Lab reports on Determination of Water Content (w) of soil sample ,soil mechanics

 

TITLE:  DETERMINATION OF WATER                           CONTENT OF SOIL

OBJECTIVE:  To determine the water content of soil sample by                      oven-dry method.

APPARATUS REQUIRED:

1. Weighing machine                                         

2. Tray or pan

3. A container (small)

4. Moisture cans 

MATERIALS REQUIRED:

1.Soil sample

THEORY:

Determining the water content of soil is a fundamental test in geotechnical engineering, soil science, and environmental engineering. The oven-dry method is a standard procedure used to measure the moisture content of soil samples accurately. This method involves drying a soil sample in an oven at a specific temperature until it reaches a constant weight. The water content is then calculated based on the weight loss due to the evaporation of water.

The water content of the soil is defined as the ratio of the weight or mass of water to the weight or mass of soil solids. it is denoted by w. It is generally expressed in percentage. Thus, the water content is given by;

w=weight or mass or water in soil sample/weight of dry soil mass *100%

w=Ww/Ws*100%

or, w=Mw/Ms*100%

The water content of soil is determined using oven drying method in the laboratory. 
let,
   M1=mass of empty moisture can
   M2=mass of moisture can +soil sample
   M3=mass of moisture can + dry soil after oven drying then, we use the following formula,   w=Ww/Ws=(M2-M3)/ (M3-M1)*100%
   

  

The lab procedure is explained below.

PROCEDURES:

1.  The soil sample was collected from the field and any lumps and foreign materials like stone, roots, plastic, etc. were removed.
2. The moisture can was cleaned properly with water and dried and soaked.
3. Then, the mass of the empty moisture can was measured. (M1)
4. The soil sample was poured into that moisture can and mass was measured. (M2)
5. Then, the moisture can was placed on the oven for 24 hours at a temperature range of about 105-110 degrees Celsius.
6. After drying, the mass of container with dry soil was measured. (M3)
7. Water content (w) is calculated using formula:

    w=(M2-M3)/(M3-M1)*100%

OBSERVATIONS AND CALCULATIONS:

Moisture can number: s-10
Room temperature: 26 degrees cel.
mass of empty container (M1): 22.5 gm
mass of container +soil sample (M2) :46.1 gm
mass of container +dry soil (M3) :41.7 gm 

Now,
       w=(M2-M3)/((M3-M1) *100%
        
         =(46.1-41.7)/(41.7-22.5)*100%
     w =22.916%

RESULT:

Thus, from the above lab experiment, the water content of given soil sample was found to be 22.916%
This value indicates that 22.919 gm of water is present per 100 gm of that soil sample.

CONCLUSION:

Hence, by this way we can easily calculate the water content of any type of soil sample in the laboratory. The determination of water content in soil is fundamental to a wide range of applications, from civil engineering to agriculture and environmental management. Accurate measurement of soil moisture content helps ensure the stability and safety of structures, optimizing agricultural productivity, managing water resources, and protecting the environment. Therefore, regular and precise determination of soil water content is essential for informed decision-making and effective project implementation across various disciplines.

PRECAUTIONS:

1. Cleanliness of all equipment should be ensured.
2. Soil samples should be handled carefully to prevent contamination.
3. Measurement of masses should be precise to minimize errors.
4. All laboratory precautions should be followed.