A method and apparatus for providing an insulating material, for example for a building, in which a premix of water and cement is provided, an air foam is formed by introducing air under pressure into a mixture and a foaming agent, and this air foam is introduced into the premix which is then stirred...http://www.google.com.au/patents/US4185923?utm_source=gb-gplus-sharePatent US4185923 - Method and apparatus for producing insulating material
