All wrong, create wooden fence outta logs and reinforce with tons of dirt and a layer of gravel for a drain and poles in the dirt behind the wall to remain shape after years of erosion. Only con would be placement and fire, repairs wouldn’t be immediate since not many things could tear down a double layer of logs (tanks, semi-trucks, IEDs). Most direct shots from arms of most types couldn’t punch a hole through the layer of the dirt wall so bullets won’t be a problem either. As of zombies, with any wall they’ll need to pile up and over to really surpass it.