It's hard to say from the pics. I would say that if you can tell the cords are cut, then I would replace it no matter what. If it is just superficial, AND if you are just driving on the street, I would say it is fine. If you are ever going to the track, it needs replaced. Keep an eye on it for bulging.
That's tough luck to cut a tire like that. There is lots of constrution near me and I have picked-up all kinds of crap in tires of my cars. Every time it happens I am miffed at the careless people that drop crap like this from their trucks.
