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Groupe

members

Vikas

Rajesh

Mayur

Yogiraj

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ime

Introduction:-

Lime is one of the important constructionmaterials. We find palaces, bridges, monuments, forts,

temples etc. constructed making use of lime as

cementing material. Though with the introduction of

cement, the use of lime has become limited nowadays,

yet lime has its own specialities and cement cannot

take its place so far as the qualities like good plasticity,

less Shrinkage, durability, good workability etc.

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Lime is obtained by heating lime stones up to

red heat in a suitable kiln..

Constituents of lime:

Clay

Sulphates

Magnesium carbonate Alkalies and oxides

silica and alumina

Calcium carbonate

pyrites

Iron

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1. Calcination

The lime is obtained by heating lime stone at certaintemperature the process of heating lime stone at red

heat in the presence of air till it decompose is known

as CALCINATION

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Following Chemical reaction takes place when lime

stones are heated and lime is obtained

Caco3 heating to about 900* c cao + co2(lime stones) (Lime) (Carban dioxide)

Following points should be observed for satisfactory result.

Temperature should not fall below 900*c

(Actually 100*C to 1200*C temperature is maintained.)

Proper exit should be provided in kiln for escape of CO2

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2. Slaking

Slaking is a process in which chemical reactiontake place between quick lime (CaO) and adefinite quantity of water. The resulting productis calcium hydroxide Ca(OH)2 (Hydrated lime)

CaO + H2O = Ca(OH)2

Lime water hydrated

limeNote: During this process quicklime cracks, swells

and is converted into powder form

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Types of lime & slaking

Fat lime :-

also called-rich, pure, white lime whiteamorphous, caustic, high affinity for water.

Slacking:

generation of heat, increase in volume,hissing sound, lumps broken to powder.

Setting:-

absorb CO2 form atmosphere andforms calcium carbonate. Shrinks, hardens slowly

cannot set under water.

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Hydraulic lime:-

feebly, moderately and eminently hydraulic lime

according to the content of clay. Slaking:-

No much heat, slaking takes 24 to 48 hours, little

expansion in volume. Setting:-

sets under water, provides strong mortar.

Poor lime:-

contains more than 30% clay not suitable forconstruction.

Hydrated lime:-

Dry powder as a result of slaking.

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Slaking of Quick lime

QUICK LIME:

It also known as caustic lime,

It is obtained by calcinations of purelime stones. (lime stones with less impurities) It

contains about 93% calcium oxide, less than 5%

silica or alumina (clay), and little amount of

magnesium oxide. It is amorphous

(Non crystalline) white and highly caustic. It has

high affinity for water. It can be slaked under

water.

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Uses of lime

Fat lime:

Use:- White wash, plastering, increases,

productivity of soil.

Hydraulic lime:

Use:- wall construction, underground, construction,damp proofing, mortar for thick walls.

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Masonry work Hydraulic lime

Mortar for plastering Fat lime

Lime coba Fat lime with

on roof and floor surkhi

Thin wall Fat lime Thick wall Hydraulic lime

White washing Fat lime

BBLC in foundation Hydraulic lime

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CLASSIFICATION AS PER IS 712

Class Suitability

Class A - structural purposes

Class B - masonry work

Class C - Finishing and plastering Class D - Finishing, plastering, white washing

Class E - masonry mortars

Class F - Finishing coat, under coat.

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Lime Mortar:

Lime + Other material Suitability

Lime Sand - General purpose

Lime Cinder - Light weight

mortar Lime Fly ash - In place of sand

Lime Pumice - Light weightmortar

Lime Surkhi - Foundation andsuperstructurenot suitable

for plastering

and pointing.

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Consuming Time

Consume: Hydraulic lime mortar within 4 hours.

Surkhi lime mortar within 24 hours.

Cement lime mortar within 2 hours.

Do not allow lime mortar ta dry, keep it wet.

Allow 105 height of wall to set for 2 days.

Protect skin of workers by oil/gloves, rubber

boots.

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Chapter at glance

Definitions:

CALCINATION:Process of heating lime stone

at red heat in the presence of air till it

decomposes.

QUICK LIME:Obtained by calcination of pure

lime stone. It is amorphous, white and highly

caustic. Possesses high affinity for water.

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SLACKING:Chemical reaction between quick

lime and water. Resulting product is Ca(OH)2.

During the process quick lime cracks, swells

and is converted into powder.

SETTING:Process of hardening lime.

HYDRAULICITY: Property of lime to set and

harden in water in absence of air.

Slacking and Setting of Limes:

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SLACKING

Fat lime:

Methods: Platform slacking, Basket method, Tankslacking

Water added to quick lime, chemical reaction,generation of heat, expansion in volume, lumps arebroken to powder, hissing sound.

Hydraulic lime:

Method:

Platform slacking: Water is sprinkled over lime kept

on platform in powder form. Plant slacking: Hydraulic lime is hydrated in huge

plants and packed in bags.

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SETTING

Fat lime:

presence of air is necessary. Calcium oxide

formed due to dehydration combines with CO2

of atmosphere and form hard substance

shrinkage take place.

Hydraulic lime:

Chemical reaction take place in presence of

water in absence of air.

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