🕑 Reading time: 1 minuteThe classification of lime as a building materials for use in construction works based on IS 712-1973 is classified to different classes based on their applications in construction. Other than the mentioned lime under specified classes, there is carbide lime. The manufacture of acetylene gives the by-product carbide lime. Under special consideration, it can be used for special plaster works. This is used only if it is available in fresh condition. If it is available in a semi-solid form, it is not recommended for any work. This is because it dries up quickly. The lime that contains clay greater that 30% is considered as poor lime.
Classification of Lime as a Building Material for use in ConstructionFollowing table shows the classification of lime and its name for use in various construction works: Table.1. Classification of Lime as a Building Material for use in Construction as per IS 712-1973
|Class A||Eminently Hydraulic Lime|
|Class B||Semi - Hydraulic Lime|
|Class C||Fat Lime|
|Class D||Magnesium or dolomite lime|
|Class E||Kankar Lime|
|Class F||Siliceous Dolomite Lime|
Preparation of Slaked LimeThe procedure behind the making of slaked lime is described in the following steps:
- The required quantity of fat lime or quicklime is placed over a platform which is wooden or masonry, free of moisture. The quicklime is produced by the burning of limestone and shells.
- Water is then sprinkled over this heap of quick lime, till it gets reduced to powder form. During the addition water, thorough mixing is done along with this, until no more water is required to completely reduce the quicklime to the powdered form.
- The final mixture is allowed to pass through the sieve of 3.35mm dimension. The residue is rejected. The final product is called the slaked lime.
- Initially, two tanks are made of 50 and 80 cm deep (Tank 1 and Tank 2 respectively). The former tank is constructed at a higher level compared to the latter, to ensure proper flow of fluid from tank 1 to tank 2.
- Initially, the tank 1 is filled with water to its half. Quick lime is then added to this, till the half depth of the tank 1 is filled. It is kept in mind to add lime to the water and not water to lime.
- Proper stirring is carried out, keeping in mind that no exposure to the air above the water level is carried out. The mixing will be continued for few minutes (around 5 minutes), till the moment the boiling ends and the whole mixture starts to thicken.
- The mixture is den allowed to flow to the tank 2, located at the lower height. For this to happen with ease, more water can be added.
- The tank 2 takes this mixture for a minimum time of 72 hours. The lower tank (tank 2) is made up of dry brick masonry, whose joints are filled with sand alone. This would facilitate the absorption of water from the slurry. This is the way, how the excess water is removed and lime putty is obtained in the paste form.
- If the exposure to the atmosphere is avoided, it can be stored for a period of say 2 weeks.