Lots of different materials and techniques have been tried, but nothing so far seems to have really stuck. As an observer I think there are two main factors: 1

Lots of different materials and techniques have been tried, but nothing so far seems to have really stuck. As an observer I think there are two main factors: 1) The types of steel used coincidentally have nearly identical coefficients of thermal expansion as the concrete used. 2) Everybody in the construction industry and the entire supply chain is familiar with and habituated to steel rebar. The inertia is tremendous. That's a very high bar to meet to gain a foothold with new materials or new techniques as the entire system has evolved to fit the pros and cons of steel rebar. Anything that departs from standard practice becomes very costly, very quickly, for a gazillion reasons.