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CEMENT AND CONCRETE MATERIALS
materials fundamentals + mix design
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CEMENT
Materials fundamentals
Sources of information
Cement manufacture + composition
Cement hydrationMicrostructure
Concrete mixes
Properties: strengthpermeabilitydurability
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Information/texts
Jackson & Dhir: Civil Engineering Materials,
5th edn, 1997
Mindess, Young & Darwin: Concrete, 2002
Neville & Brooks: Concrete Technology, 1987
Neville: Properties of Concrete 4th edn, 1995
Bensted & Barnes: Structure and Performance
of Cements, 2nd edn, 2001
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Information/journals
Cement and Concrete Research
Magazine of Concrete Research
American Concrete Institute JournalACI Journal
Materials and Structures [RILEM]
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Information/online
Virtual Cement & Concrete Testing Laboratory:
includes Electronic Monograph from Bentz at
http://ciks.cbt.nist.gov/vcctl/
See also Microstructure Images Library from Lange at
http://sftp.cee.uiuc.edu/research/dlange/micro
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Cement Manufacture
Raw materials
limestone + clay
on firing, produces a complex mixtureof synthetic minerals, principally
calcium silicates and calciumaluminates
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Manufacture
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CEMENT
World production 2001 1.6 billion tonsSteel production 900 million tons
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CEMENT
World production 2001 1.6 billion tonnes
2--5 % total CO2
emissionEnergy intensive manufacture
Various figures
are quoted.
The energy cost
of manufacture
is around 3500
kJ/kg cement
Various figures
are quoted.
The energy cost
of manufactureis around 3500
kJ/kg cement
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CEMENT
World production 2001 1.6 billion tonnEU production 2002 194 million tonne
For each tonne cement produced
0.800 tonne CO2 is also produced
0.525 tonne from decalcinationof limestone
0.335 tonne from combustionof fuel in the kiln
0.050 tonne from electricity
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CEMENT
In EU, cement industry produces
3 per cent of total anthropogenic CO
Source: Cembureau
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Civil Engineering: Materials
Cement manufacture
Some facts
Cement is the industrial material produced in by far the largest tonnage: 1.6 billion tonnes worldwide 200tonnes). Most of this cement is combined with about four times that weight of aggregate to make concret
Large-scale industrial plants: typical output of a modern cement plant is 3000 tonnes/day. Low unit cost and large production volumes mean that it is uneconomic to transport cements over long di
countries. Therefore cement is produced in virtually every country in the world.
Much of the worlds production capacity is owned by a small number of major industrial business congloGroup (formerly the Swiss company Holderbank) operates in 70 countries with technical centre in Zurich
British companies include RMC and Castle (owned by the Heidelberg group). The trend towards large mensure a good technical level in cement manufacture worldwide.
Sustainability issues
Cement manufacture is an important source of anthropogenic CO2 emissions (see overheads).
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Cement standards
The long-serving British Standard for cem
12, is being replaced by Euro-Norm EN 19
Cement Part 1: Composition, specificati
conformity criteria for common cements
*Check out this document on-line via UoE
...needs ATHENS registration
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Euro-Cements
Five families
CEM I Portland cement
CEM II Portland-composite c
CEM III Blastfurnace cement
CEM IV Pozzolanic cementCEM V Composite cement
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Euro-Cements
Other main components of composite ce
Blastfurnace slag
Silica fume
Pozzolana
Fly ashBurnt shale
Limestone
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Table 22. Mineralogical Composition of Classic Cement Clinker
Oxide Composition Cement Notatiion Common Name Concentration (wt
3CaO SiO2
C3S a lite 5565
2CaO SiO2
C2S belite 1525
3CaO Al2O
3C
3A aluminate 814
4CaO Al2O
3 Fe
2O
3C
4AF brownmillerite 812
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Clinker microstructure
C3S
C2SC2AC4AF
150 micron
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Clinker microstructure
C3S, C2S, C3A, C4AF200 micron
Cement grinding
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Cement grinding
Gypsum additions (strictly sulphate)
Particle size distribution
Images from Lange
UIUC
http://cee.ce.uiuc.edu/lange/micro
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Particle size
Powder surface area
Mean particle diameter 15-20 micron
Direct measurement of cement particle s
distribution is used for quality control in
cement manufacture
But a traditional measurement of cement
size is the Blaine surface area
Cement hydration 1
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Cement hydration 1
Heat evolution
Induction period
Cement hydration 2
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Cement hydration 2
Chemical reaction with water
All minerals involved
115 micron
Cement hydration 2
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Cement hydration 2
Principal reaction which develops
strength
C3S + water ---> C-S-H
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Cement hydration 2
Principal reaction which develops
strength
C3S + water ---> C-S-H + Ca(OH)2
Ca(OH)2
Hydrated lime or portlandite
Cement hydration 3
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y
Chemical reaction with water
All minerals involved
Formation of lime
(calcium hydroxide)
pH of pore water
Cement hydration 4
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y
Water requirement
about 30% by wt cement for complete
reaction
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Computational materials science
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pCellular automaton model of cement and concrete
D Bentz and E Garboczi NIST
Cement hydration 6
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Ce e t yd at o 6
Synchrotron X-ray view
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Summary of setting and hardening
Workability
Development of continuous network
of hydrate material
Strength development
Porosity and permeability
Timescale
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Strength and strength development
Cement Based Materials
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Mortars
Concrete
Manufactured cement based materials
Autoclaved aerated concrete
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Transport properties
Permeability
Sorptivity
see Hall & Hoff: Water Transport inBrick, Stone and Concrete 2002
PERMEABILITY property
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PERMEABILITY property
Darcys law:
u = Q/A = - kp /L
k permeability
Q volume rate of flow
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A
B