 Hello, this is Dr. Mahesh Kalyanshti, Associate Professor, Department of Civil Engineering, Valchan Institute of Technology, Soolapur. In this session, we will discuss regarding consistency limits of soil. The learning outcome of this session will be, at the end of this session, students will be able to describe various state of consistency of soil. Let us see what is the consistency of the soil. It is defined as the ease with which the soil can be handled or deformed. So it is based on the relative firmness of the soil and the ease with which we can handle the soil. In case of especially fine-grained soil, it is observed that the fine-grained soils are found in following state of the consistencies. For example, a liquid state when the water content is on higher side, then plastic state when the water content is medium, and it is found to be semi-solid or solid state when the water content is very less. So here we can see that the consistency, state of the consistency is totally dependent on the water content of the soil. And as the water content is reduced, the soil changes its consistency from one state to other state. Thus, the same soil which is very soft at high water content becomes soft, medium, stiff, stiff or hard when the water content decreases. So these words indicates the degree of firmness of the soil. So it is very soft for higher water content, then soft for reduced water content, then again it enters into medium, stiff consistency state, then stiff, hard. So these are the terminologies which are used to express the degree of firmness of the soil. So this property of the fine-grained soil to show different degree of firmness at different water content is known as consistency. So this is how we can define the consistency of the soil. Now this consistency is primarily is because of the presence of clay minerals in the soil. So we know that there are many clay minerals present in the soil and these clay minerals impart the plasticity to the soil due to which we observe the different state of consistency in the soil mass. Now let us see what are the soil consistency limits. A scientist called Utterberg developed a method to describe the consistency of fine-grained soil with varying degree of moisture content. He defined several limits of consistency which are called as Utterberg limits. So Utterberg has defined certain limits and these limits popularly are called as Utterberg limits. So the consistency limits of the soils are also called as Utterberg limits. Now what Utterberg says from 0 degree water content as the water content of the soil goes on increasing there are various limits which are been arbitrarily defined by Utterberg. So what he says from 0 degree up to one typical water content we come across with one limit which is called shrinkage limit. Then with the increase in water content again we come across with some arbitrary water content which is called as plastic limit. Further again we come across with a typical water content which is called as liquid limit. So these are the arbitrarily decided limits developed by or proposed by Utterbergs. And further it is said that when the soil is from 0 degree up to shrinkage limit then this state of consistency we call it as brittle or solid. When the soil mass is in between this shrinkage limit and plastic limit then the soil is said to be in semi-solid state and when the water content is in between plastic limit to liquid limit the soil is said to be in plastic limit sorry plastic consistency and beyond the liquid limit the soil is said to be in a liquid state. So these are the different state of consistency of the soils which are primarily based on the arbitrary limits which are set by Utterberg. Let us take another view to this figure which describes the Utterberg limit again. So in this sketch we can see on x-axis the water content is plotted and on y-axis the volume of the soil is plotted. And here we observe some boundary motion contents these are called as Utterberg limits. Now for higher water content see here for higher water content the soil is in a liquid state and it flows like a viscous fluid so it has got a tendency to flow. Slowly as the moisture content is reduced then it enters into a plastic state. So the boundary moisture content at which the soil enters from liquid state to plastic state that boundary moisture content is defined as liquid limit and in this plastic state of consistency the soil deforms without visible cracks. So we can deform the soil and the cracks are not appeared on the surface. And slowly again as the water content is reduced then the soil enters from plastic state to semi-solid state and this boundary moisture content is called as plastic limit. And when the soil is in a semi-solid state then we observe visible cracks due to deformations on the surface. And then from semi-solid state slowly as the water content is reduced further it enters into a solid state where you can see here and that boundary moisture content is called as a shrinkage limit. And beyond shrinkage limit you can see here even if you reduce the water content the soil volume of the soil remains constant it does not change whereas up to shrinkage limit we can see a consistent decrease in the volume of the soil with the decrease in the water content. So therefore this is how we can completely describe various state of consistency and the attribute limits with the help of this sketch. So with reference to this sketch we can define various limits such as liquid limit as it is been told already that it is a moisture content at the point of transition from plastic to liquid then plastic limit it means this liquid limit this limit when the moisture content percent at the point of transition from semi-solid to plastic. And last one is the shrinkage limit it is a moisture content in percent at the point of transition from solid to semi-solid state. So let us take a questions here. So I request you to answer these MCQ questions and proceed further. This is the first question consistency of soil is due to the presence of four options are given. The second question is the phase of consistency between shrinkage limit and plastic limit is called as four options and the third question is the phase of consistency between plastic limit and liquid limit is called as again four options are given. So take a pause answer these questions and resume the video. Welcome back. I hope you got the answers. So let us look at the answers. First of all this is the first question consistency of soil is due to the presence of clay mineral so which has been discussed already in the first slide. Then the second question is the phase of consistency between shrinkage limit and plastic limit is called as now for this we have to refer to the plasticity chart which has been already discussed in the earlier slides. So you can see the phase of consistency between shrinkage limit and plastic limit. So this is shrinkage limit and this is plastic limit. So in between these two limit the state is nothing but it is the semi-solid state. You can see here this is a semi-solid state. Third question is the phase of consistency between plastic limit and liquid limit is called as again using the same figure it is liquid state. Use of Atterbor's Limits. Now these limits are used in many cases in the soil mechanics especially to obtain general information about the soil and its strength, compressibility, permeability, shrinkage and soil properties. So almost all the behavioral kind of things are been expressed with the help of Atterbor Limits. The Atterbor Limits are used in empirical correlations for some engineering properties. As we know in soil mechanics we have a lot of empirical equations wherein various properties are correlated. So in these equations knowing the Atterbor Limits we can get the different properties of the soil. The most importantly the Atterbor Limits are used for the classification of soil especially the fine grained soils are classified based on the Atterbor Limits. And last one is in construction specifications. So for in the specifications especially during the guidelines of the embankment or compaction of the soil we will find that the specifications are drafted in the form of Atterbor Limits. However, at the same time we have to remember that Atterbor Limits are conducted on completely remolded soils. So they therefore do not account for the importance of the structure of the soil as related to the soil behavior. So their main usefulness is in classification of soil and only qualitatively they give some ideas about behavior. So main usefulness of this is for the classification of the soil and that too fine grained soil. However little bit idea we can get regarding the behavior of the soil and that to qualitatively we get the idea. So this is how we can use the Atterbor Limits in practice. These are the references which are used for this presentation. Thank you.