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Implementing Sustainability


Implementing Sustainability Presentation by John Harrison, managing director of TecEco and inventor of Tec and Eco-Cements and the CarbonSafe process. – PowerPoint PPT presentation

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Title: Implementing Sustainability

Implementing Sustainability
Presentation by John Harrison, managing director
of TecEco and inventor of Tec and Eco-Cements and
the CarbonSafe process.
TecEco are in the biggest business on the planet
that of solving global warming waste and water
Our slides are deliberately verbose as most
people download and view them from the net.
Because of time constraints I will have to race
over some slides John Harrison B.Sc. B.Ec.
The Problem. We have a Planet in Crisis
  • In the next 50 years it is crunch time for
  • Fresh Water
  • Global warming
  • Energy
  • Waste Pollution
  • Are you thinking about it? Do you have an answer?

Fresh Water
  • The amount of water in the world is finite. The
    number of us is growing quickly and our water use
    is growing more quickly.
  • A third of the world's population lives in
    water-stressed countries. By 2025, this is
    expected to rise to two-thirds.
  • The world's supply of fresh water is running out.
    Already one person in five has no access to safe
    drinking water.

Global Warming
Rises in the levels of carbon dioxide and other
gases (methane, water vapour)
Are causing a rapid rise in temperature
The Carbon Cycle and Emissions
Emissions from fossil fuels and cement production
are the cause of the global warming problem
Source David Schimel and Lisa Dilling, National
Centre for Atmospheric Research 2003
Energy Crisis
Peak Oil Production (Campell 2004) Most models of
oil reserves, production and consumption show
peak oil around 2010 (Campbell 2005) and serious
undersupply and rapidly escalating prices by
2025. It follows that there will be economic
mayhem unless the cement and concrete industry
acts now to change the energy base of their
Waste Pollution
Waste releases methane, can cause ill health in
the area, leads to the contamination of land,
underground water, streams and coastal waters
(destroying our fisheries) and gives rise to
various nuisances including increased traffic,
noise, odours, smoke, dust, litter and pests.
Most damaging is the release of dangerous
molecules to the global commons
There are various estimates, but we produce about
5-600 million tonnes of waste each year.
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
All these Problems Represent an Opportunity to Do
Something About Them
  • The built environment is made of materials and is
    our footprint on earth.
  • It comprises buildings and infrastructure.
  • Construction materials comprise
  • 70 of materials flows (buildings, infrastructure
  • 40-50 of waste that goes to landfill (15 of
    new materials going to site are wasted.)
  • Over 30 billion tonnes of building materials are
    used annually on a world wide basis.
  • Mostly using virgin natural resources
  • Combined in such a manner they cannot easily be
  • And include many toxic elements.
  • The single biggest materials flow (after water)
    is concrete at around 15 billion tonnes or gt 2
    tonnes per man, woman and child on the planet.

How? - The Techno-Processes Earth Systems
Underlying the techno-process that describes and
controls the flow of matter and energy are
molecular stocks and flows. If out of tune with
nature these moleconomic flows have detrimental
affects on earth systems.
Earth Systems Atmospheric composition, climate,
land cover, marine ecosystems, pollution, coastal
zones, freshwater and salinity.
Detrimental affects on earth systems
Move 500-600 billion tonnesUse some 50 billion
Manipulate, Make and Use
To reduce the impact on earth systems new
technical paradigms need to be invented that
result in underlying molecular flows that mimic
or at least do not interfere with natural flows.
Under Materials Flows in the Techno-Processes are
Molecular Flows
Take ? Manipulate ? Make ? Use ? Waste
? Underlying
molecular flow ?
If the underlying molecular flows are out
of tune with nature there is damage to the
environmente.g. heavy metals, cfcs, chalogen
compounds and CO2
MoleconomicsIs the study of the form
of atoms in molecules, their flow, interactions,
balances, stocks and positions. 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. These flows should mimic or
minimally interfere with natural flows.
There are Detrimental Affects Right Through the
Detrimental Linkages that affect earth system
Take manipulate and make impacts
End of lifecycle impacts
Materials are in the Techno-sphere Utility zone
There is no such place as away
Materials are everything between the take and
waste and affect earth system flows.
We Must Learn from Nature (Biomimicry)
  • Nature is very efficient. The waste from one
    plant or animal is the food or home for another.
  • By studying Nature we learn who we are, what we
    are and how we are to be. (Wright, F.L.
  • In nature photosynthesis balances respiration.
  • We have nothing that balances our emissions in
    the techno-process
  • There is a strong need for similar efficiency and

By learning from Nature we can all live together
  • The term biomimicry was popularised by the book
    of the same name written by Janine Benyus
  • Biomimicry is a method of solving problems that
    uses natural processes and systems as a source of
    knowledge and inspiration.
  • It involves nature as model, measure and mentor.

