Exposure Classes

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Multi Storey
Car Park
Bridge Over Road
Bridge Deck
Culvert Structure


  • Specification of Exposure class(es) for elements (EN 206)
    • For further guidance on aggressive chemicals and complex site conditions – refer to BRE Special Digest 1
  • Alignment of strength class and exposure class limiting values - EN 206 NA (most onerous)
  • Specific cement types permitted / required
  • Aggregate type / size limitations
  • Design life
  • Type of concrete (i.e. reinforced, prestressed, plain etc.)
  • Chloride class
  • Curing class
  • Thermal limitations
  • Potential operational (or construction) conditions
  • Reinforcement cover versus concrete mix trade-off for 50 & 100 year design lives(I.S. EN 206 National Annex – Annex NC)
  • Approval of finish


  • Timing of exposure to environmental conditions
  • Curing regime
  • Placing limitations (temperature)


  • Identify most onerous limiting values (from exposure class(es) /strength)
  • Mix design to satisfy these limiting values & other mix limits (e.g. alkalis)
  • Selection of suitable materials (in accordance with EN 206)
    • Cement / addition / aggregates /admixture

Further Guidance

Main Standards – Reference

I.S. EN 1990

I.S. EN 1992-1-1

Section 4 +NA

I.S EN 206

See NC annex in NA

Other Guidance Documents

BRE Special Digest 1 Concrete in aggressive ground

TII DN-STR-03012: Design for Durability : Appendix A Exposure class diagrams http://www.tiipublications.ie

IHS BRE Press, S. Matthews, Design of Durable Concrete Structures