Although H+H Celcon Limited has brought technology a long way since the 1950s, the process remains the same. The materials used in the manufacture of Celcon aircrete blocks are pulverised fuel ash (PFA), sand, cement, lime and water. The manufacturing process, which is closely monitored at all times, begins by mixing PFA, sand and water to form a slurry. The slurry is heated and mixed with cement and lime, and finally, a small quantity of aluminium powder is evenly dispersed through the mixture before it is poured into moulds.
Completing the process
The aluminium initiates a chemical reaction, generating the minute bubbles which form the characteristic aircrete structure and appearance. When the mixture has partially set, the resultant ‘cakes’ are wire-cut into blocks of predetermined size, and transferred to autoclaves for high-pressure steam curing. During this process the ingredients combine to form the calcium silicate hydrates which establish the special properties of the finished product. Each Celcon factory is equipped with process laboratories, staffed by qualified chemists and technicians who ensure strict compliance with the Company’s BS EN ISO 9002 quality control procedures.
Compared to many other materials, the manufacture of Celcon aircrete blocks is environmentally friendly. A large proportion of the product is PFA, a by-product from coal burning power stations, which would otherwise be used in landfill. The process is also highly efficient with most waste material and energy being recycled back into the process itself.