Why is the hydrometer analysis often designated 'MA'?

[JJBDMALLC]

We are having an interoffice debate over the origin of the test request designation of MA for hydrometer analysis. In our own lab we have SA for sieve analysis, and MA for hydro. Most think that the M is for mechanical, but that applies to the sieve, too. How about mass? Or is the M from the M in ML or MH? Can anyone offer an answer?

 

[DRC1]

The M I believe would apply to M in ML or MH. The M stands for silt which is the fraction that the hydrometer grades.

 

[fattdad]

You guys have a tradition that's all your own. I've worked in geotechnical firms across the country and MA stands for "mechanical analyses", which is another term for a "sieve". The hydrometer would not fall into the catigory of mechanical analysis.

f-d

 

[dirtman85]

We call it Mechanical analysis or Sedimentation....the really lazy folk just call it pipette!

 

[dirtman85]

DRC 1, does the hydrometer not measure from coarse sand size down?!

 

[JJBDMALLC]

Are we the only ones who call it an MA? I think among ourselves here we've decided that it must be a quirk of the boss. We are in agreement that MA does refer to 'Mechanical Analysis', but that Mechanical Analysis is understood to include both the sieve analysis and sedimentation, not just the hydrometer. I found a statement saying just that in Tschebotarioff's 1951 Soil Mechanics text.

 

[DRC1]

dirtman 85:
Hydrometer analysis is performed on the fraction below the #200. The hyometer analysis measures the change in density of the slurry over time as particles settle out. Coarse fraction woud settle too quickly to measure accurately.

 

[fattdad]

DRC1: I think the ASTM for hydrometer includes the soil fraction below the U.S. Standard 40 sieve. You are correct that you must use the hydrometer to differentiate below the 200 sieve (unless you happen to be one of those folks that has/uses a 320).

f-d

 

[DRC1]

You can mechanically sieve down to about 100. To properly sieve at 200, it generally needs to be washed. I have never seen soils sieved below 200, although I have seen smaller sieves. We would do hydrometers on the portion passing the 200, as the grain sieve at that point is a computed quantitiy, not a directly measured quantity.

 

[BigH]

We just use M for sieve analysis, H for hydrometer - such as M,H.