Mortar is a mixture of binding material, fine aggregate like sand, and water that is used for masonry work, plastering and pointing. It binds together bricks, stones or concrete to form a strong, durable structure. Mortar comes in different types for various uses - cement mortar for high strength applications, lime mortar above ground, lightweight mortar with fibers, fire resistant mortar, and mud mortar for rural buildings. Sand and surkhi are added to mortar to reduce cracking and provide strength, density and color.

1. MORTAR
•When a binding material, a fine aggregate and water are
mixed together in suitable proportions , they form an easily
workable paste which is termed as Mortar.
•Mortars are usually named according to the binding
material used in their preparation.
•They are essentially required for masonry work, plastering
and pointing etc.
FUNCTIONS OF MORTAR:
•To bind together the bricks or stones properly so as to
provide strength to the structure.
•To form a homogenous mass of the structure so as to
resist all the loads coming over it without disintegration.

2. •To provide a weather resisting i.e., a durable layer
between the different courses of masonry in the
structure.
•To hold coarse aggregate together in any concrete so as
to form a solid mass. The mortar used in a concrete is
termed as matrix.
•To do pointing and plastering to the structure. The
mortar used for plastering is known as plaster.
•To fill up empty joints in brick and stone masonry. The
mortar used for such purposes is a thin liquid mortar
which is termed as grout and the process is known as
grouting.
FUNCTIONS OF MORTAR Contd:

3. MIXING MORTAR:
•The sands and the cement have to be thoroughly
mixed by hand or in a mechanical mixer before
adding any water - do not use dirty water, or water
from puddles or ponds, as this could impair the final
strength of the mortar.
•Similarly, keep any sugar-containing liquids, such
as soft drinks, well away from the mix - sugar, even
in small amounts, seriously impairs the setting
ability of the cement.
PREPERATION OF MORTARS:

4. •When mixing by hand, the sands and cement are
heaped up on a mixing board or in a wheelbarrow
and repeatedly turned over and over until thoroughly
mixed.
•The color of the dry mix will change as the cement
is distributed throughout - there should be no
'streaking' of cement, and no clumps of pure sand or
pure cement.
•Once the dry ingredients are mixed, the water can
be added.

5. •If any additives are being used, such as a
plasticizer, they are normally added to the water,
and then mixed in, rather than being directly added
to the dry ingredients.
•A "well" is formed in the centre of the mixed heap,
water added to it and then folded in.
• More water is added a bit at a time and folded in
until the required consistency is attained.
•This should be when the mortar is thoroughly
mixed but is able to stand in peaks, like whipped
cream; too wet and it just makes a mess, too dry
and it's almost impossible to work.

6. Dry sand and cement in
wheelbarrow
Begin to mix sand and cement Mix to evenly distribute cement
The dry mix should be all one
colour
Add water and plasticiser Mix to required consistency

7. •When using a mechanical mixer, add half a bucket (2 or 3
liters) of clean cold water to the empty drum before adding
the dry ingredients in sequence.
• Add 4 measures of sand then 1 of cement, followed by 4
sand, then another cement and so on until the required
quantity is in the mixer.
•This ensures a more thorough mix than adding, say, 20
measures of sand and then 5 measures of cement.
•
•Again, the water is added to the revolving drum once the dry
ingredients are thoroughly blended, a bit at a time until the
required consistency is achieved.

8. For wide joints in paving or for stonework, either as
paving or as walling, a coarser mortar is often
preferred - replace half of the building/soft sand with
grit/sharp sand.
You will probably find that a coarse mortar such as
this requires less gauging water to achieve a
working consistency than does a bricklaying/general
purpose mortar.
2 x Building Sand plus
2 x Grit Sand plus
1 x cement
Mortar for Wide Joints

9. TYPES OF MORTAR & THEIR USES:
Cement mortar:
•The paste is prepared by mixing cement and sand in
suitable proportions in addition to water.
•The general proportion is 1 part of cement to 2-8 parts
clean sand.
•These mortars must be use within half an hour, i.e.; before
initial setting time of the cement.
•This type is used for all engineering works where high
strength is desired such as load bearing walls, deep
foundations, flooring etc.

10. Lime mortar:
•The paste is prepared by mixing lime and sand or surkhi in
suitable proportions in addition to water.
•If surkhi is to be added in lime mortar the equal
proportions of sand and surkhi should be mixed with lime.
•These mortars are inferior to cement mortars in strength
as well as water tightness.
•These mortars should not be used for underground works
as they set in the presence of carbon dioxide and break up
in damp conditions.
•This type is used for construction work above ground level
i.e. exposed positions.

11. Light weight mortar:
•The paste is prepared by mixing wood powder, wood
sawing or saw dust with cement or lime mortar.
•In such mortars fibers of jute coir or asbestos fibers can
also be used.
•These are generally used as fiber plasters in sound and
heat proof construction.

12. Fire resistant mortar:
•The paste is prepared by mixing aluminous cement and
finely crushed fire bricks in suitable proportions in
addition to water.
•The usual proportion are 1 part aluminous cement to 2
parts of finely crushed fire bricks.
•These are generally used for lining furnaces, ovens and
fire places with fire bricks.

13. Mud mortar:
•The paste is prepared by mixing suitable clayey soil with
water.
•The soil which is used for preparing mud mortar should
be free from grass, pebbles etc.
•These are the cheapest mortars but weakest in
strength.
•These mortars are used for brickwork of ordinary
buildings and for plastering walls in rural areas.

14. FUNCTION OF SAND AND SURKHI IN MORTARS:
Functions of sand:
•It reduces shrinkage of the building material.
•It prevents development of cracks in the mortar on drying.
•It helps in making mortars and concretes of desired
strength by varying its proportions with the binding
material.
•A well graded sand adds to the density of mortars and
concretes.
Functions of surkhi:
•It provides brick color and make the mortar economical