A Complete Guide To Concrete Types & Mixes

How concrete is classified in the UK

By strength class (C-numbers)

UK concrete is specified using strength classes written as C8/C10, C15, C20/25, C25/30, C30/37, C40/45, etc.

By composition or behaviour

You’ll also hear mixes described by what they do or contain:

By purpose (“designated” concretes)

For common applications, “designated concretes” bundle strength, durability and minimum cementitious content into simple labels – for example, GEN, RC, and PAV families used widely in UK house-building and paving. (You’ll recognise site terms like GEN 1, RC28/35, PAV1/PAV2.) 

Important note on mix selection

The examples above describe typical usage, not a specification. Ground conditions, exposure, reinforcement, thickness and curing all affect performance. Your contractor or structural engineer should confirm the final strength class, durability requirements and any additives before ordering.

EKA Concrete will batch to that agreed specification on site and adjust volumes to suit what is required. With the flexibility of a volumetric – mix on site truck. 

Further reading & resources

• CIRIA C766 – crack control in concrete (overview). ciria.org
• NHBC Standards – housing practice and acceptance criteria (concrete-related sections).
• The Concrete Society – technical notes and FAQs (e.g., crack control summary referencing C766). Concrete Society

Loads (what will it be carrying?)

Domestic slabs, paths and driveways
Most home projects fall into low to mid-range strength classes. The right choice depends on slab thickness, ground preparation and whether vehicles will use the surface.

Garages, workshops and small extensions
Heavier loads or larger spans usually call for a higher strength class and, in some cases, reinforcement. This should be confirmed at the design stage.

Vehicle traffic and point loads
Areas subject to cars, vans or repeated turning forces need careful thought. Thicker slabs, suitable joint layout and an appropriate strength class all play a part in long-term performance.

Exposure (what will it be exposed to?)

Freeze–thaw and winter conditions
External concrete can suffer surface damage during cold weather, particularly where de-icing salts are used. Air-entrained mixes are often specified to improve resistance and durability.

Agricultural environments (slurry and silage)
Concrete exposed to animal slurry, silage effluent or wash-down water faces aggressive conditions over time. Floors and yards in these settings usually require a higher-quality mix, good surface finish and proper falls to aid drainage. Local experience and professional advice are key here.

Placement and access (how will it be installed?)

Standard pours
Most domestic work is placed directly from the truck into formwork. A workable mix and proper compaction are essential to achieve the intended strength.

Restricted or awkward access
Long garden runs, narrow driveways or limited working space can affect how concrete is delivered. Volumetric on-site mixing, alongside skilful concrete pump pipeline installation, can help manage access, timing and exact quantities, reducing waste.

Practical examples

Shed base at the end of a garden
A modest-strength concrete is often suitable, provided the ground is well prepared and the base is thick enough for the shed and its contents. Access may be limited, so planning delivery and barrowing or line pump routes matters.

Domestic driveway
A mid-range strength concrete is commonly used, with attention paid to sub-base quality, joint layout and curing. Where the driveway is exposed to winter conditions, air-entrainment may be specified.

Industrial or agricultural yard with frequent vehicle use
Higher strength concrete is normally required to cope with repeated loading from forklifts, tractors or delivery vehicles. Good surface finish, drainage and ongoing maintenance make a noticeable difference to service life.

Concrete considerations in the UK

Weather conditions (cold and hot)

Cold weather

Low temperatures can slow strength gain and, in severe cases, damage concrete before it has properly hardened. Fresh concrete should be protected from freezing and kept above roughly 5 °C during the first 48 hours after placement. On colder sites, this may involve insulating the slab, enclosing the pour area, or using temporary heating. Timing matters too, overnight temperatures, wind chill and exposed locations should all be considered when planning the work. You can read more information in our full guide here.

Hot weather

Warm or windy conditions can cause concrete to lose moisture too quickly, increasing the risk of rapid setting and plastic shrinkage cracking. Managing evaporation is key. This may involve adjusting working times, using set-retarding admixtures where specified, providing shade or windbreaks, and starting curing as soon as finishing is complete. Prompt and consistent curing, using membranes or coverings, helps maintain surface quality and long-term performance.