The properties of soil which helps to assess it's  engineering behaviour and which assist in determining its classification accurately are termed as index properties of soil.

The laboratory tests, which provide information on physical properties of soil are known as classification test and numerical result of such test are known as index properties. Index properties may be divided into two general types:

• Soil grain properties
• Soil aggregate properties

The soil grain properties are the properties of the individual particle of which the soil is composed and are independent in the manner of soil formation. These properties can be determined from distributed samples. Soil aggregate properties,on the other hand, depend on the structure and arrangement of the particles in the soil mass whereas the soil grain properties are commonly used for soil identification and classification. The the soil aggregate properties have a greater influence on the engineering behaviour of soil mass some of soil grain  properties are:

• Particle size
• Grain shape
• Mineralogical composition

Some of soil aggregate properties are:

• Relative density
• Consistency
• Unconfined compressive strength
• Thixotropy
• Sensitivity and activity

The properties of soil which helps to assess it's  engineering behaviour and which assist in determining its classification accurately are termed as index properties of soil.

The laboratory tests, which provide information on physical properties of soil are known as classification test and numerical result of such test are known as index properties. Index properties may be divided into two general types:

• Soil grain properties
• Soil aggregate properties

The soil grain properties are the properties of the individual particle of which the soil is composed and are independent in the manner of soil formation. These properties can be determined from distributed samples. Soil aggregate properties,on the other hand, depend on the structure and arrangement of the particles in the soil mass whereas the soil grain properties are commonly used for soil identification and classification. The the soil aggregate properties have a greater influence on the engineering behaviour of soil mass some of soil grain  properties are:

• Particle size
• Grain shape
• Mineralogical composition

Some of soil aggregate properties are:

• Relative density
• Consistency
• Unconfined compressive strength
• Thixotropy
• Sensitivity and activity

Water content,denoted by letter `w`,is defined as the ratio of weight of water to the weight of dry soil.i.e,

$$w=W_w/W_s $$

Water content of a soil mass controls its strength and stability so it is important to determine the water content of a soil mass. The oven-drying method is a standard laboratory method for determining the water content of a soil sample. This is a most accurate method the following steps are followed.

To determine the water content in a laboratory, a sample of wet soil is placed in a container of known  weight and its weight is determined. The soil sample is then placed in an oven with temperatures set between 105 degree centigrade to 110 degree centigrade. The soil is allowed to dry for 24 hours and the weight of the container and dry soil is found out. The following calculation are done to find water content.

Let,

   `W_1=`weight of empty pan (container)

   `W_2=`weight of empty pan plus wet soil

   `W_3=`weight of empty pan plus dry soil.

Now,

Water content,`w=(Weight Of Water)/(Weight of Solid)*100`

Thus,`w=(W_2-W_3)/(W_3-W_1)*100%`

Water content,denoted by letter `w`,is defined as the ratio of weight of water to the weight of dry soil.i.e,

$$w=W_w/W_s $$

Water content of a soil mass controls its strength and stability so it is important to determine the water content of a soil mass. The oven-drying method is a standard laboratory method for determining the water content of a soil sample. This is a most accurate method the following steps are followed.

To determine the water content in a laboratory, a sample of wet soil is placed in a container of known  weight and its weight is determined. The soil sample is then placed in an oven with temperatures set between 105 degree centigrade to 110 degree centigrade. The soil is allowed to dry for 24 hours and the weight of the container and dry soil is found out. The following calculation are done to find water content.

Let,

   `W_1=`weight of empty pan (container)

   `W_2=`weight of empty pan plus wet soil

   `W_3=`weight of empty pan plus dry soil.

Now,

Water content,`w=(Weight Of Water)/(Weight of Solid)*100`

Thus,`w=(W_2-W_3)/(W_3-W_1)*100%`

Specific gravity is an important property by which the void ratio porosity degree of saturation particle size distribution etc are determined moreover it is useful in the study of quick sand condition and in estimation of zero air void line in the compaction theory a pycnometer or constant volume method has to be most reliable for the determination of specific gravity normally a 200 gram of dry mass of sample and a 500cc constant volume bottle are taken. The various steps to be followed for the determination of specific gravity G as follows:

• Find the weight of empty pycnometer
• The pycnometer is then filled with about 200 grams of dry sample and is weighted again.
• Water is then added in the pycnometer such that it is half full of water. The air in the soil sample is completely expelled by heating or suction. The water is added to its full capacity and pycnometer is weighted again.
• The pycnometer is then emptied and is filled with water only and its weight is determined.

CALCULATIONS:

Let,

`W_s=`weight of dry soil

`W_1=`weight of pycnometer plus soil plus water

`W_2=`weight of pycnometer plus water

Now, by definition,

`Specific gravity of solid =(Weight Of Solid Of Volume 'V')/(Weight Of Same Volume Of Water At 4 degrees celsius)`

Or,`G=W_s/(gamma_0 *V_s)`

Again the specific gravity of water is,

`G_t=(gamma_w *V_w)/(gamma_0 * V_w)`

      `=gamma_w/gamma_0`

Thus,`G=(W_s*G_t)/(V_s*gamma_w)`

Again,we have,

`W_2=W_1-W_s+V_s*gamma_w`

 `V_s*gamma_w=W_2-W_1+W_s`

`(W_s*G_t)/G=W_2-W_1+W_s`

`G=(W_s*G_t)/(W_s-W_1+W_2)`

Generally,`G_t=1`.so,

`G=W_s/(W_s-W_1+W_2)`

Specific gravity is an important property by which the void ratio porosity degree of saturation particle size distribution etc are determined moreover it is useful in the study of quick sand condition and in estimation of zero air void line in the compaction theory a pycnometer or constant volume method has to be most reliable for the determination of specific gravity normally a 200 gram of dry mass of sample and a 500cc constant volume bottle are taken. The various steps to be followed for the determination of specific gravity G as follows:

• Find the weight of empty pycnometer
• The pycnometer is then filled with about 200 grams of dry sample and is weighted again.
• Water is then added in the pycnometer such that it is half full of water. The air in the soil sample is completely expelled by heating or suction. The water is added to its full capacity and pycnometer is weighted again.
• The pycnometer is then emptied and is filled with water only and its weight is determined.

CALCULATIONS:

Let,

`W_s=`weight of dry soil

`W_1=`weight of pycnometer plus soil plus water

`W_2=`weight of pycnometer plus water

Now, by definition,

`Specific gravity of solid =(Weight Of Solid Of Volume 'V')/(Weight Of Same Volume Of Water At 4 degrees celsius)`

Or,`G=W_s/(gamma_0 *V_s)`

Again the specific gravity of water is,

`G_t=(gamma_w *V_w)/(gamma_0 * V_w)`

      `=gamma_w/gamma_0`

Thus,`G=(W_s*G_t)/(V_s*gamma_w)`

Again,we have,

`W_2=W_1-W_s+V_s*gamma_w`

 `V_s*gamma_w=W_2-W_1+W_s`

`(W_s*G_t)/G=W_2-W_1+W_s`

`G=(W_s*G_t)/(W_s-W_1+W_2)`

Generally,`G_t=1`.so,

`G=W_s/(W_s-W_1+W_2)`