The test shall be repeated if unless the difference between the two trail plastic limit is smaller than Repeat the test if the difference between the two trial plastic limits is greater than the acceptable range for two results that is, 1.4 percentage points. Knowing the type of soil makes it possible to determine the right protective system to keep workers safe when they're working in an excav… From all the moisture contents obtained from the test samples, the average gives the plastic limit of the soil. Test Procedure. The number of times it can be rolled into a thread without crumbling is a measure of the degree of plasticity of the soil. In this regard, soil can be considered as the foundation of all types of surface construction. e. The hardness of water may differ soil freshment. Determination of Plastic Limit is as important as Liquid Limit so as to ascertain Plasticity Index, I p of the soil. Take about 8 gm of this wet soil, make a ball out of it, and roll it on the glass plate with the palm of the hand to form a thread of uniform diameter. Definition of plastic limit test. The soil thread is rolled continuously until the diameter of the thread is 3.2 mm. For clayey soils, allow sufficient time for moisture equilibrium. It was re-designated as UBC Test Standard 18-1 in the 1994 code. This test confirms the Work and Time from LL to PL test. Casagrande (1958) studied different types of soil and evaluated plasticity by the Atterberg limits. ASTM C 136: Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates . 2. Test Procedure. As the starting procedures of liquid limit test and plastic limit test are common, the both tests are executed at the same time in most of the purposes. These test methods cover the determination of the liquid limit, plastic limit, and the plasticity index of soils. | Methods of Irrigation(Types) | Advantages & Disadvantages of Irrigation, Civil Engineering Knowledge – Indian Standard, Scaffolding | 7 Types of Scaffolding | Components, Uses & Precautions in Scaffolding, Dog Legged Staircase | Design, Components, Advantages & Disadvantages of Dog Legged Staircase, Honeycombing in concrete | Causes, Effects & Prevention of Honeycombing | 3 Types of Honeycomb, Surkhi Mortar | 3 Types of Surkhi Mortar | Advantages and Disadvantages of Surkhi Mortar, Closed Traverse | Numerical of Closed Traverse | Plotting of Closed Traverse, Breast Wall | Uses & Design of Breast Wall | Advantages & Disadvantages of Breast Wall, Pointing in Construction | 8 Types of Pointing | Importance & Uses of Pointing | Advantages & Disadvantages of Pointing, General Test Procedure of Plastic Limit Test, Ranging in Surveying | Types of Ranging | Direct Ranging | Indirect Ranging, Flow Net Construction by Graphical Method. Determination of Plastic Limit is as important as Liquid Limit so as to ascertain Plasticity Index, I p of the soil. Introduction to Plastic limit test of soil. Preparation of the Soil Sample: The preparation of the soil sample includes the following listed steps: a. Depending on the moisture content of a soil, it will appear in one of four states; solid, semi solid, plastic and liquid. It is the water content at which soil changes from plastic state to semi-solid state or it is the minimum water content at which soil rolled into threads of 3 mm diameter just crumbles. High drying time indicates a soil of medium to high plasticity. The results of this test indicate the following: 1. This testing method is used as an integral part of several engineering classifications systems to characterize the fine‑grained fractions of soils and to specify the fine‑grained fraction of construction materials. Soil Testing Labs. Indicate the type of plants that will be grown in the sampled area (such as lawn, trees and shrubs, flowers, vegetable garden or fruit trees). The adsorbed water in clayey soils is leads to the plasticity of soil. Plastic Limit (PL) test BS 1377: part 2: 1990: 5.3 Soil formation and classification Calculations: Plasticity Index (PI) = LL – PL = 64 -27 = 37 Activity of a clay = I p / % of clay = 37/11.25 = 3.0 Activity is used as an index of swelling potential of clays. Roll a small amount of wet soil between the palms of your hands until it forms a long, round strip like a wire about 3 mm thick. It gives an idea regarding the consistency of soil. The Liquid Limit (LL) of a soil is defined as the moisture content above which the soil behaves as a liquid, and the Plastic Limit (PL) is the moisture content above which the soil behaves plastically. One such test of soil is the plastic limit test. 4. The taken soil sample is then moulded into an ellipsoidal mass. Fig.5:performing plastic limit test on soil sample. A gentle downward force is then applied simultaneously and back and forth motion is applied to the top plate so that the top plate comes into contact with the side rails of the device within 2 minutes. It is denoted by ω P. Low drying time indicates a soil of low plasticity… The plastic limit of a soil is the moisture content, expressed as a percentage of the weight of the oven-dry soil, at the boundary between the plastic and semi-solid states of consistency. This is known as the liquid state. The note draws attention to the distinction between elasticity and plasticity in soils