This document discusses aggregates which are inert materials mixed with cement to produce concrete. It defines aggregates and describes their properties and types. Aggregates can be classified based on grain size, origin, density or shape. The main types are fine aggregates like sand, and coarse aggregates like gravel. Fine aggregates pass through a 4.75mm sieve while coarse aggregates are retained. Properties of aggregates that affect concrete like composition, size and texture are also covered. The goal is to educate civil engineers on aggregates used in construction.

1. AGGREGATES

2. Aggregates are the inert materials that are
mixed in fixed proportions with a Binding
Material to produce concrete.
They are materials used in construction
including sand, gravel ,crushed stones etc
They act as fillers or volume increasing
They act as fillers or volume increasing
components on the one hand and are
responsible for the strength, hardness,
and durability of the concrete on the
other hand.

3. LEARNING OBJECTIVES
This Course is designed to intimate
civil engineers about Aggregates, its
properties and types.

4. LEARNING OUTCOME
At the End of this Course, Participants should be
able :
 Define Aggregates
 Classify Aggregates and their Qualities
 Identify types of Aggregates
 List various test carried out on Aggregates

5. QUALITIES OF AGGREGATES.
It should be chemically inert, i.e., they
should not react with cement or any other
aggregate or admixture.
It should possess sufficient hardness to
It should possess sufficient hardness to
resist scratching and abrasion in the
hardened state.
It should possess sufficient toughness to
bear impact and vibratory loads.

6. QUALITIES OF AGGREGATES.
It should be strong enough to bear
compressive and normal tensile loads in
the ordinary mixture.
It should be free from impurities, inorganic
It should be free from impurities, inorganic
or organic in nature, which will affect
adversely on its quality.
It should be capable of producing an easily
workable plastic mixture on combining
with cement and water.

7. CLASSIFICATION OF AGGRECATE
BASIS OF GRAIN SIZE
BASIS OF ORIGIN
BASIS OF ORIGIN
BASIS OF DENSITY
BASIS OF SHAPE

8. 1. TYPES ON THE BASIS OF GRAIN SIZE
Aggregate Types on the basis of Grain Size
This is the most common classification,
where in two types of aggregates are
distinguished:
distinguished:
Fine aggregate
Coarse aggregate

9. FINE AGGREGATE
 In the Fine Aggregates, the grain-size lies between 4.75
mm and 0.15 mm.
 In other words, these pass-through from sieve with the
mesh size of 4.75 mm and are retained on a sieve of 0.15
mesh size.
 Sand is the most universally available natural Fine
Aggregate.

10. TYPES OF FINE AGGREGATE
a. Sand : it consist of small angular rounded grains of
silica depending upon the source from which it is
obtained. It is classified as:
i. Pit or quarry sand: it is found as deposited in the soil
and is to be excavated out. Its grains are generally
sharp or angular. It should be free from organic matter
and clay. It is usually considered to be the best fine
aggregate for use in mortar and concrete.
aggregate for use in mortar and concrete.
ii. Sea sand : it consist of fine rounded grains of brown
colour and its collected from sea shores or sea beaches.
Sea sand usually contains salt and while using that in
mortar it causes disintegration of work in which it is
used. In R.C.C work these salts will attack
reinforcement if salt content is high. These salt may
cause efflorescence. It should be used locally after
thorough washing

11. TYPES OF FINE AGGREGATE
iii. River sand : it is obtained from the banks and
beds of rivers. It may be fine or coarse. Fine
sand obtained from beds and banks of rivers is
often found mixed with silt and clay so it
should be washed before use. But coarse and
sand is generally clean and excellent for use
especially for plastering.
especially for plastering.
b. Crushed Stones: it is obtained by crushing
the waste stones of quarries to the particular
size of sand. Sand obtained from by crushing a
good quality stone is excellent fine aggregate.
Mortar made with this sand is usually used for
good quality work.

