Aggregate for concrete mixing work at the site

Aggregate

1. ECM426
ENGINEERING MATERIALS
CONCRETE
“AGGREGATES”
By
Dr Mohd Fadzil Arshad
Faculty of Civil Engineering
Universiti Teknologi Mara
Malaysia

2. LEARNING OUTCOMES
At the end of the lecture student will be
able to;
Describe and explain the basic
science and engineering
fundamentals pertaining to
characteristic of the constituents of
concrete (CO1-PO1)
Classified aggregate for making
concrete (CO1-PO1)
state the properties of aggregate
use for making concrete (CO1-PO1)

3. INTRODUCTION
TO
AGGREGATES

4. INTRODUCTION
"aggregate", is a broad category of coarse
particulate material used in construction,
including sand, gravel, crushed stone, slag,
recycled concrete and geosynthetic
aggregates.
Aggregates are a component of
composite materials such as concrete and
asphalt concrete;
the aggregate serves as reinforcement to
add strength to the overall composite
material.

5. AGGREGATES IN CONSTRUCTION
Due to the relatively high hydraulic conductivity value
as compared to most soils, aggregates are widely
used in drainage applications such as foundation and
French drains, septic drain fields, retaining wall
drains, and road side edge drains.
Aggregates are also used as base material under
foundations, roads, and railroads. To put it another
way, aggregates are used as a stable foundation or
road/rail base with predictable, uniform properties
(e.g. to help prevent differential settling under the
road or building), or as a low-cost extender that binds
with more expensive cement or asphalt to form
concrete.

6. AGGREGATES IN CONCRETE
Aggregates (fine + coarse/gravel) used in
concrete (concrete aggregates) as filler
and generally occupies 60 % to 75 % of
the concrete volume
 Fine aggregates originates of natural
sand or crushed stone with most particles
>75m (0.03in)(0.075mm) and <
4.75mm.
 Coarse aggregates consist of gravels or
crushed aggregate or combination of both
with particles sizes > 4.75mm (3/16in)
and 50mm (2 in).

7. Reduce cost of concrete
Well graded improve workability
Reduce heat of hydration
Reduce shrinkage.
Control surface hardness
Colour light reflecting properties
Control density
Control of fire
AGGREGATES IN CONCRETE

8. SOURCES FOR THESE BASIC MATERIALS
Sources for these basic materials can be
grouped into three main areas:
a)Mining of mineral aggregate deposits,
including sand, gravel, and stone;
b)Use of waste slag from the manufacture of
iron and steel;
c)Recycling of concrete, which is itself chiefly
manufactured from mineral aggregates.
In addition, there are some (minor) materials
that are used as specialty lightweight
aggregates: clay, pumice, perlite, and
vermiculite.

9. SOURCES OF AGGREGATES
Natural gravel and sand are usually dug or dredged
from a pit, river, lake, or seabed
Aggregates derived from
Igneous rocks-formed on cooling of the magma-e.g
granite, basalt- they are hard, tough and strong-
excellent aggregates
Sedimentary rocks - Stratified rock - e.g limestone,
sandstone-excellent to poor aggregates
Metamorphic rocks- Igneous or sedimentary rock
that have changed their original structure, crystal
structure or mineralogy composition due to physical
and chemical conditions below the earth surface
(high temp and pressure) – e.g marble, schist, slate
– excellent to poor
Crushed aggregate is produced by crushing quarry
rock, boulders, cobbles, or large size gravel

10. JAW & CONE CRUSHING
PLANT

11. JAW & IMPACT CRUSHING
PLANT

12. GENERAL
CLASSIFICATION
OF
AGGREGATES

13. CLASSIFICATION OF
AGGREGATES
Classifications of concrete aggregates are
based on the mixture of rocks and minerals.
Igneous rocks-formed on cooling of the magma-e.g
granite, basalt- they are hard, tough and strong-
excellent aggregates
Sedimentary rocks - Stratified rock - e.g limestone,
sandstone-excellent to poor aggregates
Metamorphic rocks- Igneous or sedimentary rock
that have changed their original structure, crystal
structure or mineralogy composition due to
physical and chemical conditions below the earth
surface (high temp and pressure) – e.g marble,
schist, slate – excellent to poor

