Cover

The window General consists of several tabs. Information about the reinforcement cover for every Group is saved in the tab Cover. In this tab the applied cover values according to the required codes are shown. If the fabrication method is Prefab, the reduction of the cover is indicated in the column Red. The column Red reduces the cover and is dependent on the exposure class and the fabrication method (I.h.w. or Prefab.) as accessible or not accessible. The cover must be provided for Top, Bottom and Side&Front of an element. The applied cover is filled with the values of the minimum cover by default. The calculated nominal cover in the column Cnom is represented. The minimum applied cover according to the rules of the Code is shown in column Min. The provided cover in the column Cover must be not less than Nominal. If element surface is uneven (W-up) or not approved (N.Appr.) cover will be increased.

The exposure classes (environmental classifications) XA and XF influence the composition of concrete (see NEN-EN 206-1/NEN 8005) because these classifications are a standard measure for the extend of the concrete corrosion itself. It doesn't mean that no requirements are met for the size of the concrete cover. The environmental classifications that are related to the corrosion of the concrete itself, occur in the combination with environmental classifications that are related to the protection of concrete steel. You can find the right environmental classification when, for example, environmental classification XF occurs frequently in combination with an environmental classification XD or XC. In this case the decisive XD or XC environmental classification should be used concerning the minimum concrete cover. For more information see Exposure classes.

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 explained 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):