What is basalt fiber and can we use it to replace steel rebar?

Basalt fiber is a material made from extremely fine fibers of basalt, which is composed of the minerals plagioclase, pyroxene, and olivine. It is similar to carbon fiber and fiberglass, having better physicomechanical properties than fiberglass, but being significantly cheaper than carbon fiber. It is used as a fireproof textile in the aerospace and automotive industries and can also be used as a composite to produce products such as camera tripods.

Answer to the second part is yes.

Basalt fibre is a fibre made of basalt, heated to high temperature to melting point and then made to a fiber, like glasfiber,

It is three times stronger then high grade construction steel and weighs only a fraction of it.

The fibers are spun to bars, even bars with the texture of rebar, but they are also formed to small fibers, that can be mixed with concrete. They are testing with mixes without any traditional steel rebar, and also they constructed a three story building with it.

yes, it can replace steel bars, but more testing and experience is needed.

Like mr. Jetley already stated , it is used as fireproof , as blankets or as a composite material