Which is the economical solution for Tunnel over head protection, SHOTCRETE or STEEL FIBERS?

Thank you for posting your query.

We have to first make out the reason for failure. If it is due to corrosion, then ideally we have to do shotcreting followed by providing steel lining at the bottom and filling up the gap with non-shrink grout for monolithic behavior.

Since this is beyond Hilti’s area of expertise and the above is based on our understanding. We hope that one of the fellow members of this portal is able to address your concern in more detail.