What is Lime?
Cementitious material (binding material)
Chemical formula of Lime
CaO
Chemical formula of limestone
CaCO3
How is lime obtained from limestone
by heating limestone, the process is called calcination
Classification of binding materials
- Air binding
- Hydraulic Binding
- Autoclave Binding
Conditions in Autoclave binding?
8-12 atm
170 C to 200 C
Sources of Lime
- Limestone (riverbeds, boulders in hills)
- Seashells (Small quantities)
- Kankar (impure lime available below ground)
Constituents of Lime
- Clay (8-30%)
- Soluble Silica
- Magnesium Carbonate (<30%)
- Alkalies and Metallic Oxides (<5%)
- Sulphate
- Iron
- Pyrites (impurities)
Classifications of Lime
- Fat lime
- Hydraulic Lime
- Poor Lime
Characteristics of Fat Lime
- low impurities (<5%)
- slow hardening and setting
- Slaking is vigorous
- sp. gravity is about 3.4
Fat lime is also known as
pure lime, white lime, rich lime, high calcium lime
Uses of Fat lime
- mortar
- plastering
- white washing
What is Hydraulic Lime
- Lime that sets in Water
Types of Hydraulic Lime
- Feebly hydraulic lime
- Moderately hydraulic lime
- Eminently hydraulic lime
Characteristics of Feebly hydraulic lime
- Clay content : 5-10%
- Slake time : few mins
- Setting time : 3 weeks
- Strength : low
- Uses : Plaster, whitewash (damp places for less imp. structures)
Characteristics of Moderately hydraulic lime
- Clay Content : 11 - 20%
- Slake time : 1 - 2 hrs
- Setting time : 1 week
- Strength : Moderate
- Uses : Superior strutures
Characteristics of Eminently hydraulic lime
- Clay content : 21 - 30%
- Slake time : Difficult to slake
- Setting time : 1 day
- Strength : high
- Uses : structures that carry more load
Characteristics of Poor Lime
- Hardens very slowly
- Slakes very slowly
- Color varies from yellow to gray
- Thin paste with water
Classification of lime according to IS (Indian Standards)
- Class A to Class F with Class A being the most superior
IS classification statement
IS: 712, 1984
