The Essentials of Concrete Bricks

Concrete bricks are used throughout a huge variety of projects, a vital aspect of everything from homes to high rises. Sold in a range of densities and sizes, concrete bricks offer strength, stability and insulation, but bring a few drawbacks such as their generally unappealing look. In this guide from Building Materials Nationwide, we’ll cover the essentials of concrete bricks, how they’re made, the types available in the UK, and how they compare to clay bricks.

What Are Concrete Bricks?

Concrete is the most popular building material in the world, used to build everything from the Colosseum of Rome to the Burj Khalifa, the tallest building in the world. Produced by mixing cement, sand, and coarse aggregates, concrete can be used to create seamless structures, but is also used to form bricks that can be used within a huge range of constructions.

Concrete bricks are standard-sized cuboid blocks used much like traditional clay bricks within buildings of various sizes. They can also be referred to as concrete blocks, or as a concrete masonry unit (CMU). There are different types of concrete bricks available, with specialist options designed to be reinforced for use within larger buildings like high-rise skyscrapers.

How Long Have Concrete Bricks Been Used?

Concrete bricks have been used in certain types of construction as far back as the late 1700s, though the methods used to create them changed over time, with the introduction of hollow bricks that could be filled with concrete after being laid. The early 20th century brought quick growth in the world of concrete bricks, with the invention of machines that could produce various sizes of brick at a much faster rate.

The Benefits of Concrete Bricks

There are some clear benefits to concrete bricks, showing why they remain the most popular building material:

• Quick Installation: Compared to clay bricks, the larger size of most concrete bricks will mean the installation process is quicker, with fewer bricks required.
• Strength and Long Life: Concrete stands the test of time, getting stronger over time, unlike some other building materials. It is not weakened by moisture or mould.
• Thermal and Acoustic Insulation: Concrete bricks offer good thermal and acoustic insulation. While acoustic insulation can make a building more habitable, increases in thermal insulation will save money by reducing heating bills.

There are also a few disadvantages to consider when choosing a building material:

• Pricing: Concrete fluctuates in price, but it will usually cost more to build with it than other methods. Especially in cases like home building, this cost difference can mean that concrete bricks aren’t the ideal choice.
• Visual Look: Compared to the look of clay bricks, the large grey look of concrete buildings might not be for everyone, particularly when used to build a house. There are facing options but this will be an additional expense.

What Types of Concrete Brick Are Available?

When buying concrete bricks there will be a choice of solid or hollow bricks. When it comes to materials and density, there are three specific options; Dense, lightweight, and aerated. You can also buy common bricks for hidden uses within a project.

• Dense Concrete Bricks: Dense concrete bricks come with a high level of strength making them suitable for use in load-bearing walls and foundations. They will have a weak level of thermal insulation and can absorb water easily.
• Lightweight Concrete Bricks: A lighter option compared to dense concrete bricks, these will offer a lower level of strength but will make up for it with better thermal insulation and lighter weight. Lightweight concrete bricks are also easy to decorate with dry lining.
• Aerated Concrete Bricks: The lightest option available, with a high percentage of air content. They can be used in a variety of smaller buildings and for non-load-bearing elements of larger buildings. They offer a good level of thermal insulation.
• Concrete Common Bricks: These general-purpose concrete bricks come with variations in colour and texture. Common bricks are designed for hidden applications rather than visible ones such as outer walls. They can be installed above or below a damp-proof course membrane.
• Hollow Concrete Bricks: When looking to build the strongest walls and buildings, hollow concrete bricks will be used. These will have a solid exterior with large holes in the centre, which can be reinforced with steel and poured concrete to create sturdy and consistent constructions.

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What Size Are Concrete Bricks?

Unlike clay bricks, there will be a variety of sizes available when buying concrete bricks. The standard size would be 440mm x 100mm x 215mm but other sizes will be available. Compared to a red clay brick which will usually be 215mm x 102.5mm x 65mm, concrete bricks are considerably bigger.

Concrete Bricks vs Clay Bricks

Both clay bricks and concrete bricks can be used within a construction project, with some key differences to consider when looking for the best option. Movement joints act to protect buildings from the natural movement of their walls. While clay-bricked houses will require a movement joint every 12 meters, those built with concrete blocks will require one every 6. Concrete blocks also have a tendency to shrink over time, which can cause cracking.

While the lifespan of concrete bricks will still be reasonable, clay bricks can last for hundreds of years, with many clay-bricked buildings persisting across the centuries. Finally, something worth considering is the aesthetic appeal of each. Bare concrete blocks are not usually seen as attractive, especially compared to red clay bricks which blend well in a variety of urban and rural environments. While there are coverings that can hide concrete brickwork, these will bring additional expenses not needed when installing clay bricks. While clay-facing bricks can be coloured in a variety of shades, such as buff bricks, concrete bricks tend to be a consistent grey.