12. COARSE AGGREGATES
 Coarse aggregates are those that are retained on the
sieve of mesh size 4.75 mm. Their upper size is
generally around 7.5 mm.
 Gravels from river bed are the best coarse aggregates in
the making of Common Concrete.
 In those situations, if they are not easily available,
Suitable rock types are crushed to the desired particle
sizes for making coarse aggregates.

13. TYPES OF COARSE AGGREGATES
a. Crushed Stones: it is an excellent coarse
aggregate and is obtained by crushing granite,
sand stone or grained lime stone and all types
of stones. Crushed stones are used for
construction of roads and railway tracks etc.
b. Gravel: it is another very good coarse
b. Gravel: it is another very good coarse
aggregate. It is obtained from river beds,
quarries and sea shores. The gravel obtained
from sea shores should be well washed with
fresh water before use in order to remove the
impurities which may be clay, salts silt etc. it
is commonly used in the preparation of
concrete.

14. TYPES OF COARSE AGGREGATES
c. Broken pieces of bricks: it is also good
artificial source of coarse aggregate. It is
obtained by breaking well burnt bricks. It is
generally used in lime concrete at places
where aggregates from natural sources are
either not available or are expensive. It can be
either not available or are expensive. It can be
used at places where low strength is required.
It should be watered well before using it in the
preparation of concrete. It is commonly used
for mass concrete in foundations and under
floors.

15. 2. TYPES ON THE BASIS OF ORIGIN
There are three types on the Basis of Origin.
i. Natural:
These include all those types of fine and
coarse aggregates, that are available in
almost ready to use form, from natural
almost ready to use form, from natural
resources.
Examples are sands from river beds, pits
and beaches, and gravels from river
banks.

16. TYPES ON THE BASIS OF ORIGIN
ii Bye-product:
These include materials obtained as
wastes from some industrial and
metallurgical engineering operations,
which possess suitable properties for
being used as aggregate.
being used as aggregate.
Examples: Cinder obtained from burning
of coal in locomotives and kilns.
And Slag is obtained from blast furnaces
as Scum is the best example from this
category.

17. 2. TYPES ON THE BASIS OF ORIGIN
iii Processed:
These form a special class in Aggregate.
They are specifically manufactured for use
in making Quality Concretes.
Examples: They include burnt clay,
Shales, vermiculite’s and perlite. They are
essential Ingredients of Lightweight
Concrete.

18. 3.TYPES ON THE BASIS OF DENSITY
Three types of aggregates are distinguished on
the basis of their weight per unit volume.
i. Standard or Normal:
These types of aggregates give strength and
weighting to the Concrete of around 2300 to
2500 kg/m3.
2500 kg/m3.
Gravels, Sand and Crushed stone, are all classed
as Standard or Normal Aggregates.

19. 3.TYPES ON THE BASIS OF DENSITY
iiHigh-Density Aggregates:
These are that type of Aggregates, which
is used in standard proportions yield in
heavy weight concretes.
Such concretes are especially useful as
Such concretes are especially useful as
shields against X-rays and radiations in
the atomic power plant.
Examples: Baryle – a natural mineral
with a specific gravity of 4.3 is an
example. Concretes with such aggregate
usually weight above 4000 kg/m3.

20. 3.TYPES ON THE BASIS OF DENSITY
iii. Light weight Aggregate:
They consist of natural and artificial materials
of very low density so that the resulting concrete
is also quite Light in weight, generally with in a
range of 350 to 750 kg/m3.
They are specially used in sound proofing and
fire proofing constructions.
They are also used extensively in the
manufacture of light weight Pre-Cast concrete
blocks.

21. 4.TYPES ON THE BASIS OF SHAPE
1. Rounded Aggregate
The rounded aggregates are completely shaped by
attrition and available in the form of seashore gravel.
Rounded aggregates result in the minimum percentage
of voids (32 – 33%) hence gives more workability. They
require a lesser amount of water-cement ratio. They are
not considered for high-strength concrete because of poor
not considered for high-strength concrete because of poor
interlocking behavior and weak bond strength.

