Different types of lime used in construction are Quick Lime, Slaked Lime, Fat Lime and Hydraulic Lime. These are obtained by the process of calcination of natural limestone over a temperature of 900-degree Celsius. Every form of lime is highly versatile and is used in environmental, construction, chemical and metallurgical industries.
Types of lime and their uses in construction are explained briefly.
Types of Lime Used in Construction
The four main types of lime used in construction are:
- Quick Lime
- Slaked Lime
- Fat Lime
- Hydraulic Lime
1. Quick Lime
Quick lime is also called caustic lime ( Calcium Oxide). This is produced by burning pure limestone ( Calcination process). It is the cheapest form of lime available which is highly amorphous and caustic. Quick lime has a great affinity towards moisture.
Quick lime is one of the key ingredients in the manufacture of cement. This is also an important material used for the treatment of drinking water.
2. Slaked Lime
Slaked lime is obtained by the process of slaking, where quick lime is combined with water. Slaked lime is also known as hydrate of lime. This is available as pure lime in the form of a white powder.
Slaked lime when exposed to the atmosphere, absorbs carbonic acid in the presence of water content. It is also called as calcium hydroxide or calcium hydrate or lime hydrate.
Slaked lime formed by adding quick lime and water gives a slurry material. This is highly suitable for mortar applications. It can also be used in plastering works and in cement as a binder.
3. Fat Lime
The lime that contains calcium oxide in high content is called as fat lime. This is also called as white lime or rich lime or high calcium lime or pure lime. It slakes vigorously when water is added to it. This slaking increases its volume two to two and a half times greater than that of quick lime.
Fat lime is used for pointing in masonry works, foundation, with surkhi to thicken the masonry walls etc.
4. Hydraulic Lime
Hydraulic lime is also called as water lime. It contains 30 percent of silica and 5 percent of alumina along with iron oxide. This lime sets when water is added to it. Hydraulic lime has the following classification:
- Eminently Hydraulic: Eminently hydraulic lime has a chemical composition similar to ordinary Portland cement (OPC). This consists of 25 to 39 percentage of silica and alumina. This type can be used for good quality mortar works.
- Semi-Hydraulic: Semi-hydraulic lime consists of 15 to 25 percentage of silica and alumina. It is used for good quality works of masonry, brickwork, and mortar. This is less stronger than eminently hydraulic lime.
- Non-Hydraulic: Non-hydraulic lime has silica and alumina in quantities of less than 15%. On the process of slaking, it undergoes less expansion. For less important works, mortar made from non-hydraulic lime is accepted.
Uses of Lime in Construction
Major uses of lime are enlisted below:
- Lime is used in the manufacturing of steel in order to remove the impurities.
- Soil stabilization for construction of roads, airfields and building foundation demands lime in large quantity.
- Lime slurry is used as mortar for masonry work and for plastering.
- Lime is used as an additive in asphalt which helps to improve the property of cohesion. Lime help to increase the resistance of asphalt towards stripping and aging.