The theory behind biomimicry is that natural
processes and systems have evolved over several
billion years through a process of research and
development commonly referred to as evolution. A
reoccurring theme in natural systems is the
cyclical flow of matter in such a way that there
is no waste of matter or energy.
Nature is very economical about all Processes. We
must also be MUCH more economical
Economically Driven Sustainability
The challenge is to harness human behaviours
which underlay economic supply and demand
phenomena by changing the technical paradigm in
favour of making carbon dioxide and other wastes
resources for new materials with lower take and
waste impacts and more energy efficient
Sustainable processes are more efficient and
therefore more economic. Natural ecosystems can
be 100 efficient. What is needed are new
technologies that allow material and energy flows
to more closely mimic natural ecosystems. Innovati
on will deliver these new technical paradigms.
Sustainability will not happen by relying on
people to do the right thing
Sustainability Culture Technology
Increase in demand/price ratio for sustainability
due to educationally induced cultural drift.

Greater Value/for impact (Sustainability) and
economic growth
Equilibrium shift
New Technical Paradigms are required that deliver
Increase in supply/price ratio for more
sustainable products due to innovative paradigm
shifts in technology.

One aspect of sustainability is that it is where
Culture and Technology meet.
Changing the Technology Paradigm
We need materials that require less energy to
make them, that last much longer and that
contribute properties that reduce lifetime
energies. The key is to change the technology
  • By enabling us to make productive use of
    particular raw materials, technology determines
    what constitutes a physical resource1
  • Pilzer, Paul Zane, Unlimited Wealth, The Theory
    and Practice of Economic Alchemy, Crown
    Publishers Inc. New York.1990

Examples of Economic Changes in Technical
Paradigms that result in Greater Sustainability
Light Globes - A Recent Paradigm Shift in
Technology Reducing Energy Consumption Light
Globes in the last 10 years have evolved from
consuming around 100 watts per 1700 lumens to
less that 20 watts per 1700 lumens. As light
globes account for around 30 of household energy
this is as considerable saving.
Robotics - A Paradigm Shift in Technology that
will fundamentally affect Building and
Construction Construction in the future will be
largely done by robots because it will be more
economic to do so. Like a color printer different
materials will be required for different parts of
structures, and wastes such as plastics will
provide many of the properties required for the
cementitious composites of the future used. A
non-reactive binder such as TecEco tec-cements
can supply the right rheology, and like a
printer, very little will be wasted.
The TecEco CarbonSafe Industrial Ecology
InputsBrinesWaste AcidCO2
OutputsGypsum, Sodium bicarbonate, Salts,
Building materials, Potable water
We must design whole new technical paradigms that
reverse many of our problem molecular flows
A Low Energy Post Carbon Waste Age?
Maybe then we can move confidently into a more
sustainable future.
The construction industry can be uniquely
responsible for helping achieve this transition
Innovative New Materials - the Key to
The choice of materials controls emissions,
lifetime and embodied energies, user comfort, use
of recycled wastes, durability, recyclability and
the properties of wastes returned to the
There is no such place as away, only a global
Re - Engineering Materials What we Build With
  • To solve environmental problems we need to
    understand more about materials in relation to
    the environment.
  • the way their precursors are derived and their
    degradation products re assimilated
  • and how we can reduce the impact of these
  • what energies drive the evolution, devolution and
    flow of materials
  • and how we can reduce these energies
  • how materials impact on lifetime energies
  • With the knowledge gained re-design materials to
    not only be more sustainable but more sustainable
    in use

Environmental problems are the result of
inherently flawed materials, materials flows and
energy systems
Changing the Techno-process
Take gt manipulate gt make gt use gt waste Driven
by fossil fuel energy with detrimental effects on
earth systems.
Improving the sustainability of materials used to
create the built environment will reduce the
impact of the take and waste phases of the
Huge Potential for Sustainable Materials
  • Reducing the impact of the take and waste phases
    of the techno-process.
  • including carbon in materialsthey are
    potentially carbon sinks.
  • including wastes forphysical properties aswell
    as chemical compositionthey become resources.
  • re engineeringmaterials toreduce the
    lifetimeenergy of buildings

Many wastes can contribute to physical properties
reducing lifetime energies
Utilizing Carbon and Wastes (Biomimicry)
  • During earth's geological history large tonnages
    of carbon were put away as limestone and other
    carbonates and as coal and petroleum by the
    activity of plants and animals.
  • Sequestering carbon in magnesium binders and
    aggregates in the built environment mimics nature
    in that carbon is used in the homes or skeletal
    structures of most plants and animals.

In eco-cement blocks and mortars the binder is
carbonate and the aggregates are preferably wastes
We all use carbon and wastes to make our homes!
Impact of the Largest Material Flow - Cement and
  • 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 currently 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
  • Much more concrete is used than any other
    building material.

