1. Water content DEFINITION:
Water content (w) or moisture content of a soil is defined as the ratio, expressed as a percentage of the weight of water in a given soil sample to the weight of solid particles (Oven dried soil).

2. THEORY: Moisture is the most influencing factor affecting the properties of soil especially fine grained soil.
It plays an important role when soil is used either as a construction material or as a foundation material. So, determination of moisture content is a must while reporting other results. 
Because of intimate relationship between soil solids, and soil moisture, apparent water content changes due to variation in drying procedure will be greater in fine grained soils.
So, the procedure of drying should be standardized. For complete drying, sandy soils take about four hours and fat clays take about 14 to 16 hours.

3. Usually the sample is kept for about 24 hours in the oven at a temperature 105CC to 110°C, so that complete drying is assured.
A temperature higher than 110°C may break the crystalline structure of clay particles resulting in the loss of chemically bound structural water.

4. CALCULATIONS 1. Oven drying method:
Weight of container + lid = W1 Weight of container + lid + Moist soil = W2. Weight of container + lid + oven dried soil = W3 Weight of water = ww = W2-W3
Weight of oven dried soil = wd = W3-W1;
Water content (%) = w = (ww / wd) x 100

5. Pycnometer Method:
Pycnometer is a 1000 ml capacity glass bottle provided with a conical top. The conical cap has a small hole approximately 5 mm in diameter at its apex. The cap can be screwed onto the glass bottle. To avoid leakage of water, a rubber washer is provided between the conical cap and the rim of the bottle.
To determine water content by this method, the value of G should be known.
This method is suitable for coarse grained soils from which the entrapped air can be easily removed.

6. Procedure:
1. Wash and clean Pycnometer and dry it.
2. Determine the mass of Pycnometer with brass cap and washer (M1) accurate to 1.0g.
3. Place about 200 to 400g of wet soil specimen in the Pycnometer wand weigh it with its cap and washer (M2).
4. Fill water in the Pycnometer containing the wet soil specimen to about half its height.
5. Mix the contents thoroughly with a glass road. Add more water and stir it. Fill the Pycnometer with water, flush with the hole in the conical cap.
6. Dry the Pycnometer from outside and take its mass (M3).
7. Empty the Pycnometer. Clean it thoroughly. Fill it with water, flush with the hole in the conical cap and weigh (M4)

7. The water content (w) of the sample is obtained as
Where
M1=mass of empty Pycnometer,
M2= mass of the Pycnometer with wet soil
M3= mass of the Pycnometer and soil, filled with water,
M4 = mass of Pycnometer filled with water only.
G= Specific gravity of solids.

8. Sand Bath Method: Sand Bath Method for the determination of soil water content is a quick field method which is employed when an electric oven is not available for drying of wet soil.
Sand is kept on a tray to a height of about 3 cm.
A container is filled with wet soil and dried by keeping on the sand bath and heating with stirring.
Few white papers are kept on top of the wet soil in the container.
The soil is said to be dry when these white papers turn brown.
Finally, dry soil is obtained and the water content can be determined with the help of the equation obtained for oven drying method.

9. Alcohol Method: The wet soil sample is first taken in an evaporating dish. Its mass is determined. Then the sample is mixed with methylated spirit (1 ml for 1 gm of soil).
The mixture is made uniform by turning the soil several times with the help of a knife. The methylated spirit is then burned.The mixture is stirred with a spatula when ignition is taking place. After the spirit is burnt away completely, the dish is allowed to be cooled, and the mass of the dry soil thus obtained is determined. The whole procedure takes about 10 minutes.

10. SPECIFIC GRAVITY OF SOIL

11. SPECIFIC GRAVITY
Specific gravity (G) is defined as the ratio of the weight of a soil solids at a given temperature to the weight of an equal volume of distilled water at that temperature, both weights being taken in air.

12. PROCEDURE Weigh the clean dry pycnometer with its cap.
Fill the pycnometer one-third full with oven dried soil taken directly from desiccator and determine its weight after screwing the cap.
Add desired distilled water to pycnometer after removing the cap, until the pycnometer is half full and stir it with a glass rod, (to assist in removal of air) and screw the brass cap.
Add desired distilled water till the pycnometer is full.
Remove remaining air by shaking after closing the screw top with one finger. Clean the outer surface of pycnometer and then determine its weight.
Empty the contents of pycnometer and thoroughly wash it.
Fill the pycnometer with distilled water till the surface of water is flush with the hole in the screw cap. Then weigh the pycnometer.
Note the temperature of water.

13. Specific gravity of soil using pycnometer:

14. CALCULATION & TABULATION
Weight of pycnometer = W1
Weight of pycnometer + oven dried soil = W2
Weight of pycnometer + oven dried soil+ remaining space completely filled with water without any air = W3
Weight pf pycnometer + full of water = W4
Weight of oven dried soil = W2.W1
Weight of water filling the pycnometer=W4-W1
Weight of water in pycnometer over and above the dry soil=W3-W2
Weight of water having the same volume of dry soil= (W4-W1)-(W3-W2)
Specific gravity of soil grains at temperature T°C

16. G27. sp. gr of water at 270 C = Gt. sp
G27 * sp.gr of water at 270 C = Gt * sp.gr of water at room temperature,t
Where, G27 & Gt are sp.gr of soil at 270 C and at room temperature, t
where, GL = sp.gr of liquid at that temperature.

17. uses of specific gravity are:
To determine size of particle by stoke's law.
To determine void ratio of a fully saturated soil on knowing its water content.
To determine the various unit weights of soils on knowing other properties of soils.