Greening the Heartland
Earthship Brighton (UK) – The first building utilising TecEco eco-cements
I will have to race over some slides but the presentation is
always downloadable from the TecEco web site if you missed
something. John Harrison B.Sc. B.Ec. FCPA.
Presentation downloadable from www.tececo.com 1
The Problem – A Planet in Crisis
TecEco are in the BIGGEST Business on the Planet -
Solving Sustainability Problems Economically
Presentation downloadable from www.tececo.com 2
A Demographic Explosion
?
Undeveloped
Countries
Developed
Countries
Global population, consumption per capita and our
footprint on the planet is exploding.
Presentation downloadable from www.tececo.com 3
Atmospheric Carbon Dioxide
Presentation downloadable from www.tececo.com 4
Global Temperature Anomaly
Presentation downloadable from www.tececo.com 5
The Techno-Process
Global
Our linkages to Systems
the bio-geo-
sphere are Atmospheric
defined by the composition,
techno process climate, land
describing and Detrimental cover, marine
controlling the affects on ecosystems,
flow of matter pollution,
earth systems
and energy. It coastal zones,
is these flows freshwater
that have systems,
detrimental salinity and
linkages to global
earth systems. biological
diversity have
all been
substantially
affected.
Presentation downloadable from www.tececo.com 6
Ecological Footprint
Our footprint is exceeding the capacity of the
planet to support it. We are not longer sustainable
as a species and must change our ways
Presentation downloadable from www.tececo.com 7
Illinois Before Settlement
Presentation downloadable from www.tececo.com 8
Illinois Now
Paper Mill
- Soda
liquor + Cl
Habitat
removal
Vehicles - carbon dioxide
Farming -
Cows - methane
Pesticide, N & K
Cities Huge impacts
Immediate and polluted water run-off.
Air pollution.
Carbon dioxide and other gases.
Other wastes. Huge linkages.
Presentation downloadable from www.tececo.com 9
Illinois with a Little Lateral Thinking & Effort
TecEco technology provides ways of
sequestering carbon dioxide and
Less paper.
utilizing wastes to create our techno - Other Cl free
world processes -
no salinity Evolution
away from
using trees –
paperless
Vehicles – more office
efficient and using
fuel cells
Organic farming.
Sequestration processes Cows – CSIRO Carbon returned
Cities: anti methane to soils. Use of
bred zeolite reduces
Porous pavement prevents water and
immediate and polluted run-off. fertilizer required
Carbon dioxide and other gases by 2/3
absorbed by TecEco eco-
cements. Less wastes. Carbon
Less impacts
based wastes converted to
energy or mulches and returned
to soils. Buildings generate own
energy etc.
Presentation downloadable from www.tececo.com 10
Impact of the Largest Material Flow - Cement and Concrete
Concrete made with cement is the most widely
used material on Earth accounting for some
30% of all materials flows on the planet and 70%
of all materials flows in the built environment.
– Global Portland cement production is in the order of 2
billion tonnes per annum.
– Globally over 14 billion tonnes of concrete are poured
per year.
– Over 2 tonnes per person per annum
TecEco Pty. Ltd. have benchmark
technologies for improvement in
sustainability and properties
Presentation downloadable from www.tececo.com 11
Embodied Energy of Building Materials
Concrete is
relatively
environmentally
friendly and has a
relatively low
embodied energy
Downloaded from www.dbce.csiro.au/ind-
serv/brochures/embodied/embodied.htm (last accessed 07 March 2000)
Presentation downloadable from www.tececo.com 12
Average Embodied Energy in Buildings
Most of the embodied energy in the
built environment is in concrete.
But because so much is used
there is a huge opportunity for
sustainability by reducing the
embodied energy, reducing the
carbon debt (net emissions) and
improving properties.
Downloaded from www.dbce.csiro.au/ind-
serv/brochures/embodied/embodied.htm (last accessed 07 March 2000)
Presentation downloadable from www.tececo.com 13
Emissions from Cement Production
Chemical Release
– The process of calcination involves driving off chemically
bound CO2 with heat.
CaCO3 →CaO + ↑CO2
∆
Process Energy
– Most energy is derived from fossil fuels.
– Fuel oil, coal and natural gas are directly or indirectly burned to
produce the energy required releasing CO2.
The production of cement for concretes accounts
for around 10%(1) of global anthropogenic CO2.
(1) Pearce, F., "The Concrete Jungle Overheats", New Scientist, 19 July, No
2097, 1997 (page 14).
Presentation downloadable from www.tececo.com 14
Cement Production = Carbon Dioxide Emissions
Metric Tonnes
2,000,000,000
1,800,000,000
1,600,000,000
1,400,000,000
1,200,000,000
1,000,000,000
800,000,000
600,000,000
400,000,000
200,000,000
0
1926
1931
1936
1941
1946
1951
1956
1961
1966
1971
1976
1981
1986
1991
1996
2001
Year
Presentation downloadable from www.tececo.com 15
Sustainability
Sustainability is a direction not a
destination.
Our approach should be holistically
balanced and involve
– Everybody, every process, every day.
+ +
Emissions reduction Mineral Sequestration
through efficiency and Eco-cements in cities
conversion to non fossil fuels + Waste utilization Geological
Seques-
tration
Presentation downloadable from www.tececo.com 16
Converting Waste to Resource
Recycle
Waste only what
Take only → Manipulate → Make → Use → is biodegradable
renewables or can be re-
Reuse assimilated
Re-make
[ ←Materials→ ]
[← Underlying molecular flows →]
Materials control:
How much and what we have to take to manufacture the materials we use.
How long materials remain of utility, whether they are easily recycled and how and
what form they are in when we eventually throw them “away”.
What we take from the environment around us, how we manipulate and make materials
out of what we take and what we waste result in underlying molecular flows that affect
earth systems.
Problems in the global commons today include heavy metals, halogen
carbon double bond compounds, CFC’s too much CO2 etc.
Presentation downloadable from www.tececo.com 17
Innovative New Materials - the Key to Sustainability
The choice of materials in construction controls emissions,
lifetime and embodied energies, user comfort, use of recycled
wastes, durability, recyclability and the properties of wastes
returned to the bio-geo-sphere.
There is no such place as “away”, only a global commons
Presentation downloadable from www.tececo.com 18
Sustainability Through Materials Innovation
Problems in the global commons today can
only be changed by changing the molecular
flows underlying planetary anthropogenic
materials flows in the techno-process so that
the every day behaviors of people interacting
in an economic system will deliver new more
sustainable flows.
This will not happen because it is the right
thing to do. Pilzer's first law states that the
technology paradigm defines resources.
Changing the flow of materials therefore has
to be economic.
WBCSD President Björn Stigson 26 November 2004
“Technology is a key part of the solutions for sustainable
development. Innovation and technology are tools for
achieving higher resource efficiency in society.”
Presentation downloadable from www.tececo.com 19
Sustainability = Culture + Technology
Increase in demand/price ratio for
$ sustainability due to educationally
induced cultural drift. Supply
Greater Value/for
Equilibrium shift impact
ECONOMICS (Sustainability) and
economic growth
Demand
Increase in supply/price ratio for more
sustainable products due to innovative #
paradigm shifts in technology.
