C25/30 Concrete Mix Design
C25/30 is one of the most commonly specified general reinforced concrete strength classes, used across a wide range of building and civil work where moderate exposure and loading apply.
Typical exposure classes
Commonly paired with XC1–XC2 carbonation exposure — reinforced concrete that is dry or occasionally wet, such as internal building elements or concrete protected from the worst of the weather. See exposure classes and durability.
Designated Concrete equivalent
Closely associated with RC25/30 in BS 8500’s Designated Concrete catalogue, one of the most widely used reinforced concrete designations for general building work. See the designated concrete catalogue.
Typical uses
General reinforced concrete — slabs, beams, foundations and walls in typical building work where exposure is moderate.
Frequently asked questions
Is C25/30 suitable for external exposed elements?
It can be for milder external exposure, but more severe carbonation, chloride or freeze-thaw exposure often calls for a higher class such as C30/37 or C35/45 — check the project’s actual exposure class assessment.
What is the BS 8500 designation closest to C25/30?
RC25/30 is the closest Designated Concrete equivalent.