Aggreggates as a building material

1. Unit No. 02
Aggregates

2. Aggregates
• 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 Aggregates:
• Classification Based on size:
• Classification Based on source:
• Classification Based on unit weight:
• ClassificationBased on shape:
• Classification Based on surface texture:

5. A) Classification Based on size:
1) Coarse aggregate: Aggregate which retained on the No.4 (4.75mm) sieve.
The function of the coarse aggregate is to act as the main loadbearing
component of the concrete.
2)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.

6. 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 use for making light weight concrete.

8. C) Classification Based on unit weight:
Aggregates are classified as Light-weight, Heavy-weight and Normal-weight aggregate
depending on weight and specific gravity.
AGGREGATE 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

9. D) ClassificationBased 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

10. ANGULAR ROUND
FLAT ELONGATED

11. E) Classification Based on surface texture:
Surface texture is a measure of the smoothness and roughness of aggregate. The grouping of aggregate is
broad and is based on visual examination of the specimen. As per IS:383-
1970 the aggregates are classified into five groups, namely, Glassy, Smooth, Granular, Crystalline,
Honeycombed and Porous.
CLASSIFICATION EXAMPLES
Glassy Black flint
Smooth Gravel, Marble
Granular Sandstone
Rough Basalt
Crystalline Granite
Honeycombed & Porous Brick, slag

12. SMOOTH ROUGH

13. Good qualities of an ideal aggregate:
An ideal aggregate used for the manufacturing of concrete and mortar, should meet the following requirements.
(1) It should consist of natural stones, gravels and sand or in various combinations of these materials.
(2) It should be hard, strong and durable.
(3) It should be dense, clear and free from any coating.
(4) It should be free from injurious vegetable matters.
(5) It should not contain flaky and elongated pieces.
(6) It should not contain any material liable to attack steel reinforcement in case of reinforced concrete.

14. Fine Aggregate:
• Fine aggregate is the essential ingredient in concrete that consists of natural sand or crushed stone.
The quality and fine aggregate density strongly influence the hardened properties of the concrete.
• The concrete or mortar mixture can be made more durable, stronger and cheaper if you made the
selection of fine aggregate on basis of grading zone, particle shape and surface texture, abrasion
and skid resistance and absorption and surface moisture.
Role of Fine Aggregate in Concrete Mix
• Fine aggregates provide dimensional stability to the mixture
• The elastic modulus and abrasion resistance of the concrete can be influenced with fine aggregate
• Fine aggregates quality also influence the mixture proportions and hardening properties
• The properties of fine aggregates also have a significant impact on the shrinkage of the concrete.

15. Properties of Fine Aggregate :
• Size
• specific gravity,
• density
• water absorption
• bulking
1) Size:
•The largest size that falls under the limit of the exact set is 4.75 mm.
•Using the largest size will give more dense concrete, but a mixture of all sizes is more
desirable and more economical.
•If cement mortar is prepared for masonry work or plastering work, very fine types of
sand of similar size is used.

16. 2) Specific gravity:
• The specific gravity of aggregates is the ratio of the density of water to its density.
• It is used for concrete mix design and if not specified the specific gravity is taken as 2.7 because
the specific gravity of most aggregates obtained from different sources falls between 2.6 and 2.8.
3) Density:
• It refers to the amount of voids or spaces between particles, as well as the total density of
aggregates considered.
• The density of sand is between 17 and 25 kN/m3.
4) Water absorption :
• Typically, for sand, water absorption is negligible, it is desirable that water absorption should be
kept to a minimum.
5) Bulking:
• Bulging is a phenomenon that causes the aggregates to swell by absorbing moisture from the
humid air.
• The concrete mix design may be inaccurate and enough additional sand is always added to
compensate for this swelling when this bulk sand will return to normal state.

17. Test On Fine Aggregates:
• Fineness modulus and grading zone of sand by sieve analysis,
• Silt content in sand and their specification as per IS 383,
• Bulking in sand.

18. 1) Fineness modules of sand and grading of sand
•Grain size distribution for concrete mixes that will provide a dense strong mixture. Ensure that the voids
between the larger particles are filled with medium particles.
•The remaining voids are filled with still smaller particles until the smallest voids are filled with a small
amount of fines.