Sustainability is where Culture and Technology meet.
Demand Supply
Presentation downloadable from www.tececo.com 20
Huge Potential for Sustainable Materials in
the Built Environment
The built environment is made of materials and is our
footprint on earth.
– It comprises buildings and infrastructure.
Building materials comprise
– 70% of materials flows (buildings, infrastructure etc.)
– 40-45% of waste that goes to landfill (15 % of new materials going
to site are wasted.)
Reducing the impact of the take and waste phases of
the techno-process. C
– By including carbon in materials C
they are potentially carbon sinks. Waste
– By including wastes for
physical properties as C
well as chemical composition C Waste
they become resources C
Presentation downloadable from www.tececo.com 21
Innovative New Materials Vital
It is possible to achieve Kyoto targets as the UK are proving, but we
need to go way beyond the treaty according to our chief scientists.
Carbon rationing has been proposed as the only viable means to
keep the carbon dioxide concentration in the atmosphere below 450
ppm.
Atmospheric carbon reduction is essential, but difficult to politically
achieve by rationing.
Making the built environment not only a repository for recyclable
resources (referred to as waste) but a huge carbon sink is an
alternative and adjunct that is politically viable as it potentially
results in economic benefits.
Concrete, a cementitous composite, is the single biggest material
flow on the planet with over 2.2 tonnes per person produced.
Eco-cements offer tremendous potential for capture and
sequestration using cementitious composites.
MgCO3 → MgO + ↓CO2 - Efficient low temperature calcination & capture
MgO + ↓CO2 + H2O → MgCO3.3H2O - Sequestration as building material
∆
Presentation downloadable from www.tececo.com 22
Sustainability Summary
A more holistic approach is to reduce energy
consumption as well as sequester carbon.
To reduce our linkages with the environment we
must convert waste to resource (recycle).
Sequestration and recycling have to be economic
processes or they have no hope of success.
We cannot stop progress, but we can change and
historically economies thrive on change.
What can be changed is the technical paradigm.
CO2 and wastes need to be redefined as resources.
New and better materials are required that utilize
wastes including CO2 to create a wide range of
materials suitable for use in our built environment.
Presentation downloadable from www.tececo.com 23
TecEco Technology
More information at www.tececo.com
Presentation downloadable from www.tececo.com 24
The TecEco Total Process
Serpentine Olivine
Mg3Si2O5(OH)4 Mg2SiO4
Crushing
Crushing
Grinding CO2 from Power
Generation or Industry Grinding
Waste Sulfuric
Screening Acid or Alkali?
Screening
Magnetic Sep.
Iron Ore. Silicate Reactor Gravity Concentration
Heat Treatment Process
Silicic Acids or Silica
Magnesite (MgCO3) Simplified TecEco Reactions
Tec-Kiln MgCO3 → MgO + CO2 - 118 kJ/mole
Reactor Process MgO + CO2 → MgCO3 + 118 kJ/mole (usually
Solar or Wind Electricity more complex hydrates)
Powered Tec-Kiln
CO2 for Geological
Sequestration
Magnesium
Magnesia (MgO) Magnesite MgCO3)
Other Wastes Thermodynamic Cycle
after
Oxide Reactor CO2 from Power Generation, Industry
Processing
Process or CO2 Directly From the Air
Tonnes CO2 Sequestered per Tonne Silicate with Various Cycles Chrysotile Forsterite (Mg
through the TecEco Process (assuming no leakage MgO to built (Serpentinite) Olivine) Billion
environment i.e complete cycles) Billion Tonnes Tonnes
Tonnes CO2 sequestered by 1 billion tonnes of mineral mined directly .4769 .6255
Tonnes CO2 captured during calcining .4769 .6255
Tonnes CO2 captured by eco-cement .4769 .6255
MgO for TecEco Cements and Total tonnes CO2 sequestered or abated per tonne mineral mined 1.431 1.876
Sequestration by Eco-Cements in the Built (Single calcination cycle).
Environment Total tonnes CO2 sequestered or abated (Five calcination cycles.) 3.339 4.378
Total tonnes CO2 sequestered or abated (Ten calcination cycles). 5.723 7.506
Presentation downloadable from www.tececo.com 25
Why Magnesium Compounds
At 2.09% of the crust magnesium is the 8th most abundant
element.
Magnesium oxide is easy to make using non fossil fuel energy and
efficiently absorbs CO2
Because magnesium has a low molecular weight, proportionally a
much greater amount of CO2 is released or captured.
CO 2 44
52 %
MgCO 3 84
CO 2 44
43%
CaCO 3 101
A high proportion of water means that a little binder goes a long
way. In terms of binder produced for starting material in cement,
eco-cements are nearly six times more efficient.
Presentation downloadable from www.tececo.com 26
TecEco Technologies
Silicate → Carbonate Mineral Sequestration
– Using either peridotite, forsterite or serpentine as
inputs to a silicate reactor process CO2 is
sequestered and magnesite produced.
– Proven by others (NETL,MIT,TNO, Finnish govt.
TecEco etc.)
Tec-Kiln Technology
– Combined calcining and grinding in a closed
system allowing the capture of CO2. Powered by Economic
waste heat, solar or solar derived energy. under
– To be proved but simple and should work! Kyoto?
Direct Scrubbing of CO2 using MgO
– Being proven by others (NETL,MIT,TNO, Finnish
TecEco govt. etc.)
Tec and Eco-Cement Concretes in the Built
Environment.
– TecEco eco-cements set by absorbing CO2 and
are as good as proven.
Presentation downloadable from www.tececo.com 27
TecEco Kiln Technology
Grinds and calcines at the same
time.
Runs 25% to 30% more efficiency.
Can be powered by solar energy or
waste heat.
Brings mineral sequestration and
geological sequestration together
Captures CO2 for bottling and sale to the oil industry
(geological sequestration).
The products – CaO &/or MgO can be used to
sequester more CO2 and then be re-calcined. This
cycle can then be repeated.
Suitable for making reactive reactive MgO.
Presentation downloadable from www.tececo.com 28
A Post – Carbon Age
We all use carbon and wastes to make our homes!
“Biomimicry”
Presentation downloadable from www.tececo.com 29
Drivers for TecEco Technology
Government Influence
TecEco kiln technology could be the first
Carbon Taxes non fossil fuel powered industrial process
Provision of Research Funds
Environmental education
Consumer Pull
Huge Markets
Producer Push Environmental sentiment
Cost and technical Cement 2 billion
The opportunity cost of
advantages? tonnes.
compliant waste disposal Competition?
Bricks 130,000
Profitability and cost
recovery million tonnes
Technical merit
Resource issues
Robotics
Research objectives
TecEco cements are the only binders capable of utilizing very
large quantities of wastes based on physical property rather than
chemical composition overcoming significant global disposal
problems, and reducing the impact of landfill taxes.
TecEco eco-cements can sequester CO2 on a large scale and will
therefore provide carbon accounting advantages.
