i don´t know, if all species can dig through cork, but i think most of them, especially if they are big or have big mandibles. lokk at there nests in the nature, if they live in nests, there they have to dig in hard soil or wood. That may helps.
for example, i think lasius flavus is a good ant fpr cork nests, if the humitity is high enough. you can humidify the nest on the edge of the cork. water goes in automatically, but it need some time.
good luck