TL;DR
Add a new type of wall made of reinforced concrete instead of stoneWhat ?
Now that we have refined concrete (which requires iron sticks and steel as well as concrete) it would be nice to have a new type of wall made with this new concrete, a reinforced concrete wall. I would suggest it have an actual damage resistance to physical damage (enough that a small biter or maybe even a medium one would have no chance of damaging it at all) as well as 2-5 times the hitpoints of standard stone wall. And maybe it could also reduce or eliminate the ability of biters (but still not spitters) to reach over a wall and damage stuff on the other side.Why ?
I don't really care about concrete paths in my factory. A 'nice looking' factory isn't very relevant to me. The extra walking speed is kind of nice, but also not really important. This provides me with little or no incentive to ever make reinforced concrete.But, a wall that was a lot tougher than a regular stone wall would be really nice and give me a lot of incentive to make this new material. It would also allow people who cared a lot about the look of their factory to have even more options to make it more visually interesting as the new wall type would presumably look different from a stone wall. The fact the new material takes iron and steel to create makes this realistic as well.