Generally speaking, it is mostly pasted under the slab of carbon fiber strengthening, and it is rarely pasted on the surface of the slab, unless the slab is a cantilever component. The load bearing characteristic of most slabs is that the middle part is bent downward, so it should be pasted on the lower part of the slab to improve the bending resistance.

Can't it be pasted on the slab?

Actually, it's not true, because sticking carbon fiber cloth is to make up for the lack of tensile and bending resistance, so sticking carbon fiber cloth should prescribe the right medicine. When overhanging members such as bay windows and corridors need to be reinforced, because their stress characteristics are opposite to those described above, they must be pasted on the surface of the slab.

In short, the sticking position of the carbon fiber cloth should be the same as the layout of the tensioned main steel bars of the original structure