C40/50 Concrete Mix Design
C40/50 sits toward the higher end of common strength classes, typically specified for the most severe durability exposure — marine chloride exposure or aggressive chemical ground conditions — or where high strength is itself the structural requirement.
Typical exposure classes
Often paired with XS2–XS3 (seawater chloride, including tidal/splash/spray zones) or XA2–XA3 (aggressive chemical attack), reflecting some of the most demanding EN 206 exposure conditions, as well as high-strength structural applications. See exposure classes and durability.
Designated Concrete equivalent
Closely associated with RC40/50, at the upper end of BS 8500’s standard Designated Concrete reinforced series; beyond this, projects typically move to a fully Designed Concrete specification for bespoke high-performance requirements. See the designated concrete catalogue.
Typical uses
Marine and coastal structures, foundations in aggressive ground, and heavily loaded or high-durability structural elements.
Frequently asked questions
Is C40/50 always Designed rather than Designated Concrete?
RC40/50 exists as a Designated Concrete designation, but very demanding or unusual combinations of exposure at this strength level often move to a Designed Concrete specification for the flexibility it gives; see Designated vs Designed Concrete.
What is the BS 8500 designation closest to C40/50?
RC40/50 is the closest Designated Concrete equivalent.