FLY-ASH INTRODUCTION

FLY-ASH INTRODUCTION.

Fly ash brick First invented in 2007..... American civil engineer Henry liu announced the invention of a new type of fly ash brick in 2007. Lius’s brick is compressed of at 4,ooo psi and cured for 24 hrs in a 150 F(66 C) steam bath, then toughened with air entrainment agent , so that it lasts for more than 100 freeze thaw cycles. Owing to high concentration of calcium in class c fly ash , the brick can be described as self cementing. Since method contains no clay and uses pressure instead of heat ,it saves energy, reduces mercury pollution,costs 20% less than traditional manufacturing techniques.

 This type of brick is now manufactured under license in USA. 

Fly ash bricks are constructed at least partially from the residue of burnt coal .Depending on the type of coal that is burned, the resulting fly ash can take a number of different forms. Some kinds of fly ash require a cementing agent, such as quicklime or Portland cement . Other types contain a large enough percentage of lime that they are self setting, requiring only the addition of water to be turned into fly ash bricks. These bricks have been utilized in construction since the 1950s in some parts of the world, and in certain configurations are able to meet or exceed specifications for clay or cement bricks.

 When coal is burned, one of the results is a fine powder known as fly ash. While other ashes might settle at the base of the furnace where the coal is being burned, fly ash is light and fine enough that flue gases often are able to carry it up through the chimney. In the past, this ash was typically allowed to escape into the atmosphere, though in many locations environmental regulations the fly ash must be captured for safe disposal or reuse. Since toxic materials like mercury and lead may be highly concentrated in fly ash, this can lead to environmental or health concerns.