This document provides information on aggregates used in traditional building materials. It defines aggregates as fillers used with binding materials that are derived from rocks. Aggregates make up 70-80% of concrete's volume and influence its properties. Aggregates are broadly classified into fine aggregates smaller than 4.75mm and coarse aggregates larger than 4.75mm. The document discusses various types of coarse aggregates based on geological origin, size, shape, and unit weight. It also covers properties of aggregates like strength, shape, specific gravity, moisture content and tests conducted on aggregates. Alkali aggregate reaction and measures to prevent it are summarized.

1. UNIT-1
TRADITIONAL BUILDING MATERIALS
“AGGREGATE”

2. INTRODUCTION
• Filler with binding material
• Derived from rocks
• Form body of concrete
• Reduce shrinkage and effect economy
• Occupy 70 -80 % of volume and have considerable influence
on properties of concrete.
• Important to obtain good quality of aggregates.
• Not chemically inert
• Chemically active by exhibiting chemical bond at interface of
aggregates and cement paste.
• securing volumetric stability and durability.

3. CLASSIFICATION
• Broadly aggregates are classified into two
categories:-
1. Fine aggregate (>0.07mm & passing through
4.75mm)
2. Coarse aggregate(retained on 4.75 mm sieve
& <80mm)

5. COARSE AGGREGATE

6. CLASSIFICATION
• On the basis of geological origin:-
– Natural
– Artificial
• On the basis of size:-
– All-in-aggregate
– Graded aggregate
• On the basis of shape:-
– Angular aggregate
– Flaky aggregate
• On the basis of unit weight:-
– Normal
– Heavy
– Light

7. GEOLOGICAL ORIGIN
• NATURAL AGGREGATE:-
– obtained by crushing rocks.
– Also by weathering action/natural agencies of rocks.
– Most widely used are igneous rocks.
• ARTIFICIAL AGGREGATE:- (not used for R.C.C
works)
– Broken bricks (brick bats suitable for mass concreting
e.g. foundations)
– Blast furnace slag (precast concrete products, fire
resistant but responsible for corrosion due to sulphur
content)
– Synthetic aggregates (thermally processed materials
such as expanded clay and shale) (light weight
concrete)

8. SIZE
• All-in-aggregate:-
– Different fractions of fine and coarse sizes.
– They are not recommended for quality concrete.
• Graded aggregate:-
– Aggregate most of which passes through a
particular size of sieve are known as graded
aggregate.
– e.g.: a graded aggregate of nominal size 20mm
means an aggregate of which passes IS sieve 20
mm.

9. SHAPE
• Elongated aggregate:-
– Length is 1.8 times or nine fifths of its mean
dimension.
• Flaky aggregate:-
– Least lateral dimension should be less than 0.6
times or three fifths of the mean dimension.
– Orient in one plane with water and air voids
underneath.
– Adversely effect durability and are restricted to
maximum of 15 %.

11. UNIT WEIGHT
AGGREGATE SPECIFIC
GRAVITY
UNITWEIGHT
(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

12. SURFACE TEXTURE
(SMOOTHNESS & ROUGHNESS)
CLASSIFICATION EXAMPLES
Glassy Black flint
Smooth Gravel, Marble
Granular Sandstone
Rough Basalt
Crystalline Granite
Honeycombed & Porous Brick, slag

13. GOOD QUALITIES 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 sandor
in various combinations of thesematerials.
• It should be hard, strong anddurable.
• Itshould 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 containany materialliableto attack
steel reinforcement in caseof reinforcedconcrete.

14. CHARACTERISTICS OF AGGREGATES:
• Important characteristics of aggregates
which influence the properties of resulting
concrete mix are discussed as under:
– Aggregate containing the constituents which
generally react with alkalies in cement cause
excessive expansion, cracking of concrete
mix, should never be used. Suitability of
aggregates should be judged either by
studying its service history or by laboratory
tests.

