Now the pre-mat is installed.  The pre-mat is a sacrificial layer of rebar that is installed and embedded with concrete.  The pre-mat gives an initial structural layer and a mounting platform for the balance of the structural rebar.

Now the pre-mat is installed. The pre-mat is a sacrificial layer of rebar that is installed and embedded with concrete. The pre-mat gives an initial structural layer and a mounting platform for the balance of the structural rebar. (Jan Pregowski)