Hollow block in Ahmedabad

AAC block has been produced for more than 70 years, and it offers several significant advantages over other cement construction materials, one of the most important being its lower environmental impact.

Unlike most other concrete applications, AAC block is produced using no aggregate larger than sand. Quartz sand, calcined gypsum, lime and Ultratech Cement and water are used as a binding agent. Aluminum powder is used at a rate of 0.05%–0.08% by volume . In some countries, like India and China, fly ash generated from thermal power plants and having 50-65% silica content is used as an aggregate.

When AAC block is mixed and cast in forms, several chemical reactions take place that give AAC block its Light weight and thermal properties. Aluminum powder reacts with calcium hydroxide and water to form hydrogen. The hydrogen gas foams and doubles the volume of the raw mix. At the end of the foaming process, the hydrogen escapes into the atmosphere and is replaced by air.

When the forms are removed from the material, it is solid but still soft. It is then cut into either blocks or panels, and placed in an autoclave chamber for 12 hours. During this steam pressure hardening process, when the temperature reaches 190° Celsius and the pressure reaches 8 to 12 TMT bars and Tmt bar supplier, quartz sand reacts with calcium hydroxide to form calcium silica hydrate, which gives AAC block its high strength and other unique properties. After the autoclave process, the material is ready for immediate use on the construction site.