There's a wire crossing my concrete driveway in the slot which I tripped on
and kicked up and need to put back.

It just about fits in the groove, almost filling the groove. I think it's
for the low-voltage lights but I'm not sure what it's for.

What "material" would I use to "caulk" the wire back into the groove so
that it's protected from people tripping on it like I did?