[TowerTalk] Concrete; How to mix on site?

[Richard & Martha Wilder]

My plan is to mix one yard of concrete on site using materials
found on site except hauling in the Portland Cement.  The main
reason for not hauling in ready-mix is to use  gravel and sand
remaining from other building projects.  The secondary reason 
is hauling 340 pounds of Portland 400 feet across rugged land
is much easier than 2700 pounds of mix.  I'll rent the smallest
mixer I can find.  (Yes, it's for a tower.  You knew that.)

THE QUESTION:  How do I rate the several types of gravel that I
have and the local sand (I'm on the same sand bar as the sand pit
down the road) to be sure my on-site materials are suitable?  
Is there a web site that discusses tests or grading for sand 
and gravel?

>>>>> Please reply directly and I'll post a summary. <<<<<

I have found some souces for mix ratios and am searching the web
for more opinions.  Here is some interesting finds.
   *  is from concrete-solutions.com/products and 
   ** is from http://grove.ufl.edu

  componet        S.G*.    lbs*      lbs**
  cement          3.15     340       336
  sand (dry)      2.65     940      1362
  gravel (dry)    2.66    1210       912
  water (wet)     1.00     210       unknown
                        
73, Dick, K3DI   
  ----------------------------------------
  Dick's lifetime address is k3di@arrl.net

PS: The "water (wet)" was to see if you're awake.


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