Lime

LIMESTONE

Lime is a more or  less impure calcium oxide (CaO) and obtained by the alcination. Lime acts as a binding or cementing material in engineering constructions.

Uses of lime : Lime is used for the following purposes.
1. White washing.
2.lime punning.
3. making mortar.
4.making concrete.
5.Manufacturing cement.
Technical Terms : To understand the manufacturing process of lime the following technical terms are to be understood thoroughly.
Calcination: This is the heating of limestone to redness in air.
Quick lime or caustic lime : This is the lime  immediately after calcination of limestone.
Slaking :When water is poured on quick lime it gives rise to heat due to certain chemical reactions and this process is termed as slacked or hydration.
Slaked lime : The substance left slaking of quick lime is called slaked lime or hydrate of lime.
Setting : when lime is mixed with water to from a paste it hardens and this process is called setting or hardening of lime.
Hydraulicity : This is the property of the lime for setting under water.
Constiuents of limestone : Limestone exist in nature either  as pure or impure calcium carbonate. The following are the main constitents.
Calcium oxide :  This is the principal constituent of limestone. It acts as a binder.
Clay : Clay in small quantity retards slaking and in large proportion arrests slaking . it causes setting of lime and renders it insoluble in water .it  should , therefore, be proportioned properly with the remaining constituents. Generally 5 to 10% of clay presence in limestone is recommended because with this the lime will make excellent mortar.
Slilica and alumina : they impart hydraulicity in lime .
Magnesium carbonate : It slakes lime more slowly evolves less heat expands less set more slowly but finally gains greater strength.
Alkalies and metallic oxides : They impart hydraulicity in lime. sulphates small quantity of sulphates retards the slaking action and increases the rapidity of setting.
Iron pyrites : Presence of iron pyrites is highly objectionable as they  reduce the strength of lime.  
Lime is a more or  less impure calcium oxide (CaO) and obtained by the alcination. Lime acts as a binding or cementing material in engineering constructions.
Uses of lime : Lime is used for the following purposes.
1. White washing.
2.lime punning.
3. making mortar.
4.making concrete.
5.Manufacturing cement.
Technical Terms : To understand the manufacturing process of lime the following technical terms are to be understood thoroughly.
Calcination: This is the heating of limestone to redness in air.
Quick lime or caustic lime : This is the lime  immediately after calcination of limestone.
Slaking :When water is poured on quick lime it gives rise to heat due to certain chemical reactions and this process is termed as slacked or hydration.
Slaked lime : The substance left slaking of quick lime is called slaked lime or hydrate of lime.
Setting : when lime is mixed with water to from a paste it hardens and this process is called setting or hardening of lime.
Hydraulicity : This is the property of the lime for setting under water.
Constiuents of limestone : Limestone exist in nature either  as pure or impure calcium carbonate. The following are the main constitents.
Calcium oxide :  This is the principal constituent of limestone. It acts as a binder.
Clay : Clay in small quantity retards slaking and in large proportion arrests slaking . it causes setting of lime and renders it insoluble in water .it  should , therefore, be proportioned properly with the remaining constituents. Generally 5 to 10% of clay presence in limestone is recommended because with this the lime will make excellent mortar.
Slilica and alumina : they impart hydraulicity in lime .
Magnesium carbonate : It slakes lime more slowly evolves less heat expands less set more slowly but finally gains greater strength.
Alkalies and metallic oxides : They impart hydraulicity in lime. sulphates small quantity of sulphates retards the slaking action and increases the rapidity of setting.
Iron pyrites : Presence of iron pyrites is highly objectionable as they  reduce the strength of lime.