What Is The Strongest Concrete Mix?

24th January 2025

While writing our latest blog on choosing the right concrete mix, we realised that a lot of the decision comes down to concrete strength. So, if you are looking for something for the foundations of a multi-storey building, busy roads or pavements or for structural beams and columns, you will probably be wondering what is the strongest concrete mix?

The answer to that is fairly simple. C40 is the concrete mix design known to be the strongest, so this is the one used in heavy-duty projects where high load capacity is needed.

At 2 Brothers Concrete & Pumping, we produce all concrete design mixes, from the weaker C10 for domestic DIY projects right through to C40 for commercial and industrial construction. With a combined 25 years of experience and a team of experts at the helm, we know everything there is to know about concrete production and strength.

In this blog, we explain how C40 is the strongest concrete design mix and when it might be used.

The Strongest Concrete Mix Ratio

We don't think we need to explain the importance of concrete strength to you; chances are you already know (unless this is a pub quiz question and you are cheating - but even then, you don't need to know why it's important), so we are going to dive right in and answer your question.

As mentioned above, C40 is the strongest concrete mix in the UK. It is made using the same ingredients as the other grades, but the difference is the ratios.

C40 consists of a mix ratio of 1:2:3 (1 part cement, 2 parts sand, 3 parts aggregate). Along with these ingredients, it has a water-to-cement ratio of around 0.4 to 0.45. This is lower than a typical concrete mix, making it a more dense concrete mix.

The increased amount of aggregate is what enhances the strength of the mix, and it reduces shrinkage. However, aggregate can be coarse, so slightly more sand is added to the mix to fill the gaps created by the aggregate. This further optimises the mix's strength.

What Defines Concrete Strength?

If you are still reading this, even after you have the answer to that burning question, you must be looking to become an expert! Now that you know what the strongest concrete mix is, we're going to take a deeper look into what defines the strength of the material.

Concrete strength is measured in terms of compressive strength. For this, we use the measurement MPa, which stands for Megapascals. C40 has a compressive strength of 40 MPa, making it the concrete with the highest compressive strength (probably not surprising this far into the blog).

So, how does it gain this? Through the ratio of ingredients, the curing process and the quality of the materials - if the concrete is made with recycled aggregate, the strength might not be as good.

Factors That Impact Concrete Strength

Of course, there are several factors that impact the strength of concrete, and the strongest concrete mix is no exception.

Water-cement ratio - lower water content fills voids but creates a denser mixture.
Aggregate quality and size - the size of the aggregate impacts strength as it determines the gaps within the mixture. Plus, the cleanliness of the ingredients ensures proper chemical and physical properties of the concrete.
Curing process - the proper curing process will ensure hydration while also minimising the risk of cracking. Ideally, the concrete needs to be kept moist for seven - 28 days.
Use of additives and admixtures - fibres and other additives can be mixed into the mixture to enhance its strength and durability.

Applications of the Strongest Concrete Mix

With all this information, we bet you are now desperate to know when the strongest concrete mix is used.

Wait no longer! Here is a list of typical applications for C40:

Residential buildings - structural flooring components, basements and outdoor areas.
Commercial buildings - flooring structures in offices, retail flooring and parking structures.
Industrial settings - warehouse and factory floors and cold storage facility walls.
Infrastructure - Bridges, motorways, roads and tunnels.
Educational and health - flooring in hospitals, laboratories and schools.
Airports and transport terminals - airport flooring, hanger flooring and runways.
Prefabricated buildings - concrete panels are integrated into modular buildings.

Order The Strongest Concrete Mix From 2 Brothers

Well, you made it to the end! And now you know everything there is to know about the strongest concrete mix in the UK, C40.

It is made with more aggregates and sand and less water to create a dense mixture that cures to develop a load capacity of 40 MPa.

Thanks to this, C40 is used across a wide variety of projects, from public infrastructure such as roads to high-rise building structural beams or industrial flooring.

At 2 Brothers Concrete & Pumping, this is just one of the concrete design mixes we can produce in our mix-on-site service.

With our fleet of volumetric trucks, we produce your concrete on-site, meaning we only make the amount you need. So, you don't pay for concrete that you don't use.

Plus, reaching your project site is easy with our concrete pumps - we have boom and line pumps offering flexibility and extended reach.

If you think C40 is right for your project, get in touch with our experts today to order it. Or if you don't need concrete quite as strong as that, still get in touch because we can provide any other concrete design suitable for your project.

Call us on 01489 552737 or complete our online contact form, and we will call you back as soon as possible.