ASTM for specific gravity in clays and silts 1

[pelelo]

Engineers,

What is the ASTM followed to perform specific gravity tests for Clays and silts?

I am aware that C127 is for gravels and C128 is for sands.

Someone told me he runs C128 for silts and clays as well but this doesn't make sense.

Please advise.

 

[TigerGuy]

Try ASTM D854, it's a similar process to C128, but there are definite differences.

 

[pelelo]

Thanks Tigerguy,

I noticed ASTM D854 considers the material passing sieve No. 4.

If you need to test clays or silts, I would understand the material you need to test is the one passing No. 200, however this standard doesn't mention anything about this. By testing material passing No. 4, I could be testing both fine particles and sandy particles.

On other note, I have watched few youtube videos and some lab technicians use material passing No. 40 instead. This ASTM doesn't mention anywhere the use of sieve No. 40.

 

[GeoEnvGuy]

The sample prep for D854 for silts and clays should be the same, No. 4 so your just excluding any oversized. I don't see a point to exclude the fine sand portion from a silt and clay sample if it is still formed by they same geological process. You could argue if you have a till with a wide grainsize distribution you might want to consider running the coarse material with C127 and the No. 4 portion with D854.

 

[zelgar]

ASTM D7928-21e1, Standard Test Method for Particle-Size Distribution (Gradation) of Fine-Grained Soils Using the Sedimentation (Hydrometer) Analysis