14. Classifications of concrete aggregates are based
on the density.
Generally aggregates classified into three:
a)Normal Aggregates
b)Heavyweight Aggregates
c)Lightweight Aggregates
Classifications of concrete aggregates are based
on the particle size
a)Gravels
b)Coarse aggregates
c)Fine aggregates
d)Quarry dust
CLASSIFICATION OF
AGGREGATES

15. Classifications of concrete
aggregates are based on the
particle size
a)Gravels
b)Coarse aggregates
c)Fine aggregates
d)Quarry dust
The aggregates can be crush or
un-crush
CLASSIFICATION OF
AGGREGATES

16. Coarse aggregate

are materials retained on 5 mm are materials retained on 5 mm
BS410 test sieve.BS410 test sieve.

can be classified into three can be classified into three
categories :categories :
- uncrushed- uncrushed
- crushed- crushed

17. CLASSIFICATION OF AGGREGATES

18. Fine Aggregate
Is a material which passed through a
5 mm BS 410 test sieve.
Sand is generally considered to have a
lower size limit of about 0.07 mm,
material between 0.06 mm and
0.002 mm is classified as silt, and
smaller particles are called clay.

19. FINE AGGREGATE
River sand
coral sand
mining sand
Quarry dust

20. DENSITY OF
AGGREGATES

21. RELATIVE DENSITY

it is defined as the ratio of the it is defined as the ratio of the
aggregate’s unit weight to that of aggregate’s unit weight to that of
water mix design.water mix design.

it is important factor affecting the it is important factor affecting the
density of the resulting concrete.density of the resulting concrete.

22. DENSITY OF AGGREGATES
Appearance relative density =
mass of dry aggregates/solid volume of
aggregate
Saturated surface dry relative density =
(mass of aggregate + water in pores)/
volume of aggregates including pores
Oven dry relative density =
mass of dry aggregates/ volume of
aggregate including pores

23. NORMAL AGGREGATES
Gravels, sand, normal
crushed stones.
Bulk S.G = 2.2-2.4,
Bulk density = 2200 to 2400
kg/m
3
,
Most commonly used

24. Heavy/High Density
Aggregate

having high specific gravity ranges having high specific gravity ranges
from 2.8 to 2.9 and bulk density from from 2.8 to 2.9 and bulk density from
2,800 to 2,900 kg/m2,800 to 2,900 kg/m
33
..

i.e magnetite, hematite and barytes.i.e magnetite, hematite and barytes.

are not suitably graded.are not suitably graded.

25. HEAVYWEIGHT AGGREGATES
crushed stones e.g. limestone, dolomite and
granite. Bulk Density >2080kg/m
3
Specific gravity range 2.8 – 2.9
Unit weight range 2800 – 2900
kg/m^3
Use in concrete of compressive
strength about 20 –21 N/mm^2.
Cement aggregate ratio 1.5 – 1.9
W/C between 0.5 – 0.65

26. Lightweight aggregate
 a particle density of less than 2,000 kg/m
3
.
 subdivided into two groups :
- natural
i.e (pumice, foamed lava, porous
limestone)
- artificial
i.e (fly ash, steel slag, sintered slate)

27. LIGHTWEIGHT AGGREGATES
Natural or manufactured e.g
pumice, scoria, pearlite, Bulk
Density < 1120kg/m
3
Density < 2000 kg/m^3
or dry loose density <
1200 kg /m ^3.
Can be subdivided :
Natural occurring
materials
Eg pumice, foamed lava ,
volcanic tuff
Natural occurring
materials which require
processing
Eg expanded clay, shale,
slate, perlite, vermiculite
Industrial by product
Eg. Sintered fuel ash,
sintered slate, expanded
blast furnace slag

28. CHARACTERISTI
CS OF
AGGREGATES

29. CHARACTERISTICS OF AGGREGATES
FOR CONCRETE
Generally aggregate used
in concrete must be :
a)Clean
b)Hard and strong
c)Properly shaped
d)Well graded.

