Not sure what stone dust is. You may get some ideas from the hypertufta forum. Suzi

25 years ago I had to choose between stone dust and sand when laying a brick patio using standard sized bricks. The underlying ground here in Virginia is fairly high content clay, I can absolutely state that stone dust is the way to go.... here are a few pointers; 1. Use a rigid but moderately flexible edge guard to define the area. I used aluminum about 4 inches tall. Don's use something softer like plastic or nylon as it will flex and your bricks will start to migrate all over the place no matter whether you use sand or stone dust. 2 . Use 4 inches of stone dust, but apply 2 inches first...then compact it with a manual or mechanical tamper....then thoroughly soak with water and wait a couple of days before applying the 2nd layer of stone dust and tamping and watering again. (BTW, I really don't understand the comments about stone dust not draining well....you will see the water soak quickly through the stone dust.) 3. Make the area as level as possible using a screed (look it up :) 4. Install some water permeable landscaping membrane on a fairly well leveled area. This will promote drainage and stop weeds from infiltrating from below. I will also make it easier to slide the bricks into place. 5. Install the brick. Either full size bricks or the thinner pavers. I used full size bricks which are more stable. To ensure that the bricks are level with one another, place a piece of piece of wood (approx 3" x 8" by 3/4" ) across the surfaces of the brick you are working on and its adjoining bricks...then hammer it with a large mallet until they all the bricks are even. Give then some good wacks...full-sized bricks can take it so long as you use wood as a buffer. Be gentler with the thinner pavers. 6. Depending upon your personal preference, you can butt the bricks directly up against one another or place a think spacer between them. I use pieces of asphalt roofing shingles to maintain uniform spacing. I like the look and using spacers allowed me to adjust the alignment for bricks which may not be uniform size. 7. Regardless of which way you go on item 6, sweep stone dust into the joints between the bricks. Wet the area, let it dry and repeat again. The irregular shapes of the stone dust will lock the bricks into position much better than sand, which is more round. Sand will not get into some of the smaller joints between bricks. 28 years later I am still VERY happy with my results. Occasionally a nearby tree root will distort things a bit but that will happen with either sand or stone dust. I just remove a few bricks and cut out the root. The only periodic maintenance I need to do is sweep new stone dust in the spaces between the bricks one ever 4-5 years. Good luck.

There is an old myth, one that I subscribed to for years, that adding sand, stone dust, to clay soils would give you an adobe like soil. However, according to the instructions on making Adobe from the University of New Mexico that is not how to make Adobe. Adding the stone dust to your clay soil would be like adding any other type of sand, or granite dust which is stone dust, or rock phosphate which is stone dust, or limestone which is rock dust, or greensand which is also a rock dust. Depending on the source of that stone dust and how much baterial activity your soil has that stone dust could provide some type of necesssary macro and micro nutrients.

Hello thelink123: You should not use "play sand" as it will not stabilize or compact effectively for any walkway, be it bluestone or brick. Let the play sand collect dust (if it can) and build your base with compactable gravel. Here's a before/after sequence on a typical bluestone project. Here in Chicago we would provide 6" of compacted CA-6 with a 1" bedding course of torpedo sand, CA-15 or CA-16 depending on the specific application. Good luck with your bluestone!