For the reinforcement of concrete members adequate concrete covering layers should be designed. These layers protect the reinforcement against negative environment conditions and ensure good bonding conditions for reinforcement bars and fire resistance.
Main normative requirements, for ordinary and prestressed reinforcement , are presented in codes EN 1992-1-1 and related national annexes.
Below you find a number of basic parameters for choosing proper design covering layer:
- Structural class S1… S6 EN 1992-1-1 #4.4.1.2(5)
- Exposure class X0… XS3 EN 1992-1-1 #4.4.1.2(5)
- Peculiarities of casting (Uneven):
- surface features (ribbed finishes, exposed aggregate…) EN 1992-1-1 #4.4.1.2(11)
- concrete cast directly against soil or cast against prepared ground EN 1992-1-1 #4.4.1.3(4)
- Peculiarities of the applied fabrication technology:
- quality assurance system type (monitoring of concrete covering during fabrication) EN 1992-1-1 #4.4.1.3(3)
- Diameter of reinforcement bars
- Concrete aggregate size
Based on these parameters a minimum cover of reinforcement can be calculated (EN 1992-1-1 (4.2)) and a nominal required covering can be estimated (EN 1992-1-1 (4.1)). The design value of covering is not allowed to be less than the calculated nominal covering. For the fire calculations, additional rules according to the EN 1992-1-2 must be applied.
Concrete cover at beams (a) and floors (b):
