Particle size distribution

[ThePear]

Hi,

I have issues with the hydrometer test. Firstly the hydrometer sometimes is out of range at the start of a test.

I use the South African National Standards method which is a slight variant of the ASTM method. After the Tube has been shaken and the particles dispersed I'll place the tube in a waterbath and take readings at; 30sec, 2min, 4min, 8min etc. Now if the bouoncy of the hydrometer is too high and the reading 60+ could I leave the initial readings out and interpolate the readings from my first reading, lets say at 8min? The whole idea is to get the particle sizes passing 0.06mm diameter and 0.002.

Mainly, am I doing something wrong or is it normal to have out of range readings initially?

 

[Erdbau]

Can you use less soil in the cylinder and still be within the weight ranges prescribed in the method? That's the first place to start.

 

[dBasement]

Does your method include this?: After the hydro test is complete, reshake the cylinder and wash everything through a 0.075mm wash and dry sieve the remaining sample.

If so, just use the numbers from your dry sieve for the sizes greater than 0.075mm.