Presentation downloadable from www.tececo.com 30
Drivers for Change – Robotics
Using Robots to print buildings is all quite simple from a
software, computer hardware and mechanical
engineering point of view.
The problem is in developing new construction materials
with the right flow characteristics so they can be
squeezed out like toothpaste, yet retain their shape until
hardened
– Once new materials suitable for the way robots work have been
developed economics will drive the acceptance of robots for
construction
– Concretes for example will need to evolve from being just a high
strength grey material, to a smorgasbord of composites that can
be squeezed out of a variety of nozzles for use by a robotic
workforce for the varying requirements of a structure
TecEco cement concretes have the potential of
achieving the right shear thinning
characteristics required
Presentation downloadable from www.tececo.com 31
TecEco Cements
information at web site
MoreMore slides on www.tececo.com
Presentation downloadable from www.tececo.com 32
TecEco Cements
SUSTAINABILITY
PORTLAND + or - POZZOLAN
Hydration of the Reaction of alkali with
various components pozzolans (e.g. lime with fly
of Portland cement ash.) for sustainability,
for strength. durability and strength.
DURABILITY TECECO CEMENTS STRENGTH
TecEco concretes are
MAGNESIA a system of blending
reactive magnesia,
Hydration of magnesia => brucite for strength, workability, Portland cement and
dimensional stability and durability. In Eco-cements usually a pozzolan
carbonation of brucite => nesquehonite, lansfordite and an
with other materials
amorphous phase for sustainability.
and are a key factor
Presentation downloadable from www.tececo.com for sustainability. 33
The Magnesium Thermodynamic Cycle
Presentation downloadable from www.tececo.com 34
TecEco Cement Sustainability
TecEco technology will be pivotal in bringing about
sustainability in the built environment.
– The CO2 released by calcined carbonates used to make binders
can be captured using TecEco kiln technology.
– Tec-Cements Develop Significant Early Strength even with
Added Supplementary Materials.
• Around 25 = 30% less total binder is required for the same strength.
– Eco-cements carbonate sequestering CO2
– Both tec and eco=cements provide a benign low pH environment
for hosting large quantities of waste overcoming problems of:
• Using acids to etch plastics so they bond with concretes.
• sulphates from plasterboard etc. ending up in recycled construction
materials.
• heavy metals and other contaminants.
• delayed reactivity e.g. ASR with glass cullet
• Durability issues
Presentation downloadable from www.tececo.com 35
TecEco Formulations
Tec-cements (Low MgO)
– contain more Portland cement than reactive magnesia. Reactive magnesia
hydrates in the same rate order as Portland cement forming Brucite which uses
up water reducing the voids:paste ratio, increasing density and possibly raising
the short term pH.
– Reactions with pozzolans are more affective. After all the Portlandite has been
consumed Brucite controls the long term pH which is lower and due to it’s low
solubility, mobility and reactivity results in greater durability.
– Other benefits include improvements in density, strength and rheology,
reduced permeability and shrinkage and the use of a wider range of
aggregates many of which are potentially wastes without reaction problems.
Eco-cements (High MgO)
– contain more reactive magnesia than in tec-cements. Brucite in porous
materials carbonates forming stronger fibrous mineral carbonates and therefore
presenting huge opportunities for waste utilisation and sequestration.
Enviro-cements (High MgO)
– contain similar ratios of MgO and OPC to eco-cements but in non porous
concretes brucite does not carbonate readily.
– Higher proportions of magnesia are most suited to toxic and hazardous waste
immobilisation and when durability is required. Strength is not developed
quickly nor to the same extent.
Presentation downloadable from www.tececo.com 36
TecEco Cement Technology
Portlandite (Ca(OH)2) is too soluble, mobile
and reactive.
– It carbonates, reacts with Cl- and SO4- and being
soluble can act as an electrolyte.
TecEco generally (but not always) remove
Portlandite using the pozzolanic reaction
and
TecEco add reactive magnesia
– which hydrates forming brucite which is another
alkali, but much less soluble, mobile or reactive
than Portlandite.
In Eco-cements brucite carbonates
The consequences of need to be considered.
Presentation downloadable from www.tececo.com 37
Why Add Reactive Magnesia?
To maintain the long term stability of CSH.
– Maintains alkalinity preventing the reduction in Ca/Si ratio.
To remove water.
– Reactive magnesia consumes water as it hydrates to possibly
hydrated forms of brucite.
To reduce shrinkage.
– The consequences of putting brucite through the matrix of a
concrete in the first place need to be considered.
To make concretes more durable
Because significant quantities of carbonates are
produced in porous substrates which are affective
binders.
Reactive MgO is a new tool to be understood
with profound affects on most properties
Presentation downloadable from www.tececo.com 38
What is Reactive MgO? or Lattice Energy Destroys a Myth
Magnesia, provided it is reactive rather than “dead
burned” (or high density, crystalline periclase type), can
be beneficially added to cements in excess of the amount
of 5 mass% generally considered as the maximum
allowable by standards prevalent in concrete dogma.
– Reactive magnesia is essentially amorphous magnesia with low
lattice energy.
– It is produced at low temperatures and finely ground, and
– will completely hydrate in the same time order as the minerals
contained in most hydraulic cements.
Dead burned magnesia and lime have high lattice
energies
– Crystalline magnesium oxide or periclase has a calculated lattice
energy of 3795 Kj mol-1 which must be overcome for it to go
into solution or for reaction to occur.
– Dead burned magnesia is much less expansive than dead burned
lime (Ramachandran V. S., Concrete Science, Heydon & Son Ltd.
1981, p 358-360 )
Presentation downloadable from www.tececo.com 39
Summary of Reactions Involved
In Tec-Cements
We think the reactions are
Notice the
Magnesia
relatively independent.
Brucite
low
solubility of MgO + H2O Mg(OH)2
M3A + 6H + M3AH6 (or similar ?)
brucite
compared In Eco - Cements
Silicates and aluminosilicates
to Magnesia Brucite Amorphous Lansfordite Nesquehonite
Portlandite
MgO + nH2O Mg(OH)2.nH2O + CO2 MgCO3.nH2O + MgCO3.5H2O + MgCO3.3H2O
and that
nesquehoni Form: Massive-Sometimes Fibrous Often Fibrous Acicular - Needle-like
crystals
te adopts a
more ideal Hardness: 2.5 - 3.0 2.5
habit than Solubility (mol.L-1): .00015 .01 .013 (but less in acids)
calcite & Compare to the Carbonation of Portlandite
aragonite
Portlandite Calcite Aragonite
Ca(OH)2 + CO2 CaCO3
Form: Massive Massive or crystalline More acicular
Hardness: 2.5 3.5
Solubility (mol.L-1): .024 .00014
Presentation downloadable from www.tececo.com 40
Strength with Blend & Porosity
Tec-cement concretes
150
Eco-cement concretes 100
50
High Porosity
0
Enviro-cement concretes
High OPC High Magnesia
100-150
STRENGTH ON
ARBITARY SCALE 1-100
50-100
0-50
Presentation downloadable from www.tececo.com 41
Tec-Cement Concrete Strength Gain Curve
Concretes are more often than not made to strength.