22. 4.TYPES ON THE BASIS OF SHAPE
2. Irregular Aggregates
The irregular or partly rounded aggregates are partly
shaped by attrition and these are available in the form
of pit sands and gravel. Irregular aggregates may
result 35- 37% of voids. These will give lesser
workability when compared to rounded aggregates. The
bond strength is slightly higher than rounded
bond strength is slightly higher than rounded
aggregates but not as required for high strength

23. HOPE EVERYTHING IS CLEAR SO FAR?

24. 4.TYPES ON THE BASIS OF SHAPE
3. Angular Aggregates
The angular aggregates consist well defined edges
formed at the intersection of roughly planar surfaces and
these are obtained by crushing the rocks. Angular
aggregates result maximum percentage of voids (38-
45%) hence gives less workability. They give 10-20%
more compressive strength due to development of
more compressive strength due to development of
stronger aggregate-mortar bond. So, these are useful in
high strength concrete manufacturing.

25. 4.TYPES ON THE BASIS OF SHAPE
4. Flaky Aggregates
When the aggregate thickness is small when
compared with width and length of that aggregate it is
said to be flaky aggregate. Or in the other, when the
least dimension of aggregate is less than the 60% of its
mean dimension then it is said to be flaky aggregate.

26. 4.TYPES ON THE BASIS OF SHAPE
5. Elongated Aggregates
When the length of aggregate is larger than the other
two dimensions then it is called elongated aggregate or
the length of aggregate is greater than 180% of its
mean dimension

27. PROPERTIES OF AGGREGATES
 Composition
 Size and Shape
 Surface Texture
 Specific Gravity
 Bulk Density
 Voids
 Voids
 Porosity and Absorption
 Bulking of Sand
 Fineness Modulus of Aggregate
 Surface Index of Aggregate
 Deleterious Materials

28. PROPERTIES OF AGGREGATES
 1. Composition
Aggregate consisting of such materials that
can chemically react with alkalis in cement and cause
excessive expansion, cracking, and deterioration of
concrete mix should never be used. Therefore it is
necessary to test aggregates to ensure whether there is
the presence of any such constituents in aggregate or
the presence of any such constituents in aggregate or
not.
 2. Size and Shape
The size and shape of the aggregate particles
greatly influence the quantity of cement required
in concrete mix and hence ultimately the economy of
concrete.

29. PROPERTIES OF AGGREGATES
 3. Surface Texture
The development of hard bond strength between coarse aggregate
and cement paste depends upon the surface roughness, surface
texture, and porosity of coarse aggregate. In case the surface is
but porous, the maximum bond strength will develop in concrete.
In porous surface aggregates, the bond strength of aggregate
increase as cement paste start setting.
 4. Specific gravity
The ratio of the weight of oven-dried aggregate which is kept for 24
hours at a temperature of 100 to 100°C, to the weight of an equal
The ratio of the weight of oven-dried aggregate which is kept for 24
hours at a temperature of 100 to 100°C, to the weight of an equal
volume of water displaced by saturated dry surface aggregate is
called the specific gravity of aggregates.
Specific gravity is mainly oh two types:
Apparent specific gravity
Bulk specific gravity
The specific gravity of major aggregates falls within the range of 2.6
to 2.9.

30. PROPERTIES OF AGGREGATES
 5. Bulk Density
Bulk density of aggregate can be defined as the weight
of coarse aggregate required to fill the unit volume of
the container. It is generally expressed in kg/liter.
Bulk density of aggregates particles depends upon the
following 3 factors which are:
 Degree of compaction
Grading of aggregates
 Grading of aggregates
 The shape of aggregate particles
 6. Voids
The empty spaces left between coarse
aggregate particles are known as voids. The volume of
voids equals the difference between the total volume of
the aggregate mass & the volume occupied by
the particles alone.

31. PROPERTIES OF AGGREGATES
 7. Porosity and Absorption
The holes produced in the rocks at the time of
the solidification of the molten magma, due to
air bubbles, are known as pores.
Water absorption may be defined as the difference
between the weight of very dry aggregates and
the weight of the saturate aggregates with the surface
dry condition.
dry condition.
 8. Bulking of Sand
It can be defined as an increase in the bulk volume of
the quantity of sand in a moist condition over the
volume of the same quantity of dry or
completely saturated sand.
The proportion/ratio of the volume of moist sand due to
the volume of sand when dry is called a bulking factor.

