Concrete Ingredient (Part 2)
Transcript of Concrete Ingredient (Part 2)
Concrete Ingredient (Part 2)
2101311 Civil Engineering Materials
Department of Civil Engineering
Faculty of Engineering
Chulalongkorn University
Aggregate
âĒ Aggregate was originally viewed as an inert
and inexpensive material
âĒ In fact, aggregate is not truly inert because
its physical, thermal and sometimes
chemical properties influence the
performance of concrete
3
Aggregate
âĒ The acceptance of an aggregate for use in
concrete on a particular job should be
based upon specific information obtained
from tests used to measure the aggregate
quality, or upon its service record, or both
4
Classification of aggregates
Classification of aggregates
âĒ Unit weight
âĒ Source and method of preparation
âĒ Shape and texture
âĒ Petrographic (āđāļāļāļāļēāļĄāļāļēāļĢāļĻāļāļĐāļēāļāļēāļāļāļĢāļāļ§āļāļĒāļēāđāļāļĒāļ§āļāļāļŦāļ)
6
Unit weight Classification
We can classified the aggregates into 3
groups
âĒ Light Weight Aggregate
Unit weight : 300 â 1,100 kg/m3
âĒ Normal Weight Aggregate
Unit weight : 2,400 â 3,000 kg/m3
âĒ Heavy Weight Aggregate
Unit weight : more than 4,000 kg/m3
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Source and method of preparation
Classification
âĒ Aggregates may be broadly classified as
natural or artificial
âĒ Screening and washing in the process
may be used to make an aggregate
suitable for concrete
8
Source and method of preparation
Classification
âĒ Natural Aggregates
â Natural sands and gravels are the
product of weathering and the action of wind
or water, while stone sands and crushed
stone are produced by crushing natural
stone
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Source and method of preparation
Classification
âĒ Artificial Aggregates
Products of processes developed to
manufacture aggregates with special
properties, such as expanded clay, shale
or slate that are used for lightweight
aggregates
âĒ Some lightweight aggregates such as
pumice or scoria also occur naturally.
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Shape and texture classification
Classification Description Examples
Rounded
(āļĄāļ)Fully water-worn or completely shaped by
attraction
River or seashore gravel;
desert, seashore and wind
blown sand
Irregular
(āļāļāļāđāļāļĒāļ§)Naturally irregular, or partly shaped by attrition and
having rounded edges
Other gravels; land or dug flint
Flaky
(āđāļāļ)Material of which the thickness is small relative to
the other two dimensions
Laminated rock
Angular
(āđāļŦāļĨāļĒāļĄ)Possessing well-defined edges formed at the
intersection of roughly planar faces
Crushed rocks of all types;
talus; crushed slag
Elongated
(āļĒāļēāļ§)Material, usually angular, in which the other two
dimensions
-
Flaky and
elongated
(āđāļāļāđāļĨāļ°āļĒāļēāļ§)
Material having the length considerably larger than
