Fiber-reinforced cement composites are an interesting alternative: https://onlinelibrary.wiley.com/doi/pdf/10.1002/suco.201700147 https://onlinelibrary.wiley.c

Fiber-reinforced cement composites are an interesting alternative: https://onlinelibrary.wiley.com/doi/pdf/10.1002/suco.201700147 https://onlinelibrary.wiley.com/doi/pdf/10.1002/suco.2017001... Some German researchers seem to think that carbon fiber-reinforced polymer "rebar" could be more durable than steel bars with similar cost and lower weight: https://www.aboutcivil.org/carbon-reinforced-concrete-building-cube https://www.aboutcivil.org/carbon-reinforced-concrete-buildi... Unfortunately, the terminology is not well standardized, and when you look up "carbon fiber reinforced concrete", you never know if you're going to get a fiber-reinforced cement composite (incorporating carbon fibers directly into the cement matrix) or a CFRP rebar system. Regardless, there do seem to be some improvements on the horizon.