Reinforcement covering

     Slab

Beam

     Column

Footing

Conventional structure (50 years life span) in areas with common environmental conditions

The covering of reinforcement ensures: (a) safe transmission of bond forces, (b) protection of steel against corrosion (c) adequate fire resistance.

The required reinforcement covering (For construction details see Volume A, §2.6.1) depends on the environmental conditions, as explained below:

Environmental conditions

The environmental conditions can vary from the most usual to the most extreme. These conditions are analytically described and classified in EC2 and EN206-1.

The main conditions for the Greek region are the following:

Category XC2: Wet, rarely dry. Most of the foundations are included in this category.

Category XC3: Environment with moderate humidity. Concrete inside buildings with moderate or high air humidity. External concrete sheltered from rain.

Category XC4: Environment with cyclic wet and dry.

Category XD1: Moderate humidity. Concrete surfaces exposed to airborne chlorides.

Category XD2: Wet environment, rarely dry. Concrete, totally immersed in water containing chlorides e.g. swimming pools. Concrete exposed to industrial waters containing chlorides.

Category XS1: Exposed to airborne salt but not in direct contact with sea water. Structures near to or on the coast.

·          for slabs 5 mm are deducted

·          in case of a special concrete quality assurance production procedure, 5 mm are deducted

·          in case of a designed building’s life span of 100 years, 10 mm are added

·         For the surfaces of the footing’s shoes - with casted concrete – which are in direct contact with the ground (in cases of suitable formation or a footing mix) it should be c_min≥k₁=40 mm, whilst in cases of direct ground contact c_min≥k₂=75 mm

Note:

·         In category XC2, the minimum concrete class is C25/30. This class includes the majority of foundations. In order to avoid problems created by the use of different concrete classes in the foundation and the superstructure, it is recommended to use the concrete class of the superstructure in the foundation as well.

Conventional structure (50 years life span) in areas with common environmental conditions

Building in the city center under ‘common environmental conditions’, with a conventional life span (which means 50 years), using reinforcement bars up to: Ø10 for slabs, Ø20 for beams, Ø25 for columns and Ø20 for the footings’ shoes which will be based on a footing mix.

For Slabs: c_min,b,=10 mm, c_min,dur=25mm-5mm=20 mm à c _min=max(10mm, 20mm, 10mm) à c_min=20 mm

For Beams: c_min,b,=20 mm, c_min,dur=25 mm à c_min=max(20mm, 25mm, 10mm) à c_min=25 mm

For Columns: c_min,b,=25 mm, c_min,dur=25 mm à c_min=max(25mm, 25mm, 10mm) à c_min=25 mm

For Footings: c_min,b,=20 mm, c_min,dur=25 mm à c_min=max[max(20mm, 25mm, 10mm), 40mm] à c_min=40