the width, and the width considerably larger than
the thickness
-
Particle shape classification of aggregates (āļĢāļāļĢāļēāļāļāļāļāļĄāļ§āļĨāļĢāļ§āļĄ)according to BS 8U: Part 1: 1975; with examples
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Shape and texture classification
13
āļĨāļāļĐāļāļ°āļāļ§āļāļāļāļĄāļ§āļĨāļĢāļ§āļĄ
(āđāļāļ§)(āđāļĢāļĒāļ)
(āđāļĄāļ)(āļŦāļĒāļēāļ)
(āļāļĨāļ)
(āļĢāļāļāļ)
Shape and texture classification
âĒ Effect of the shape and surface texture of
aggregate:
â More water is required when there is a greater
void content of the loosely-packed aggregate
â Flakiness and shape of the coarse aggregate
have an appreciable effect on the workability
of concrete
â The workability decreases with an increase in
the angularity number
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Bond
âĒ The bond between the surface of the
aggregate particles and cement matrix is a
decisive factor for the strength of concrete
âĒ Both the shape and surface texture of
aggregate influence considerably the bond
and therefore the strength of concrete
18
Bond
âĒ A rougher texture results in a greater
adhesion or bond between the particles and
the cement matrix
âĒ The larger surface area of a more angular
aggregate provides a greater bond but
reduce workability
19
Bond
âĒ Softer and porous particles, allowing
penetration by the paste, possess a better
bond than those textures which do not
permit the paste penetration
20
Strength
âĒ The compressive strength of concrete
cannot significantly exceed that of the
major part of the aggregate contained
therein, although it is not easy to
determine the crushing strength of
aggregate itself
21
Strength
âĒ The aggregate crushing value (ACV) test is
prescribed by BS 812: Part 110 - 1990 is a useful
guide when dealing with aggregates of unknown
performance
22
Standard Aggregate
Crushing Value
Apparatus
Toughness
âĒ Toughness can be defined as the resistance
of aggregate to failure by impact
âĒ To determine the toughness of aggregate
we use aggregate impact value (AIV) test
as described by BS 812 Part 112 â 1990
âĒ The impact is provided by a standard
hammer falling 15 times upon the aggregate
in a cylindrical container
23
Hardness
âĒ Hardness, or resistance to wear, is an
important property of concrete used in
road and in floor surface subjected to
heavy load
âĒ The aggregate abrasion value of the bulk
aggregate is assessed using BS 812 Part
113, while the Los Angeles test is
prescribed by ASTM C131
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Physical Properties
âĒ Specific gravity
âĒ Unit weight
âĒ Porosity, absorption and moisture content
âĒ Bulking of sand
âĒ Unsoundness due to volume changes
âĒ Thermal properties
âĒ Deleterious substances
âĒ Sieve analysis, grading curve and fineness
modulus26
Specific gravity
Specific gravity of aggregate:
âĒ Bulk specific gravity
