Density of stockpiled scrap metal?

[Davidmat]

I am looking for densities of stockpiled scrap metal to Estimate ground bearing pressures at the base of the pile. I am assumming that densities will vary from the top of the pile to the bottom. I've done some research and came up with densities between 70 and 80 PCF but found that hard to believe given that solid metal densities are near 500 PCF. Can you help?

 

[jheidt2543]

Davidmat,

Here is my suggestion: I called the local scrap metal dealer and asked the size and load weight of their trailers. They have to keep accurate records of their loads, since that is how they get paid, by the ton of scrap metal. Their "average" load is 40,000 lbs in a trailer that is 48'long x 8'wide x 5' deep. That computes to 40,000 lbs/1920 cf = 20.83 pcf. Now you have to remember that, even though the unit weight of metal may be in the 500 pcf range, there is a LOT of open space in a scrap metal pile. It also depends on the type of metal (crushed cars, machine parts etc.). But in my opinion, the 70 - 80 pcf you quote sounds like it is in the neighborhood to me.

Hope this helps.

 

[flamby]

Density of scrap = (metal density) / (1+porosity)

where porosity = volume of voids / volume of metal pieces

Now it is all a question of guessing how porous the bulk is. Huge sized pieced with irregular shape will give you high porosity. As you decrease the size of pieces, porosity comes down to an optimum level at nearly powdered stage and then starts increasing again. Only you are in a position to guess the porosity and if you can do that, you have your answer. In case, I wouldnt know what those guys will be putting up there, I would have gone for a figure of 250 PCF to sleep well while they do what they want;-).

 

[scrappie]

Davidmat. You can contact ISRI, which stands for the Institute of Scrap Recycling Industries for a copy of their scrap specifications. However here is a quick breakdown of density by grade of scrap.

bundles 75#/ft3
busheling 50
prepared structural 55
turnings 50
shredded 60-70
muni 50
cast iron borings 100+