The use of tec-cement results in
– 20-30% greater strength or less binder for the same strength.
– more rapid early strength development even with added pozzolans.
– Straight line strength development for a long time
MPa
HYPOTHETICAL TEC-CEMENT STRENGTH GAIN CURVE
strength gain
with less
Tec – Cement Concrete with
10% reactive magnesia ? cement and
added
? pozzolans is of
? great economic
and
?
OPC Concrete environmental
importance.
Plastic Stage 3 7 14 28 Log Days
Presentation downloadable from www.tececo.com 42
Reasons for Strength Development in Tec-Cements.
Reactive magnesia requires considerable water to hydrate
resulting in:
– Denser, less permeable concrete.
– A significantly lower voids/paste ratio.
Higher early pH initiating more effective silicification
reactions?
– The Ca(OH)2 normally lost in bleed water is used internally for reaction
with pozzolans.
– Super saturation of alkalis caused by the removal of water?
Micro-structural strength due to particle packing (Magnesia
particles at 4-5 micron are a little over ½ the size of cement
grains.)
Slow release of water from hydrated Mg(OH)2.nH2O supplying
H2O for more complete hydration of C2S and C3S?
Formation of MgAl hydrates? Similar to flash set in concrete
but slower??
Presentation downloadable from www.tececo.com 43
Water Reduction During the Plastic Phase
Observable Relevant Water is
Characteristic
Consumption
Fundamental required to
of water during plasticise
Water plastic stage Voids concrete for
Hydrated
placement,
Binder however once
Binder + Variables such as % Materials placed, the less
supplemen
tary
hydration of mineral,
density, compaction,
water over the
cementitio % mineral H20 etc. Unhydrated amount required
us
materials
Binder for hydration the
better.
High water Less water Magnesia
for ease of
Log time
for strength consumes water
placement and durability
as it hydrates
Less water results in less shrinkage and cracking and producing solid
improved strength and durability. Concentration of material.
alkalis and increased density result in greater strength.
Presentation downloadable from www.tececo.com 44
Tec-Cement Compressive Strength
3 14.365 18.095 19.669 5.516
TEC-CEMENT COMPRESSIVE STRENGTH
40 3 16.968 19.44 20.196 6.656
9 19.466 20.877 13.39 3.417
STRENGTH ( MPa) 35 9 24.248 24.408 15.39 4.434
30 9 29.03 27.939 17.39 5.451
21 24.54 35.037 25.493 11.992
25 21 28.403 36.323 28.723 13.933
21 32.266 37.609 31.953 15.874
20
15
OPC(100%)
10
OPC(90%)+MgO(10%)
5
0
0 2 4 6 8 10 12 14 16 18 20 22 24
CURING TIME (days)
Graphs by Oxford Uni Student
Presentation downloadable from www.tececo.com 45
Tec-Cement Tensile Strength
TEC - CEMENT TENSILE STRENGTH
STRENGTH (MPa) 6
5
4
3
OPC(100%)
2
1
OPC(90%)+ MgO(10%)
0
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
CURING TIME (days)
Graphs by Oxford Uni Student
Tensile strength is thought to be caused by change in surface
charge on MgO particles from +ve to –ve at Ph 12 and
electrostatic attractive forces
Presentation downloadable from www.tececo.com 46
Other Strength Testing to Date
BRE (United Kingdom)
•2.85PC/0.15MgO/3pfa(1 part) : 3 parts sand - Compressive strength
of 69MPa at 90 days.
•Note that there was as much pfa as Portland cement plus magnesia.
Strength development was consistently greater than the OPC control
TecEco Large Cement Company
MPa
Strength Development of Tec-Cement Concrete
60
30
40 25
Strength, MPa
20
Compressive
20 Sam ple 1
15 Strength
10
Sam ple 2
0 5
0
17 30 56 89 0 5 10 15 20 25 30
Days w ater cured
Days
Modified 20 MPa mix
Presentation downloadable from www.tececo.com 47
Increased Density – Reduced Permeability
Concretes have a high percentage (around 18% - 25%)
of voids.
On hydration magnesia expands 116.9 % filling voids
and surrounding hydrating cement grains and
compensates for the shrinkage of Portland cement.
Brucite is 44.65 mass% water.
Lower voids:paste ratios than water:binder ratios
result in little or no bleed water less permeability and
greater density.
– Compare the affect to that of vacuum dewatering.
Presentation downloadable from www.tececo.com 48
Reduced Permeability
As bleed water exits ordinary Portland
cement concretes it creates an
interconnected pore structure that
remains in concrete allowing the entry of
aggressive agents such as SO4--, Cl- and
CO2
TecEco tec - cement concretes are a
closed system. They do not bleed as
excess water is consumed by the
hydration of magnesia.
Consequences:
– Tec - cement concretes tend to dry from
within, are denser and less permeable and
therefore stronger more durable and more
waterproof. Cement powder is not lost near the
surfaces.
– Tec-cements have a higher salt resistance and
less corrosion of steel etc.
Presentation downloadable from www.tececo.com 49
Tec-Cement pH Curves
Tec-Cement (red) - more affective
pozzolanic reactions
pH
HYPOTHETICAL pH CURVES
OVER TIME (with fly ash)
13.7 ? Tec – Cement Concrete with 10% reactive
?
11.2 ? magnesia (red). Ph maintained by brucite
10.5 OPC Concrete
OPC Concrete – Lower long term pH due
to consumption of lime and carbonation
Plastic Log Time
Stage
Presentation downloadable from www.tececo.com 50
Lower More Stable Long Term pH with Less Corrosion
In TecEco cements the long
term pH is governed by the
low solubility and carbonation
rate of brucite and is much
lower at around 10.5 -11,
allowing a wider range of
aggregates to be used,
reducing problems such as
AAR and etching. The pH is
still high enough to keep
Fe3O4 stable in reducing
conditions.
Eh-pH or Pourbaix Diagram
The stability fields of hematite,
magnetite and siderite
Steel corrodes below 8.9
in aqueous solution; total
dissolved carbonate = 10-2M.
Presentation downloadable from www.tececo.com 51
Reduced Steel Corrosion
Steel remains protected with a passive oxide coating of Fe3O4
above pH 8.9.
– A pH of over 8.9 is maintained by the equilibrium Mg(OH)2 ↔ Mg++ + 2OH-
for much longer than the pH maintained by Ca(OH)2 because:
– Brucite does not react as readily as Portlandite resulting in reduced
carbonation rates and reactions with salts.
Concrete with brucite in it is denser and carbonation is
expansive, sealing the surface preventing further access by
moisture, CO2 and salts.
Brucite is less soluble and traps salts as it forms resulting in
less ionic transport to complete a circuit for electrolysis and
less corrosion.
Free chlorides and sulfates originally in cement and aggregates
are bound by magnesium
– Magnesium oxychlorides or oxysulfates are formed. ( Compatible phases
in hydraulic binders that are stable provided the concrete is dense and
water kept out.)
Presentation downloadable from www.tececo.com 52
Corrosion in Portland Cement Concretes
Both carbonation, which
renders the passive iron
oxide coating unstable or
chloride attack (various
theories) result in the
formation of reaction
products with a higher
electrode potential
resulting in anodes with
the remaining passivated
steel acting as a cathode.
