Non-metallic rebar (eg GFRP rebar, Basalt rebar) is also an option that's becoming more popular, though I've only seen it in low-importance structures. Both hav

Non-metallic rebar (eg GFRP rebar, Basalt rebar) is also an option that's becoming more popular, though I've only seen it in low-importance structures. Both have very different design considerations than steel though: they essentially don't yield until failure loads, they have thermal expansion different axial vs radial, etc.