Masonry - Aircrete block manufacture
Aircrete blocks are produced by mixing of Fly ash, also known as pulversided fuel ash (pfa), and/or finely ground sand with cement and/or lime slurry into which a small quantity of aluminium powder is added. The slurry is discharged to partly fill large steel moulds where a reaction between the aluminium powder and alkaline environment in the mix takes place to generate tiny bubbles that stabilise to form the Aircrete cellular structure. The slurry rises and sets to form a firm but relatively soft ‘cake’, which is then cut into the desired rectangular solid block size by tensioned wires on cutting frames. Curing takes place in autoclaves under steam and pressure before the blocks are removed, packaged and ready for use.
For further information see the Autoclaved Aerated Concrete Products Association