How is concrete made?

A common question we’ve been asked here at Oxfordshire Concrete: Just how exactly is concrete made? First, we must dispel a myth – concrete and cement are NOT the same thing. You’ll find that cement is actually simply a component of concrete!

In its simplest form, concrete is a mixture of 3 things:

  • Water
  • Aggregate (such as rocks sand or gravel)
  • Cement powder

The cement powder and water acts as a binding agent with the aggregate. You can use a fine aggregate such as sand or a course aggregate such as gravel. Through the chemical reaction of hydration, this paste hardens and gains strength to form concrete.


Proportions of materials

To make sure you have a strong and durable concrete, you need to make sure that you have the proportions of each of the key elements above in careful proportion. If the mixture is too watery it will produce a smoother concrete, however this could cause cracking later down the line. If the mixture has too little water, then this will create a rough surface and porous concrete.

Usually, a concrete mix would be split into the following proportions:

  • 10-15% cement
  • 60 – 75% aggregate
  • 15- 20% water


What happens if there are any impurities in the water?

The water is a very essential part to the concrete mix. If the water contains impurities, then this could not only affect the setting time of the concrete, but also the strength of the concrete as well. It can also lead to a whole host of other problems such as staining, corrosion of reinforcement and reduced durability.

When it comes to the specifications of a concrete mixture, there are usually limits on chlorides, alkalis, sulphates and solids that are within the water used. You will find that most drinking water is suitable for mixing concrete.


How do you include reinforcement in concrete?

Concrete works well in compression, but not when it comes to tension. This is where reinforced concrete comes into play with the use of steel reinforcing bars which mesh together. The inclusion of steel bars means that the concrete will now be reinforced against bending and stretching by providing tensile strength.

The steel bars that are used in this process (also known as rebar, short for reinforcing bar) are usually made from twisted or nobbled strands of steel which allows the concrete to anchor firmly without fear of slipping.


If you’re looking for a supplier of concrete for your commercial or domestic project, we here at Oxfordshire Concrete Ltd are ready to help! Simply get in contact with our team now and we can see how we can benefit your project. If you’re just looking for some inspiration, why not check out our other posts such as How to Lay a Concrete Patio or Wood Effect Concrete – How to Make Concrete Look Like Wood.