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www.LC3.ch
LC3: A breakthrough technology
to reduce CO2 emissions from cementitious materials
Professor Karen Scrivener, FREng
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We don’t have much time left!
2
https://www.mcc-berlin.net/en/research/co2-budget.html
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Drastic consequences!
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Two reports in recent years
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Cement Based Materials:
cannot be replaced by alternatives
0 2000 4000 6000 8000 10000 12000 14000 16000 18000
Cementitious
Wood
Ceramic
Iron
Lime
Asphalt
Glass
Aluminium
Copper
Materials production (Mt/year)
Cementitious materials make up
~50%
of everything we produce.
In the light of this,
CO2 emissions of 5-10%
very good
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Concrete is an environmentally friendly material
Material MJ/kg kgCO2/kg
Cement 4.6 0.83
Concrete 0.95 0.13
Masonry 3.0 0.22
Wood 8.5 0.46
Wood: multilayer 15 0.81
Steel: Virgin 35 2.8
Steel: Recycled 9.5 0.43
Aluminium: virgin 218 11.46
Aluminium recycled 28.8 1.69
Glass fibre composites
100 8.1
Glass 15.7 0.85
ICE version 1.6a
Hammond G.P. and Jones C.I
2008 Proc Instn Civil Engineers
www.bath.ac.uk/mech-eng/sert/embodied/
Rela
tive e
nerg
y, C
O2
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Forecast growth
We need solutions for people in developing countries
0
2000
4000
6000
8000
2015 2025 2035 2045
Pro
du
ctio
n (
Mt)
OECD
China
India
Other
11 10
54
32
8
22
2637
0%
20%
40%
60%
80%
100%
2015 2050
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How to meet this challenge sustainably
Solutions need to be:
➢ Practical, usable by unskilled workers
➢ Economically viable
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What is available on earth?
Na2O
K2O
Fe2O3
MgO
CaO
SiO2
Al2O3
Too soluble
Too low mobility in alkaline solutions
The most useful
Mg
K
rest
Na
Ca
Fe
Al
Si
O
Slag
cement
blend
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Al2O3CaO
Portland
Cement
10
Hydraulic minerals in the system CaO-SiO2-Al2O3
Calcium aluminate /calcium sulfo aluminate
SiO2
BUT, what sources of
minerals are there
which contain Al2O3 >>
SiO2 ?
Bauxite – localised,
under increasing
demand for Aluminium
production,
EXPENSIVE
Even if all current
bauxite production
diverted would still only
replace 10-15% of
current demand.
Less CaO > less CO2
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Portland based cement will continue to be dominant
➢ Incredible economy of scaleClinker very low cost
➢ Raw materials abundant nearly everywhere
➢ Easily to manipulate open time
➢ Robust
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Extending use of blended cements
12
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Evolution of Clinker substitution
13
2%4%
5% 5% 6% 6% 6% 6% 6% 7% 7% 7%4%
4%
4% 4% 5% 5% 5% 5% 5% 5% 5% 5%
1%
2%
3%3%
3%4% 4% 4%
4%4% 4% 4%
1%
2%
2%2%
2%2%
2% 2% 2%2% 2% 2%
4%
2%
1%1%
1%1%
1% 1% 1%1% 1% 1%
0%
5%
10%
15%
20%
25%
1990 2000 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
Limestone
Slag
Fly ash
Puzzolana
Others
• Almost no progress in last 8 years
• Only 3 substitutes used in quantity
Clinker substitution most successful strategy to reduce CO2
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0 2000 4000 6000
Calcined Clay
Filler
Portland cement
Fly ash
Slag
Natural Pozzolan
Vegetable ashes
waste glass
silica fume
Mt/yr
Used Available
limestone
Availability of SCMs
Classic SCMs – fly ash and slag are
only around 15% of current cement
production, will drop to < 10% in near
future
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There is no magic solution
▪ Blended with SCMs will be best solution for sustainable cements for foreseeable future
▪ Only material really potentially available in viable quantities is calcined clay.
▪ Synergetic reaction of calcined clay and limestone allows high levels of substitution: EPFL led LC3 project supported by SDC. Started 2013
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LC3 project partners
➢ EPFL
➢ UCLV, Cuba; Fernando Martirena
➢ TARA, India; Soumen Maity
➢ IIT Delhi, India; Shashank Bishnoi
➢ IIT Madras, India; Ravindra Gettu, Manu Santhanam
➢ Sinoma, China; Sui Tongbo
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What is LC3
LC3 is a family of cements,
the figure refers to
the clinker content
• 50% less clinker
• 40% less CO2
• Similar strength
• Better chloride resistance
• ASR resistant
0
20
40
60
80
100
PC PPC30 LC3-50 LC3-65
Mas
s p
rop
ort
ion
(%
)
GypsumLimestoneCalcined clayClinker
0
10
20
30
40
50
60
70
PC LC3-50C
om
pre
ssiv
e s
tre
ngt
h
(MP
a)
1 day
7 days
28 days
90 days
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Why can we get such high replacement levels» Calcination of
kaolinite at
700-850°C
gives
metakaolin:
much more
reactive than
glassy SCMs
» Synergetic reaction of
Alumina in metakaolin
with limestone to give
space filling hydrates
OPC
205 10 15 25Position [ 2Q ]
CHMs
Strät .Strät . C4AF AFtAFtAFt AFtHcMc
MsHc
1d
28d
LC3-50
205 10 15 25
Position [ ]
CHMs
Strät.Strät . C4AF AFtAFtAFt AFtHcMc
MsHc
2Q
1d
28d
silicon
aluminium
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What kinds of clay are suitable?