15. – The size and shape of the aggregate particles
mainly influence the quantity of cement required in
a concrete mix and ultimately economy of the
concrete. For the preparation of economical
concrete, one should use largest coarse
aggregates feasible for the structure.
– Type of structure Max. size of aggregate
1. Mass concrete work 40 mm
i.e. dams, retaining walls,
piers and abutments, etc.
2. R.C.C work i.e. beams, 20 mm
columns, etc
3. Flooring 10 mm

16. PROPERTIES
• STRENGTH
• PARTICLE SHAPE
• SPECIFIC GRAVITY
• BULK DENSITY
• VOIDS
• POROSITY
• MOISTURE CONTENT

17. STRENGTH
• Should be equal to that of concrete.
• Rocks commonly used as aggregates have a
higher compressive strength.
• Tests conducted for evaluation of strength are
crushing, impact and ten % fines test.
• Crushing test is more reliable.
• Toughness by impact test.
• Hardness by abrasion test.

18. SHAPE & TEXTURE
• Shape influences the properties of fresh
concrete more than hardened concrete.
• Round & irregular aggregates are highly
workable but yield low strength.
• Flaky aggregates require more cement paste,
produce maximum voids.
• Angular shape is best.
• Shape and texture governs water
requirement.

19. SPECIFIC GRAVITY
• SG lies between 2.6 – 3.5 for natural
aggregates.
• Influences strength and absorption of
concrete.
• Low SG high porosity and therefore poor
durability and low strength.
• Density greatly depends upon specific gravity.

20. BULK DENSITY & VOIDS
• Depends upon particle size , grading and
moisture content.
• A higher bulk density of coarse aggregate is an
indication of fewer voids to be filled by sand
and cement.
• If the voids are more in the concrete , the
strength will be low.

21. POROSITY
• The entrapped air bubbles in the rocks during
their formation lead to minute holes called as
pores or cavities.
• The porosity of rocks is less than 20%.
• The concrete becomes permeable and effects
bond.
• The porous aggregate absorbs more moisture,
resulting in loss of workability.

22. MOISTURE CONTENT
• A high moisture content increases the W/C
ratio to an appreciable extent.
• The surface moisture expressed as a % of the
weight of the saturated surface dry aggregate
is known as moisture content.

23. DELETERIOUS MATERIALS &
ORGANIC IMPURITIES
• Organic matters, clay, shale, coal, iron pyrites,
etc., may have harmful or chemical effects on
the aggregates.
• Affects the properties of concrete and are
undesirable.
• Salts cause efflorescence.
• Sulphides cause surface staining.

24. ALKALI AGGREGATE REACTION
• Inert material till 1940.
• Extensive expansion and complete disruption and
disintegration of the concrete is known as alkali
aggregate reaction or concrete cancer.
• The trouble is due to reaction between silica in
aggregate and alkalis in cement.
• A reactive aggregate , if in finely ground state will
inhibit the action.
• Reaction between cement and aggregate can be of two
types:- alkalis with either silicas or carbonates in the
aggregate.
• Reaction with silicas is common.

25. • The AAR takes place only in presence of water
or water vapour.
• The water forms strong caustic solute with
alkalis of cement.
• This caustic liquid attacks reactive silica to
form alkali silica gel (AAR GEL) of unlimited
swelling type.

26. Concept clarity

27. Pics of Alkali Aggregate Reaction

28. Factors affecting Alkali Aggregate
Reaction
1) Reactive type of aggregates [REACTIVE SILICA], have been
found to have serious effects IF PRESENT IN SMALL
QUANTITIES BUT NOT if it constitutes the whole of
aggregate.
2) High alkali content of cement. If there is very small amount
of alkalis in cement and very reactive silica it is not a
problem, however the increase in alkali content [> 0.6 %] of
cement posses issues of AAR.
3) Availability of Moisture Content. AAR occurs ONLY in the
presence of moisture, which is the reason why AAR is NOT
observed in the interior mass of concrete.
4) Temperature Conditions should be favourable, generally in
the range of 10 to 380C.

