Designated Concrete vs Designed Concrete
BS 8500 recognises more than one way to specify concrete. The two most common on UK projects are Designated Concrete and Designed Concrete — this page explains the difference and when each is the appropriate choice.
Designated Concrete
Designated Concrete is chosen from a fixed list of standard concretes (for example RC-series concretes for reinforced work, PAV-series for pavements, GEN-series for general/foundation use, and others) that a certified concrete producer already has approved mix designs for, under a third-party certification scheme. The specifier simply states the designation code — the producer supplies concrete already proven to meet it, without a separate mix design exercise for that project.
This makes Designated Concrete quick to specify and straightforward to procure for common, well-understood applications where a standard designation already fits the exposure and strength requirement.
Designed Concrete
Designed Concrete is specified by performance: the specifier states the requirements — strength class, exposure class(es), consistence (workability) class, maximum aggregate size, and any other project-specific limits — and the concrete producer designs a mix to meet them, submitting the mix design for approval. This gives more flexibility than a standard designation and is generally used where the project's requirements do not fit an existing designated mix, where a larger or more critical structure justifies a purpose-designed mix, or where a specific combination of constituents or performance is needed.
Which one applies to this calculator?
The calculator on this site works through the Designed Concrete route — it proportions a mix from the performance requirements you enter (strength class, exposure class, consistence and materials) using the EN 206 absolute-volume method, in the same way a producer would develop a mix design to meet a Designed Concrete specification. It does not select from the fixed Designated Concrete designation list.
Frequently asked questions
Which is cheaper?
Designated Concrete is often more economical to procure for common applications because the producer already holds an approved, certified mix — no separate mix-design and approval process is needed for that project. Designed Concrete can cost more to set up but suits projects with requirements a standard designation does not cover.
Can I use Designated Concrete for any exposure class?
No. Each designation is only valid for the exposure classes and applications it was established for. Check the current BS 8500-2 designation tables, or use Designed Concrete, if your exposure class or application falls outside what a designation covers.
Is there also a “prescribed” option?
Yes — BS 8500 also recognises Prescribed Concrete, where the specifier states the exact mix proportions and constituents directly, and Standardised Prescribed Concrete, a smaller fixed list similar in spirit to Designated Concrete. These are less commonly used than Designated and Designed Concrete on typical projects.