Am building a section of a modern bridge, and have made the basic core of the bridge from Balsa wood, as it's very light but strong.Plus the weight of the vehicle on top is quite light.
Now what I have planned to get the texture is to coat the wood in cork sheet, and glue with UHU which wont dissolve with water contact, then apply pollyfilla[spackle] to the cork surface.

Wondering if this will work for the concrete texture?
I may have to sand and reapply and sand back the pollyfilla a few times, or am I going about this all wrong?

Ain't used the cork method before for concrete or a modern bridge

I think that should work, I used polyfilla dust on the surfaces of my concrete building in my T-90 Diorama.

I actually found that thin plasterboard sheets are also good, alternatively you could do as was done in the awesome Pripyat Dio and paint over card with artists gesso. That can give a good concrete like texture also.

Well what I did have planned was to use 5mm foamboard over the balsa and then apply the filla to that.
I think I will try it over cork sheet as it has a texture and see how it works...by the way, nice dio.Gave me a few ideas.

Concrete texture? Why? Most modern concrete structures are poured smooth, not rough, so any smooth finish suitably painted would do. Any small imperfections will be barely noticeable at 1/35 scale.

There are two main exceptions. The first is board-marking, where the nearly dry surface is, well, marked with a board - a plank pressed into the concrete to give a textured finish that looks for all the world as though someone's pressed it with a plank. This has gone out of fashion now.

The other exception is coarse-grained concrete where the matrix contains visible gravel instead of being fine particles. This was popular in the 1950s and 60s but, again, has gone out of fashion. How modern for your purposes is "modern"?

I have found that using Terra Cota spray paint (you can purchase it at your local Lowes or Home Depot) lends a hand in producing textures. On another not, it works AWESOME in producing the texture of the no slip found on armored vehicles. Mask it of, Terra Cota it and once dry, paint to your desired color.......