To build without tension you have to build structures that basically look like Roman structures [1]: a bunch of tightly spaces arches so that the entire thing is in compression, with no meaningful tension anywhere.

But it turns out that's pretty inconvenient; we really like doing dozens of feet of span for highway overpasses, building floors, and everything else. So we put rebar in all the concrete and just acknowledge that that means it has an absolute maximum lifespan of a century or two, and will certainly not last for millennia the way pure concrete in pure compression can.

[1]: https://www.theartnewbie.com/blog/rome/roman-arch