Passive Coating Fe3O4 intact
Corrosion
Anode: Fe → Fe+++ 2e- The role of chloride in Corrosion
Cathode: ½ O2 + H2O +2e- → Anode: Fe → Fe+++ 2e-
2(OH)- Cathode: ½ O2 + H2O +2e- → 2(OH)-
Fe++ +2Cl- → FeCl2
Fe++ + 2(OH)- → Fe(OH)2 + O2 → FeCl2 + H2O + OH- → Fe(OH)2 + H+ + 2Cl-
Fe2O3 and Fe2O3.H2O (iron oxide Fe(OH)2 + O2 → Fe2O3 and Fe2O3.H2O
and hydrated iron oxide or rust) Iron hydroxides react with oxygen to form rust.
Note that the chloride is “recycled” in the reaction
and not used up.
Presentation downloadable from www.tececo.com 53
Reduced Delayed Reactions
A wide range of delayed reactions can
occur in Portland cement based concretes
– Delayed alkali silica and alkali carbonate
reactions
– The delayed formation of ettringite and
thaumasite
– Delayed hydration of minerals such as dead
burned lime and magnesia.
Delayed reactions cause dimensional
distress and possible failure.
Presentation downloadable from www.tececo.com 54
Reduced Delayed Reactions (2)
Delayed reactions do not appear to occur to the
same extent in TecEco cements.
– A lower long term pH results in reduced reactivity after the
plastic stage.
– Potentially reactive ions are trapped in the structure of
brucite.
– Ordinary Portland cement concretes can take years to dry out
however the reactive magnesia in Tec-cement concretes
consumes unbound water from the pores inside concrete,
probably holding it for slow release to extended hydration
reactions of Ca silicates.
– Magnesia dries concrete out from the inside. Reactions do
not occur without water.
Presentation downloadable from www.tececo.com 55
Durability - Reduced Salt & Acid Attack
Brucite has always played a protective role during
salt attack. Putting it in the matrix of concretes in
introduces considerable durability.
Brucite does not react with salts because it is a least
5 orders of magnitude less soluble, mobile or
reactive.
– Ksp brucite = 1.8 X 10-11
– Ksp Portlandite = 5.5 X 10-6
TecEco cements are more acid resistant than
Portland cement
– This is because of the relatively high acid resistance (?) of
Lansfordite and nesquehonite compared to calcite or
aragonite
Presentation downloadable from www.tececo.com 56
Bingham Plastic Rheology
Finely ground reactive
magnesia consumes water but Smaller grains (eg
also acts as a plasticiser microsilica.
Portland cement grains
Mean size 10 - 15 The magnesia
micron grains act as ball
bearings to the
Portland cement
grains and also fill
Reactive Magnesia the voids densifying
grains Mean size 5 - the whole
6 micron
There are also surface charge affects
Presentation downloadable from www.tececo.com 57
Bingham Plastic Rheology
It is not The strongly
known positively
how + Etc. charged small
deep O
+ + Mg++ atoms
+
these + O +
attract water
layers + - (which is polar) in
get
O
O -
+
O
-
Mg++ - deep layers
+
+ affecting the
- -
O O
+
rheological
+ O - +
properties and
+ + making concretes
+
less “sticky” with
Etc. added pozzolan
Ca++ = 114, Mg++ = 86 picometres
Presentation downloadable from www.tececo.com 58
Rheology
Second layer low slump tec-
Tech Tendons
cement concrete
First layer low slump tec-cement
concrete
TecEco concretes and mortars are:
– Very homogenous and do not segregate easily. They exhibit good
adhesion and have a shear thinning property.
– Exhibit Bingham plastic qualities and react well to energy input.
– Have good workability.
TecEco concretes with the same water/binder ratio have a
lower slump but greater plasticity and workability.
A range of pumpable composites with Bingham plastic
properties will be required in the future as buildings will be
“printed.”
Presentation downloadable from www.tececo.com 59
Reduced Shrinkage
Net shrinkage is reduced due
to stoichiometric expansion of Legend
Magnesium minerals, and Portland Cement Concretes
reduced water loss.
Tec-Cement Concretes
Drying Shrinkage
Plastic Settlement
Stoichiometric (Chemical) Shrinkage
Stoichiometric (Chemical) Expansion
Log Time, days
Dimensional change such as shrinkage
results in cracking and reduced durability
Presentation downloadable from www.tececo.com 60
Reduced Shrinkage – Less Cracking
Cracking, the symptomatic
Large Cement Company result of shrinkage, is
undesirable for many reasons,
Test Age but mainly because it allows
(days) Microstrain entry of gases and ions
reducing durability. Cracking
7 133 can be avoided only if the
stress induced by the free
14 240 shrinkage strain, reduced by
creep, is at all times less than
28 316 the tensile strength of the
concrete. Tec-cements also
56 470 have greater tensile strength.
Tec-cements exhibit higher tensile strength and
less shrinkage and therefore less cracking
Presentation downloadable from www.tececo.com 61
Volume Changes on Hydration
When magnesia hydrates it expands:
MgO (s) + H2O (l) ↔ Mg(OH)2.nH2O (s)
40.31 + 18.0 ↔ 58.3 (minimum) molar mass
11.2 + liquid ↔ 24.3 (minimum) molar volumes
Up to 116.96% solidus expansion depending on
whether the water is coming from stoichiometric
mix water, bleed water or from outside the
system. In practice less as the water comes from
mix and bleed water.
The molar volume (L.mol-1)is equal to the molar
mass (g.mol-1) divided by the density (g.L-1).
Presentation downloadable from www.tececo.com 62
Volume Changes on Carbonation
Consider what happens when Portlandite
carbonates:
Ca(OH)2 + CO2 CaCO3
74.08 + 44.01 ↔ 100 molar mass
33.22 + gas ↔ 36.93 molar volumes
– Slight expansion. But shrinkage from surface water
loss
Compared to brucite forming nesquehonite as
it carbonates:
Mg(OH)2 + CO2 MgCO3.3H2O
58.31 + 44.01 ↔ 138.32 molar mass
24.29 + gas ↔ 74.77 molar volumes
– 307 % expansion (less water volume reduction) and
densification of the surface preventing further
ingress of CO2 and carbonation. Self sealing?
The molar volume (L.mol-1)is equal to the molar
mass (g.mol-1) divided by the density (g.L-1).
Presentation downloadable from www.tececo.com 63
Dimensionally Control Over Concretes
During Curing?
Portland cement concretes shrink around
.05%. Over the long term much more (>.1%).
– Mainly due to plastic and drying shrinkage.
The use of some wastes as aggregates causes
shrinkage e.g. wood waste in masonry units, thin
panels etc.
By varying the amount and form of magnesia
added dimensional control can be achieved.
Presentation downloadable from www.tececo.com 64
TecEco Cement Concretes –Dimensional Control
Combined – Hydration and Carbonation can
be manipulated to be close to neutral.
– So far we have not observed significant shrinkage in
TecEco tec - cement concretes (5% -10% substitution
OPC) also containing fly ash.
