For having a Falcon 9 (almost) land on it, the SpaceX barge doesn't seem to have faired too badly:
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In June 2015 the first model barge was replaced, and here is an image of the deck of that barge:
It doesn't look like it's coated with just asphalt, and it certainly isn't wood (although it almost seems like one can see wood grain on top). What material is the top of this barge coated with?