âĒ Absolute specific gravity
âĒ Apparent specific gravity
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Density of materialSpecific gravity
Density of water
Specific gravity
âĒ The bulk specific gravity (bulk particle
density) refers to the volume of the solid
material including all pores
âĒ The absolute specific gravity or the
absolute particle density refers to the
volume of the solid material excluding all
pores
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Specific gravity
âĒ The apparent specific gravity (the apparent
particle density) refers to the volume of
solid material including the impermeable
pores, but not the capillary pores
âĒ The test methods for specific gravity are
prescribed by BS 812 Part 107 and ASTM
C 127 for coarse particles and C 128 for
fine particles
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Unit weight
âĒ āļŦāļāļ§āļĒāļ āļģāļŦāļāļāļāļāļāļĄāļ§āļĨāļĢāļ§āļĄāļāļ āļ āļģāļŦāļāļāļāļāļāļĄāļ§āļĨāļĢāļ§āļĄāļāļāļĢāļĢāļāđāļāļĄāļ āļģāļāļāļ°āļŦāļāļāļŦāļāļ§āļĒāļāļĢāļĄāļģāļāļĢ
âĒ āđāļāļŠāļģāļŦāļĢāļāđāļāļĨāļĒāļāļ āļģāļŦāļāļāļāļāļāļĄāļ§āļĨāļĢāļ§āļĄāđāļāļāļāļĢāļĄāļģāļāļĢāđāļāļāļģāļĢāļāļģāļāļ§āļāļŠāļāļŠāļ§āļāļāļŠāļĄāļāļāļāļāļĢāļ
âĒ āļāļāļŠāļāļāļāļģāļĄ ASTM C29
âĒ āļŦāļāļ§āļĒāļ āļģāļŦāļāļāļāļāļāļĄāļ§āļĨāļĢāļ§āļĄāļāļāļāļĄāļāļģāļĢāļ°āļāļ§āļģāļ 1,450 â 1,750 āļāļ/āļĄ3
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Unit weight
âĒ Unit weight āļ āļāļāļāļāļģāļĢāļāļĢāļ°āļāļģāļĒāļāļāļģāļ āļĢāļāļĢāļģāļāļāļāļāļĄāļ§āļĨāļĢāļ§āļĄ āđāļĨāļ°āļŠāļ āļģāļāļāļģāļĢāļāļāđāļāļ
âĒ āļāļģāļĢāļāļĢāļĢāļāļāđāļāļāļāļģāļāļāļāđāļŦāļŦāļāļ§āļĒāļ āļģāļŦāļāļāļāļģāļāļāļ āđāļāļ āļŠāļ āļģāļāļŦāļĨāļ§āļĄ āļŦāļĢāļ āļāļĢāļ°āļāļāđāļāļ
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Porosity, absorption and
moisture content
âĒ āļŠāļ āļģāļāļāļ§āļģāļĄāļ āļāļāļāļāļĄāļ§āļĨāļĢāļ§āļĄāđāļāļāđāļāđāļāļ 4 āđāļāļ
â Oven dry (āđāļŦāļāļāļ§āļĒāđāļāļēāļāļ)
â Air dry (āđāļŦāļāđāļāļāļēāļāļēāļĻ)
â Saturated surface dry; SSD(āļāļĄāļāļ§āļāļ§āđāļŦāļ)
â Moist (āļāļ§āđāļāļĒāļ)
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Bulking of sand (āļāļēāļĢāļāļāļāļāļ§āļāļāļāļāļĢāļēāļĒ)
âĒ In case of sand, there is effect of the
present of moisture so called bulking,
which is increase in the volume of a
certain mass of sand caused by films of
water pushing the sand particles apart
âĒ The bulking does not affect the
proportioning of materials by mass
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Bulking of sand
Dry Moisture content
3 â 5 %
Saturated
34
āļāļĢāļāļāļĢāļēāļĒāļāļ āđāļĢāļāļāļāļāļ§āļāļāļāļ āļēāļāļāļ§āļāļĢāļēāļĒāļ āļēāđāļŦāđāļĄāļāļāļĢāļēāļĒāļāļĒāļŦāļēāļāļāļēāļāļāļ āļāļĢāļĄāļēāļāļĢāļāļāđāļāļĄāļāļ
āļāļĢāļēāļĒāđāļŦāļ āļāļĢāļēāļĒāđāļāļĒāļāļĄāļēāļ
Unsoundness due to volume changes
âĒ The physical causes of large or permanent
volume change of aggregate are freezing and thawing (āļāļēāļĢāđāļāļāļāļ§āđāļĨāļ°āļāļēāļĢāļĨāļ°āļĨāļēāļĒāļāļāļāļ āļē), thermal
