3. INTRODUCTION:-
Aggregate are the important constituent in
concrete. Aggregate are granular material,
derived from the most part from the natural
rocks, crushed stones, or natural gravels
and sands.
Aggregate generally occupy about 70% to
80% of the volume of concrete and can
therefore be expected to have an important
influence on it properties.
4. CLASSIFICATION OF
AGGREGATE:-
a)CLASSIFICATION BASED ON SIZE:
>Coarse aggregate:
Aggregate which retained on the No.4 (4.75mm)
sieve. The function of the coarse aggregate is to act
as the main load-bearing component of the concrete.
>Fine aggregate:
Aggregate passing No.4(4.75mm) sieve and
predominately retained on the No.200 (75µ) sieve.
The fine aggregate serve the purpose of filling all the
open space in between the coarse particles.
5. b)CLASSIFICATION BASED ON SOURCE:
>Natural aggregates:
This kind of aggregate is taken from natural deposits
without changing their nature during the process production
such as crushing and grinding.
>Manufactured (synthetics) aggregates:
This is a kind of man-made materials produced as a
main product or an industrial by-product. Some example are
blast furnace slag, air cooled slag and broken bricks.
Synthetics aggregates are produced by thermally processed
materials such as expanded clay and shale used for making
light weight concrete.
6. c)CLASSIFICATION BASED ON UNIT WEIGHT:
Aggregates are classified as Light-weight,
Heavy-weight and Normal-weight aggregate
depending on weight and specific gravity.
AGGREGAT
E
SPECIFIC
GRAVITY
UNIT
WEIGHT
(kN/m3)
BULK
DENSITY
(kN/m3)
EXAMPLE
normal-
weight
2.5-2.7 23-26 15.20-16.80 sand
heavy-weight 2.8-2.9 25-29 >20.80 Scrap iron
light-weight 12 <11.20 dolomite
7. d)CLASSIFICATION BASED ON SHAPE:
The shape of aggregates is an important
characteristic, since it affect the workability of
concrete.
CLASSIFICATION EXAMPLE
Rounded River or seashore gravels
Partly rounded Pit sands & Gravels
Angular Crushed Rocks
Flaky Laminated rocks
8. TESTS ON AGGREGATE:-
The test usually conducted on coarse aggregates
are
>PARTICLE SIZE
>FLAKINESS &ELONGATION INDEX
>MOISTURE CONTENT
>SPECIFIC GRAVITY AND WATER ABSORPTION
>TEN PERCENT FINE VALUE
>AGGREGATE CRUSHING VALUE
>AGGREGATE IMPACT VALUE
> AGGREGATE ABRASION VALUE
9. IMPACT VALUE TEST
The aggregate impact value gives a relative
measure of the resistance of an aggregate to sudden
shock or impact. The impact value is some times
used as an alternative to its crushing value.
Material passing 12.5mm and retained on 10mm
sieve is taken.
10. AGGREGATE CRUSHING VALUE:-
The aggregate crushing value gives a relative
measure of resistance of an aggregate to crushing
under a gradually applied compressive load. The
aggregate crushing strength value is useful factor to
know the behavior of aggregates when subjected to
wear.
CRUSHING VALUE=>
weight of fraction passing the sieve
total weight of sample
11. AGGREGATE ABRASION VALUE:-
The aggregate abrasion value gives a relative
measure of resistance of an aggregate to wear when
it is rotated in a cylinder along with some abrasive
charge
12. SIEVE ANALYSIS
Sieve analysis is also called as Particle size value.
In determination of the proportions of the
particles with in certain ranges in an aggregate
by separation on various sieves of different size
openings, may be defined as sieve analysis.
FINENESS MODULUS=
cumulative % of agg retained on each sieve
100
13. SPECIFIC GRAVITY OF AGG.
Sp.Gr. is used in certain computations for concrete mix design
or control work, such as, absolute volume of aggregate in
concrete. It is not a measure of the quality of aggregate.
Sp.Gr.=
Weight of Agg. (WA)
Weight of an equal volume of water (VA*ρw)
=
WA
VA*ρw
=
ρA
ρw
Density of Agg.
Density of Water
14. FLAKINESS & ELONGATION
INDEX
FLAKINESS INDEX=>
weight of particle passing through the gauge
weight of sample
ELONGATION INDEX=>
weight of particle retained on length gauge
weight of sample
15. GOOD QUALITYIES OF AN IDEAL AGGREGATE:
An ideal aggregate used for the manufacturing of
concrete and mortar, should meet the following
requirements.
It should consist of natural stones, gravels and sand or
in various combinations of these materials.
It should be hard, strong and durable.
It should be dense, clear and free from any coating.
It should be free from injurious vegetable matters.
It should not contain flaky (angular) and elongated
pieces.
It should not contain any material liable to attack steel
reinforcement in case of reinforced concrete.
17. GENERAL INTRODUCTION:
•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.
•When a binding material, ( a fine & a coarse
aggregate) and water are mixed in suitable
proportions , they form an easily workable mix
which is termed as plastic, wet or green concrete.
18. 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.
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.
19. 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.
20. 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.
21. 6 – 9 m Dia
Ht: 40 cm
Width: 30 cm
BULLOCK DRIVEN GRINDING MILL
25. 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.
30. 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.
31. 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.
32. FUNCTION OF SAND IN MORTARS:
•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.
33. PROPERTIES
Workability
Water Retentivity & Air content
Stiffening and hardening
Compressive strength
Flexural strength
34. WORKABILITY
Workability may be defined as the behavior of a mix
in respect of all the properties required, during
application, subsequent working and finishing.
Ease of use, i.e. the way it adheres or slides on the
trowel.
Ease of spread on the masonry unit.
Ease of extrusion between courses without
excessive dropping or smearing.
Ease of positioning of the masonry unit without
movement due to its own weight and the weight of
additional courses
35. WATER RETENTIVITY & AIR CONTENT
This is the property of mortar that resists water loss
by absorption into the masonry units (suction) and to
the air, in conditions of varying temperature, wind and
humidity. Water retentivity is related to workability.
The air content of the mortar in its plastic state is also
important. In order to achieve good durability it is
necessary that there is sufficient air content
(entrained air) to enable freeze-thaw cycles to be
resisted without disrupting the matrix of the material.
36. STIFFENING AND HARDENING
The progression of stiffening, defined in the European
Standard as workable life, refers to the gradual
change from fresh or plastic mortar to setting or set
mortar.
Hardening refers to the subsequent process whereby
the set mortar progressively develops strength.
37. COMPRESSIVE STRENGTH
The use of too much cement will
produce a more rigid mortar, which
may result in vertical cracking
passing through units and mortar
joints as stresses are imposed
Use of the appropriate mortar should
not result in cracking, but any that
does occur, (e.g. due to movement),
will tend to follow the joints, which
will be much easier to repair
38. FLEXURAL STRENGTH
Traditional masonry
construction tended to be
massive relative to modern
structures, typically with very
thick walls. This meant that
the mass or bulk generally
resisted the various forces
applied to it.
The development of modern
masonry units and advances
in mortar technology have led
to more slender structures
which are more vulnerable to
lateral forces e.g. wind loads.
