Some Remarks Towards Surface Reinforcement Used in Concrete Members

The present paper deals with the special situations, when the cover of reinforcement of structural members exceeds 50 mm, and it may be appropriate to provide a surface reinforcement. The new Model Code 2010 [1,2] mentions such a reinforcement, but doesn’t specify its type, cover and the area amount. However such a surface reinforcement is able to increase the bending and especially shear resistance of structural members, subjected to bending and shear. In addition to that the surface reinforcement reduces an expansion and width of cracks.According to Eurocode 2 [3], Part 1-1 in Annex J – Detailing rules for particular situations – there are some special cases when such a surface reinforcement should be used. It is necessary to use this reinforcement type when:•diameter of designed bars is greater than 32 mm, or equivalent diameter of bundled bar exceeds this limit;•cover to reinforcement is greater than 70 mm (for enhanced durability);•crack widths without using surface reinforcement exceed allowed limit;•reinforced concrete structure is subject to fire and there is a risk of falling off of a concrete in the later stage of a fire exposure according to Part 1-2 of Eurocode 2 [5,6].The surface reinforcement should consist of wire mesh or small diameter bars and should be placed outside of links.This paper analyses different values of the surface reinforcement cover and the increase of bending and shear resistance due to surface reinforcement of RC beams. It also includes an explanation of the effect of the surface reinforcement on expansion and width of cracks.