Hydrometer Analysis

 

Testing objectives:
Distribution of soil particles having sizes less than 75 micron (Fine Grained soils) is often determined by a sedimentation process using a hydrometer to obtain the necessary data such as the borderline between clay and silt. Using this test the GSD or grain size distribution for soils containing appreciable amount of fines is obtained.

Need and Scope:

Properties of fine soils is highly dependent upon the fractions of clay and other components.  HA test is carried out to obtain these fractions.


Particle sizes:

Silts have sizes ranging between 2 and 75 micron and clays are finer than 2 microns.

 

Notice: For more information about this test and calculations please refer to your class notes. Here is the plot that you are required to turn in with your reports.

 

 

 

Photos: Please notice that, step #s on pictures match step #s on your lecture notes.

Test Equipments

Step 1- Taring the weight of the Beaker

Step1- Taking 50 g of oven dry soil in a beaker

Step 2-Making a %4 solution of dispersing agent

Step 2-Mixing the solution throughly

Step 3-Take 125 cc of mixture prepared in step 2

Step 3- ... and add it to the soil taken in step 1

Step 3- This should be allowed to soak for about 8 to 12 hours

Step 4- take a 1000cc graduated cylinder and add 875 cc of distilled water plus 125 CC of dispersing mixture from step 3

Step 5- Record the temperature of the cylinder of step 4

Step 6- Put the hydrometer in the cylinder of step 5 and record the two corrections Fm and Fz

Step 6- Fz=6 and Fm=1, the two corrections are obtained

Step 7- mix the soil prepared in step 3 using a spatula

Step7- ... Pour it into the mixer cup, wash the soils that stick to the sides of the beaker using distilled water

Step 8- The mixer cup

Step 8- add distilled water to the soil in mixer cup to make it about two-thirds full.

Step 8- Mix it for about 2 minutes using the mixure

Step 8- Cntd.

Step 9- Pour the mix into the second graduated 1000-cc cylinder. Make shre that all of the soil solids are washed out of the mixer cup. Fill the graduated cylinder with distilled water to bring the water level to 1000 cc mark

Step 9- at the end of step 9, you should have these two cylinders

Steps 11 & 12

step 13- After each reading the hydrometer is put into the transparent cylinder (R)