> The number of individuals who know how to make a can of Coke is zero. This reminds me a fact I remember time to time. If civilization collapses after, say, a world war, I most probably can't make a pot, can't grow plants, can't differentiate if one is edible or not, can't dig for petrol, can't make plastic (or even glass), can't reinvent concrete, can't make gunpowder etc., you get the point. I can only write softw…
You need to burn limestone until it collapses into a powder, then add sand and water. Done. For stronger cement, add clay powder.
Have you never had relatives who built a house? Sure, usually you'd buy the powdered stone, but I've heard stories of my great grandparent's generation making it on site.