29. Control of Alkali Aggregate reaction
a) By selecting non – reactive aggregate.
b) By using Low Alkali Cement.
c) By controlling Moisture Content.
d) By using Puzzolonas [REACTIVE SILICA]
– The aggregates are found to be reactive when they
contain silica in a particular proportion and fineness.
When fly-ash or surkhi or dust is added this optimum
condition of silica being in particular proportion and
fineness is disturbed and the aggregates become passive.
e) By adding air-entraining agents.
– Alkali silica gel which imparts pressure over the set
cement gel, can be negated with the addition of air
entraining agents which absorb the osmotic pressure.

30. SOUNDNESS
• Soundness is defined as the ability of
aggregate to resist changes in volume as a
result of changes in physical conditions.
• The conditions like freezing, thawing,
temperature changes, alternate wetting and
drying.
• Porous and weak aggregates undergo
excessive volume changes under these
conditions.

31. THERMAL PROPERTIES
• The coefficient of thermal expansion of
concrete increase with that of coarse
aggregate.
• Any difference in the coefficients of coarse
aggregate and cement paste may break the
bond between the two.

32. FINENESS MODULUS (F.M)
• It is a numerical index of fineness, giving some
idea about the mean size of the particles in
aggregates.
• The sum of cumulative percentage of residues
retained on each of the Indian standard sieves
(80mm, 40mm, 20mm,10mm, 4.75mm, 2.36m
,1.18mm, 600 microns, 300 microns and 150
microns each succeeding sieve has half the
aperture of the previous one), divided by the
100,is known as “Fineness modulus” of the
aggregates.

33. • The fineness modulus of an aggregate is roughly
proportional to the average size of particles of
the aggregates.
• The F.M. varies between 2 to 3.2 for fine
aggregate, between 5.5 to 8 for coarse aggregate
and between 3.5 to 6.5 for all in aggregate.
• The objective of finding F.M. is to grade the given
aggregate for the required strength and
workability of concrete mix with minimum
cement.
• Higher the F.M. aggregate result in harsh concrete
mixes and lower F.M. results in uneconomical
concrete mixes.

34. TESTSONAGGREGATE
• PARTICLESIZE
• FLAKINESS&ELONGATIONINDEX
• MOISTURE CONTENT
• SPECIFICGRAVITYANDWATERABSORPTION
• TENPERCENTFINEVALUE
• AGGREGATECRUSHING VALUE
• AGGREGATEIMPACTVALUE
• AGGREGATEABRASION VALUE

35. PARTICLE SIZE
35
Sieveanalysis is also called asParticle size
value. In determination of the
proportions of the particles with in
certain rangesin an aggregate by
separation on various sievesof different
size openings, maybe defined assieve
analysis.
FINENESS MODULUS = cumulative%of agg
retained on eachsieve/100

36. 36

37. FLAKINESS & ELONGATION INDEX
• Large number of flaky particles more
voids more mortar to fill voids
uneconomy effects durability.
• Aggregates may break down easily under
heavy loads.
• Also called shape test.
• I.S. 2836 part-1

38. TEST
Apparatus required:-
• Aggregate sample
• Digital balance
• Elongation gauge & Thickness gauge
• Test sieves of sizes – 63mm, 50mm, 40mm,
31.5mm, 25mm, 20mm, 16mm, 12.5mm and
10mm & 6.3 mm.