19. Procedure - Fineness Modulus of Sand
Sample preparation
Take a sample of fine aggregate in pan and placed it in dry oven at a temperature of 100 – 110oC. After
drying take the sample and note down its weight.
Test Procedure - Fineness Modulus of Sand
• Take the sieves and arrange them in descending order with the largest sieve on top.
• If mechanical shaker is using then put the ordered sieves in position and pour the sample in the top
sieve and then close it with sieve plate.
• Then switch on the machine and shaking of sieves should be done at least 5 minutes.
• If shaking is done by the hands then pour the sample in the top sieve and close it then hold the top two
sieves and shake it inwards and outwards, vertically and horizontally.
• After some time shake the 3rd and 4th sieves and finally last sieves.
• After sieving, record the sample weights retained on each sieve.
• Then find the cumulative weight retained.
• Finally determine the cumulative percentage retained on each sieves.
• Add the all cumulative percentage values and divide with 100 then we will get the value of fineness
modulus.

20. Calculation of Fineness Modulus of Sand
Let us say the dry weight of sample = 1000gm After sieve analysis the values appeared are tabulated
below.
Sieve size
Weight retained
(g)
Cumulative
weight
retained(g)
Cumulative
percentage
weight Retained
(%)
Cumulative
percentage
weight Passing
(%)
4.75mm 10 =0+10=10 1 =100-1=99
2.36mm 112 =10+112=122 12.2 =100-12.2=87.8
1.18mm 108 =122+108=230 =23 =100-23=77
0.6mm 220 =230+220=450 =45 =100-45=55
0.3mm 250 =450+250=700 =70 =100-70=30
0.15mm 300 =700+300=1000 =100 =0
Total 251.2

21. • Therefore, fineness modulus of aggregate = (cumulative % retained) / 100
= (251.2/100) = 2.51
• Fineness modulus of fine aggregate is 2.51. It means the average value of aggregate is in between
the 2nd sieve and 3rd sieve.
• It means the average aggregate size is in between 0.3mm to 0.6mm as shown in below figure.
Values of Fineness Modulus of Sand
Fineness modulus of fine aggregate varies from 2.0 to 3.5mm. Fine aggregate having fineness modulus
more than 3.2 should not considered as fine aggregate. Various values of fineness modulus for different
sands are detailed below.
Type of sand Fineness modulus range
Fine sand 2.2 – 2.6
Medium sand 2.6 – 2.9
Coarse sand 2.9 – 3.2

22. Fineness modulus limits for various zones of sand according to IS 383-1970 are tabulated below
Sieve size Zone-1 Zone-2 Zone-3 Zone-4
10mm 100 100 100 100
4.75mm 90-100 90-100 90-100 95-100
2.36mm 60-95 75-100 85-100 95-100
1.18mm 30-70 55-90 75-100 90-100
0.6mm 15-34 35-59 60-79 80-100
0.3mm 5-20 8-30 12-40 15-50
0.15mm 0-10 0-10 0-10 0-15
Fineness modulus 4.0-2.71 3.37-2.1 2.78-1.71 2.25-1.35

23. 2) Bulking of sand
•BULKING OF SAND:-
•Bulking in sand Occurs When dry sand interacts with the atmospheric moisture. Presence of moisture content forms a thin layer
around sand particles. This layer generates the force which makes particles to move aside to each other. This results in the increase of
the volume of sand.
•Excessive presence of moisture content in the sand makes concrete to less durable and lose its strength. Remember, excessive
presence of moisture content increase the workability of concrete but loses its strength.
•As per IS2386-3 Bulking in Sand, Presence of 4% of moisture content in sand increases 25% of its volume.
•The extent of sand bulking depends on the grading of sand. Finer Sand possesses more bulking than the medium and coarse sand.
Thus, Bulking in the sand is high for fine sand and low for coarse sand. An increase of bulking in sand effects concrete mix and
results in harsh behaviour while placing.
•Moisture content less than 5% should be preferred for construction purposes.
•In order to calculate the bulking of sand/ Percentage of moisture content in the sand, the moisture content of sand is further
increased by adding some more water. Due to this, the sand particles pack close to each other and the Bulking of sand is gradually
decreased. Therefore this helps in finding the actual volume of sand(dry sand). In simple words, the dry sand and fully saturated sand
have the exact volume.
% of Moisture content Percentage of Bulking with respect to volume
2% 15%
3% 20%
4% 25%
5% 30%