and investigtes the behavior of soils in the laboratory cylindrical compression test as a result of this distinction. Although it is the most used method to evaluate plasticity, the large number of variables involved hinders a detailed correlation of the parameters with the behavior of the clay. Cohesionless soils are non-plastic. Compaction Factor Test – Workability of Concrete, Retaining Walls – Types, Design, Stability, Concrete Curing – Methods – Curing of Concrete. Low plasticity … Plasticity of Soils. The plasticity index (PI) is a measure of the plasticity of a soil. Plastic limit of soil can be defined as the water content at which the soil begins to crumble when rolled into threads of the specified size. Plasticity Index of Soil Plasticity Index of Soil (PI) It is the numerical difference between the liquid limit and the plastic limit of a soil and indicates the magnitude of the range of the moisture contents over which the soil is in a plastic condition as defined by the tests. The Swedish Scientist, A. Atterberg defined the plastic limit as, boundary of soil between the plastic and solid state. Plastic Limit (PL) Liquid Limit (LL) Increasing moisture content Semi- Solid Plastic Liquid STATE LL = PL PI = 0 Non plastic (silt) LL > PL PI > 0 Plastic clays PI = LL-PL Burmister (1949) Classification 5-10 Low plasticity 1-5 Slightly plastic 0 Nonplastic >40 Very high plasticity 20-40 High plasticity 10-20 Medium plasticity PI Description. If sufficient water is mixed with a soil it can be made into a slurry and behaves as a thick or viscous liquid. ASTM D 4318: Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils. The plasticity index of a soil is the numerical difference between the liquid and plastic limits, the range of water content over which the soil behaves plastically. The test procedure of the plastic limit test of soil includes the following series of steps: 1. b. Soil should contain a sufficient amount of water to be fresh and should show the plastic state(soil in liquid state with viscous nature) when moulded in different shapes. Soils possessing the characteristics of more than one group are termed as boundary soils and are designated by dual group symbols. Field test for plasticity of wet soil . Inactive clays: < 0.75 Normal clays: 0.75 – 1.25 Active clays: > 1.25 41 The plasticity of a soil is its ability to undergo deformation without cracking. Plastic Limit Rolling Device (optional). The liquid limit, plastic limit, and plasticity index of soils are also used extensively, either individually or together, with other soil properties to correlate with engineering behavior such as compressibility, hydraulic conductivity (permeability), compactibility, shrink-swell, and shear strength. It is an indication of the “clayeyness” or plasticity of a clay. You have entered an incorrect email address! This test confirms the Work and Time from LL to PL test. Engineering Properties:-The main engineering properties of soils are permeability, compressibility and shear strength. One complete motion of the hand forward and back to the starting position is regarded as one stroke count. 5. Plasticity testing is a basic measure of the nature of fine particles of a soils, <0.425 mm. The main importance of the plastic limit test of soil can be summarized as follows: 1. When the plasticity index and liquid limit plot in the hatched portion of the plasticity chart, the soil is given dual symbol CL – ML. Coarse grained soils are those soils whose individual particles are visible by the naked eye. AASHTO T 87 – Dry Preparation of Disturbed Soil and Soil Aggregate Samples for Test . After the sample of soil has dried properly, about 1.5 to 2.0gm of the soil specimen from the prepared plastic limit specimen is taken. The value of the plastic limit is used to classify the fine-grained soils and evaluating the activities of clayey soil. 4. Plastic limit test is one of the laboratory tests used internationally to differentiate or classify soils into groups. The results in Figures 6.1 and 6.3 indicate that CS may be used with high-plasticity soil to reduce its plasticity. Plastic limit is defined as the minimum amount of moisture content, in percent, at which a cohesive soil change from a plastic state to a semisolid state. This includes all soils having more than 50% of its particles passing a No. The properties of the soil such as plasticity, compressibility or strength of the soil always affect the design in the construction. It is an important index property of fine grained soil, especially for clayey soils. Add distilled water and thoroughly mix such that the soil mass becomes plastic enough to be easily molded with the fingers. Compressibility indicates deformations produced in soils (C.L.). Atterberg soil indexes are calculated from the test results of liquid and plastic limits tests to classify soil types and properties: Plasticity Index, or PI, is the plastic limit subtracted from the liquid limit and indicates the size of the range between the two boundaries. 7. Ground Glass Plate: The ground glass plate having 30 cm (12 in.) It indicates the degree of plasticity of the soil. Clays are known to be the plastic fines. 