Proctor test on coarse aggregates

[TaniaABS]

Hi, I'm new on this site but found it quite interesting. I'm looking for a simple formula used to calculate maximum density of a corase aggregate (>30% retained 20 mm seive) from a specific gravity result.

I used this formula with my previous employer. We would determine specific gravity (comparable to ASTM c127) and aply this formula to calculate the density to be used as replacement of proctor value. It was something like

(x * SG)/(y *c)

c is worth 0,98 it's correction value I think...

I'm looking for x and y, and where this formula might come from.

I work in Québec, Canada and therefor do not use the same standards but they are mostly based on aashto and astm.

If anyone has any clue it would be greatly appreciated.
Thank you

 

[Ron]

This is a basic weight-volume relationship that can be found in any soil mechanics/geotechnical textbook.

The "98" you refer to is likely the percent compaction that is desired.

Unfortunately, this method is only a representation of a density that could be achieved base on the solid particles of soil without consideration to air voids and moisture filled voids, both of which are necessary for your consideration.

 

[SixDegrees]

The relevant parameter to compute maximum density is void ratio, which is a measure of the amount of voids in the soil. The specific gravity is a constant and does not change with compaction.

Dry Density = (GammaWater * Specific Gravity)/(1+Void Ratio).

Therefore your

X=GammaWater (62.4 pcf)
Y=(1+Void Ratio) minimum void ratio at maximum density

and as noted by Ron the 0.98 is most likely a % Compaction.

So you need to determine Minimum void ratio for the coarse aggregate.

You can determine the maximum density for about $100.

 

[bimr]

There is a spreadsheet on this site as well as an explanation:

http://civilx.unm.edu/laboratories_ss/pcc/spgrav.htm