– At some ratio, thought to be around 10% reactive
magnesia and 90% PC volume changes are
optimised as higher additions of MgO reduce
strength.
– The water lost by Portland cement as it shrinks is
used by reactive magnesia as it hydrates also
reducing shrinkage.
Presentation downloadable from www.tececo.com 65
Tec - Cement Concretes – Less or no Dimensional Change
Reactive Magnesia
?
+.05% +- Fly Ash?
? ?
?
?
Composite Curve ?
? ? 28 90 days
Tec-Cement Concrete
-.05%
Portland Cement
HYDRATION THEN CARBONATION OF REACTIVE MAGNESIA AND OPC
It may be possible to engineer a particle with slightly delayed expansion to
counterbalance the expansion and then shrinkage concretes containing gbfs.
Presentation downloadable from www.tececo.com 66
Less Freeze - Thaw Problems
Denser concretes do not let water in.
Brucite will to a certain extent take up internal
stresses
When magnesia hydrates it expands into the pores
left around hydrating cement grains:
MgO (s) + H2O (l) ↔ Mg(OH)2 (s)
40.31 + 18.0 ↔ 58.3 molar mass
11.2 + 18.0 ↔ 24.3 molar volumes
39.20 ↔ 24.3 molar volumes
38% air voids are created in space that was occupied
by magnesia and water!
Air entrainment can also be used as in conventional
concretes
TecEco concretes are not attacked by the salts used
on roads
Presentation downloadable from www.tececo.com 67
Eco-Cements
Eco-cements are similar but potentially superior to
lime mortars because:
– The calcination phase of the magnesium thermodynamic cycle
takes place at a much lower temperature and is therefore more
efficient.
– Magnesium minerals are generally more fibrous and acicular than
calcium minerals and hence add microstructural strength.
– Water forms part of the binder minerals that forming making the
cement component go further. In terms of binder produced for
starting material in cement, eco-cements are nearly six times more
efficient.
– Magnesium hydroxide in particular and to some extent the
carbonates are less reactive and mobile and thus much more
durable.
Presentation downloadable from www.tececo.com 68
Eco-Cement pH Curves
pH
HYPOTHETICAL pH CURVES
OVER TIME
13.7 ? Eco – Cement Concrete with 75% reactive magnesia
?
11.2 ? (red). Ph maintained by brucite and hydrated carbonates
10.5 OPC Concrete
PC Concrete – Ph maintained by lime and
calcite (Ca(OH)2 carbonates more readily.)
Plastic Log Time
Stage
Presentation downloadable from www.tececo.com 69
Eco-Cement Strength Development
Eco-cements gain early strength from the hydration of
PC.
Later strength comes from the carbonation of brucite
forming an amorphous phase, lansfordite and
nesquehonite.
Strength gain in eco-cements is mainly microstructural
because of
– More ideal particle packing (Brucite particles at 4-5 micron are
under half the size of cement grains.)
– The natural fibrous and acicular shape of magnesium
carbonate minerals which tend to lock together.
More binder is formed than with calcium
– Total volumentric expansion from magnesium oxide to
lansfordite is for example 473 volume %.
Presentation downloadable from www.tececo.com 70
Eco-Cement Concrete Strength Gain Curve
HYPOTHETICAL STRENGTH
GAIN CURVE OVER TIME
(Pozzolans added)
MPa
OPC Concrete ?
?
? Eco – Cement Concrete with
? 50% reactive magnesia
3 7 14 28 Log Days
Plastic
Eco-cement bricks, blocks, pavers and mortars etc. take a
Stage
while to come to the same or greater strength than OPC
formulations but are stronger than lime based formulations.
Presentation downloadable from www.tececo.com 71
Eco-Cement Micro-Structural Strength
Elongated growths of
lansfordite and Portland clinker minerals
nesquehonite near the (black). Hydration
surface, growing inwards providing Imperfect
over time and providing structural framework.
microstructural strength.
Micro spaces filled with
hydrating magnesia
Flyash grains (red) (→brucite) – acting as a
reacting with lime “waterproof glue”
producing more CSH and
if alkaline enough
conditions bonding
through surface Mysterious amorphous
hydrolysis. Also acting as phase?
micro aggregates.
Presentation downloadable from www.tececo.com 72
Carbonation
Because magnesium has a low molecular weight,
proportionally a greater amount of CO2 is captured.
Carbonation results in significant sequestration
because of the shear volumes involved.
Carbonation adds strength.
Carbonates are the stable phases of both calcium and
magnesium.
The formation of carbonates lowers the pH of concretes
compromising the stability of the passive oxide coating
on steel.
Some steel reinforced structural concrete could be
replaced with fibre reinforced porous carbonated
concrete.
Presentation downloadable from www.tececo.com 73
Chemistry of Carbonation
There are a number of carbonates of magnesium. The main
ones appear to be an amorphous phase, lansfordite and
nesquehonite.
The carbonation of magnesium hydroxide does not proceed as
readily as that of calcium hydroxide.
– Gor Brucite to nesquehonite = - 38.73 kJ.mol-1
– Compare to Gor Portlandite to calcite = -64.62 kJ.mol-1
The dehydration of nesquehonite to form magnesite is not
favoured by simple thermodynamics but may occur in the long
term under the right conditions.
Gor nesquehonite to magnesite = 8.56 kJ.mol-1
– But kinetically driven by desiccation during drying.
Reactive magnesia can carbonate in dry conditions – so keep
bags sealed!
For a full discussion of the thermodynamics see our technical
documents.
TecEco technical documents on the web
cover the important aspects of carbonation.
Presentation downloadable from www.tececo.com 74
Ramifications of Carbonation
Magnesium Carbonates.
– The magnesium carbonates that form at the surface of tec –
cement concretes expand significantly thereby sealing off further
carbonation.
– Lansfordite and nesquehonite are stronger and more acid
resistant than calcite or aragonite.
– The curing of eco-cements in a moist - dry alternating environment
seems to encourage carbonation.
Portland Cement Concretes
– Carbonation proceeds relatively rapidly at the surface. Vaterite
followed by Aragonite and Calcite is the principal product and
lowers the pH to around 8.2
Presentation downloadable from www.tececo.com 75
Proof of Carbonation - Minerals Present After 18 Months
XRD showing carbonates and
other minerals before removal of
carbonates with HCl in a simple
Mix (70 Kg PC, 70 Kg MgO,
colouring oxide .5Kg, sand
unwashed 1105 Kg)
Presentation downloadable from www.tececo.com 76
Proof of Carbonation - Minerals Present After 18 Months and
Acid Leaching
XRD Showing minerals remaining
after their removal with HCl in a
simple mix (70 Kg PC, 70 Kg
MgO, colouring oxide .5Kg, sand
unwashed 1105 Kg)
Presentation downloadable from www.tececo.com 77
TecEco Binders - Solving Waste Problems
There are huge volumes of concrete produced annually ( 2
tonnes per person per year.)
An important objective should be to make cementitous
composites that can utilise wastes.