24. • The percentage of bulking can be determined by following this method:-
1. Take a simple container and add 2/3 part of sand in it.
2. Measure the exact height of sand using the scale and note it down. (H1)
3. Now fill the container up to 2/3 part with water. (Same height of Sand)
4. Now add the measured sand to the container and wait for some time to settle down.
5. Now calculate the height of Sand in water. (H2)
• Bulking of Sand Formula:-

25. • EXAMPLE:
For suppose the measured height of Sand is 200mm and height of sand with water = 160mm then
• From the above table, it is clear that the Sample has 4% of Moisture content in it. Due to this
25% of the volume is increased in the sand.

26. Bulking of Sand Significance
• In simplified terms, it can be said that bulking of sand is simply the looseness of soil without compacting.
Usually, water reduces the pores in sand and compacts the sand.
• Sand is used in concrete for reduction of segregation and fill out the pores between cement and coarse
aggregates. For example, we need 1 m3 of sand in concrete, we need to know the approximate sand bulkage
value. If the given sample has a bulkage of 25% then we need to take 25% more sand or 1.25 times of the
sand while volume batching to get 1 m3 of sand for concrete.
• If we don’t take this extra amount of sand considering the bulkage value, the total volume will be lessened to
75% after adding water. We know that the quality of concrete depends a lot on the proper proportioning of the
contents. Generally, we consider the wet volume of concrete is 1.5 times the volume of dry concrete, in this
case, we are typically using approximately 30% of sand bulkage and 20% of wastage. If we do not consider
the bulkage of sand, the total quantity will be lessened and will impact on the overall concrete quality.

27. 3) Silt Content in sand
Object: To find out the Silt content in sand
Apparatus
A measuring cylinder (250ml),Water,Sand
Procedure for the Test
•Firstly, a 50ml solution of 1% salt and water is prepared in the measuring cylinder. The addition of salt
increases the settlement time of silt.
•The sample of sand to be tested is then added to the cylinder until the level reaches 100ml.
•50ml of the solution of salt and water is again added to the measuring cylinder.
•Close the open end of the measuring cylinder and shake it well.
•After a period of 3-4 hours, you will notice a layer of silt settled over the sand.Now note down the volume V1
of the silt layer settled over the sand.
•Note down the volume V2 of the settled sand.
Repeat the procedure a couple more times to get the average.
Percentage of Silt Content = (V1/V2) x 100
V1 – Volume of silt layer
V2 – Volume of sand layer
The permissible value of silt content in Sand is 8%, hence the sand sample is ok and can be used for
construction purposes.

28. Properties of coarse aggregate
• Size
• Shape
• Surface Texture
• Specific Gravity
• Bulk Density
• Water Absorption
• Soundness
Coarse aggregate: Coarse aggregate is stone which are broken into small sizes and irregular in shape. In
construction work the aggregate are used such as limestone and granite or river aggregate.
Aggregate which has a size bigger than 4.75 mm or which retrained on 4.75 mm IS Sieve are known as Coarse
aggregate.

29. Size &Shape :
• size and shape of the aggregate particles greatly influence the quantity of cement required in concrete
mix and hence ultimately the economy of concrete. IS: 456 recommended the below choose the maximum
size of coarse aggregate to be used in PCC and RCC mix.
• The maximum size of coarse aggregate in concrete making should be less than,
• 1/4th of the minimum dimension of the RCC member. Ex: beam 300mm((1/4)*200)=50mm
• 1/5th of the minimum dimension of the RCC member.
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.
Specific Gravity:The ratio of the weight of oven-dried aggregate which is kept for 24 hours at a
temperature of 100 to 110°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 of 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. 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
• The shape of aggregate particles
Water 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.
Soundness:

31. Characteristics Requirements For Good Quality Coarse Aggregate
• Aggregate must be strong and hard enough to resist the crushing action.
• They should not have cover of organic materials, clay, and dust otherwise it will affect the bonding
strength of concrete and aggregate.
• The aggregates used for concrete must be durable.
• Coarse aggregates for concrete should be chemically inactive.
• They should not contain excessive amount of angular, sharp, and hard particles.
• The aggregate shape should be ideally spherical or cubical.
• It must be chemically inert material.
• They should be free from any hygroscopic slat.
• Aggregate should not have water absorption more than 5% of their actual weight.
• They should be soft and porous in nature.
• The ideal size of coarse aggregates should be such that it should pass the through IS 63 mm sieve and retains
on 4.75 mm IS sieve.
• Aggregate used for construction must be free from any disintegrated pieces, alkalis, vegetable matter, etc.

32. Test On Coarse Aggregates:
•Fineness modules of Coarse Aggregates and grading of aggregate
•Determine crushing value
•Determine impact value
•Determine abrasion value
•Flakiness index
•Elongation index

33. Fineness modules of Coarse Aggregates and grading of aggregate
• Fineness modulus of coarse aggregates represents the average size of the particles in the coarse aggregate by an index
number. It is calculated by performing sieve analysis with standard sieves. The cumulative percentage retained on each
sieve is added and subtracted by 100 gives the value of fine aggregate. Higher the aggregate size higher the Fineness
modulus hence fineness modulus of coarse aggregate is higher than fine aggregate. Coarse aggregate means the aggregate
which is retained on 4.75mm sieve when it is sieved through 4.75mm. To find fineness modulus of coarse aggregate we
need sieve sizes of 80mm, 40mm, 20mm, 10mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm and 0.15mm. Fineness
modulus is the number at which the average size of particle is known when we counted from lower-order sieve size to
higher-order sieve. So, in the calculation of coarse aggregate we need all sizes of sieves.
• Determination of Fineness Modulus of Coarse Aggregates
To find fineness modulus we need to perform sieve analysis and for that above mentioned sieve sizes, mechanical shaker and
digital weigh scale are required.
• Sample preparation
Take a sample of coarse aggregate in pan and placed it in dry oven at a temperature of 100 – 110oC. After drying take the
sample weight to nearest gram.
• Test Procedure for Fineness Modulus of Coarse Aggregates
Arrange the sieves in descending order and put the arrangement on mechanical shaker. It is suggested that, to know the exact
value of fineness modulus for coarse aggregate, mechanical shaker will give better value than hand shaking because of
more no. of sieves and heavy size particles. After proper sieving, record the sample weights retained on each sieve and find
out the cumulative weight of retained particles as well as cumulative % retained on each sieve. Finally add all cumulative
percentage values and divide the result with 100. Then we get the value of fineness modulus.
• Example for Fineness Modulus Calculation
Let us say dry weight of coarse aggregate = 5000g Values after sieve analysis are

35. Sieve size Weight retained(g)
Cumulative weight
retained (g)
Cumulative %
retained (g)
Cumulative %
passing (g)
80mm 0 =0 =0 =100-0=100
40mm 250 =0+250=250 =(250/5000)*100=5 100-5=95
20mm 1750 =250+1750=2000 =40 100-40=60
10mm 1600 =2000+1600=3600 =72 100-72=28
4.75mm 1400 =3600+1400=5000 =100 100-100=0
2.36mm 0 =5000+0=5000 =100 100-100=0
1.18mm 0 =5000+0=5000 =100 100-100=0
0.6mm 0 =5000+0=5000 =100 100-100=0
0.3mm 0 =5000+0=5000 =100 100-100=0
0.15mm 0 =5000+0=5000 =100 100-100=0
Sum =35850 =717

36. • Therefore, fineness modulus of coarse aggregates = sum (cumulative % retained) / 100
= (717/100) = 7.17
•
Maximum size of coarse aggregate Fineness modulus range
20mm 6.0 – 6.9
40mm 6.9 – 7.5
75mm 7.5 – 8.0
150mm 8.0 – 8.5
Limits of Fineness Modulus

38. 2.Determine 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.
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

40. 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 10minutes.
• 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%

42. Determine impact value
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.
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 50mm 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.

