The Constructor

Classification of Lime as a Building Material for use in Construction

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The 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 Construction

Classification of Lime as a Building Material for use in Construction

Following 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
The Class A lime are the hydraulic lime, that undergoes setting under the action of water. These are used for the construction of structures like arches and domes. Class B is semi-hydraulic in nature. They are limited to small area work, like in masonry constructions. Class C are called as fat lime. Another name for the same is quick lime or white lime or non-hydraulic lime. These are used for works like whitewashing, as a final coat for plastering etc. It is also used in the making of masonry mortar with the help of an additional pozzolanic material. Class D is categorized for lime that is of magnesia or dolomite origin. For finishing works of plastering and whitewashing, the class D lime can be used Kankar lime is the lime that is categorized under the class E. This lime is produced by the burning of lime nodules that are mainly found in the black soils, that constitutes silica. This forms to be hydraulic in nature. The main application of Kankar lime is in masonry mortar. The siliceous dolomite lime is grouped under the class F lime. This is mainly used in the finishing coat of plaster or for its undercoat. The compressive strength gained by the mortar mix of lime and cement, for different classes are shown in table 2. Table.2: Compressive Strength of Lime Mortar Mixes and Cement Mortar Mixes

Preparation of Slaked Lime

The procedure behind the making of slaked lime is described in the following steps: Preparation of Lime Putty Before the use of quicklime in lime mortar, it is made into lime putty. The procedure of lime putty preparation is explained in the following procedures: The addition of water in a gradual means will make the hydraulic lime slaked. When compared to quicklime, the hydraulic lime requires lesser water. The fat quick lime is said to slake by an amount of twice, in the powder form and by one and a half parts of paste. The hydraulic lime slakes by an amount of one and half in the powder form and by the same quantity in the paste form.

Storage of Lime as a Building Material

If it is necessary to store quick lime for a longer period, it is advised to store it in airtight vessels or in the form of large heaps, to ensure that no air is coming in reaction with the mixture. The package of slaked lime can be done for three to four months with the help of gunny bags, craft papers or polyethylene bags etc. This after the package must be stored in a dried place. The area must be weatherproof. The floor must be watertight and impervious. In construction requirement, there are certain specifications demanded like, the lime slaked should be having a package period of one week or more than four, for their application.

Handling of Lime and Precautions

The lime has certain health effects, that is harmful if it is not properly treated. The breathing of lime creates many respiratory problems. The lime can react with the moisture in the human body, creating certain ill effects. So, the workers dealing with the lime in the construction site is advised to use goggles, boots, respirators and other protections whatever is necessary. In most of the cases, the workers oil their body, to avoid any undesirable reactions. The slaking of lime is a process, which produces a large amount of heat, i.e. it is highly exothermic in nature. So, high precautions are taken to ensure that no trouble is caused to the workers dealing with it and all the chances for fire hazard are avoided. Read More: Building Lime – Properties of Lime, Advantages and Uses in Construction Laboratory Testing of Lime to be Used as a Building Material in Construction Laboratory Tests on Building Lime as per Indian Standard Code IS 6932-1973 Field Tests on Building Lime for Quality in Construction Works
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