File Name: liquid limit and plastic limit test of soil .zip
Soils intended to support structures, pavements, or other loads must be evaluated by geotechnical engineers to predict their behavior under applied forces and variable moisture conditions. Soil mechanics tests in geotechnical laboratories measure particle size distribution, shear strength, moisture content, and the potential for expansion or shrinkage of cohesive soils. Atterberg limits tests establish the moisture contents at which fine-grained clay and silt soils transition between solid, semi-solid, plastic, and liquid states. In , Swedish chemist and agricultural scientist Albert Atterberg was the first person to define the limits of soil consistency for the classification of fine-grained soils. Karl Terzhagi and Arthur Casagrande recognized the value of characterizing soil plasticity for use in geotechnical engineering applications in the early s. Casagrande refined and standardized the tests, and his methods still determine the liquid limit, plastic limit, and shrinkage limit of soils. This blog post will define the Atterberg limits, explain the test methods, and discuss the significance of the limit values and calculated indexes.
Contents [ hide show ]. The consistency and behavior of a clayey soil is different as are the engineering properties at varying degrees of moisture content. Thus, the boundary between each state can be defined based on a change in the clay's behavior. Swedish scientist Albert Atterberg was the first person to define the limits of soil consistency for the classification of fine-grained soils and later, they were refined by Arthur Casagrande. Depending on the water content of a soil, the soil may be in one of four states: solid, semi-solid, plastic and liquid. The Liquid Limit LL or w LL , also known as the upper plastic limit, is the water content at which the soil changes from the liquid state to a plastic state. It is the minimum moisture content at which a soil flows upon application of very small shear force.
Historical Version s - view previous versions of standard. More D 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. See Section 6 , Interferences. When subjected to repeated wetting and drying cycles, the liquid limits of these materials tend to increase. The amount of increase is considered to be a measure of a shale's susceptibility to weathering.
The plastic limit is one of the measured parameters of the Atterberg limits test ASTM, , which is used for differentiating consistency states of finer particles in soil material. If coarser particles are present coarse sand, gravel, cobbles , the finer particles act as matrix and may govern the behavior of the soil mass. Consistency states depend on water content; with increasing water, the consistency states are solid, semisolid, plastic, and liquid. The plastic limit is the water content at which a soil-water paste changes from a semisolid to a plastic consistency as it is rolled into a 3. The Atterberg limits test also includes the plasticity index, which is calculated as the difference between the liquid limit and the plastic limit. All Atterberg limits are determined on samples of soil that pass the 40 sieve ASTM, , which has 0.
The Atterberg limits are a basic measure of the critical water contents of a fine-grained soil : its shrinkage limit , plastic limit , and liquid limit. 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 authors would like to thank the discusser for his interest in their paper and for his contributions on the mechanisms taking place within the plastic limit test. This, however, depends on the purpose for which a plasticity index is required.
Undrained shear strength of a soil at the liquid limit water content can be considered to be around 1. Plasticity index of soils has been defined by one school of thought as a range of water content producing a fold variation in their undrained shear strength. The undrained shear strength-water content relationship has been found to be linear in the log—log plot for a wide range of water contents beginning from around the plastic limit to near the liquid limit. Normalization of undrained shear strength—water content relationship in a log—log plot has led to the conclusion that the water content at the liquid limit and at the plastic limit, obtained by cone penetration, could also be uniquely related. This contradicts the original understanding of Atterberg limits, namely liquid and plastic limits which are two independent parameter not related at all. Undrained shear strength of a soil from water content around the liquid limit to water content around the plastic limit can be determined by the fall cone test. Determination of liquid limit by the fall cone test is based on the premise that soil assumes a unique state at the liquid limit yielding a unique shear strength.
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Organic soils in particular undergo changes as a result of oven-drying or even extended air-drying. Other soils containing clay may agglomerate, lose absorbed.Reply