We manufacture aircrete, predominantly our range of Celcon Blocks, in three state-of-the art factories in Kent and Yorkshire. Our Borough Green factory, subject of a major rebuilding programme, is the most modern and efficient aircrete factory in Europe. We also benefit from the support and experience of our colleagues across Europe, with manufacturing plants and sales offices owned and operated by H+H International, our parent company.
In 2024 we celebrate 75 years of Celcon Blocks being manufactured in the UK and are looking forward to continuing to serve our customer partners and the construction industry for another 75.
What is Aircrete?
Aircrete is a lightweight masonry material, combining the strength, durability and thermal efficiency of concrete with the ease of use that comes with a lighter material, easy to cut and work on site.
The materials used in the manufacture of H+H aircrete are: sand, pulverised fuel ash (PFA), cement, lime and water. These are combined into a slurry where a small amount of aluminium powder is added to the mix. This initiates a chemical reaction, generating minute bubbles which form the characteristic aircrete structure and appearance.
When the mixture has partially set, the resultant “cakes” are wire-cut into blocks or panels and transferred into autoclaves for high pressure curing.
The Origins of Aircrete
Originally known as cellular concrete, aerated concrete was first produced in Scandinavia in 1924. At this time the cellular concrete was made from Portland cement, water and a foaming agent. After mixing, it was poured directly into the required position on site and used primarily for insulating roof screeds and underground pipe insulation.
In the 1950s Celcon developed the process to manufacture aerated concrete into blocks and Danish scientists added pulverised fuel ash (PFA). A waste product from coal-fired power stations, the PFA gives the product strength, yet makes it light enough to pick up with one hand.
H+H aircrete manufactured in the UK is traditionally comprised of 80% PFA, giving excellent sustainability credentials as well as great performance. Sand is also used in the mix and, depending upon the availability of PFA.