30. The required
characteristic of
aggregates includes:
a)Chemical stability
b)Abrasion resistant
c)Resistant to freezing and
thawing
CHARACTERISTICS OF AGGREGATES
FOR CONCRETE

31. PHYSICAL PROPERTIES OF AGGREGATE

StrengthStrength

Deformation/modulus of elasticityDeformation/modulus of elasticity

ToughnessToughness

HardnessHardness

Volume changeVolume change

PorosityPorosity

Relative densityRelative density

32. Commonly the strength of aggregate
is in the range of 70 to 360 N/mm
2
.
Igneous rock are much stronger than
sedimentary and metamorphic rocks.
Strength of Aggregate

33. Strength of Aggregate
The strength can be determined by :
 Aggregate crushing value (ACV)
 Aggregate impact value (AIV)
 Ten percent fines value

34. DEFORMATION/MODULUS OF
ELASTICITY

Can be determined by running the Can be determined by running the
compression test on specimen from compression test on specimen from
the parent rock.the parent rock.

Modulus of elasticity of concrete Modulus of elasticity of concrete
increases with the increase of increases with the increase of
aggregate modulus.aggregate modulus.

35. Toughness of Aggregate
Defined as resistance to failure by impact.
Determined by Aggregate Impact Test.
Important for concrete used in road
pavement.

36. Hardness

defined as resistance of an aggregate defined as resistance of an aggregate
to wear, load or applied pressure.to wear, load or applied pressure.

determined by an abrasion test.determined by an abrasion test.

important for concrete used in road important for concrete used in road
pavementpavement

37. Volume Change

change in the volume of the aggregate.change in the volume of the aggregate.

it is due to moisture movements in it is due to moisture movements in
aggregates.aggregates.

may result in a considerable shrinkage may result in a considerable shrinkage
of the concrete.of the concrete.

38. Porosity of aggregate

porosity of aggregate contributes to porosity of aggregate contributes to
the overall porosity of concrete.the overall porosity of concrete.

Porosity = 100 WGs / (W+100) %Porosity = 100 WGs / (W+100) %
where :where :
W is the water absorption (%)W is the water absorption (%)
Gs is the specific gravity on SSDGs is the specific gravity on SSD

39. Shape and Surface
Texture

Shape and surface texture of aggregates
can affect the properties of concrete.
The external characteristics can be
assessed by observation.

40. Particle Shape Classification
(BS 812 : Part 1 : 1975)
ClassificationClassification DescriptionDescription ShapesShapes
RoundedRounded Fully water-worn or Fully water-worn or
completely shaped completely shaped
by attritionby attrition
River or seashore River or seashore
gravel, desert, gravel, desert,
seashore and wind-seashore and wind-
blown sand.blown sand.
IrregularIrregular Naturally irregular or Naturally irregular or
partly shaped by partly shaped by
attrition and having attrition and having
rounded edgesrounded edges
Other gravels, land Other gravels, land
or dug flintor dug flint
FlakyFlaky Material which the Material which the
thickness is small thickness is small
relative to the other relative to the other
two dimensionstwo dimensions
Laminated rockLaminated rock

41. Particle Shape Classification (cont’d)
(BS 812 : Part 1 : 1975)
ClassificationClassification DescriptionDescription ShapeShape
AngularAngular Possessing well-defined Possessing well-defined
edges formed at the edges formed at the
intersection of roughly intersection of roughly
planar facesplanar faces
Crushed rocks of all Crushed rocks of all
types, talus, crushed types, talus, crushed
slag.slag.
ElongatedElongated Material usually angular, Material usually angular,
in which the length is in which the length is
considerably larger than considerably larger than
the other two dimensionsthe other two dimensions
--
Flaky and Flaky and
elongatedelongated
Material having the Material having the
length considerably length considerably
larger than the width, larger than the width,
considerably larger than considerably larger than
the thicknessthe thickness
--
Source : Neville, A.M. (2002). Properties of Concrete, Prentice Hall,
England

