I want mats for my floor of the sawdust bin, which I figure is workable and inexpensive. Right now we just have dirt. We have a tarp top over the bin walls, which sometimes leaks in spots with rain or snow buildup. This means that bedding will need to drain dry at times and for us, asphalt would not drain as well.
Also if I want to move the bin location at a future time, I can just lift the mats. We move the wood fiber by hand to stalls, no loaders. So a firm floor of mats will make it easier when we get to the bottom of the pile. Less of a composting issue with the bottom layer. We get 40 cubic feet at a time, that is what the delivery truck holds. Wood fiber is dried, so I try to keep it dry. That size pile does last us a good while. We like the wood fiber which is like fine mulch shreds, also cheaper than sawdust from the seller. Very absorbent. Our old sawdust guy was getting very unreliable, so we changed and have been happy with the new wood fiber folks.