changes at temperature above freezing,
and alternating wetting and drying
35
Unsoundness due to volume changes
âĒ If the aggregate is unsound, such change
in physical condition result in deterioration
of concrete and even extensive surface
cracking
âĒ The testing of unsoundness is prescribed
by ASTM C88 in which aggregate is
subjected alternately to immersion in
sulphate solution and to drying
36
Thermal properties
âĒ There are 3 thermal properties that may be
significant in the performance of concrete
â Coefficient of thermal expansion
â Specific heat
â Conductivity
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Thermal properties
âĒ Coefficient of thermal expansion (āļāļēāļĢāļāļĒāļēāļĒāļāļ§āđāļĄāļāđāļāļāļāļ§āļēāļĄāļĢāļāļ)
âĒ The coefficient of thermal expansion of
aggregate determines the corresponding
value of concrete especially when we
consider the fire safety
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Thermal properties
âĒ Specific heat
â āļāļ§āļēāļĄāļĢāļāļāļ āļēāđāļāļēāļ°
â āļāļ§āļēāļĄāļŠāļēāļĄāļēāļĢāļāļāļāļāļ§āļŠāļāđāļāļĒāļ§āļāļāļāļēāļĢāļāļāļāļ§āļēāļĄāļĢāļāļ
âĒ Conductivity
â āļāļ§āļēāļĄāļŠāļēāļĄāļēāļĢāļāđāļāļāļēāļĢāļ āļēāļāļ§āļēāļĄāļĢāļāļ
âĒ The last two are of interest in mass
concrete, but usually not in ordinary
structural works. 40
Deleterious substances
âĒ There are 3 broad categories of
deleterious substances that may be found
in aggregate for concrete
âĒ Impurities which interfere the processes of
cement hydration such as organic impurities (āđāļāļ āđāļĻāļĐāđāļāđāļĄ āļāļāļāđāļāļēāđāļĨāļ°āļŠāļĨāļēāļĒāļāļ§)
41
Deleterious substances
âĒ Coating preventing the development of
good bond between aggregate and
cement paste such as clay, silt and other fine materials (āđāļāļ āļ āļ āļāļāļāđāļāļēāļ°āļāļ§āļĄāļ§āļĨāļĢāļ§āļĄ)
âĒ The certain particles which are weak or unsound (āđāļāļ āļĢāļ°āđāļāļāļŦāļāļāļēāļāļ āđāļāļē āļāļēāļāļāļĢāļāđāļāļŦāļāļ āļŦāļāļāļĢāļāļāļāļĄāļēāļāļ§āļĒ)
42
Deleterious substances
âĒ The test method for organic impurities for
fine aggregate is prescribed by ASTM C
40
âĒ The test methods for clay, silt and fine
dust contents for fine aggregate are
prescribed by BS 812 Part 103 and ASTM
C 33
43
Sieve analysis, grading curve
and fineness modulus
âĒ Sieve analysis (āļāļēāļĢāļ§āđāļāļĢāļēāļ°āļŦāļāļāļēāļāļāļĨāļ°) â āļĄāļ§āļĨāļĢāļ§āļĄāļŦāļĒāļēāļ: āļāļāļēāļāđāļŦāļāļāļ§āļē sieve No. 4 (4.75 mm)
â āļĄāļ§āļĨāļĢāļ§āļĄāļĨāļ°āđāļāļĒāļ: āļāļāļēāļāđāļĨāļāļāļ§āļē sieve No. 4 (4.75 mm)
âĒ Fineness modulus (āđāļĄāļāļĨāļŠāļāļ§āļēāļĄāļĨāļ°āđāļāļĒāļ) â āđāļāļāļāļ§āđāļĨāļāļāļāļāļāļāļāļāļāļēāļāđāļāļĒāļāļĢāļ°āļĄāļēāļāļāļāļāļĄāļ§āļĨāļĢāļ§āļĄāļĨāļ°āđāļāļĒāļ
â āļĄāļ§āļĨāļĢāļ§āļĄāļĨāļ°āđāļāļĒāļāļāļ°āļĄāļāļē fineness modulus āļ āļēâ āļĄāļ§āļĨāļĢāļ§āļĄāļŦāļĒāļēāļāļāļ°āļĄāļāļē fineness modulus āļŠāļâ fineness modulus āļāļāļāļāļĢāļēāļāļāļ§āļĢāļĄāļāļēāļāļĢāļ°āļĄāļēāļ 2.3-3.2
