One thing to be aware of is that some masonry can be severely stained by the chemical reaction of curing cement. Pavers are very bad about this, and you can just about ruin a paver driveway by spilling concrete on it. I think bricks are a little more forgiving, but you would still have to clean all the excess concrete residue off them after the concrete dried. This might entail using acid. So why risk it? Styrofoam is not that expensive. And it easy as pie to work with.
"True eloquence consists in saying all that is necessary, and only that which is."
François Duc de La Rochefoucauld