TecEco cements provide a benign environment suitable for
waste immobilisation
Many wastes such as fly ash, sawdust , shredded plastics
etc. can improve a property or properties of the
cementitious composite.
There are huge materials flows in both wastes and
building and construction. TecEco technology will
lead the world in the race to incorporate wastes in
cementitous composites
Presentation downloadable from www.tececo.com 78
TecEco Binders - Solving Waste Problems (2)
TecEco cementitious composites represent a
cost affective option for both use and
immobilisation of waste.
– Lower reactivity
• less water
• lower pH
– Reduced solubility of heavy metals
• less mobile salts
– Greater durability.
• Denser.
• Impermeable (tec-cements).
• Dimensionally more stable with less shrinkage and cracking.
– Homogenous.
– No bleed water.
TecEco Technology Converting Waste to Resource
Presentation downloadable from www.tececo.com 79
Role of Brucite in Immobilization
In a Portland cement brucite matrix
– PC takes up lead, some zinc and germanium
– Brucite and hydrotalcite are both excellent hosts for toxic and
hazardous wastes.
– Heavy metals not taken up in the structure of Portland cement
minerals or trapped within the brucite layers end up as
hydroxides with minimal solubility. The brucite in TecEco cements
Layers of has a structure comprising
electronically electronically neutral layers and
neutral brucite Van der
suitable for waals is able to accommodate a wide
trapping bonding variety of extraneous
balanced holding the
cations and layers substances between the layers
anions as well together. and cations of similar size
as other
substances. substituting for magnesium
Salts and
other
within the layers and is known
substances to be very suitable for toxic and
trapped
between
hazardous waste
the layers. immobilisation.
Presentation downloadable from www.tececo.com 80
Lower Solubility of Metal Hydroxides
There is a 104 difference
Concentration of Dissolved Metal, (mg/L)
Pb(OH) *Equilibrium
2
10 Cr(OH) 3 pH’s in pure
Zn(OH) 2 water, no
other ions
100 Ag(OH) present. The
Cu(OH) 2 solubility of
Ni(OH) 2 toxic metal
10 -2 hydroxides is
Cd(OH) 2 generally less
Equilibrium pH of brucite at around pH
10 -4 10.52 than at
is 10.52 (more ideal)*
higher pH’s.
10 -6
6 7 8 9 10 11 12 13 14
Equilibrium pH of
Portlandite is 12.35*
Presentation downloadable from www.tececo.com 81
TecEco Materials as Fire Retardants
The main phase in TecEco tec - cement concretes is Brucite.
The main phases in TecEco eco-cements are Lansfordite
and nesquehonite.
Brucite, Lansfordite and nesquehonite are excellent fire
retardants and extinguishers.
At relatively low temperatures
– Brucite releases water and reverts to magnesium oxide.
Mg(OH)2 ↔ MgO + H2O
– Lansfordite and nesquehonite releases CO2 and water and convert to
magnesium oxide.
MgCO3.nH2O ↔ MgO + CO2 + H2O
Fires are therefore not nearly as aggressive resulting in less
damage to structures.
Damage to structures results in more human losses that
direct fire hazards.
Presentation downloadable from www.tececo.com 82
TecEco Cement
Implementation
Summary
Presentation downloadable from www.tececo.com 83
High Performance-Lower Construction Costs
Less binders (OPC + magnesia) for the same strength.
Faster strength gain even with added pozzolans.
Elimination of shrinkage reducing
associated costs. Foolproof
Tolerance and consumption of water. Concrete?
Reduction in bleed water enables finishing of lower
floors whilst upper floors still being poured and
increases pumpability.
Cheaper binders as less energy required
Increased durability will result in lower
costs/energies/emissions due to less frequent
replacement.
Because reactive magnesia is also an excellent
plasticiser, other costly additives are not required for
this purpose.
A wider range of aggregates can be utilised without
problems reducing transport and other
costs/energies/emissions.
Presentation downloadable from www.tececo.com 84
TecEco Concretes - Lower Construction Costs (2)
Homogenous, do not segregate with pumping or work.
Easier placement and better finishing.
Reduced or eliminated carbon taxes.
Eco-cements can to a certain extent be recycled.
TecEco cements utilise wastes many of which improve
properties.
Improvements in insulating capacity and other properties will
result in greater utility.
Products utilising TecEco cements such as masonry and
precast products can in most cases utilise conventional
equipment and have superior properties.
A high proportion of brucite compared to Portlandite is water
and of Lansfordite and nesquehonite compared to calcite is
CO2.
– Every mass unit of TecEco cements therefore produces a greater volume
of built environment than Portland and other calcium based cements.
Less need therefore be used reducing costs/energy/emissions.
Presentation downloadable from www.tececo.com 85
Summary
Simple, smart and sustainable?
– TecEco cement technology has resulted in potential solutions to a
number of problems with Portland and other cements including
shrinkage, durability and corrosion and the immobilisation of many
problem wastes and will provides a range of more sustainable
building materials.
Climate Change Pollution
Durability Corrosion
Strength Delayed Reactions
Placement , Finishing Rheology
Shrinkage Carbon Taxes
The right technology at the right time?
– TecEco cement technology addresses important triple bottom line
issues solving major global problems with positive economic and
social outcomes.
Presentation downloadable from www.tececo.com 86
TecEco Doing
Things
Presentation downloadable from www.tececo.com 87
The Use of Eco-Cements for Building Earthship Brighton
By Taus Larsen, (Architect, Low Carbon Network Ltd.)
The Low Carbon Network (www.lowcarbon.co.uk) was established to raise awareness of the links between
buildings, the working and living patterns they create, and global warming and aims to initiate change
through the application of innovative ideas and approaches to construction. England’s first Earthship is
currently under construction in southern England outside Brighton at Stanmer Park and TecEco
technologies have been used for the floors and some walling.
Earthships are exemplars of low-carbon design, construction and living and were invented and developed in the USA
by Mike Reynolds over 20 years of practical building exploration. They are autonomous earth-sheltered buildings
independent from mains electricity, water and waste systems and have little or no utility costs.
For information about the Earthship Brighton and other projects please go to the TecEco web site.
Presentation downloadable from www.tececo.com 88
Repair of Concrete Blocks. Clifton Surf Club
The Clifton Surf Life Saving Club was built by first
pouring footings, On the footings block walls were
erected and then at a later date concrete was laid in
between.
As the ground underneath the footings was sandy, wet
most of the time and full of salts it was a recipe for
disaster.
Predictably the salty water rose up through the footings
and then through the blocks and where the water
evaporated there was strong efflorescence, pitting, loss
of material and damage.
The TecEco solution was to make up a
formulation of eco-cement mortar which we
doctored with some special chemicals to prevent
the rise of any more moisture and salt.
The solution worked well and appears to have
stopped the problem.
Presentation downloadable from www.tececo.com 89
Mike Burdon’s Murdunna Works
Mike Burdon, Builder and Plumber.
I work for a council interested in sutainability and
have been involved with TecEco since around
2001 in a private capacity helping with large
scale testing of TecEco tec-cements at our
shack.
I am interested in the potentially superior
strength development and sustainability aspects.
