| Although H+H Celcon Limited has brought aircrete technology a long way forward since the 1950s, the manufacturing process remains much the same as it has always been. 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. 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. Every 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. The manufacture of Celcon aircrete blocks is environmentally friendly compared to many other materials. 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. Celcon Technology taking us forward Celcon was one of the first building products manufacturers to have its own UKAS approved laboratory. In 1999, H+H Celcon Limited relocated its central laboratory from Essex to a brand new facility at Borough Green in Kent. Originally set up over 30 years ago to pioneer developments in aircrete, the laboratory maintains a continuous programme of quality control, product testing and research and development. It is amongst the few in the UK that has been accredited for thermal conductivity testing, allowing Celcon to confidently market its blocks as insulation units. H+H Celcon Limited has a policy of continual development in all aspects of the process, in new products and in new applications. By playing an active part in European developments for new codes and standards, H+H Celcon Limited will remain in full compliance with the requirements when they are finally introduced to replace the existing British Standards. Celcon Quality assurance All Celcon block factories have achieved BSI Quality Assurance status as set out in BS EN ISO 9002 (formerly BS 5750:Part 2). H+H Celcon Limited is registered as a Firm of Assessed Capability and holds the appropriate certificates; copies of these certificates are available on request. | 
