Okay, this one is really throwing me for a loop and I thought someone here might know the answer because my Google-Fu is coming up short on this. We just had fresh sidewalks poured by a contractor throughout our suburb. This was about two months ago. Today we noticed that many of the sidewalks have one or more fasteners installed in the slabs. These look like they could be Ramset or similar fasteners, they look like large nails with washers and they are in random spots in the top of the slabs. I can't recall when the contractor put the sidewalks in what kind of rebar/mesh they used but I know they were moving fast and other than some roadkill they didn't appear to be compacting, etc. Are these pre-emptive repairs to the new slabs? What possible purpose can they serve? Thanks!