For several years, I've watched our 30-year-old concrete steps deteriorate more and more. They've probably been exposed to salting in winter, and of course, the concrete is now crumbling. At least, that's what I thought. From what I can see after chipping away loose pieces from the steps, there is a core of hard concrete, and a much more porous sandy layer outside, on which slate was laid. See pictures below. Is this a normal construction, and could my plan to knock off all loose material and replace the slate with wood/decking work?
At first, I thought the steps were a lost cause, but they seem very stable inside?
Here are the pictures:
The sad steps where, as you can see, I've chipped a hole in the concrete, and sand is falling out:
I continue chipping and see that there is a much harder core inside, which appears completely intact and not of the same material as the surrounding porous sand and "concrete" or whatever you want to call it. Plaster?
I go to another part of the steps and easily remove a slate tile:
Looking a bit closer here, I start to get a bit worried. The steps look so badly damaged that a rescue seems impossible:
But even here, I chip away the sandy and gray slightly harder material, and find a solid core of concrete, completely intact:
As I mentioned above, it seems there is a concrete core inside, but why is there this sand outside? It's like a hollow shell when you remove a slate tile. If you knock on the shell, you reach the sand. Then comes the concrete core. Why was it made like this?
As I see it, I should be able to remove the slate tiles, chip through the shell, and remove all the sand, then replace it with wooden decking mounted on "joists" made of 3 mm metal or similar (which would be drilled and fastened into the concrete)?
Yes, it would be nice with slate, but I'm afraid it will cause issues when I try to reassemble it, so to speak. What should I replace the sand with, since a certain thickness is required and it will be difficult with regular adhesive? Sorry, but this isn't really my area
I don't think it is prefabricated; it is cast in place with the slate stone set in mortar. It is a common way to build.
It is possible to remove the slate stone, remove the mortar, and reset everything with cement mortar.
