When the concrete was laid, 12 years ago, the surface was overworked, bringing too much water to top, creating a powdery surface. It was then sprayed with a cement product finish. That finish has been peeling off, exposing the soft underneath. The concrete mass is hard, just the top few mm are soft. Any suggestions as to treatment to restore. I have considered hiring a concrete grinder to remove the soft stuff. Can I bring the surface back to original level to match up with existing drains drains? Suggested products to do the job? Your thoughts will be greatly appreciated. JFW