This refers to the Overlay Tile Repair System (OTRS) provided to repair the ceramic tiles, not the plug system provided to repair the reinforced carbon-carbon portions of the heat shield.
The third method is a mechanical repair that uses
insulating blankets to fill cavities that are then
covered by an overlay of carbon silicon carbonate
installed using augers that penetrate directly into
healthy tiles. The overlay system consists of Saffil
insulation blankets, pre-packaged in a variety of
shapes and sizes, which provide radiant heat
protection when installed in the cavity. A thin
(0.03 inches) overlay cover made of a high-
temperature resistant, flexible material such as
carbon-silicon carbide -- which can hold its shape
as a shield against plasma flow -- is installed over
the damaged tile and insulation blanket using
augers screwed directly into adjacent healthy
tiles. Around the edges, between the overlay and
the existing tile, a fabric gasket is used to prevent
hot gasses from penetrating beneath the overlay.
Source Inflight Inspection and Repair
Source STS-127 EVA checklist supplemental material
Not sure how to answer "how did its physical properties compare to the tiles?" because they were totally different materials.