One thing that makes a lot of difference in the coverage a person gets per ton of rock is if it has fines or has been screened to remove fines.
Fines have their place. If a person needs the rock to "pack" finer particles are essential.
But a person will get more coverage, or in other words a bigger volume load, if the fines are removed. Rock with the fines removed is lighter per volume than the same maximum size rock with fines.
It is like filling a jar with marbles. When filled it will weigh a certain amount. But if sand is added and the jar shaken so the sand will fill the pores between the marbles, the same volume container will weigh more with the sand (fines) than without the fines.
Graded rock with the fines removed usually is higher priced per ton than rock with the fines included. For a road where it needs to pack using this cheaper per ton rock works well. But rocks with the fines removed will go further because there is more volume. The same number of tons in a truck load will result in a significantly larger volume load of rock with fines removed than with fines left in. It costs a little more per ton (because it costs to run the rock over more screens to remove the fines) but will have significant better coverage in applications where the fines are not needed or not desired. Cheaper per ton does not always translate to cheaper per project.
For bank erosion control the rock with fines removed will go farther. On the other hand, if the pond could use additional lime anyway (is acidic). Much of the fines will wash into the water with wave action and be of benefit.
So which to use? It depends.
Last edited by snrub; 11/18/17 11:07 AM.
