for civil engineering and construction technology students!

1. DEFINITION
Binders are substances that are used to bind
inorganic and organic particles and fibers to
form strong, hard and/or flexible components.
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2. THE BINDING ACTION
 The binding action is generally due to chemical
reactions which take place when the binder is
heated, mixed with water and/or other materials,
or just exposed to air.
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3. TYPES OF BINDERS TO BE DISCUSSED
Binders
Lime
Gypsum Plasters
Asphalt Cement
Portland Cement
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4. MAIN GROUPS OF BINDERS
There are three main groups of binders: -
1. Mineral binders
2. Bituminous (Asphalt)binders
3. Synthetic binders
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5. 1. MINERAL BINDERS
Mineral Binders
Non-hydraulic binders Hydraulic binders
E.g. Lime, Gypsum plasters E.g Portland cement
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6. 1.1 NON-HYDRAULIC BINDERS
 Non-hydraulic binders are only harden in the
presence of air
 The most common non-hydraulic binder is:-
A. Lime.
B. Gypsum
Hardening of non-hydraulic binder/lime depends on
its combination with carbon dioxide from the air
(carbonation), by which it again becomes calcium
carbonate (limestone).
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7. Cont’d
 Gypsum is a non-hydraulic binder which
occurs naturally as a soft crystalline rock.
 The chemical name is calcium sulfate
anhydrate (CaS04.2H20).
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8. Cont’d
 By gentle heating up to about the boiling point
of water, calcium sulfate hemi-hydrate
(CaSO4.1/2H2O) is produced, more commonly
known as "Plaster of Paris", which when mixed
with water sets in 10 minutes.
The common name for calcium sulfate hemi-hydrate
is known as Plaster of Paris
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9. 1.2 HYDRAULIC BINDERS
 Hydraulic binders require water to harden
and develop strength.
 The most common hydraulic binder is
Portland cement.
Hydraulic binders are usually available in the
form of a fine powder. Why?
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10. Cont’d
 On account of their affinity to water,
hydraulic binders must be stored in absolutely
dry conditions.
Why?
Answer:- to avoid premature setting and
hardening (pre- hydration and carbonation).
 Even humid air can cause hydration.
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11. 2. BITUMINOUS BINDERS/ASPHALT
 "Asphalt" is a dark brown to black, highly
viscous, hydrocarbon produced from
petroleum distillation residue.
This distillation can occur naturally, resulting in
asphalt lakes, or occur in a petroleum
refinery.
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12. 3. SYNTHETIC BINDERS
 Synthetic binders are generally produced by
industrial processes.
They can either be used as adhesives or as
surface coatings and are either applied hot, or
as an emulsion, or with a solvent.
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13. Cont’d
 Synthetic admixtures which bind loose
particles together are mainly resins derived
from plant materials or mineral oil.
 Adhesives are used to stick larger particles,
components, membranes, sheets, boards, tiles, etc.
on another surface.
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14. LIME
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15. General
Lime is one of the oldest known cementing
material
Lime is found in many parts of the world in its
natural form as a rock of varying degree of
hardness.
Lime is mainly composed of calcium oxide (CaO).
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16. Cont’d
Lime in its pure form associates with CO2 to give white
CaCo3.
Lime deposits are generally found mixed with impurities
such as CO2, Fe2 O3, and MgCO3.
Depending on the impurities, lime deposits acquire
different colors.
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17. Production of lime
 Lime is produced by burning the raw material limestone
CaCO3.
 Chalk , shell and coal can have CaCO3 content
exceeding 98 %
Dolomite mineral has as low as 54 %
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18. Burning process
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19. A. VERTICAL SHAFT KILN
 Raw materials are fed in at the top &
the finished product drawn off through an
opening at the bottom.
Limestone
~10000c
Lime
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21. B. ROTARY KILN
 The raw materials fed in at the top &
the finished product is drawn off at the
bottom continuously.
Limestone
Lime
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22. CLASSIFICATION OF LIME
 Commercial lime is classified into three
groups:-
1.Quick lime (Caustic lime)
2.Hydrated lime (Slaked lime)
3.Hydraulic lime
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23. 1. QUICK LIME
 The manufacture of quick lime consists
in burning the limestone in some form
of vertical kilns to a temperature of
10000c.
CaCO3  CaO+CO2
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24. Quick Lime:
Is obtained by calcining (burning) the
purest available calcium carbonate
Gives out considerable heat
Swells two to three times of its original
volume upon addition of water
Takes much time in hardening
Is used for plastering and white washing
Is not suitable for being used as mortar
because of its poor strength and slow
hardening
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25. 2. HYDRATED LIME (SLAKED LIME)
Quick lime can never be used as such for
construction purposes but must be
mixed with water.
CaO+H2O Ca (OH)2 + heat
 This process is called slaking and the
product (calcium hydroxide) is called
slaked lime or hydrated lime.