TecEco Pty. Ltd. have benchmark technologies for
improvement in sustainability and properties
Embodied Energy of Building Materials
Concrete is relatively environmentally friendly
and has a relatively low embodied energy
Downloaded from
es/embodied/embodied.htm (last accessed 07 March
Average Embodied Energy in Buildings
Most of the embodied energy in the built
environment is in concrete.
Because so much concrete is used there is a huge
opportunity for sustainability by reducing the
embodied energy, reducing the carbon debt (net
emissions) and improving properties that reduce
lifetime energies.
Downloaded from
es/embodied/embodied.htm (last accessed 07 March
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 of global anthropogenic CO2.
  • Pearce, F., "The Concrete Jungle Overheats", New
    Scientist, 19 July, No 2097, 1997 (page 14).

Arguments that we should reduce cement production
relative to other building materials are nonsense
because concrete is the most sustainable building
material there is. The challenge is to make it
more sustainable.
Cement Production Carbon Dioxide Emissions
Between tec, eco and enviro-cements TecEco can
provide a viable much more sustainable
TecEco Technologies Take Concrete into the Future
  • More rapid strength gain even with added
  • More supplementary materials can be used reducing
    costs and take and waste impacts.
  • Higher strength/binder ratio
  • Less cement can be used reducing costs and take
    and waste impacts
  • More durable concretes
  • Reducing costs and take and waste impacts.
  • Use of wastes
  • Utilizing carbon dioxide
  • Magnesia component can be made using non fossil
    fuel energy and CO2 captured during production.

Tec -Cements
Tec Eco-Cements
TecEco Binder Systems
Hydration of the various components of Portland
cement for strength.
Reaction of alkali with pozzolans (e.g. lime with
fly ash.) for sustainability, durability and
TecEco concretes are a system of blending
reactive magnesia, Portland cement and usually a
pozzolan with other materials and are a key
factor for sustainability.
Hydration of magnesia gt brucite for strength,
workability, dimensional stability and
durability. In Eco-cements carbonation of brucite
gt nesquehonite, lansfordite and an amorphous
phase for sustainability.
TecEco Formulations
  • Tec-cements (5-15 MgO, 85-95 OPC)
  • 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 voidspaste
    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 its 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 (15-95 MgO, 85-5 OPC)
  • 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
  • Enviro-cements (5-15 MgO, 85-95 OPC)
  • 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.

Tec Eco-Cement Theory
  • Many Engineering Issues are Actually
    Mineralogical Issues
  • Problems with Portland cement concretes are
    usually resolved by the band aid engineering
    fixes. e.g.
  • Use of calcium nitrite, silanes, cathodic
    protection or stainless steel to prevent
  • Use of coatings to prevent carbonation.
  • Crack control joins to mitigate the affects of
    shrinkage cracking.
  • Plasticisers to improve workability.
  • Portlandite and water are the weakness of
  • TecEco remove Portlandite it and replacing it
    with magnesia which hydrates to Brucite.
  • The hydration of magnesia consumes significant

Tec Eco-Cement Theory
  • Portlandite (Ca(OH)2) is too soluble, mobile and
  • 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, consuming significant water and
    concentrating alkalis forming Brucite which is
    another alkali, but much less soluble, mobile or
    reactive than Portlandite.
  • In Eco-Cements brucite carbonates forming
    hydrated compounds with greater volume

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 raise the early Ph.
  • Increasing non hydraulic strength giving
  • 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

Reactive MgO is a new tool to be understood with
profound affects on most properties
Strength with Blend Porosity
Tec-cement concretes
Eco-cement concretes
High Porosity
Enviro-cement concretes
High OPC
High Magnesia
TecEco Technology in Practice
gt 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.
  • Also noticeable was the fact that the concrete
    was not as "sticky" as it normally is with a fly
    ash mix and that it did not bleed quite as much.
  • Shrinkage was low. 7 days - 133 micro strains, 14
    days - 240 micro strains, 28 days - 316 micros
    strains and at 56 days - 470 microstrains.

