, September 15, 2018
It is also the maximum water content below which the volume of the soil remains constant irrespective of the change in the water content. That means we need 25% of water in volume to make a standard consistency of cement. Plastic Limit: The minimum water content at percent on dry bases at which a soil enters from semi-solid state to plastic state is known as plastic limit and this test involves rolling out a thread of the fine portion of soil on a non-porous, flat surface. 2. The three consistency limits are shown in Fig. It is the minimum water content at which the soil remains in plastic state and can be molded to any shape without rupture. In 1911, Mr. Atterberg (A Swedish soil scientist) first demonstrated the significance of these limits, hence these limits are termed as Atterberg limits. Cone index (kPa) Sticky limit 15 1.22 0.0012 26 106 17.7 1.25 0.001 29 109 Plastic limit 22 1.32 0.0005 16 104 32 1.4 … In practice , the property of consistency is associated only with fine – grained soils, especially clay. 1. In this article we will discuss about the types and uses of consistency limits of soil. The liquid limit is a measure of the compressibility of the soil, that is, the decrease in volume of saturated soils under loads from the structure. In general, the higher the clay content present in a given soil, the higher is the liquid limit. The Plastic limit test is performed by repeated rolling of an ellipsoidal-sized soil mass by hand on a non-porous surface. ii. 4. strength with which soil materials are held together or the resistance of soils to deformation and rupture Liquid limit test:(Mechanical liquid limit device) Object: Determination of the liquid limit of soil by mechanical liquid limit device. Required fields are marked *. Such soils cannot sustain heavy loads at high water content. When soil is at plastic limit, the liquidity index is 0. 6. View CONSISTENCY LIMIT TEST.docx from CIVIL ENGI 1012488 at UCSI University, Cheras. The boundary water content between liquid state and plastic states of consistency of soil is called liquid limit (As shown in above figure.) Earth work can be carried out easily with the least effort when the water content of the soil is at plastic limit. It can also be defined as minimum water content at which a soil will just begin to crumble when rolled into a thread of about 3mm in diameter. The liquid limit of soils can be determined by any one of the following two methods: Plastic limit is the water content at which a soil changes from the plastic state to the semi-solid state. There are some definite water contents which are decide the state of the soil. The plastic and liquid limits obtained by the Casagrande’s method were 22.10 and 26.30% for. Solid. When the diameter of the soil thread reaches 3 mm, the soil thread is worked back to form a ball. Save my name, email, and website in this browser for the next time I comment. - It is also known as relative consistency. Consistency limits and its determination. The water contents at which the soil changes from one state to the other are known as consistency limits or Atterberg limits. This problem has been attacked in different ways by different agencies and countries. It merely describes the … Shrinkage limit =[ W(V-V0)(sp. Liquidity Index. It indicates the relative ease with which a soil can be deformed. 4. 14. So soil consistency is being discussed as a separate chapter after giving some idea about soil water. 2.Distilled water is mixed to the soil thus obtained in a mixing disc to formuniform paste. • A small portion of the ball is taken and is rolled on the glass plate with fingers, to make it into thread of uniform diameter of 3mm over its entire … It can also be defined as minimum water content at which soil flows by gravity with a little or no shearing resistance. 4.Trim it to a depth o… The water contents at which the soil changes from one state to the other are known as … Some Chemical and Physical Properties of Kojima Polder Soil Mechanical composition >2.0mm 2.0-0.2mm 0.2.0.02mm 0.02-0.002mm <0.002mm Degree of dispersion Coefficient of permeability 0 0.81~. - Ic is 100 % when soil is dried in an electric oven ( for 24 hrs at )., SL shrinkage limit ; G-H: Friable-firm consistency ; 1: hard firm consistency remains constant of! 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