I have a concrete patio in my backyard that's in pretty good condition. We don't like how it looks, so we'd like to cover it up with brick or pavers. Looking online, it appears that most people install pavers over gravel, so I was wondering if it was a good idea to lay the pavers straight on the concrete patio. Would drainage be an issue? What kind of cement would I use to secure the pavers on the concrete?
If you have a drainage issue, or you're likely to have freezing conditions, I'd personally want to lay a small coating of gravel across the concrete first - allow that pent-up water to get out of the way.
If you're building this in, say, Phoenix, though, that may not really matter and laying them directly atop the concrete shouldn't be a problem.
To the 'cement' part of your question: why not go with dry-laid? As long as there is some form of rim to the patio, or you're not driving over them, dry-laying would make both maintenance and modification easier.
If you are not in a freezing condition, then the only other problem I see is that the pavers will shift on top of the concrete pad. Gravel would make that worse. You are going to have to brace the pavers to keep them from shifting.
I would not put pavers on top of concrete. I was going to do that (I live in Illinois) but my contractor said NO. He ripped out the old concrete patio and installed pavers (Unilock) and it looks fantastic! I believe in the long run, the cost of replacement is well worth it as opposed to putting pavers on top of a concrete slab. Your concrete slab might look decent now, but over the years it will will eventually crack all over and become uneven due to the constant freeze/thaw cycles over the years, so you can imagine what will happen to those pavers if they are on top of that patio. Like another poster said, if you live in a temperate climate, it probably would not hurt to put pavers over a slab.