9. Test for deflocculation demand
The clay to be tested has to be taken out from the bulk supply by ‘Cone and Quarter’ method - the sample to be prepared is around 1 kg. From this master sample take out about 500 gms and soak it in distilled water about 250 ml. After soaking, stir it for few minutes and leave the sample overnight.
- Prepare a mixture of Sodium Silicate and Soda Ash solution by mixing them in 3:1 ratio. The concentration to be maintained is 10%.
- Stir the clay slurry, add slowly the above solution till we get a reasonable flow.
- Test the fluidity by using a Torsion Viscometer or Lehman Viscometer.
- If the fluidity reaches the standard level, stop the addition of the solution and note this as the deflocculation demand of that particular clay.
