My driveway (4 car in size) has the usual cracks that most everyone else has but I hear a "hollow" sound when tapping on the concrete in several areas. Recently I had an oak tree next to the driveway cut down and while this was being done a large branch fell on the driveway creating a new crack. A triangular section surrounded by cracks now is every so slightly loose and somewhat wobbles when walking on it. When tapping on this section, there is a definately "hollow sound" here as well. I can't easily remove this section to look underneath I'm guessing because of wire mesh in the concrete (??). If I just patch the cracks with cement will this hold for a while or should I call someone for more extensive repairs? If repairing myself is an option, can someone tell me what the best way to do this is? Thanks in advance for anyones help.

I moved into my house 2 years ago and I'm finally getting around to cleaning up the conctrete patio in the backyard. Gutting and remodeling the interior came first. I think it's mostly just ground in dirt and not stained so I don't think a chemical wash is needed. I know nothing of powerwashing concrete so any advice on how to get started and what mistakes to avoid would be great. The only thing I know right now is I need to rent a washer with at least 3000 psi. thanks