44. 1)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.
2)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.
3)Pour the aggregates to fill about just 1/3 rd depth of measuring cylinder.
4)Compact the material by giving 25 gentle blows with the rounded end of the tamping rod.
5)Add two more layers in similar manner, so that cylinder is full.Strike off the surplus aggregates.
6)Determine the net weight of the aggregates to the nearest gram(W1).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.
7)Fix the cup firmly in position on the base of machine and place whole of the testsample in it and compact by giving 25
gentle strokes with tamping rod.
8)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.
9)Give 15 such blows at an interval of not less than one second between successive falls 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.
10)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.
11)The mean of two observations, rounded to nearest whole number is reported as the Aggregate Impact Value.
12)Aggregate impact value = (W2/W1) x 100=(5/100)*100=5%
Where, W1 is total weight of dry sample=100gm
W2 is weight of portion passing through 2.36 mm sieve.-5gm
PROCEDURE:

45. 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

46. Determine 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.

48. 6
4

49. 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.
•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.

51. Sieve size
(square hole)
Weight of test
sample in gm
Passing (mm)
Retained 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
4.75 2.36 5000
Table 1: Grading of Test Samples – *Tolerance of ± 12 percent permitted.

52. Calculation:
• Original weight of aggregate sample = W1=10Kg,
• Weight of aggregate sample retained = W2 =7.2Kg
• Weight passing 1.7mm IS sieve = W1 – W2 g= 10-7.2= 2.8Kg
• Abrasion Value = (W1 – W2 ) / W1 X 100 =((2.8)/10)*100=28%
• Maximum abrasion value ranges between 30 % to 60 % for various pavement types.

53. Flakiness index
•The flakiness index of aggregate is the percentage by weight of particles in it whose least
dimension (thickness) is less than three-fifths of their mean dimension.
•The test is not applicable to sizes smaller than 6.3 mm
•Flakiness Index of aggregate is the percentage by weight of aggregate particles whose least
dimension is less than 0.6 of their mean dimensions. This test is applicable to aggregates having
size larger than 6.3mm.
•To calculate the flakiness index of the given sample of aggregates, the weight of each fraction of
aggregates passing and retaining on the specified set of sieves is noted first. The pieces of
aggregates are made to pass through the slot of specified thickness of gauge and then they are
weighed. Then the flakiness index is calculated as the total weight of material passed through
various thickness gauges, expressed as a percentage of total weight of the sample gauged.
•Flakiness Index = [W2/ W1] x 100
•Where, W2= Weight passed from 0.6 x dmean size
W1= Total weight of aggregates
•Flakiness Index of aggregates used in road construction should be less than 15% and normally
does not exceed 25%.

56. •Elongation index
•The elongation index on an aggregate is the percentage by weight of particles whose
greatest dimension (length) is greater than 1.8 times their mean dimension.
•The elongation index is not applicable to sizes smaller than 6.3 mm.
•The elongation index is the total weight of the material retained on the various length
gauges expressed as a percentage of the total weight of the sample gauged. The
presence of elongated particles in excess of 10 to 15 per cent is generally considered
undesirable, but no recognized limits are laid down.
•Elongation index : Weight of retained partical/ Weight of sample aggregate
(W1/W)*100=(260/1000)*100=26%

58. Bulk Density:
•The cylindrical measure is filled about 1/3 each time with thoroughly mixed aggregate
and tamped with 25 strokes by a bullet ended tamping rod, 16 mm diameter and 60 cm
long.
•The net weight of the aggregate in the measure is determined and the bulk density is
calculated in kg/litre.

