I am trying to find out what is the exact procedure and system for preparing, mixing, laying and then patting down sandwash.

I am not proposing in doing this myself, but I am trying to find how it should be done, following my recent experience from somebody who said they could do it.

im assuming you mean getting a pebble look floor, theres several ways around it, lay a concrete floor let it set then a screed with the coloured pebbles or stones you want in them, they level and towel it, for pebbles they let it set for a short time after laying then wash out the concrete top mix, if its stones they can do the same if internal finish they will use a big industrial grinder over the top, hence concrete polished floor then its sealed.

 

Like theres variations but that a roundabout way of doing it.