3. AS 1289 3.2.1 Determination of the plastic limit of a soil – Standard Method AS 1289 3.3.1 Calculation of the plasticity index of a soil AS 1289 3.4.1 Determination of the linear shrinkage of a soil – Standard Method Testing to the relevant sections of AS 1289 was … 3. Casagrande defined the plastic limit as the water content at which a thread of soil just crumbles when it is carefully rolled out to a diameter of 3 mm (1/8”). sides and square in shape with a thickness of 1 cm. It indicates the toughness index of soil. 40 sieve, according to ASTM D4318-00 (ASTM, 2003). | Advantages, Disadvantages & Uses, What is Irrigation? For plasticity, use the test to determine wet-soil plasticity (see Section 8.1). A ball formed from clay-like soils, which have high plasticity, can be tossed repeatedly from hand to hand without breaking. The test results are used for the design of conventional and piled foundations but can also be used in short term stability of slopes and underground openings. Simple Correlations Between Soil Plasticity and Expansion Potential Soil Expansion Potential (ASTM D-4829) This test was developed in Orange County, California in the mid-1960s and introduced in the 1973 Uniform Building Code as UBC Test Standard 29-2. You may want to e-mail or telephone the soil testing labs prior to sending your soil sample to obtain current soil processing procedures and fees. When the plastic limit is equal to or greater than the liquid limit, the plasticity index is reported as zero. A soil sample is subjected to three stresses at right angles with the vertical stress increased until the specimen fails. The value of the plastic limit is used to classify the fine-grained soils and evaluating the activities of clayey soil. Activity Number of a soil sample is the ratio of the plasticity index to the clay-size fraction (particles finer than 2µm). Why to test Liquid limit of Soil? The main importance of the plastic limit test of soil can be summarized as follows: 1. Units of Measure The plasticity index of a soil is the numerical difference between its liquid and plastic limits. Plastic limit test is one of the laboratory tests used internationally to differentiate or classify soils into groups. Thus, distilled water can be used. 3. b. The Plastic limit test is performed by repeated rolling of an ellipsoidal-sized soil mass by hand on a non-porous surface. Calculate the average of the two water contents (trial plastic limits) and round to the nearest whole number; this value is the plastic limit, PL. Plasticity Index is the range of water content over which a soil behaves plastically. The longer the drying period, the greater the capacity of the soil to hold water. Materials that cannot be rolled in this manner are nonplastic or have extremely low plasticity. Fine grained soils are those soils whose individual particles are not visible by the naked eye. Save my name, email, and website in this browser for the next time I comment. Lay persons can get a rough measure of soil plasticity by the ball test, the worm test … Lay persons can get a rough measure of soil plasticity by the ball test, the worm test and the dilatancy test. 2. The Ball Test. Inactive clays: < 0.75 Normal clays: 0.75 – … AND PLASTICITY INDEX OF SOILS. 2. The basic definition of plasticity is: The property of a material to be deformed repeatedly without rupture by the action of a force, and remain deformed after the removal of force. The water content of the soil taken is then reduced to a consistency such that it can be rolled easily without the soil sticking on the hands by spreading or by mixing the soil continuously on the glass plate or in the mixing dish. Plasticity index is a measure of degree of plasticity of soil which indicates qualities of binding particles exist in clay soil. Geologists traditionally measure soil plasticity by cutting a groove in soil placed in a plastic cup and dropping the cup repeatedly onto a plastic base to see how many blows it takes for the groove to close. As the starting procedures of liquid limit test and plastic limit test are common, the both tests are executed at the same time in most of the purposes. 6. Low-plasticity soils such as silt, fall apart when tossed back and forth. Hand Rolling Method: In the hand-rolling method, the rolling of the soil mass is done manually by hands. To know more about coarse grained soil and fine grained soil please read m… A two (2) inch sample of the “snake” is broken-off and held by one end. Finally, the water content of the soil contained in the containers is determined. This process is continued until the thread crumbles and the soil can no longer be rolled into a 3.2-mm diameter thread. Stress and strain paths obtained in drained and undrained cylindrical compression tests on a variety of undisturbed and remodeled soils are examined. While performing the experiment, temperatures should be maintained to prevent fast dryness of the soil. Figure 16-6.