I'm attempting to build a concrete garden planter - 6" thick wall, 1/2m high running about 9m around a small square garden. The client would like it to have a 'timber grain finish' from the shuttering. Does anyone know how fine the concrete ballast should be to achieve this. Most ready mix bags have a 10mm ballast - I'm guessing any smaller would lack sufficient structure, but does it leave a sufficiently finished surface?
Having not really done this before, any tips on good shuttering and rebar requirements would be appreciated especially as the timber grain effect is a mostly one shot project.