Liquid Limit And Plastic Limit Test Of Soil Pdf
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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.
The precise definition of the liquid limit is based on standard test procedures. Liquid Limit can be determined using the Casagrande cup method or a cone penetrometer. In the Casagrande cup method , the soil paste is placed in the Casagrande cup, and a groove is made at the center of it see procedure below.
The limit is defined as the moisture content, in percent, required to close a distance of 0. It is difficult to adjust the moisture content in the soil to meet the required Hence, at least three tests for the same soil are conducted at varying moisture contents, with the number of blows, N, varying between 15 and 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.
The Plastic limit test is performed by repeated rolling of an ellipsoidal-sized soil mass by hand on a non-porous surface. If the thread crumbles at diameter smaller than 3 mm, the soil is too wet.
If the thread crumbles at a diameter greater than 3 mm, the soil is drier than the plastic limit. The sample can then be remolded and the test repeated.
Once the appropriate size rolls are made, their moisture content is assessed using the procedure described previously. The shrinkage limit SL is defined as the water content at which the soil changes from a semi-solid to a solid state.
At this moisture content the volume of the soil mass ceases to change with further drying of the material. The shrinkage limit is determined as follows. A mass of wet soil, M 1 , is placed in a porcelain dish The volume of oven-dried soil is determined by using mercury to occupy the vacant spaces caused by shrinkage. The mass of mercury is determined and the volume decrease caused by shrinkage can be calculated from the known the density of mercury.
Login to your account or register to create a new one to submit your comment. Create a free account and view content that fits your specific interests in geotechnical engineering Learn More. Atterberg Limits Laboratory Testing. The test procedure to find the Liquid Limit of soil consists of the following steps. Cut a groove at the center of the soil paste with the standard grooving tool.
Lift the cup and drop it from a height of 10mm, using the crank-operated cam. Measure the water content required to close a distance of Repeat the procedure at least three times for the same soil at varying moisture contents. Plot the moisture content of the soil, in percent, and the corresponding number of blows on semi-logarithmic graph. Draw the best-fit straight line through the plotted points. The moisture content corresponding to N 25, determined from the curve, is the liquid limit of the soil.
Plastic Limit 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. Image Gallery. Selected Topics. William A. Jun, 25, Geotechnical Engineering has been - throughout th Woods Feb, 03, The following obituary is distributed through the Round Shaft.
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Atterberg Limits: A Quick Reference Guide
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 Plastic Limit is as important as Liquid Limit so as to ascertain Plasticity Index, Ip of the soil. The plastic limit of a soil is the moisture content.
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. While both equations 14 and 15 are statistically significant, it could be argued that these correlations would improve if a plastic limit value based on a strength criterion were available rather than the current one based on ductility.
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.
Теперь уже окаменел Стратмор. Рука Сьюзан задрожала, и пейджер упал на пол возле тела Хейла. Сьюзан прошла мимо него с поразившим его выражением человека, потрясенного предательством. Коммандер не сказал ни слова и, медленно наклонившись, поднял пейджер. Новых сообщений не. Сьюзан прочитала их. Стратмор в отчаянии нажал на кнопку просмотра.
Разве это не услуга. Сьюзан промолчала. Она поняла: все дело в деньгах.