Now we come to the tricky part... if all we want to make is concrete slabs, then the mix + water = the slab. However, these days in most construction you end up with ferroconcrete, which is basically iron (NOT steel) rebar in concrete, because their expansion and contraction rates are identical. So, mix + water + iron ingot (or iron rebar if you want, but that's an extra item that can just be handwaved) = feroconcrete. Which has uses in paved roads, walls, and higher-tiered buildings.
We already have Iron Sticks that could be used as rebar. https://forums.factorio.com/wiki/inde ... Iron_stick
Personally, I like the idea of adding sand. It can be used for glass and advanced electronics as well as concrete/cement. The recipe for concrete/cement it a bit trickier though. Realistically (from info from previous posts), it should be something like cooked stone + sand. However, cooked stone already gives stone bricks. Either we will have to have something else, like a stone crusher, and then cook the crushed stone, or otherwise have a new recipe for bricks, perhaps involving clay (which would then be another new resource, which perhaps could also be an ingredient for cement). Once you have cement, adding stone and water would make concrete / concrete bricks, which could then be used. Cement, stone, water, and iron sticks could make reinforced concrete which could be used for stronger / more advanced structures.
I also like the idea of aluminum being added, as a metal that would be used near end game. Especially if it is more complex to process than iron or copper. It definitely makes sense that many of the rocket parts would use aluminum as well as the advanced armors / shields, and even perhaps a higher levels of weapons and gun turrets / ammo.
Uranium also sounds interesting, however, if it's only use would be power plants, then it might not be worth it. If you could also make low level nukes and perhaps advanced cannon shells from the uranium, then it might be worth it, but definitely the more uses the better.
I also like the idea that different biomes would give different amounts / rates of some of these new resources (and oil). That matches the real world to some extent, and would give you reasons for building rail lines to different biomes.
So that's what I think, but no one has to follow what I think, I'm the guy that made a mod that added 5 new types of science packs to make existing researches more complex / consuming to perform