39. ELONGATION GUAGE

40. THICKNESS GAUGE

41. PROCEDURE
• Take the aggregate sample which contains minimum
200 pieces of any fraction.
• Sieve the sample through mentioned sieves i.e., from
63mm to 6.3mm sieves.
• The aggregate retained on 63mm and passed
through 6.3mm should not be considered.
• The aggregate passed through 63mm and retained
on 6.3mm and its above sieves is taken along with
sieves. Now we have specified size range for every
particle.
• Now weigh aggregate retained on different sieve and
note down the total weight as “W1”

42. RESPECTIVE SLOTS IN GAUGES

43. • For determining F.I., the aggregate retained on
sieves are separated.
• Now each aggregate is passed through the
corresponding slot in the thickness gauge.
• F.I. = (W1/W2) X 100
– Where, W1 is weight of aggregate passing through
the slot of thickness gauge.
– W2 is the total weight of sample.

44. • For determining E.I., the aggregate retained
on sieves are separated.
• Then each aggregate piece is passed through
the corresponding slot of length gauge.
• E.I. = (W1/W2) x 100
– Where, W1 is weight of aggregate retained on
length gauge.
– W2 is total weight of aggregate.

45. MOISTURE CONTENT
• A sample of 2 kg of aggregate is used for
conducting the test.
• The sample should be throughly washed to
remove finer particles, dust etc., & then
placed in wire basket and immersed in
distilled water at room temperature for a
period of 24 hrs.
• Then the aggregates are removed & gently
surface dried with a dry cloth and weighed.

46. • The aggregates are then placed in an oven at a
temperature of 100 to 110 degree C for 24 hrs.
• After 24 hrs, aggregates are removed and
cooled in air tight container and weighed.
• Water Absorption = (W1/W2) x 100
– Where, W1 is weight in gm of the surface dry
aggregate.
– W2 is weight in gm of oven dried aggregate.
• Water absorption shall not exceed 2%.

47. Sp.Gr.isusedin certain computations for concretemix
designor control work, suchas,absolute volume of
aggregatein concrete.It isnot ameasureof the quality
ofaggregate.
Sp.Gr.=
Weightof Agg.(WA)
Weightof anequalvolume ofwater (VA*ρw)
=
W
A
VA*ρw
=
ρA
ρw
DensityofAgg.
SPECIFIC GRAVITY
DensityofWater

48. AGGREGATE IMPACT VALUE TEST
• The aggregate impact value gives a relative measure of
the resistance of an aggregate to sudden shock or
impact.
• The property of a material to resist impact is known as
toughness. Due to movement of vehicles on the road
the aggregates are subjected to impact resulting in
their breaking down into smaller pieces.
• The aggregates should therefore have sufficient
toughness to resist their disintegration due to impact.
This characteristic is measured by impact value test.
• The aggregate impact value is a measure of resistance
to sudden impact or shock, which may differ from its
resistance to gradually applied compressive load.

49. APARATUS
The apparatus as per IS: 2386 (Part IV) – 1963 consists of:
• A testing machine weighing 45 to 60 kg and having a metal base with a
painted lower surface of not less than 30 cm in diameter. It is supported
on level and plane concrete floor of minimum 45 cm thickness. The
machine should also have provisions for fixing its base.
• A cylindrical steel cup of internal diameter 102 mm, depth 50 mm and
minimum thickness 6.3 mm.
• A metal hammer or tup weighing 13.5 to 14.0 kg the lower end being
cylindrical in shape, 50 mm long, 100.0 mm in diameter, with a 2 mm
chamfer at the lower edge and case hardened. The hammer should slide
freely between vertical guides and be concentric with the cup. Free fall of
hammer should be within 380±5 mm.
• A cylindrical metal measure having internal diameter 75 mm and depth 50
mm for measuring aggregates.
• Tamping rod 10 mm in diameter and 230 mm long, rounded at one end.
• A balance of capacity not less than 500g, readable and accurate up to
0.1g.

