This method covers the determination of the plastic limit of a soil as defined hereunder by measuring the lowest moisture content at which the soil can be rolled. Determination of plastic limit of soil the constructor. The plastic limit of a soil is the moisture content. The liquid limit ll it is defined as the percentage moisture content at which a soil changes with decreasing wetness from liquid to plastic consistency or with increasing wetness from plastic to liquid consistency. Determination of plastic limit is as important as liquid limit so as to ascertain plasticity index, i p of the soil.
At this water content plastic limit, the soil will crumble when rolled into threads of 3. Limitations of liquid limit test procedure for determination of the plastic limit. Determination of the plastic limit of a soil by means of a. The average of the three tests will be the plastic limit of the soil. In order to promote public education and public safety, equal justice for all, a better informed citizenry, the rule of law, world trade and world peace, this legal document is hereby made available on a noncommercial basis, as it is the right of all humans to. Liquid limit, plastic limit, and plasticity index of soils abstract atterberg limits are a basic measure of the critical water contents of a finegrained soil, such as. The value of liquid limit helps in classification of fine grain soil. Prasanna3 a note on the determination of plastic limit of finegrained soils geotechnical testing journal, vol. The plastic limit signifies the percentage of moisture at which the soil changes, with decreasing wetness, from a plastic to a semisolid state, or with increasing wetness, from the semisolid to the plastic state. It then starts to crush when rolled into filaments of 3mm diameter. Methods of testing soils for engineering purposes soil classification tests determination of the plastic limit of a soil standard method standard by standards australia, 01011995. The plastic limit of a soil is the moisture content at which soil begins to behave as a plastic material. After we have done the experiment liquid limit and plastic limit tests, we found that the plastic index of the soil is equal to 27 and the liquid limit of the soil is equal to 50.
The use of this technique for the plastic limit determination and for the identification of nonplastic soils has not been fully explored. Liquid limit ll or wl the water content, in percent, of a soil at the arbitrarily defined boundary between the semiliquid and plastic states. The plastic limit may be defined as the minimum moisture content at which the soil remains in a plastic state. California test 226 determination of moisture content by oven drying. Liquid limit ll is defined as a limiting water content separating the viscous liquid state and plastic state of soil consistency. 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. The plastic limit pl is the water content, in percent, at which a soil can no longer be deformed by rolling into 3. Bearing capacity determination by limit analysis by wai f. Soil is treated as a perfectly plastic medium with the associated flow rule after drucker. Any fine grained soil having natural water content close to its plastic limit is expected to have high shear strength and low compressibility. Standard test methods for liquid limit, plastic limit, and plasticity index of soils1 this standard is issued under the. The method has potential uses in both plastic limit determination and in shear strength. The standard threadrolling method for determining the plastic limit has long been. The plastic limit is the minimum water content at which soil starts to show plastic behaviour.
Experiment to determine the plastic limit of a given soil. Plastic limit of soilsplastic limit is defined as the lowest moisture content and expressed as a percentage of the weight of the oven dried soil at which the. For assessment of the plastic limit of soil sample theory the plastic limit of a soil refers to the water proportion of the soil beneath which it ends to be plastic. Determination of plastic limit is as important as liquid limit so as to ascertain plasticity index, ip of the soil. Determine liquid limit of soil specimen by casagrande method. What is the plastic limit and liquid limit of soil. The determination of the plastic limit and plasticity index of soils scope this method covers the determination of the plastic limit of a soil as defined hereunder by measuring the lowest moisture content at which the soil can be rolled into threads 3 mm in diameter without the threads crumbling. The device enables the operator to perform the test on four to five specimens simultaneously. From the chart we found that the type of soil was falling under inorganic silts of.
This lab is performed to determine the plastic and liquid limits of a finegrained soil. Pdf plastic limit is an important property of finegrained soils. It flows to close the groove in just 25 blows in casagrandes liquid limit device. Bureau of reclamation division of research and laboratory services geotechnical branch. It is also define as the maximum water content at which a reduction of water content will not cause a decrease in the volume of the soil mass. The plastic limit of a soil is the moisture content, expressed as a percentage of the weight of the ovendry soil, at the boundary between the plastic and semisolid states of consistency. Pdf a note on the determination of plastic limit of finegrained.
Ruwan rajapakse pe, ccm, cce, avs, in geotechnical engineering calculations and rules of thumb second edition, 2016. A rolling device was developed in order to obtain plastic limits in a more expeditious and uniform fashion. In 1911, the swedish agriculturist atterberg divided the entire range of soil state from liquid to solid state into four stages, which is known as atterberg. A note on the determination of plastic limit of fine.
The device may be operated by either a hand crank or electric motor. It is the water content at which a soil changes from plastic to liquid behavior. Dry liquid limit shrinkage limit plastic limit hard candy cheese soft butter lean soup 0. In each state, the consistency and behavior of a soil is different and consequently so are its engineering properties. The primary purpose of this study was to investigate the possibility of using a unique. It also dictates that the very strict specification for rolling the soil threads into diameters of 3. Pdf determination of plastic limit of soil using modified methods.
The operator should at no time attempt to produce failure at exactly 3. With your download, get the 18 best papers relevant to this one, including 14 top related papers. Standard test methods for liquid limit, plastic limit, and. This document covers the determination of the liquid limit and the plastic limit only. As the moisture content of a soil decreases the soil passes from the liquid state to the plastic state to the solid state.
The atterberg limits liquid limit, plastic limit, and shrinkage limit provide a very useful indication of the properties of the tailings. The plastic limit, also known as the lower plastic limit, is the water content at which a soil changes from the plastic state to a semisolid state. A number in parentheses indicates the year of last. The range of moisture contents over which the soil is plastic is used as a measure of the plasticity index. The liquid limit of a soil is the water content at which the soil behaves practically like a liquid, but has small shear strength. Determination of liquid limit and plastic limit of soil. They have been used in soil mechanics for over 50 years, providing a measure of the moisture content at which a soil tailings changes from. Definition liquid limit is defined as the water content at which the soil changes from liquid state to plastic state. Determination of plastic limit of a soils by means of a rolling device a new approach to the determination of the shear strength of clays by the fallcone test theory and practice of the fall cone.
The determination of the plastic limit shall be in accordance with aashto method t90, appendix vi18. The values of liquid limit are required to calculate flow index, toughness index etc. The liquid limit shall be checked by the standard method. The liquid limit is the water content at which a soil changes from a liquid to a plastic state. Plastic limit test, procedures, sample calculations. Determining liquid limits of soils txdot designation. Liquid limit, plastic limit, and plasticity index of soils abstract atterberg limits are a basic measure of the critical water contents of a finegrained soil, such as its shrinkage limit, plastic limit, and liquid limit. In this article test methods used for determination of soil plastic limit in accordance with astm d4148 will be presented. The water content at which soil sample change from plastic state to semisolid state. The liquid limit ll is arbitrarily defined as the water content, in percent, at which a pat of soil in a standard cup and cut by a groove of standard. Pdf plastic limit of nnegrained soib is conventionally determined in the laboratory by the soil thread rolling method. The standard threadrolling method for determining the plastic limit has long been criticized for requiring considerable judgments from the operator. The standard threadrolling method for determining the plastic limit.
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