ASTM for specific gravity in clays and silts 1

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

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.

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.

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