With concrete reinforcement steel what does Y12 bar mean and what does R10 bar mean?

The numbers refer to the different diameters of the rebar used to reinforce the concrete. R specifies round bar. Y or N specify deformed bar. See below. == * Round mild steelreinforcement bar - R6 R10 R12 R16 R20 R24 R28 R33 * Deformed reinforcement bar - N12 N16 N20 N24 N28 N32 N36 * Stock lengths of reinforcement bar - up to 12 metres * S12 Pool Steel - Mild steel bars (not tempcore) that is very easy to bend by hand * Processed reinforcement bars - custom cut and bent to required needs * Dowel Bars - precut, often galvanised round bars used when one slab joins another * Galvanising - Plain Reinforcement Steel bars can also be supplied galvanised *Deformed Bar was previously called Y-Bar eg: Y12, Y16 but through product improvements the tempcore strength was increased (now 500Mpa) and is now denoted as N-Bar as listed above