32. QUESTIONS

33. PROPERTIES OF AGGREGATES
 9. Fineness Modulus
Fineness modulus is commonly utilized to get an idea of
how coarse or fine the aggregate is. More fineness
modulus value indicates that the aggregate is a coarse
sand small value of fineness modulus indicated that the
aggregate is finer.
Fineness modulus is a factor obtained by adding
the cumulative percentages of aggregate retained on each of
the sieves ranging from 80 mm to 150 mm micron and
the sieves ranging from 80 mm to 150 mm micron and
dividing this by 100.
 10. Specific Surface Area of Aggregate
The total surface area of aggregate particles per unit weight
of the material is called specific surface. This is an indirect
measure of the aggregate grading. The specific surface rises
with the reduction in the size of aggregate particles.
The specific surface area of the fine aggregate is very much
lesser than that of the coarse aggregate.

34. PROPERTIES OF AGGREGATES
 11. Deleterious Materials
Aggregate should not contain any harmful material in
such a quantity to affect the durability and strength of
the concrete.
Deleterious materials might cause one of the following
effects on cement or concrete mix:
To interfere with hydration of cement
 To interfere with hydration of cement
 To prevent the development of proper bond
 To reduce strength and durability
 To modify setting times

35. TEST ON AGGREGATES
 Crushing test
 Abrasion Test
 Impact Test
 Soundness Test
 Shape test
 Bitumen Adhesion test
 Specific gravity test
 Water absorption test
 Moisture content

36.  Crushing Strength Test on Aggregates
Aggregate crushing value gives the Crushing strength of
aggregate up to which it can bear the load without fail.
To conduct crushing strength test we need compression
testing machine, cylindrical measure, plunger and Isa
sieves. First sieve the sample aggregate Apply the load
at uniform rate of 40 tonnes load in 10 minutes. Then
stop the machine and crushed aggregate is sieved
through 2.36mm sieve and aggregate passing 2.36mm
through 2.36mm sieve and aggregate passing 2.36mm
sieve is weighed. Aggregate crushing value can be
obtained from below formula: Aggregate crushing value
= (W2/W1) *100 % ,

37.  Abrasion Test on Aggregates
Hardness property of aggregate is determined by
conducting abrasion test. Los Angeles abrasion testing
machine is used to conduct this test. For this test, the
sample taken should be clean and dried. The sample is
weighed W1 and placed in Los Angeles testing machine
and the machine is operated. Machine should be rotated
at a speed of 20-33 revolutions per minute. After 1000
revolutions the sample is taken out and sieved through
revolutions the sample is taken out and sieved through
1.7mm sieve. Sample retained on 1.7mm is washed and
dried and note down its weight W2. Aggregate abrasion
value = {(W1-W2)/W2} x 100%

38.  Impact Test on Aggregates
Impact value of aggregate will give aggregate capability
against sudden loads or forces. For this test also
aggregate passing through 12.5mm and retained on
10mm sieve is taken and oven dried. Fill the cylinder
with aggregate in 3 layers, 25 strokes of tamping for
each layer. Weight w1 noted. The cylinder is placed in
impact testing machine which consist a hammer. After
placing the cylinder, hammer is raised to 380mm and
placing the cylinder, hammer is raised to 380mm and
release freely. Then it will blow the aggregates. Repeat
it for 15 such blows. After that take down the sample
and aggregate passing through 2.36mm sieve is weighed
as w2. Aggregate impact value = (W2/W1) *100 %

39.  Soundness Test on Aggregates
To determine the weathering resistance of aggregate
soundness test is conducted. If the resistance against
weathering is good for aggregate, then it will have high
durability. For soundness test we need some chemical
solutions namely sodium sulphate or magnesium
sulphate. The sample of aggregate passing through
10mm sieve and retained on 300 micron sieve is taken.
Dry and weigh the sample and immerse them in the
Dry and weigh the sample and immerse them in the
chemical solution for difference in weight loss. The
weight loss should be below 12% if sodium sulphate is
used below 18% if magnesium sulphate is used.