45
Sieve analysis, grading curve and
fineness modulus
âĒ The test methods are prescribed by BS 812
Part 1 and ASTM C 136
46
Sieve analysis, grading curve and
fineness modulus
48Fineness modulus = āļāļĨāļĢāļ§āļĄāļāļāļāļāļģāļĢāļāļĒāļĨāļ°āļāļģāļāļŠāļ°āļŠāļĄāļāļāđāļĢāļāļĄāļģāļāļĢāļāļģāļāļāļ No. 100 100
Sieve analysis, grading curve and
fineness modulus
50
āļāļāļēāļāļāļĨāļ°āļĄāļēāļāļĢāļāļēāļāļāļāļāļĄāļ§āļĨāļĢāļ§āļĄāļŦāļĒāļēāļ āļāļēāļĄ ASTM C33
Graded aggregate - āļĄāļ§āļĨāļĢāļ§āļĄāļāļĨāļ°āļāļāļģāļ- āļĄāļ§āļĨāļĢāļ§āļĄāļāļĄāļāļāļģāļ
āļĨāļāļŦāļĨāļāļāļāđāļSingle size aggregate - āļĄāļ§āļĨāļĢāļ§āļĄāļāļāļģāļāđāļāļĒāļ§- āļĄāļ§āļĨāļĢāļ§āļĄāļāļĄāļāļāļģāļāļŦāļāļ
āļĄāļģāļāđāļāļāļāđāļĻāļĐ āđāļĨāļ°āļĄāļĄāļ§āļĨāļĢāļ§āļĄāļāļāļģāļāđāļĨāļāļāļ§āļģāļāļŠāļĄāļāļĒāļāļ§āļĒ
Sieve analysis, grading curve and
fineness modulus
51
āļāļāļēāļāļāļĨāļ°āļĄāļēāļāļĢāļāļēāļāļāļāļāļĄāļ§āļĨāļĢāļ§āļĄāļĨāļ°āđāļāļĒāļ
Sieve analysis, grading curve and
fineness modulus
52
āļāļāļēāļāļāļĨāļ°āļĄāļēāļāļĢāļāļēāļāļāļāļāļĄāļ§āļĨāļĢāļ§āļĄ āļāļēāļĄ BS 882Nominal size = nominal maximum size = āļāļāļēāļāđāļŦāļāļŠāļāļāļāļāļĄāļ§āļĨāļĢāļ§āļĄ= āļāļāļēāļāļāļ°āđāļāļĢāļāļāđāļĨāļāļāļŠāļāļāļĄāļ§āļĨāļĢāļ§āļĄāļŠāļēāļĄāļēāļĢāļāļāļēāļāđāļāđāļāļāļāļŦāļĄāļ (āļŠāļ§āļāļāļāļēāļāļāļĒāļāļāļāļ°āđāļāļĢāļāļāļāļĒāļāļ§āļē 5%)
References
âĒ ACI Committee 221, âGuide for Use of Normal Weight Aggregates for
Concrete (ACI 221R-96),â American Concrete Institute, Farmington
Hills,Mich., 1996, 29 pp.
âĒ ASTM Standards, Concrete and Aggregates, American Society for
Testing and Materials, V. 04.02, Philadelphia, 1997.
âĒ C 29, âTest for Density (unit weight) of Aggregate.â
âĒ C 33, âSpecifications for Concrete Aggregates.â
âĒ C 40, âTest for Organic Impurities in Sands for Concrete.â
âĒ C 131, âTest for Resistance to Abrasion of Small Size Coarse
Aggregate by Use of the Los Angeles Machine.â
âĒ C 142, âTest for Clay Lumps and Friable Particles in Aggregates.â
âĒ C 535, âTest for Resistance to Abrasion of Large Size Coarse
Aggregates by Use of the Los Angeles Machine.â
54
References
âĒ Boonchai Stitmannaithum, "Advance Concrete Technology (Lecture
Note)" Chulalongkorn University 2005 : Chapter I Materials for
Concrete
âĒ āļāļĢāļāļāļē āļāļāļāļēāļāļĢāļ°āđāļŠāļĢāļ āđāļĨāļ°āļāļĒ āļāļēāļāļĢāļāļāļāļĐāļāļĨ, âāļāļāļāđāļĄāļāļ āļāļāļāđāļāļĨāļēāļ āđāļĨāļ°āļāļāļāļāļĢāļâ, āļŠāļĄāļēāļāļĄāļāļāļāļāļĢāļāđāļŦāļāļāļĢāļ°āđāļāļĻāđāļāļĒ, āļāļĄāļāļāļĢāļāļ 7, 2556.
âĒ Mehta,P.K. and Monterio, P.J.M., "Concrete : Microstructure,
Properties, and Materials", 3rd Edition, 2006
âĒ Siam Cement Group, "Cement and Applications", 4th edition, 2003
âĒ CPAC Concrete Academy: The Concrete Product and Aggregate
co.,ltd; http://www.cpacacademy.com
âĒ Portland Cement Association (PCA). Cement & Concrete Technology;
http://www.cement.org/
âĒ http://www.engineeringcivil.com/test-to-check-consistency-of-
cement.html 55