51. PROCEDURE
• The test sample consists of aggregates sized 10.0 mm 12.5 mm. Aggregates may be
dried by heating at 100-110° C for a period of 4 hours and cooled.
• Sieve the material through 12.5 mm and 10.0mm IS sieves. The aggregates passing
through 12.5mm sieve and retained on 10.0mm sieve comprises the test material.
• Pour the aggregates to fill about just 1/3 rd depth of measuring cylinder.
• Compact the material by giving 25 gentle blows with the rounded end of the
tamping rod.
• Add two more layers in similar manner, so that cylinder is full.
• Strike off the surplus aggregates.
• Determine the net weight of the aggregates to the nearest gram(W).
• Bring the impact machine to rest without wedging or packing up on the level plate,
block or floor, so that it is rigid and the hammer guide columns are vertical.
• Fix the cup firmly in position on the base of machine and place whole of the test
sample in it and compact by giving 25 gentle strokes with tamping rod.
• Raise the hammer until its lower face is 380 mm above the surface of aggregate
sample in the cup and allow it to fall freely on the aggregate sample. Give 15 such
blows at an interval of not less than one second between successive falls.

52. • Remove the crushed aggregate from the cup and sieve it through 2.36 mm
IS sieves until no further significant amount passes in one minute. Weigh
the fraction passing the sieve to an accuracy of 1 gm. Also, weigh the
fraction retained in the sieve.
• Compute the aggregate impact value. The mean of two observations,
rounded to nearest whole number is reported as the Aggregate Impact
Value.
• Aggregate impact value = (W2/W1) x 100
– Where, W1 is total weight of dry sample
– W2 is weight of portion passing through 2.36 mm sieve.
Recommended Aggregate Impact Test Values
Aggregate Impact Value Classification
<20% Exceptionally Strong
10 – 20% Strong
20-30% Satisfactory for road surfacing
>35% Weak for road surfacing

53. AGGREGATE CRUSHING VALUE
• I.S. 2386-PART 4
• Aggregate crushing value test on coarse aggregates
gives a relative measure of the resistance of an
aggregate crushing under gradually applied
compressive load.
• Coarse aggregate crushing value is the percentage by
weight of the crushed material obtained when test
aggregates are subjected to a specified load under
standardized conditions.
• Aggregate crushing value is a numerical index of the
strength of the aggregate and it is used in construction
of roads and pavements.

54. APARATUS
• A steel cylinder 15 cm diameter with plunger and base
plate.
• A straight metal tamping rod 16mm diameter and 45 to
60cm long rounded at one end.
• A balance of capacity 3 kg readable and accurate to one
gram.
• IS sieves of sizes 12.5mm, 10mm and 2.36mm
• A compression testing machine.
• Cylindrical metal measure of sufficient rigidity to retain its
from under rough usage and of 11.5cm diameter and 18cm
height.
• Dial gauge

56. PROCEDURE
• Coarse aggregate passing 12.5mm IS sieve and retained on a10mm IS sieve
are selected and heated at 100 to 110°C for 4 hours and cooled to room
temperature.
• Put the cylinder in position on the base plate and weigh it (W).
• Put the sample in 3 layers, each layer being subjected to 25 strokes using
the tamping rod. Care being taken in the case of weak materials not to
break the particles and weigh it (W1).
• Level the surface of aggregate carefully and insert the plunger so that it
rests horizontally on the surface. Care being taken to ensure that the
plunger does not jam in the cylinder.
• Place the cylinder with plunger on the loading platform of the
compression testing machine.
• Apply load at a uniform rate so that a total load of 40T is applied in 10
minutes.

57. • Release the load and remove the material from the
cylinder.
• Sieve the material with 2.36mm IS sieve, care being
taken to avoid loss of fines.
• Weigh the fraction passing through the IS sieve (W2).
• Calculation of Aggregate Crushing Value
– The ratio of weight of fines formed to the weight of total
sample in each test shall be expressed as a percentage, the
result being recorded to the first decimal place.
• Aggregate crushing value = (W2 x 100) / (W1-W)
– W2 =Weight of fraction passing through the appropriate
sieve
– W1-W =Weight of surface dry sample.
• The aggregate crushing value shall not exceed 30%

59. TEN PERCENT FINES TEST
• The ten percent fines value gives a measure of
the resistance of an aggregate to crushing,
that is applicable to all aggregates.
• The sample for test consists of surface dry
aggregates passing through a 12.5 mm sieve
and retained on 10 mm sieve.
• Test sample is dried in oven for a period of
four hours at a temperature of 100 to 1100C.

