Stone dust used for concrete mixing

[Stimw]

Interesting. I end up with quite a bit of fly ash from one of my burners and I've been curious about using it.

I worked for a company back in the mid 70's that sold building materials and made and sold concrete block.
They also sold "TRUE" Cinder block! A term that is so sloppily used today to describe any block.
There were local companies that used coal fired power plants and they paid local drivers $50. a semi load for the cinders left over from the plants.
They had a machine that ground up the cinders and they made cinder block.
The block was mostly used in fire walls, had a higher rating than concrete and sold for about 20% higher than the concrete block!
Also used in load bearing walls without problems.
They might have used sand also in the mix. ???