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26. Forms of hydrated lime
 Depending upon the amount of water added during the
slaking process, three forms of hydrated lime are
commonly produced:-
a) Dry hydrate, a dry, fine powder, formed by adding just
enough water (Dry-Slaking) to slake the lime, which is
dried by the heat evolved.
b) Milk of lime, made by slaking quicklime with a large
excess of water (Wet-Slaking) and agitating well, forming
a milky suspension;
c) Lime putty, a viscous mass, formed by the settling of
the solids in the milk of lime.
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27. 3. HYDRAULIC LIME
 Is prepared by burning impure limestone
that contains clay, producing compounds
similar to those present in Portland cement.
It is stronger but less fat or plastic than non-hydraulic
lime.
 Hydraulic lime is manufactured in the same
way as quick lime, although a somewhat higher
temperature is required in burning.
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28. SETTING AND HARDENING OF LIME
 Slaked lime hardens or sets by gradually
losing the water through evaporation and
absorbing carbon dioxide from the air.
 Thus changing back from calcium hydroxide,
Ca (OH)2 to calcium carbonate,
CaCO3 or limestone.
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29. The Lime cycle
CaCO3
Burning
Drying
Ca(OH)2 CaO
Slaking
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30. USES OF LIME
1. Lime as a construction material
 As mortar (lime mortar) mixed with sand.
 Lime is used in cement mortar to make it
more workable
 As plaster (lime plaster)
 As a whitewash, when it gives a sparkling
white finished at a very low cost
 As lime concrete
 As a stabilizer in soil constructions with clayey
soils
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31. 2. Lime as an industrial material
In industry, lime finds many applications:-
 As a flux in the metallurgical industry
 As a refractory material for lining
metallurgical furnaces;
 As a raw material for the manufacture of
glasses.
3. Lime as an agricultural input
 Lime is used for improving the productive
qualities of soils.
 It is added to the poor soils to enrich their
lime content.
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32. GYPSUM PLASTERS
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33. General
 Gypsum is a combination of sulfate of lime with
water of crystallization.
 Gypsum occurs naturally as:
 Hydrous sulfate of lime (Ca SO4
2H2O) which is generally 76% CaSO4
and 24% H2O,
 Anhydrate (Ca SO4).
 Pure gypsum is known as alabaster
and it is a white translucent crystalline
mineral
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34. Gypsum plasters
 Gypsum plasters are used in the arts and
in building construction.
 Gypsum plasters are manufactured by
heating the raw material gypsum at either
moderate or high temperatures the results
being plaster of Paris or hard-finish plaster
respectively.
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35. A. PLASTER OF PARIS
 If some of the water of crystallization is driven
off by incomplete dehydration at a temperature
just above the boiling point of water (1000c), pure
finely ground gypsum, a semi-hydrated plaster is
obtained which is known as plaster of Paris.
(CaSO4.2H2O)+Moderate Heat (CaSO4 .1/2 H2O) +1/2 H2O
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36. Cont’d
Plaster of Paris:-
 is a white powder having a specific gravity of 2.57.
 is also known as low-temperature gypsum derivative
or semi-hydrated plasters (hemi hydrate).
 When mixed with sufficient water to form a plastic
paste, it sets very rapidly (retarder must be added)
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37. Cont’d
Glue, sawdust or blood can be added to Retard the
setting time of the plaster.
Owing to rapidity of setting, its use in structures is
limited to ornamental work.
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38. Complete cycle in gypsum used as plaster
Hydration Moderate heat
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`
CaSo4.2H2O
CaSo4.1/2H2O

39. B. HARD-FINISH PLASTER
Produced by burning gypsum to a
considerably higher temperature .
Hard-finish plaster is also known as anhydrous
plaster or high-temperature gypsum
derivative.
(CaSO4. 2H2O)+High Heat CaSO4+ 2H2O
 This plaster is less soluble with consequent
reluctance to absorb water in the process of
re crystallization.
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40. Other Derivatives of Gypsum
1.Gypsum Ready Mixed Plaster
Is calcined gypsum(CaSo4.1/2H2O) mixed at the
mill with mineral aggregate to serve as a base to
receive various coats.
Contains about 60% of CaSo4.1/2H2O
2.Gypsum Neat plaster
Contains about 66% of CaSo4.1/2H2O by weight.
The addition of aggregate is made on site.
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41. 3.Gypsum Wood fibered plaster
Composed of not less than 66% of
CaSo4.1/2H2O and about 1% wood fiber.
4 . Gypsum bond plaster
Used as a bonding scratch -coat over
monolithic concrete.
It contains not less than 93% of CaSo4.1/2H2O
and not less than 2% or more than 5% of
hydrated lime.
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42.  5.Gypsum Gauging Plaster
Is prepared for mixing with lime putty for the
finish coat.
Contains not less than 66% of
CaSo4.1/2H2O
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43. Thank you !!!
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