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Na+, Ca++, H2O
Three basic clay structures
silicon
aluminium
Kaolinite (1:1)Illite (Micas)
(2:1)Montmorillonite (2:1)
(Smectites)
“Metakaolin”, sold as high purity product for paper, ceramic, refractory industries
Requirements for purity, colour, etc, mean expensive 3-4x price cement
Clays containing metakaolin available as wastes
– over or under burden NOT agricultural soil
Much much less expensive often available close to cement plants
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Over 50 clays studied from around the world
% of calcined kaolinite in the calcined clay
0% 50.3%17.0% 35.0%38.9% 66.2% 79.4% 95%
Quartz Pure kaolinite
Different calcination conditions
Different compositions,
impurities
Different physical properties
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Calcination Temperature window 700-850°
600-700
dehydroxlation
complete but
reactivity
increases
ideal
range
700-850
850-1000
Surface area
reduced
reactivity
decreases
>1000
crystalline
phases
formed
no
reactivity
<600
Not reactive
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Benchmark test of clay strength
Calcined kaolinite content overwhelming parameter
➢ Compressive strength EN 196-1 at 1, 3, 7, 28 and 90 d
➢ Linear increase of strength with the MK content of calcined clays
➢ Similar strength to PC for blends containing 40% of calcined kaolinite from 7d onwards
➢ At 28 and 90 days, little additional benefit >60%
➢ Minor impacts of fineness, specific surface and secondary phases
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Ideal kaolinite content40-60%
Higher contents, possible to use more limestone
Even better economics and ecology
Lower contents can be enriched by separation
separated fine quartz can be sold as separate product
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Availability of suitable clays, yellow pink and light green regions, and others
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Suitable clays presently stockpiled as waste
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Comparison of calcined kaolinitic clay, slag and fly ashBinary systems 70% clinker
Ternary systems, with limestone 50% clinker
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Global cement production
Billion tons/year
Clinker factor, global
average
%
Global SCM volume
Billion tones/year
Global CO2
reduction
Million tones/year
2006 2.6 79 0.5
2050 (CSI study)
4.4 73 1.2 200
2050 (with LCC)
4.4 60 1.8 600
Global potential of LC3
∆ = 400 million
tonnes per yr
> whole of CO2
emissions
of France
Potential impact of LC3 technology
IEA: International Energy
Agency study for
CSI: Cement
Sustainability Initiative
of WBCSD: World
Business Council for
Sustainable Development
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LC3 has been produced and used in full scale trials
Uses existing technologyRotary kiln
Flash calcineretc
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Cuba – 1st Industrial trialJan 2013: Clay sourcingPontezuela (300 t)
March 2013: Clay calcination Siguaney (110 t
August 2013: Cement grinding (130 t)
Sept-Dec. 2013: Cement use in construction
Jan-July 2014: Evaluation of concrete made with LC3
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Industrial block manufacture plant
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Prefabrication plant Cuba
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House built at Santa Clara, Cuba with LC3
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INDIA: Calcination
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Blending and grinding
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Evaluation in building materials
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Evaluation in building materials
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Industrial productionKJS Concrete Pvt. Ltd., Dadri
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Demonstration structure
Around 14 tonnes of CO2 saved
Compared to existing solutions
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Hollow Core Slabs
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Key Advantages
• Chloride resistance
• ASR mitigation
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Chloride ponding ASTM
Apparent diffusion coeffs.
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Porosity characterization by MIP
➢ Significant refinement of porosity already at 3 days of hydration
LC3-50 (95%) 3d
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Porosity characterization by MIP
➢ Significant refinement of porosity already at 3 days of hydration
LC3-50 (95%) 3d
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Very dense
microstructure
Strong pore refinement
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Alkali silica reaction
Chappex 2012
Impact of alumina on aggregates
No alumina
Alumina in solution
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Perceived problems• Workability
• Carbonation
• Colour
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LC3
➢ Limestone and calcined clay are both much softer than clinker
➢ With intergrinding, high blaine and clinker is likely to be underground. But situation can be improved by separate grinding or addition of calcined clay at separator
➢ However effect of limestone and impurities in clay has positive influence
➢ Good flowable concrete can be obtained with use of superplasticizers
➢ In some formulation SP dosage may even be less
➢ No segregation, no bleeding
➢ Further improvements possible with PSD optimisation, grinding aids, etc
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Indoor
PC
PPC30
LC3-50
3D 28D
Outdoor
3D 28D
2 years natural conditions : similar to other blends
PC
PPC30
LC3-50
Carbonation
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Reducing calcium content; reduces buffer to carbonation
CaCO3
CaO Ca(OH)2
+H2O
CO2 +CO2
All CaO content can react with CO2,
not just portlandite
Carbonation
Leemann, et al(2015) :
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What about colour
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» Intensity determinedby iron concrete
FLSmidth 2013
» Red to greyby kiln atmosphere
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Colour control. IPIAC technology
Calcination with reduction during cooling
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Concluding remarks ➢ Future cements will be based on Portland cement clinker with
increasing levels of incorporation of SCMs
➢ Calcined clays are the only realistic option for extending the use SCMs
➢ Possible to obtain similar mechanical properties to OPC / CEM I with 50% clinker and clays with >40% kaolinite
➢ Calcined clays have very positive impact on:
▪ Chloride ingress
▪ ASR
➢ If we are serious about more sustainable concrete we need to use cements with lower CO2 emissions, e.g LC3 clinker/ calcined clay / limestone blends
➢ Europe has an important role to play in facilitating uptake worldwide:standards and research
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