40.  Shape test on Aggregates
Shape of aggregate is also important consideration for
the construction of pavement. Aggregate should not
contain flaky and elongated particles in it. If they
contain this type of particles, they will affect the
stability of mix. The percentage by weight of aggregates
whose least dimension is less the 3/5th of its mean
dimension is called as flakiness index. The percentage
by weight of aggregate particles whose greatest
by weight of aggregate particles whose greatest
dimension is 1.8th times their mean dimension is called
as elongation index. In this test shape test gauges are
taken and minimum of 200 pieces containing sample is
passed through respective gauges. Material retained on
Thickness gauge and material retained on length gauge
is weighed to an accuracy of 0.1

41.  Specific gravity test on Aggregates
Specific gravity of an aggregate is the ratio of its mass
to that of an equal volume of distilled water at specific
temperature. The specific gravity of aggregate is of two
types. Bulk specific gravity, in which total volume of
aggregates along with their void space is considered.
Apparent specific gravity, in which the volume of
aggregates without considering void spaces is taken into
account.
account.
Bulk specific gravity G = {dry weight of aggregate/total
volume of aggregate}/ density of water Apparent specific
gravity G= {dry weight of aggregate/volume of aggregate
without void space}/ density of water

42.  Water absorption test on Aggregates
This test helps to determine the water absorption value
of aggregate. To perform this test minimum 2 kg sample
should be used. The sample should be cleaned and dried.
Place the sample in wire basket and dip the basket in
distilled water bath. To release the air between
aggregates just lift and dip the basket for about 25 times
in 25 seconds.

43. QUESTIONS

44. USES OF AGGREGATES IN CONSTRUCTION
 In the construction industry, aggregates are used in
concrete considering its economic factor and its
strength which it is provided to concrete.
 Aggregates are also used as ballast in road and
railway works to resist the overall load, to distribute
the load properly to the soil base, and drain off the
rainwater.
They also play a major role in sewage treatment
 They also play a major role in sewage treatment
processes and water filtration. quickly from road.
 Aggregates has a major effect on concrete
properties such as abrasion resistance,
hardness, elastic modulus, and another characteristic
like durability, strong, and cheaper.
 Aggregates are used to backfills, fills, drainage, and
filtration work.

45. USES OF AGGREGATES IN CONSTRUCTION
 Aggregate can also be used to create the braking
moisture and vapor barriers under the slab.
 Coarse aggregates are primly used to prepare base
for driveways and roadways.

46. USES OF AGGREGATES IN CONSTRUCTION
 Aggregate acquire 60-65% volume of concrete.
 It used to provide rigid structure to concrete.
 Aggregate helps in reducing shrinkage and surface
cracking of concrete.
 Coarse aggregate are used in concrete to build mega
structures for example different components of
a building, bridges, foundations, etc.
a building, bridges, foundations, etc.
 As high the coarse aggregate size lesser the surface
area and therefore it requires lesser binding material
(cement), which result in low cost construction.
 A mix of coarse and fine aggregate in concrete used to
make it more denser, harder and durable
against atmospheric action.

47. USES OF AGGREGATES IN CONSTRUCTION
 Aggregates are used in road construction for base, sub
base, and surface of roads in various forms.
 Aggregate are used in soil stabilization process using
cementitious materials (blends of cement, fly ash, slag,
lime).

48. USES OF AGGREGATES IN CONSTRUCTION
 They are also used in stabilization process
with bituminous materials (bitumen or tar).
 Stabilized with other materials (resins, fibers, geo-
synthetics).
 On roads, aggregate help in equal distribution of the
load and direct rainwater running off from the road
load and direct rainwater running off from the road
surface.

49. HOPE EVERYTHING IS CLEAR SO FAR?

50. THANK YOU