59. • Take a sample of 2 kg of aggregates. Wash the sample thoroughly to remove finer particles and dust from it.
• After washing, place aggregates in the wire basket and immerse it in distilled water at a temperature between 22°C and
32°C with a cover of at least 5 cm of water above the top of the basket.
• Immediately, after immersion, remove the entrapped air from the sample by lifting the basket containing aggregates 25
mm above from the base of the tank and allow it to drop again. Continue this process at least 25 times at the rate of about
one drop per second. The basket and aggregates shall remain completely immersed during this process as well as for a
period of 24 ± ½ hours afterwards.
• Then the basket and the sample are jolted and weighed in the water at a temperature of 22 to 32°C. If it is necessary for
them to be transferred to a different tank for weighing, they are jolted 25 times as described above in the new tank before
weighing. Note down this weight of aggregates and basket in water as A1.
• After that, remove the basket and the aggregates from the water and allow to drain for a few minutes. After that, empty
the aggregates from the basket on the dry clothes and return the empty basket to the water, jolt it 25 times and weigh in
water. Note down the weight of basket suspended in water as A2.
• Gently dry those aggregates with the dry cloth. Transfer aggregates to the second dry cloth if the first one cannot remove
optimum moisture residue from them. After that spread out them in one layer for at least 10 minutes for surface to get dry
completely and avoid direct sunlight on them. Then take the weight of these dry aggregates, which are saturated and note
it as B.
• Next, place the aggregates in the oven on the shallow tray at a temperature of 100 to 110°C and maintain this temperature
for next 24 ± 1/2 hours. Then remove aggregates from the oven and cool in an airtight container. After that, measure the
weight of the aggregates and note down this weight of oven-dry aggregates as C.
Specific gravity of different sizes of aggregates.

60. • Indian Standard Specification IS : 2386 (Part III) of 1963 gives various procedures to find out the
specific gravity of different sizes of aggregates.
• Calculation
Calculations of specific gravity, apparent specific gravity, and water absorption of aggregates are as
follows:
• Specifc Gravity=C/( A – B)
• Apparent Specifc Gravity=C /(C – B)
• Water Absorption= 100(B - C ) / C

61. Quality of Water
• Generally, quality of water for construction works are same as drinking water. This is to ensure that
the water is reasonably free from such impurities as suspended solids, organic matter and dissolved
salts, which may adversely affect the properties of the concrete, especially the setting, hardening,
strength, durability, pit value, etc. The water shall be clean and shall not contain sugar, molasses or
gur or their derivatives, or sewage, oils, organic substances. If the quality of water to be used for
mixing is in doubt, cubes of 75 mm in cement mortar 1:3 mix with distilled water and with the
water in question shall be made separately. The latter type of cubes should attain 90% of the 7
days’ strength obtained in cubes with same quantity of distilled water. Alternatively, the water shall
be tested in an approved Laboratory for its use in preparing concrete / mortar. The water quality for
construction shall be tested or monitored regularly, as it affects the overall strength of concrete

62. Permissible Limits for Type of Solid in water for Construction
work
Name of Impurities Permissible Limits
1.Organic matter 200 mg/lit
2.Inorganic matter 3000 mg/lit
3.Sulfates ( as SO2 ) 400 mg/lit
4.Chlorides (as Cl)
a) For plain concrete
b) For R. C. C.
2000 mg/lit
500 mg/lit
5.Suspended matter 2000 mg/lit

63. Use of sea water for mixing concrete
• Sea Water should not be used for preparation of any concrete (PCC or RCC). It has a salinity of
about 3.5 per cent. In that about 78% is sodium chloride and 15% is chloride and sulphate of
magnesium. Sea water also contain small quantities of sodium and potassium salts. This can react
with reactive aggregates in the same manner as alkalies in cement. Therefore sea water should not
be used even for PCC if aggregates are known to be potentially alkali reactive.
• The strength of concrete reduces when sea water is used for mixing. It can also corrode the
reinforcement in certain cases which can lead to massive structure failure. However some research
workers says that sea water can be used in un-reinforced concrete or mass concrete. Sea water
slightly accelerates the early strength of concrete. But it reduces the 28 days strength of concrete by
about 10 to 15 per cent. This loss of strength could be made up by redesigning the mix or by
addition of proper admixtures. Water containing large quantities of chlorides in sea water may
cause efflorescence and persistent dampness. When the appearance of concrete is important sea
water may be avoided. The use of sea water is also not advisable for plastering purpose which is
subsequently going to be painted.

65. Thank You