Classification of Lime

Lime

Lime is obtained by burning lime stone, depending upon percentage of calcium carbonate (caco₃) presence in limestone, it is classified into Class A, B, and C, and they are used for masonry, plastering, mortar, etc. The lime that is obtained from the calcinations of the pure lime stone is called quick lime. By burning kankar, shells of sea animals and boulders of limestone from the bank of Old River, lime stone is obtained. We will discuss about classification of lime.

Classification of Lime

The classifications of lime are; Fat lime, Hydraulic lime, and poor lime.

Fat Lime

This fat lime is named as high calcium lime, pure lime, rich lime, or white lime. It is obtained from the pure limestone, shell and coral. It absorbs carbon dioxide when it is left in air, and gets transferred into calcium carbonate. When compared with quick lime, the volume of fat lime gets increased to about 2 - 2 1/2 times.

Properties of Fat lime

• It hardens very slowly.
• It is having the high degree of plastic.
• The color is pure white.
• In the presence of air, it tends to set very slowly.
• It slakes vigorously.

Use of Fat lime

It is used in white washing and plastering of walls. IT forms lime mortar with sand, which sets in thin joints. This type of mortar can be used to apply in thin joints of brickwork and stone work.

Hydraulic lime

Hydraulic lime has the capacity to set and harden even under water, where the quick lime cant able to do it. The composition of the hydraulic lime is different from quick lime; it contains a definite quantity of clay which gives its hydraulic property. Hydraulic lime consists of 70-80% of CaO and clay about 15 – 30%.Hydraulic lime is obtained by burning the limestone containing rich in clay, or adding clay materials to the lime stone while burning.  Depending upon the hydraulicity, it is divided into feebly hydraulic, moderately hydraulic, and eminently hydraulic.

Poor lime

This is one among the classifications of lime. This lime is called as impure lime or lean lime. The properties of poor lime are,

• This poor lime consists of 30% clay.
• It slakes very slowly.
• The thin paste is formed along with water.
• It never gets dissolved with water and gets frequently changed.
• It is use to hardens very slowly.
• The binding property is very poor.

Questions:

• What is called lime?
• Explain classifications of lime?