-Roll or thread test. Plasticity testing is a basic measure of the nature of fine particles of a soils, <0.425 mm. b. It indicates the amount of clay present. This standard was adopted by ASTM in 1988. It must be taken care that during the rolling process, the end the thread of soil must not contact the side rail. ASTM D 6913 (formerly part of ASTM D 422): Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis Soils consist of particles with various shapes and sizes. Then, the soil thread is broken into several slices and the slices are squeezed together, kneaded between the thumb and first finger of each hand, reformed into an ellipsoidal mass and finally re-rolled. eb 15-025 page 2 of 16 table of contents i. introduction.....3 ii. They will expand in wet conditions and shrink in dry conditions. If the soil holds together, the soil is considered to be cohesive. High plasticity (CH). The top plate is placed in contact with the soil mass. The general test procedure of the plastic limit test has been briefly explained below. Plastic Limit (PL) test BS 1377: part 2: 1990: 5.3 Soil formation and classification Calculations: Plasticity Index (PI) = LL – PL = 64 -27 = 37 Activity of a clay = I p / % of clay = 37/11.25 = 3.0 Activity is used as an index of swelling potential of clays. View fullsize. This test method describes the procedures for determining the liquid limit, plastic limit, and plasticity index of a soil including cement or lime treated soils. 2. This parameter cannot be negative if plastic limit, in some exceptions, is larger than liquid limit, ignoring negative value, it is considered zero. The thread is then further deformed on each stroke such that the diameter of the soil thread reaches 3.2mm. Information regarding the plasticity of a soil is very important in soil engineering and certain standard limits tests have been prescribed for determination of the same. It indicates the degree of plasticity of the soil. After performing a visual test, you can use the plasticity test to determine if the soil is cohesive or granular. The plasticity index is the size of the range of water contents where the soil exhibits plastic properties. The thumb penetration test can be used to estimate the unconfined compressive strength of cohesive soils. The Atterberg Limits (ASTM Test D-4318) define the ranges in moisture content that a soil will behave as a solid, plastic and liquid. For example, symbols GW – GC means that the soil is well-graded gravel with some clay fines. A metallic rod having a diameter of 3.2mm and 100mm long. Sieve Analysis of Aggregates. The plastic limit is essential to ascertain the plasticity index of the soil. Again, another 1.5 to 2.0gm of the prepared soil from the specimen is taken and the process up to step 3 is repeated until the container has at least 6gm of soil sample. The liquid and plastic limits of soils are both dependent on the amount and type of clay in a soil and form the basis for the soil classification system for cohesive soils based on the plasticity tests. In this regard, the soil is considered non-plastic if the soil thread cannot be rolled down to 3.2 mm at any possible moisture conditions. Most method for determination of plastic limit is by rolling a thread of soil (on glass plate) until it crumbles at a diameter of 3 mm. Permiability indicates facility with which water can flow through soils. 2. If the moist soil rolls into a thread, it has some plasticity. For sandy soils, first determine the plastic limit; if it cannot be determined, report the plasticity index as Np (non-plastic). The plasticity of a soil is its ability to undergo deformation without cracking. In other words, the plastic limit may be defined as the moisture content where the thread of soil breaks apart at a diameter of 3.2 mm (about 1/8 inch). Then, the pieces of the crumbled thread are collected together and placed in a container of known mass. 400 mm Canadian Metric sieve. cone penetrometer for Liquid limit and plasticity index test of soil: Cone Penetrometer Test Standard : IS 2720-Part 5:1985, Reaffirmed 2010 Test Apparatus: Cone penetrometer; Evaporation dishes; Air tight containers; Spatula, 425 micron IS sieve; 45cm square and 10mm thick glass plate, pallet knives, Balance of 0.1 gm accuracy, Beaker, Oven thermostatically controlled. Low drying time indicates a soil of low plasticity… The plastic limit of a soil is the moisture content, expressed as a percentage of the weight of the oven-dry soil, at the boundary between the plastic and semi-solid states of consistency. For cohesive soil, the thumb penetration and pocket penetrometer tests help determine the unconfined compressive strength. Sandy soil and gravelly soil fall in this group. Significance of plastic limit. Plasticity Chart for USCS to identify the type of soil based on its Atterberg limitsUsing the Atterberg limits of the soil sample found in the simplified Table 6, it can be seen that the soil used in the experiment is classified under CL or clays with low plasticity (lean clays). Thus, to ensure the quality of the soil, various tests are conducted. About 20gm (minimum) of the soil is taken which is selected from the soil prepared for the liquid limit test. The adsorbed water in clayey soils is leads to the plasticity of soil. Soil can be regarded as the structural basis of any type of construction as the majority of the structures are erected on the soil itself. If your soil samples have been analysed and classified using the USDA textural classes (see Table 4) , you may use this as a basis for defining the USC group to which your soil samples belong, as shown in Table 24 . 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