Silt Content Test of Sand (Fine Aggregates)

AIM

To find-out the silt content in sand (fine aggregates)

Apparatus

Related image
Measuring cylinder
  1. Measuring cylinder – 250ml
  2. Sand  – Specimen
  3. Water
  4. Salt Solution

Procedure

  • The measuring cylinder should be free from moisture and dry.
  • Fill the water up to 50 ml with 1% salt solution.
  • Then add sand to it until the level reaches 100 ml. 
  • Again add salt solution up to the level of 150 ml.
  • Close the mouth of the cylinder and shake well then keep the cylinder on a flat surface.
  • The silt content shall be settled over the sand layer after 2 hours.
  • Now note down the silt layer alone volume as V1 ml (settled over the sand)
  • Then note down the sand volume (below the silt) as V2 ml
  • Repeat the procedure two more times to get the average.

How to calculate the percentage of Silt?

  1. V1 = Volume of Silt layer (Silt settled over the sand layer).
  2. V2 = Volume of the Sand layer (which is settled under the silt).

Percentage of Silt = (V1/V2) x 100

The permissible Silt content in sand percentage is only 6%.

Report/Observation Table 

S.NO DESCRIPTION SAMPLE NO
SAMPLE 1 SAMPLE 2 SAMPLE 3
1 Volume of Sample (V1) ml
2 Volume of Silt (V2) ml
3 Percentage of Silt (V2/V1) x 100
Average 

Technical Discussion

Effect of Silt fines on concrete properties:
  • Increase in water/cement ratio result to a decrease in the compressive strength of concrete 
  • The increase in sand fines content has also been found to decrease the compressive and tensile strengths of concrete
  • Inadequate sand fine content also has adverse effect of the strength of concrete due to poor adhesion
  • The decrease in slump value as a result of increase in fines percentage in sand can be attributed to the fact that finer particles have larger surface area which absorbs more water in concrete mix.
Advertisements

Comment Here

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s