We don't have any concrete, but the soil can get about as hard, it seems. And we had a problem with some horses pawing pretty deep into the ground a few years ago. We put pea gravel down several inches deep in there, then put some salvage belting on top. That works great! They don't slip. Liquids go through, and solids are easy to get out with a silage fork or shovel ('easy' being a term used by me, a person who doesn't do that job!)
The belting is in pieces two to four feet wide. It is about a half to three quarters inch thick and is very heavy. I notice it being moved with a small skid steer, as many of the pieces we have are ten feet long, or more. Those are about two and a half feet wide, I think. I believe they cut them to fit with some electric tool. Not sure what it is.
We got some at Cammacks at Union Center, but most recently have gotten it in Rapid City at a quarry. They use it to haul rock about a quarter of a mile, I believe, and it wears out to the point they can no longer use it.
Probably will also use some straw or wood shavings on top of the belting for absorbency and warmth of baby calves. Mostly hoping we don't have to have them in the barn at all! We calve most every thing in pastures, but probably will watch hiefers a little closer, especially if the weather gets bad. I think we won't start till about first of March, and that is too early for our weather! But it is nice to get them done before the cows start.
mrj