What is Hacking (of Concrete) in Construction?
Hacking refers striking of surfaces such as RCC walls, columns, beams, slabs etc., with a chisel to dent the surface inroder to create a proper mechanical bond with cement mortar/gpysum plaster directly applied on it.
Why is Hacking Important?
Since concrete finished surface is smooth, plastering materials would not bond with such surfaces. Dents created by hacking concrete surfaces will help in mechanical bonding of plasters (cement motar & gypusm plaster)
Recommendation on Right amount of Hacking:
It is advisable to have 300 to 350 dents on an average per square meter.
Also, It is recommended to have mechanical bonding (by hacking) always for plaster surfaces although you use chemical bonding materials. Although bonding chemical helps in bonding between surfaces, mechanical keys will always enhance the plaster bonding with substrate.
Hacking should be done atleast after 3 days from date of casting the concrete. Proper curing should be ensured before hacking is done to avoid any hairline cracks.