I need some advice on repairing my crumbling (ugly) spillover wall in my pool. The wall separates the spa and the main pool. I had this problem (although not to this extend) a few years back when tiles were falling off and some small cracks appearing and even though I am not a stranger to concrete/tiling DIY work I decided that it is better to leave it to professionals in this case. So I hired a pool company to do the "professional" repair for me. They cut off the top two inches of the wall off (basically to make it flat) then re-built the concrete and tiled over it. It looked really good for one season! I was very careful about maintaining chemistry in the pool and I made sure that my water level is below the tile line during winter (as I always do) since it can get really cold in MA. As you can see from the pictures below, now two years later all the work that they did fell apart and now it is actually worse than it was before because since they cut a big chunk of old concrete off and the new concrete they poured did not attach well, the damage is more extensive. I tried contacting the contractor several times with no success and honestly at this point I don't want to deal with them anyways so I would like to attempt to repair it myself. I really do not think I can do any worse then what they did so I am ready and willing The wall length is about 9 1/2 feet. Some questions I have before I jump right in:
1) After removing all loose and cracked concrete, I am planing on building a form to put on top of the wall so I can re-pour the top and re-build the spillover. What concrete mixture I need to use for this application? What is the best way to make sure the newly poured concrete attaches well to the existing foundation? How long to let it cure before tiling?
2) After concrete is cured, what is recommended thinset to set the tiles on? Same question about grout? Do I need to seal it?
3) The problem area usually starts around the spillover opening so instead of using tiles, I am planing on using something larger to minimize the grout lines. Any recommendations on what to use?
4) Any other advice from someone who attempted such repairs? Any gotchas? Any alternative way to address this issue instead of rebuilding it the same way it was (removing the wall completely is cost prohibitive for me but maybe other options)? I would appreciate any feedback.
Finally some pictures of the ugliness (please ignore the stuff on the bottom, I haven't vacuumed the pool yet):