Fastening stone stair treads to a CMU base in a removable manner

Question

I'm designing a very, very low set of landscape stairs (really more like a wide stoop) to transition two areas of my yard. My plan is to pour a concrete base slab, build a core with CMUs on top of that, and then clad everything in natural limestone. I'd like to integrate low-voltage lighting under the tread noses.

My plan so far is to cut a network of grooves into the CMU core to run the low-voltage wires from the fixtures back to the transformer. The treads would then go on top, concealing the fixtures and wires. However if I mortar the treads in place, it will be very difficult to replace the fixtures when they inevitably fail. Could I get away with some kind of less permanent fastening, like a masonry caulk that could be cut away when the treads need to be removed? The stone treads are quite heavy, and are mostly held in place by their weight. I think I would only need something to keep them from rocking/budging.

Answer 1

Stairs need to be EXTRA safe, because a loose stair is potentially deadly. It's not something you want to mess around with, heavy or not. Could you drill and bolt them toward the back of each tread, running the bolts down into the concrete below the CMU blocks? You could countersink the bolt heads on the tread stone and fill them with sand or something to hide them, then vacuum out the sand if you ever need to remove the bolts to lift the tread. If you do that, use stainless steel hardware all around.