Soils liquid limit

A group of (originally) seven limits of soil consistency, or relative ease with which material can be deformed or made to flow. The only Atterberg limits that are still in common use are the liquid limit, plastic limit, and plasticity number. 

The difference between the liquid limit and the plasticity limit of a soil or similar material. Also termed the plasticity index . See also Atterberg Limits, Liquid Limit, Plastic Limit. 

On site the soil type is determined by a finger test. For this the soil is moistened down to the liquid limit, then kneaded between the fingers and assessed for roughness by rubbing between the fingers, the feel of the individual granules, and deformability (degree and repeatability). 

After volatilization, biodegradation and photooxidation are the most important removal mechanisms for gasoline hydrocarbons released to surface soils (Air Force 1989). Photooxidation in surface soils is less important than in surface water environments since infiltration of the liquid product into the soil will limit exposure to solar radiation (Bossert and Bartha 1984). 

Atterberg limits Liquid limit Plastic limit Shrinkage limit Soil classification, preliminary indication of behavior such as sensitivity of clays to loss of strength on remolding, and estimate of compressibility of "normally loaded" clays... 

In this system, the acidity of the soil liquid is limited by the amount of mobile anions. The more important are the sulphate, nitrate and chloride ions, all of which originate from the precipitation. The chloride ions are usually accompanied by an equivalent amount of sodium ions, which are not taken up by the plants and retained by the humus to any significant degree. Most of the nitrates are consumed by the vegetation. 

British Standard for soils, for example16, defines a liquid limit at which a soil passes from the plastic to the liquid state and determines it by the liquid limit test. The test consists of preparing a sample of wet soil and pushing it into a test cup. A cone... 

It is not known how the liquid limit for soils compares with the flow moisture limit for coal and minerals it seems that there would be some merit in bringing the two together and comparing their values for different materials. 

Liquid Limit The minimum water content for which a small sample of soil or similar material will barely flow in a standardized test method (9, 10). Also termed the upper plastic limit. See also Atterberg Limits, Plastic Limit, Plasticity Number. 

ASTM Method for Liquid Limit, Plastic Limit, and Plasticity Index of Soils (D 4318-83)... 

Fine-grained soil which contains clay minerals in the presence of water can be remolded. As the amount of water in the soil increases the material moves through various physical states. These states are solid to semisolid to plastic and finally to a liquid state. The Atterberg limits describe the firmness (i.e., consistency) of this remolded soil with varying moisture contents. The transition from semisolid to plastic state is defined as the plastic limit. The point of transition from plastic to liquid state is defined as the liquid limit. Both of these limits are defined in terms of water contents using simple mechanical tests. A third limit defined as the plasticity index is the difference in percent water content between the liquid limit and the plastic limit. The test procedure has been described in detail in ASTM (D4318). 

Reference and Area Texture Mineralogy Organic Matter and Type Soil and Description Liquid Limit (a i) Plastic Limit (a>p) Plasticity Index (7p)... 

Undrained shear strength of remolded material may be estimated on the basis of the index test results. Using the theories of critical state soil mechanics (Schofield and Wroth, 1968), and assuming the undrained shear strength at the plastic limit is 70 times that at the liquid limit, it may be shown (Weaver and Schultheiss, 1990) that... 

Youssef, M.F., El Ramli, A.H., and El Demery M. 1965. Relationships between shear strength, consolidation, liquid limit and plastic Umit for remoulded clays. Proceedings of the 6th International Conference on Soil Mechanics and Foundation Engineering, Montreal, Canada, Vol 1. 

The liquid limit (tt L or LL) of a material is the water content at which the soil passes from the liquid to plastic condition and is determined by the liquid limit test. 

The plasticity index, apart from being used to classify soils into groups or categories, in relation to the liquid limit, makes it possible to comparatively assess soils in terms of compressibility, permeability, volume change and dry strength (cohesiveness in dry conditions). Table 1.4 gives the expected changes on these properties when either 7p (PI) or (LL) varies. 

The test consists of the measurement of the penetration depth of a standard cone, with a mass of 80 g, forced into the soil material. By carrying out measurements at different moisture contents, a diagram similar to the number of blows versus moisture content is obtained. The liquid limit is determined as the moisture content at which the penetration depth is equal to 20 mm. 

The coarse soil material is divided into three major groups (A-1, A-2 and A-3) and seven subgroups (A-l-a, A-l-b, A-3, A-2-4, A-2-5, A-2-6 and A-2-7), depending on the retained percentage in certain sieves, the liquid limit and the plasticity index. The A-1 group is considered to be the coarsest, whereas the A-3 group is the least coarse. 

The group index of a soil material depends on the liquid limit, plasticity index and the percentage passing through the 0.075 mm sieve. The relationship used to calculate the GI is as follows ... 

Figure 1.5 Plasticity index (PI) graph with liquid limit (LL). (Reprinted from ASTM D 2487, Standard Practice for Classification of Soils for Engineering Purposes [Unified Soil Classification System], West Conshohocken, PA ASTM International, 2011. With permission [ ASTM International].)...

AASHTO T 89. 2013. Determining the liquid limit of soils. Washington, DC American Association of State Highway and Transportation Officials. 

ASTM D 4318. 2010. Standard test method for liquid limit, plastic limit and plasticity index of soils. West Conshohocken, PA ASTM International. 

Silts and clays liquid limit greater than 50 Slight to medium Slow to none Slight to medium MH Inorganic silts micaceous or diatomaceous fine sandy or silty soils, clastic silts ... 

The values of these limits are used in various aspects. There is a close relationship between the limits and properties of a soil sueh as eompressibility, permeability and strength. Thus the Atterberg limits are not only used to identify the soil s classification, but it also allows for the use of empirieal correlations for some other engineering properties. Liquid limit test is to elassify soils and to find the plasticity index of soil because different soils have various plastie limits. The shrinkage limit is much less commonly used than the liquid and plastic limits. 

The plasticity index is a measure of the plasticity of a soil. The plasticity index is the size of the range of water contents where the soil exhibits plastic properties. The PI is the difference between the liquid limit and the plastic limit (PI = LL - PL). Soils with a high PI tend to be clay, those with a lower PI tend to be silt. 

Supposing, however, that the displaced materials were fine-grained soils which could be considered to be remoulded. The boundaries between Varnes terms would correspond to their Atterberg limits the Shrinkage, Plastic and Liquid Limits would separate dry, moist, wet and very wet soils. The observations then describe states of the displaced materials rather than water contents. So the term, "condition suggested by Hungr et al. (2001, p. 225) is preferred here. 

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