42. Surface Texture of
Aggregates
ClassificationClassification DescriptionDescription ExamplesExamples
GlassyGlassy Conchoidal FractureConchoidal FractureBlack Flint, Vitreous Black Flint, Vitreous
SlagSlag
SmoothSmooth Water-worn, or Water-worn, or
smooth due to the smooth due to the
fracture of laminated fracture of laminated
or fine-grained rockor fine-grained rock
Gravels, chert, Gravels, chert,
slate, marble, some slate, marble, some
rhyolitesrhyolites
GranularGranular Fracture showing Fracture showing
more or less uniform more or less uniform
rounded grainsrounded grains
Sandstones, ooliteSandstones, oolite
Source : Neville, A.M. (2002). Properties of Concrete, Prentice Hall,
England

43. Water Absorption of Aggregate
(BS 812, ASTM C 127, EN 1097-6)
Water absorption of aggregate
as the weight of water absorbed
by an oven dry aggregate in
reaching the saturated and
surface dry condition.
is expressed as percentage of
the weight of the dry aggregate.

44. Water Absorption of
Aggregate (cont’d)
it is determined by measuring the increase in
weight of an oven dry sample immersed in
water for 24 hours and weighed at a saturated
and surface dry condition.

45. Moisture content

is expressed as a percentage of the is expressed as a percentage of the
weight increased of the saturated weight increased of the saturated
surface dry aggregate.surface dry aggregate.

water absorption represent the water water absorption represent the water
contained in the aggregate in the SSD contained in the aggregate in the SSD
condition.condition.

46. Moisture content

moisture content is the water in moisture content is the water in
excess of that, the total water content excess of that, the total water content
of a moist aggregate is equal to the of a moist aggregate is equal to the
sum of absorption and moisture sum of absorption and moisture
content.content.

47. Oven dry or bone dry
Four (4) conditions of moisture content
Air dryWet and damp
Moisture
Aggregate
Saturated and surface
dry

48. GRADING OF
AGGREGATES

49. GRADING OF AGGREGATE
can have considerable effect on the
workability and stability of concrete
mix.
The particle size distribution of
aggregate should be such that the
smaller particles fill the voids
between the larger particles.

50. PARTICLE SIZE DISTRIBUTION
Dense and
strong
Unpacked and
loose
Uneconomic

51. GRADING CURVE
(DERIVED FROM BS 882)

54. WHAT HAPPEN IF THE GRADING CURVE
…
Lower than the specified grading
curve, the aggregate is coarser and
segregation of mix might take place.
Lies well above the specified curve,
the aggregate is finer and more water
will be required, thus increasing the
cement content.

55. WHAT HAPPEN IF THE GRADING CURVE
…. (CONT’D)
is steeper than the specified, it
indicates an excess of middle-size
particles and leads to harsh mix.
is flatter than the specified grading
curve, the aggregate will be deficient
in middle size particles.

56. DURABILITY
AND
DELETERIOUS
SUBSTANCES
IN
AGGREGATES

57. DELETERIOUS SUBSTANCES IN
AGGREGATES
Deleterious substance is refer to the
clay, silt, decayed vegetable, salt,
unsound particles, etc. contained with
the aggregates supplied.
This deleterious substance when used
in concrete will influence the
properties, quality and durability
(during fresh and harden state)of
concrete produced.

58. Clay content will decrease the bond between
aggregate and cement
Slit will requires additional water for given
workability
Organic impurities may acidic that reduces
the alkalinity of cement paste and influence
the hydration of cement, affect setting time
and strength.
Soluble salt in marine aggregate cause
corrosion
Unsound aggregates contain reactive
aggregate cause alkali silica reaction
DELETERIOUS SUBSTANCES IN
AGGREGATES

59. RECYCLE CONCRETE
AGGREGATE

60. RECYCLE CONCRETE
AGGREGATE