UK PRELIMINARY PROPORTIONING

Explore a UK trial mixture without turning BS 8500 into a fixed recipe.

Record the concrete class and exposure context, enter composition limits only when you have verified them for the project, and inspect the water, cement and aggregate balance. The tool deliberately avoids guessing compliance values from the exposure dropdown.

BS 8500 / BS EN 206 context · verify project editions

Why the limit fields are manual: UK durability specification depends on the current BS 8500 route, exposure, constituent combination and project requirements. The 2023 edition also changed how some durability limiting values are handled. A generic table would be less trustworthy than asking you to enter the requirement you have actually verified.

Concrete context & verified project limits

A strength class is not a complete concrete specification.

Strength class Exposure class (context only) Planning strength margin (N/mm²)Enter a margin justified by the relevant production/trial evidence. Trial free water-cement ratio Verified project max w/c (optional) Verified project min cement (kg/m³, optional) Design air content (%) Max aggregate size (mm) Consistence class Aggregate shape Coarse aggregate share % (blank = model start)

C28/35 and C32/40 are used in UK practice as derived strength classes; do not assume the same class list applies unchanged in every European country.

Material properties & admixture response

Replace defaults with current source data whenever possible.

Cement specific gravityFine aggregate specific gravityCoarse aggregate specific gravityUse water-reducing admixture?Admixture dose (% of cement)Expected water reduction (%)Use supplier/trial evidence for the chosen combination.Admixture specific gravity

PRELIMINARY TRIAL MIX

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Estimate material cost Estimate carbon impact

Planning mean strength-N/mm²

Used w/c-entered / verified cap

Starting water-kg/m³ · model estimate

Cement-kg/m³

Starting proportions per m³

Ingredient	kg/m³ / %	Absolute volume m³

Mass ratio (cement : water : fine : coarse) = -. Do not convert this into a universal nominal mix ratio.

Calculation trail

Trial-batch checks

Specified consistence and retention through the expected delivery/placement period.
Air where specified, density/yield, cohesion and segregation/bleeding behaviour.
Finishability, pumpability or other placement requirements relevant to the work.
Strength and any durability/performance testing required by the specification.
Aggregate moisture corrections before production quantities are issued.

UK USE

Use BS 8500 to specify the concrete; use this tool to interrogate a starting mixture.

The calculator is most useful when the specification work is already done and you want to understand how verified limits, water demand and constituent properties interact.

Confirm whether the project uses designated, designed, prescribed or another permitted specification route.
Use the editions actually required by the contract.
Enter composition limits only after verifying they apply to the selected concrete and constituent system.
Use trial and production evidence for final proportions and acceptance.