Interesting question. See https://www.strombergarchitectural.com/materials/gfrp doesn't look like they produce anything resembling rebar. Why not ask them?

Hello Aziz Ibrahim Abdulla ,

In the late 1990s, someone at the company where I worked brought in a sample of a polymeric and/or composite rebar. Unfortunately, I don't remember the name of the manufacturer, but at the time we were partnered with Hilti. I just checked the Internet, and Hilti does currrently have a FAQ page on this topic: https://ask.hilti.in/questions/what-is-the-use-of-replacing-the-steel-rebars-by-gfrp-rebars-in-the-concrete-structures/pkyc26 . Until I happened to see your question, I had completely forgotten about alternatives to steel rebar. Thanks for an interesting question.

Regards,

Tom Cuff

It is a good question ...

I am interesting in this subject...

because there is no alternative material such equivalent to the efficiency of rebar in terms of its resistance to tensile strength and its bearing of loads...

Rebar is recommended on concrete measuring 5 – 6 inches thick. You do not need rebar for a 4-inch slab of concrete on grade. A 4-inch-thick slab cast on the ground and in permanent contact with it will float and rebar is not required. https://www.gizmoplans.com/do-you-need-rebar-for-4-inch-slab/

Direct alternatives to rebar include the use of aggregate materials or metal mesh. Metal mesh ranges from chicken coop wire to fencing. Any type of metal mesh that you may have lying around can be used as a substantial support for concrete. https://www.ehow.com/list_7615263_rebar-alternatives.html

Kindly check https://www.architectmagazine.com/technology/two-natural-rebar-alternatives-for-concrete_o