No

1. In the name of Allah, the most beneficent and most merciful

2. CE-106 Civil Engineering Materials and Concrete
Technology
Aggregates
• Aggregates occupy at least three-quarters of the volume
of concrete. Aggregate is cheaper than cement and it is,
therefore, economical to put into the mix as much of
aggregates and as little of cement as possible.
• Economy is not the only reason for using aggregates,
aggregates give a higher volume stability and better
durability to concrete.
• Cement paste alone has no such higher volume stability,
strength and durability.
CE 106 Civil Engg. Materials and Concrete Technology By. D2r. Khan Shahzada

3. 3
Aggregates Cont…
Classification of aggregates according to size:
• The size of aggregates used in concrete ranges from tens
of millimeters to particles less than one-tenth of a
millimeter in cross section.
• The maximum size of aggregate depends on the size of
section and congestion of reinforcement used in
concrete.
• The aggregates can be classified according to size by
ASTM as,
• Coarse Aggregates: which retain on sieve#4
• Fine Aggregates: which passes through sieve#4
CE 106 Civil Engg. Materials and Concrete Technology By. Dr. Khan Shahzada

4. 4
Aggregates Cont…
Classification of Aggregates according to shape:
 British Standard classification of aggregates according to
shape is as,
• Rounded:
fully water-worn or completely shaped by abrasion
(physical wear). e.g river or sea shore gravel, desert and
wind blown sand.
• Irregular:
Naturally irregular or partly shaped by abrasion and having
rounded edges. e.g hard grey siliceous stone)
CE 106 Civil Engg. Materials and Concrete Technology By. Dr. Khan Shahzada

5. 5
Aggregates Cont…
• Flaky:
Materials of which the thickness is small relative to the
other two dimensions. e.g laminated rock.
• Angular:
Possessing well defined edges formed at the intersection of
roughly planar faces. e.g crushed rocks of all types
• Elongation:
Materials usually angular in which the length is
considerably larger than the other two dimensions.
CE 106 Civil Engg. Materials and Concrete Technology By. Dr. Khan Shahzada

6. 6
Aggregates Cont…
• Flaky and Elongated:
Materials having the length considerably larger than the
width and the width considerably larger than the thickness.
Flakiness Index:
The mass of flaky particles expressed as a %age of the
mass of the sample is called flakiness index.
Elongation Index:
The mass of elongated particles expressed as a %age of the
mass of the sample is called elongation index.
CE 106 Civil Engg. Materials and Concrete Technology By. Dr. Khan Shahzada

7. 7
Aggregates Cont…
Classification of Aggregates according to weight:
• The aggregates having the bulk density from 1520-1680
Kg/m3 are called normal weight aggregates.
• Normal weight aggregates are further classified as natural
aggregates and artificial aggregates.
•The natural aggregates are; Sand, gravel, crush rock such
as granite, quartzite, and sand stone etc.
•The artificial aggregates are; broken bricks, air-cool slag,
fly ash, bloated clay etc.
CE 106 Civil Engg. Materials and Concrete Technology By. Dr. Khan Shahzada

8. 8
Aggregates Cont…
Assignment#4
1. Gradation of aggregate
2. Sieve Analysis
CE 106 Civil Engg. Materials and Concrete Technology By. Dr. Khan Shahzada

9. 9
Aggregates Cont…
Light weight aggregates:
• The aggregates having the bulk density less than 1100
kg/m3, are called light weight aggregates. light weight
aggregates can be;
• Processed natural materials (e.g expanded clay or
expanded shale)
• processed by-products (e.g foamed slag)
• unprocessed materials (e.g pumice)
• light weight concrete results in significant benefits in
terms of load bearing elements of smaller x-section and
also give better thermal insulation than ordinary concrete.
CE 106 Civil Engg. Materials and Concrete Technology By. Dr. Khan Shahzada

10. 10
Aggregates Cont…
Heavy weight aggregates:
• The aggregates having the bulk density more than 2080
kg/m3, are called heavy weight aggregates. Heavy weight
aggregates include Iron, Steel, Limonite etc.
• heavy weight aggregates produce heavy weight concrete
which is used in the construction of radiation shields.
• radiation shields protect the operating personnel against
the biological hazards in the nuclear energy industry or x-ray,
gamma ray at therapy centers.
CE 106 Civil Engg. Materials and Concrete Technology By. Dr. Khan Shahzada

11. 11
Aggregates Cont…
Classification of Aggregates according to surface texture:
Aggregates can be classified on the basis of surface
texture into the following (British Standard
classification);
1. Glassy
2. Smooth
3. Granular
4. Rough
5. Crystalline
6. Honeycombed
The surface texture of the aggregates affects its bond to the
cement paste and also influence the water demand of the
mix, especially in the case of fine aggregates.
CE 106 Civil Engg. Materials and Concrete Technology By. Dr. Khan Shahzada

12. 12
Aggregates Cont…
Density of Aggregates:
 Bulk density: The mass of aggregates per unit total
volume of aggregates including voids, is called bulk
density.
 Absolute density: Mass per unit volume of the solid
particles only is called absolute density.
 Relative Density: relative density or specific gravity of
aggregates is the ratio of specific mass (absolute
density) of aggregates to the density of water.
 The density or specific mass of water at 40C is taken as
1000 kg/m3 or 62.4 lbs/ft3.
CE 106 Civil Engg. Materials and Concrete Technology By. Dr. Khan Shahzada

13. 13
Aggregates Cont…
Absorption of Aggregates:
The water absorption of aggregate is determined by
measuring the increase in mass of an oven-dried sample
when immersed in water for 24 hours. The ratio of the
increase in mass to the mass of the dry sample,
expressed as a percentage, is called absorption.
 Absorption (%) = ((Wet mass – Dry mass)/Dry mass )*100
 Moisture Content of Aggregates:
 Aggregates exposed to rain collect a considerable
amount of moisture on the surface of the particles. This
surface moisture is expressed as a percentage of the
mass of the saturated and surface dry aggregates and is
called moisture content.
CE 106 Civil Engg. Materials and Concrete Technology By. Dr. Khan Shahzada

14. 14
Aggregates Cont…
Bulking of Sand:
Bulking is the increase in the volume of a given mass of
sand caused by the films of water pushing the sand
particles apart.
Causes: Segregation and honey combing in concrete
Soundness of Aggregates:
The ability of aggregates to resist excessive changes in
volume as a result of changes in physical condition.
 Chemical reaction between the aggregates and the alkalis
in cement causes expansion of aggregates.
 Freezing and thawing and alternate wetting and drying
are the physical causes of permanent volume changes of
aggregates.
CE 106 Civil Engg. Materials and Concrete Technology By. Dr. Khan Shahzada

15. 15
Sardar Ahtsham Ibrar UET PeshaWar Civil
Dept