60. PROCEDURE
• The cylindrical measure is filled by the test sample of
aggregate in three layers of approximately equal
depth, each layer being tamped 25 times.
• The test sample in the cylinder with the plunger in
position is placed in the compression testing
machine. The load is applied at a uniform rate so as
to cause a total penetration of the plunger of about
20mm for normal crushed aggregates in 10 minutes.
• For rounded or partially rounded aggregates, the
load required to cause a total penetration of 15mm is
applied where as for honeycombed aggregates a
penetration of 24mm is applied in 10 minutes.

61. • After the maximum specified load is reached, the
load is released and the aggregate from the
cylinder is sieved from 2.36mm IS sieve.
• The fines passing 2.36mm.IS sieve is weighed and
expressed as a percentage of by weight of the test
sample.
• Normally this % will fall within the range 7.5 to
12.5.
• Load required for 10% fines = 14x / (y + 4)
– x = load in tones
– y = mean percentage fines from two tests at x tone
load.

62. AGGREGATE ABRASION VALUE
• The abrasion value of coarse aggregate may be
determined by either Deval machine or Los
Angeles machine.
• 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.
• The percentage wear of the aggregates due to
rubbing with steel balls is determined and is
known as Los Angeles Abrasion Value.
• ABRASIVE CHARGE:- cast iron spheres or steel
balls approximately 48 mm in diameter and
weighing between 390 to 445 gm.

64. 64

65. PROCEDURE
• The test sample consists of clean aggregates dried
in oven at 105° – 110°C. The sample should
conform to any of the gradings shown in table 1.
• Select the grading to be used in the test such that
it conforms to the grading to be used in
construction, to the maximum extent possible.
• Take 5 kg of sample for gradings A, B, C & D and
10 kg for gradings E, F & G.
• Choose the abrasive charge as per Table 2
depending on grading of aggregates.
• Place the aggregates and abrasive charge on the
cylinder and fix the cover.

66. • Rotate the machine at a speed of 30 to 33
revolutions per minute. The number of
revolutions is 500 for gradings A, B, C & D and
1000 for gradings E, F & G. The machine should be
balanced and driven such that there is uniform
peripheral speed.
• The machine is stopped after the desired number
of revolutions and material is discharged to a tray.
• The entire stone dust is sieved on 1.70 mm IS
sieve.
• The material coarser than 1.7mm size is washed,
dried in oven at 105 – 110 degree C & weighed
correct to one gram.

67. Sieve
size
(square
hole)
Weight
of test
sample
in gm
Passing
(mm)
Retaine
d on
(mm)
A B C D E F G
80 63 2500*
63 50 2500*
50 40 5000* 5000*
40 25 1250 5000* 5000*
25 20 1250 5000*
20 12.5 1250 2500
12.5 10 1250 2500
10 6.3 2500
6.3 4.75 2500

68. Grading No of Steel balls
Weight of charge
in gm.
A 12 5000 ± 25
B 11 4584 ±25
C 8 3330 ± 20
D 6 2500 ± 15
E 12 5000 ± 25
F 12 5000 ± 25
G 12 5000 ± 25

69. • Original weight of aggregate sample = W1 g
• Weight of aggregate sample retained = W2 g
• Weight passing 1.7mm IS sieve = W1 – W2 g
• Abrasion Value = (W1 – W2 ) / W1 X 100
• Maximum abrasion value ranges between 30
% to 60 % for various pavement types.