To date we have poured two slabs, footings, part
of a launching ramp and some tilt up panels
using formulations and materials supplied by
John Harrison of TecEco. I believe that research
into the new TecEco cements essential as
overall I have found:
1. The rheological performance even without plasticizer was excellent. As testimony to this the contractors on the site
commented on how easy the concrete was to place and finish.
2. We tested the TecEco formulations with a hired concrete pump and found it extremely easy to pump and place. Once in
position it appeared to “gel up” quickly allowing stepping for a foundation to a brick wall.
3. Strength gain was more rapid than with Portland cement controls from the same premix plant and continued for longer.
4. The surfaces of the concrete appeared to be particularly hard and I put this down to the fact that much less bleeding was
observed than would be expected with a Portland cement only formulation
Presentation downloadable from www.tececo.com 90
Tec-Cement Slab Whittlesea, Vic. Australia
On 17th March 2005 TecEco
poured the first commercial slab
in the world using tec-cement
concrete with the assistance of
one of the larger cement and
pre-mix companies.
– The formulation strategy was to
adjust a standard 20 MPa high fly
ash (36%) mix from the company as
a basis of comparison.
– Strength development, and in
particular early strength
development was good.
Interestingly some 70 days later the
slab is still gaining strength at the
rate of about 5 MPa a month. Strength Development of Tec-Cement Concrete
– Also noticeable was the fact that the
concrete was not as "sticky" as it 30
normally is with a fly ash mix and 25
that it did not bleed quite as much. Strength, MPa
20
Compressive
– Shrinkage was low. 7 days - 133 15 Strength
10
micro strains, 14 days - 240 micro
strains, 28 days - 316 micros strains 5
and at 56 days - 470 microstrains. 0
0 5 10 15 20 25 30
Days w ater cured
Presentation downloadable from www.tececo.com 91
Embodied
Energies and
Emissions
Presentation downloadable from www.tececo.com 92
CO2 Abatement in Eco-Cements
For 85 wt% Portland No Capture Capture
Aggregates Cements Capture CO2 CO2. Fly and
15 wt%
15 mass%
Portland
11.25% mass%
reactive
11.25% mass%
reactive
Bottom Ash
Cement 11.25% mass%
cement, 85 magnesia, 3.75 magnesia, 3.75
reactive magnesia,
mass% mass% Portland mass% Portland
Eco-cements in 3.75 mass%
aggregate cement, 85 cement, 85
Portland cement,
porous products mass% mass%
Emissions 85 mass%
aggregate. aggregate.
absorb carbon .32 tonnes to aggregate.
dioxide from the the tonne. Emissions Emissions Emissions
After .37 tonnes to .25 tonnes to the
atmosphere. .126 tonnes to the
carbonation. the tonne. After tonne. After tonne. After
Brucite carbonates Approximately carbonation. carbonation. carbonation.
forming lansfordite, .299 tonne to approximately approximately Approximately .113
the tonne. .241 tonne to .140 tonne to
nesquehonite and tonne to the tonne.
the tonne. the tonne.
an amorphous
phase, completing
the thermodynamic
cycle. Greater Sustainability
.299 > .241 >.140 >.113
Bricks, blocks, pavers, mortars and pavement made using eco-cement, fly
and bottom ash (with capture of CO2 during manufacture of reactive
magnesia) have 2.65 times less emissions than if they were made with
Portland cement.
Presentation downloadable from www.tececo.com 93
Energy – On a Mass Basis
From
From From From Manufacturi
Manufacturi From Manufacturi From Manufacturi ng Process
ng Process Manufacturin ng Process Manufacturin ng Process Energy
Relative to Energy g Process Energy g Process Energy Release
Raw Material Release Energy Relative Release Energy Relative to Release with
Used to 100% Release with Product 100% Release with Mineral 100% Inefficienci
make Efficient Inefficiencies Used in Efficient Inefficiencies Resulting Efficient es
Cement (MJ.tonne-1) (MJ.tonne-1) Cement (MJ.tonne-1) (MJ.tonne-1) in Cement (MJ.tonne-1) (MJ.tonne-1)
Portlan
d
CaCO3 + Cemen Hydrated
Clay 1545.73 2828.69 t 1807 3306.81 OPC 1264.90 2314.77
CaCO3 1786.09 2679.14 Ca(OH)2 2413.20 3619.80
MgCO3 1402.75 1753.44 MgO 2934.26 3667.82 Mg(OH)2 2028.47 2535.59
Presentation downloadable from www.tececo.com 94
Energy – On a Volume Basis
From From From
Manufacturi From Manufacturi From Manufacturi From
Relative ng Process Manufacturin ng Process Manufacturin ng Process Manufacturin
to Raw Energy g Process Energy g Process Relative Energy g Process
Material Release Energy Relative Release Energy to Mineral Release Energy
Used to 100% Release with Product 100% Release with Resulting 100% Release with
make Efficient Inefficiencies Used in Efficient Inefficiencies in Efficient Inefficiencies
Cement (MJ.metre-3) (MJ.metre-3) Cement (MJ.metre-3) (MJ.metre-3) Cement (MJ.metre-3) (MJ.metre-3)
CaCO3 Portland Hydrate
+ Clay 4188.93 7665.75 Cement 5692.05 10416.45 d OPC 3389.93 6203.58
CaCO3 6286.62 8429.93 Ca(OH)2 5381.44 8072.16
MgCO3 4278.39 5347.99 MgO 9389.63 11734.04 Mg(OH)2 4838.32 6085.41
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Global Abatement
Without CO2 With CO2
Capture during Capture during
manufacture manufacture
(billion tonnes) (billion tonnes)
Total Portland Cement Produced Globally 1.80 1.80
Global mass of Concrete (assuming a 12.00 12.00
proportion of 15 mass% cement)
Global CO2 Emissions from Portland Cement 3.60 3.60
Mass of Eco-Cement assuming an 80% 9.60 9.60
Substitution in global concrete use
Resulting Abatement of Portland Cement CO2 2.88 2.88
Emissions
CO2 Emissions released by Eco-Cement 2.59 1.34
Resulting Abatement of CO2 emissions by 0.29 1.53
Substituting Eco-Cement
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Abatement from Substitution
Building Realisti Size of Substit CO2 Emission Emission/Sequestrati Net Abatement
Material to be c% World uted Fact From on from Substituted
substituted Subst- Market Mass ors Material Eco-Cement (Tonne
itution (millio (million (1) Before for Tonne
by n tonnes) Substituti Substitution
TecEco tonnes on Assumed)
technol
ogy
Concretes already have low lifetime energies. Emission Emission Abatem Abatem
s - No s - CO2 ent - No ent
If embodied energies are improved could Capture Capture Capture CO2
substitution mean greater market share? Capture
Bricks 85% 250 212.5 0.28 59.5 57.2 29.7 2.3 29.8
Steel 25% 840 210 2.38 499.8 56.6 29.4 443.2 470.4
Aluminium 20% 20.5 4.1 18.0 73.8 1.1 0.6 72.7 73.2
TOTAL 426.6 20.7 633.1 114.9 59.7 518.2 573.4
Figures are in millions of Tonnes
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