Presentation; LIME

2. Presented by
.Sharafat Hussain
L-14CE-08
QUCEST LARKANA

3. LimeLime

4. LimeLime
• Lime has been used as a cementing material since times
immemorial.
• Many past structures are still in good shape, which were
constructed using lime as a binding material.
• But in recent times cement has replaced the use of lime
to a great extend.
• No doubt cement is remarkable material yet lime mortars
have some good properties e.g. good workability and
plasticity, less shrinkage on drying, durability etc.
• Lime is cheaper too and is locally available.

5. Classification of LimeClassification of Lime
Limes are usually divided into three classes:
• Fat, rich, pure, high calcium or white lime
• Poor or lean lime
• Hydraulic lime
- Feebly hydraulic lime
- Moderately hydraulic lime
- Eminently hydraulic lime

6. Fat, rich, pure, high calcium or white limeFat, rich, pure, high calcium or white lime
• It has high calcium oxide content. It
contains about 93% of calcium oxide and
5% impurities in the form of clay.
• Setting and hardening depend upon
absorption of carbon dioxide from
atmosphere.
• It is obtained by calcining the purest
available calcium carbonate.
CaCO3 → CaO + CO2

10. • Addition of water breaks
up lumps of quick lime to
powder, gives out
considerable head and
swells to two to three
times of original volume
giving fat lime.
• It is slow in setting.
• Used for plastering and
white washing.
• Not suitable for mortar
because of poor strength
and slow hardening.

11. Poor or lean timePoor or lean time
• It contains more than
5% of clayey
impurities because of
which it takes longer
to slake than fat lime.
• It sets and hardens
slowly.
• It is used both for
plaster and lime
mortar.

12. Hydraulic LimeHydraulic Lime
• This type of lime sets under water, hence
called Hydraulic Lime.
• It is used building works where strength is
required.
• On calcination, carbon dioxide escapes
leaving behind quick lime which reacts
with silica and alumina.

13. Three sub-division of Hydraulic LimeThree sub-division of Hydraulic Lime
• Feebly Hydraulic Lime: It contains less than 15%
silica and alumina.
• Moderately Hydraulic Lime: It contains 15 to 25
percent silica and alumina. It gives the stronger
mortar than feebly hydraulic lime and suitable for
good class masonry.
• Eminently Hydraulic Lime: Its composition is
very similar to Ordinary Portland Cement. It
contains 25 to 30 percent silica and alumina. It
must be very finely ground and screened before
use otherwise the coarser particles are likely to
slake after use.

14. TerminologyTerminology
• Quick Lime: The
calcined material,
major part of which is
calcium oxide.

15. Hydraulic LimeHydraulic Lime
• Lime containing small quantities of silica
and alumina.

16. Hydrated LimeHydrated Lime
• A dry powder
obtained on treating
quick lime with
sufficient water to
satisfy its chemical
affinity with water
under the condition of
its hydration.

17. Lump LimeLump Lime
• Quick lime as it
comes from kiln.

18. Manufacture of LimeManufacture of Lime
• Fat lime is obtained by burning lime
stones which are the purest forms of
calcium carbonate.
• Whereas the hydraulic lime is obtained by
burning Kankar.
• Hydraulicity of lime obtained from kankar
is because of presence of clay in it.

19. Kankar is of two types:
1. Nodular Kankar: It is found
either on the surface or a few
feet below surface in alluvial
soils. Kankar found below the
soil has better hydraulic
properties than those of the one
found on surface.
Nodular kankar is far superior
to block or quarried kankar
because of its better hydraulic
properties, better weathering
properties and easier collection.

20. 2. Quarried or block
kankar: It is found in
blocks a few feet
below ground or on
or near the banks of
rivers or their
tributaries. Blocks
are generally 5 to
30 cm thick.

21. Principal Stages in LimePrincipal Stages in Lime
ManufacturingManufacturing
• Calcination or burning
• Hydration or slacking

22. Lime BurningLime Burning
Like bricks, lime stones
too are burnt in either
clamps or kilns.

23. Clamp BurningClamp Burning
• Quantity is so small to spend much for setting of kiln.
• On clear surface about 5 m in diameter alternate layers
of broken lime stones and fuel are laid.
• The inward sloped sides are plastered with mud to stop
the loss of heat.
• The clamp is then fired at the bottom.
• Disappearance of blue flames at top is an indication of
the burning of lime having completed.
• After the burning and cooling of clamp, pieces of quick
lime are hand picked.
• The clamp burning is uneconomical because of more
fuel consumption.
• Also the quick lime carries an admixture of ash.

24. Kiln BurningKiln Burning
• Quantity of lime to be obtained is large
then permanent structures of kilns are
constructed.
• Kilns could be either of the intermittent
type or the continuous.

25. Intermittent Kiln (Country Kiln)Intermittent Kiln (Country Kiln)
• Fuel is not in contact with the lime.
• Big pieces of lime are used to make a sort
of arch on which smaller pieces of lime
stones are loaded.
• Burning should be gradual so that the
stones forming the arch do not get split.
• It takes normally two days to burn and one
day to cool.

26. Continuous KilnContinuous Kiln
• Commonly used.
• Top should be covered over with mud leaving a
hole 0.5 meter in dia in the center.
• Burning proceeds continuously and the kiln is
not allowed to cool down.
• Burnt material is drawn out daily and fresh
charge of stone and fuel is added from top.
• Overburnt pieces are discarded whereas under-
burnt ones are reloaded into kiln.
• Remaining material is slacked or ground in a
mill.

27. Artificial Hydraulic LimeArtificial Hydraulic Lime
• Where good hydraulic lime stone is not available
hydraulic limes stone can be manufactured
artificially.
• The quick lime is slacked and required quantity
of clay is then mixed to get the same
composition as that of good hydraulic lime
stone.
• It is then made into balls, dried and burnt in
kilns.
• Burnt balls are then ground dry to get artificial
hydraulic lime.

28. Slaking of LImeSlaking of LIme
• Quick lime should be slaked as
soon as possible otherwise it
may change its properties due
absorption of moisture and
carbon dioxide from the
atmosphere.
• If, however, delay is
unavoidable then the lumps of
quicklime should be stored in
heaps.
• The heaps should be covered
to minimize direct atmosphere
contact.

29. Methods of SlakingMethods of Slaking
• Platform Slaking
• Tank Slaking

30. Platform SlakingPlatform Slaking
• Water is sprinkled in small
quantities through rose cans
over lumps of quicklime spread
in 15cm thick layer on a water
tight masonry platform until the
lumps break into fine powder.
• The stuff is periodically turned
over.
• The stuff is left over to allow
the process of slaking to
continue for 24 hours. The
slaked lime is then screened
through sieves.

31. Tank SlakingTank Slaking
• This method is done when the slaked lime is
needed in the form of putty.

32. Precautions Taken in Handling LimePrecautions Taken in Handling Lime
• Quicklime shall not be
allowed to come in contact
with water before slaking.
• While slaking, quicklime
gives out immense heat as
such all precautions against
fire hazard should be taken.
• Workers handling lime
should be provided with
suitable goggles and
respirators, as lime dust
causes irritation.

33. • Since lime causes skin burns,
particularly if the skin is moist,
as such workers should be
provided with rubber gloves,
gum boots and skin protective
cream.
• After working with lime exposed
portions of the body should be
washed with abundant fresh
water.
• Workers handling milk of lime,
which is hot, should oil their
skin daily to avoid skin burns.