That's a good question..hmmm..You COULD lay them over your walk and patio over sand;however the drainage would be poor..that could cause a problem in the winter when the water freezes under your pavers...you may get some heaving..I'd talk to a sales rep or the paver's manufacturer..
job would raise the level of your patio and
walk by about three inches. The bricks
along the edges would be prone to loosen.
What is commonly done here in Los Angeles
with stable but unpretty concrete is to lay
large terra cotta tiles from Mexico. It's
a standard adhesive and grout thing, like a
kitchen counter on a grand scale. The added
thickness can be held under an inch.