Repair of Concrete Roof

[raystr2025]

I have come across a problem in my project in which the concrete roof - the historical square rebar is exposed on the bottom face (only 3 of the 4 sides are in concrete).
We removed the terra cotta tiles that were originally there under this concrete roof, I guess they used the terra cotta as cover (?).
I asked the senior engineers in my office and one said to expose more deeper into the concrete
so they can expose rest of the faces of the square rebar and then form and pump the new concrete.

However I think creating chipping and creating pockets will undermine the structural integrity of the roof
(the historical loading for roof is D+L 1200 psf from 1905, today there is roadway above).

Is there a way to restore the concrete cover without disturbing any more of the roof or creating pockets on the sides to expose more of the rebar to form and pump?

 

[BridgeSmith]

You could consider FRP composite reinforcement/strengthening.

 

[Michel60]

The terracotta (hollow clay tile?) may be the form work. There are historic proprietary concrete systems that used the clay tile in a shallow vault to support the reinforced concrete fill. A web search might turn up a few examples that you could compare with what you've found.

Small areas of delamination might be repairable by chipping and grouting, but gravity will be working against you. For repairs of any magnitude proceed cautiously.