TecEco Technology in Practice
gt Porous Pavement
Allow many mega litres of good fresh water to
become contaminated by the pollutants on our
streets and pollute coastal waterways
Capture and cleanse the water for our use?
TecEco Technology in Practice
gt Whittlesea, Vic. Australia
  • First Eco-cement mud bricks and mortars in
  • Tested up twice as strong as the PC controls
  • Mud brick addition rate 2.5
  • Addition rate for mortars 18 not 13 because of
    molar ratio volume increase with MgO compared to

TecEco Technology in Practice
gt Earthship Brighton, UK
By Taus Larsen, (Architect, Low Carbon Network
Ltd.) The Low Carbon Network (
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.
Englands 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.
TecEco Technology in Practice
gt Clifton Surf Life Saving 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
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.
TecEco Technology in Practice
gt Mike Burdons 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

TecEco Technology in Practice
gt DJ Motors, Hobart
Tec-Cement concretes exhibit little or no
shrinkage. At 10 substitution of MgO for PC the
shrinkage is less than half normal. At 18
substitution with no added pozzolan there was no
measurable shrinkage or expansion.
The above photo shows a tec-cement concrete
topping coat (with no flyash) 20mm thick away
from the door and 80 mm thick near the door. Note
that there has been no tendency to push the tiles
or shrink away from the borders as would normally
be the case.
TecEco Technology in Practice
gt Island Block and Paver,Tasmania
TecEco Tec and Eco-Cement blocks are now being
made commercially in Tasmania and with freight
equalization may be viable to ship to Victoria
for your green project. Hopefully soon we will
have a premix mortar available that uses
TecEco Technology in Practice
gt Foamed Concretes
Foamed TecEco cement concretes can be produced to
about 30 weight reduction in concrete trucks
using cellflow additive or to about 70 weight
reduction using a foaming machine with mearlcrete
additive (or equivalents)
Clayton Sth  MELBOURNE  AUSTRALIA 3169PH  61 3
9547 0255    FX  61 3 9547 0266
Tec Eco Cement Foamed Concrete Slabs
gt Foamed Concrete Slabs
Clayton Sth  MELBOURNE  AUSTRALIA 3169PH  61 3
9547 0255    FX  61 3 9547 0266
TecEco Technology in Practice
gt Foamed Concretes Panels
Imagine a conventional steel frame section with a
foamed concrete panel built in adding to
structural strength, providing insulation as well
as the external cladding of a structure. Rigid
Steel Framing have developed just such a panel
and have chosen to use TecEco cement technology
for the strength, ease of use and finish. Patents
applied for by Rigid Steel Framing
Solutions in Steel ABN 48 103 573 039   TEL 61 7 3271 3900FAX 61 7 3271 270180 Mica StreetCarole Park 4300QueenslandAustralia
Please direct commercial enquiries to Rigid Steel
Framing at
TecEco Technology in Practice
gt Foamed Concretes Panels
Rear view of test panels showing tongue and
groove and void for services.Interior
plasterboard is fixed conventionally over gap for
  • 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 much more efficient.
  • Magnesium hydroxide in particular and to some
    extent the carbonates are less reactive and
    mobile and thus much more durable.

  • Have high proportions of reactive magnesium oxide
  • Carbonate like lime
  • Generally used in a 15-112 paste basis because
    much more carbonate binder is produced than
    with lime
  • MgO H2O ltgt Mg(OH)2
  • Mg(OH)2 CO2 H2O ltgt MgCO3.3H2O
  • 58.31 44.01 ltgt 138.32 molar mass (at least!)
  • 24.29 gas ltgt 74.77 molar volumes (at least!)
  • 307 expansion (less water volume reduction)
    producing much more binder per mole of MgO than
    lime (around 8 times)
  • Carbonates tend to be fibrous adding significant
    micro structural strength compared to lime

Mostly CO2 and water
As Fred Pearce reported in New Scientist Magazine
(Pearce, F., 2002), There is a way to make our
city streets as green as the Amazon rainforest.
CO2 Abatement in Eco-Cements
No Capture11.25 mass reactive magnesia, 3.75
mass Portland cement, 85 mass
aggregate. Emissions.37 tonnes to the tonne.
After carbonation. approximately .241 tonne to
the tonne.
Portland Cements15 mass Portland cement, 85
mass aggregate Emissions.32 tonnes to the
tonne. After carbonation. Approximately .299
tonne to the tonne.
Capture CO211.25 mass reactive magnesia, 3.75
mass Portland cement, 85 mass
aggregate. Emissions.25 tonnes to the tonne.
After carbonation. approximately .140 tonne to
the tonne.
Capture CO2. Fly and Bottom Ash11.25 mass
reactive magnesia, 3.75 mass Portland cement, 85
mass aggregate. Emissions.126 tonnes to the
tonne. After carbonation. Approximately .113
tonne to the tonne.
For 85 wt Aggregates 15 wt Cement
Eco-cements in porous products absorb carbon
dioxide from the atmosphere. Brucite carbonates
forming lansfordite, nesquehonite and an
amorphous phase, completing the thermodynamic
Greater Sustainability
.299 gt .241 gt.140 gt.113Bricks, 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.
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
  • The natural fibrous and acicular shape of
    magnesium carbonate minerals which tend to lock
  • More binder is formed than with calcium
  • Total volumetric expansion from magnesium oxide
    to lansfordite is for example volume 811.

Eco-Cement Strength Gain Curve
Eco-cement bricks, blocks, pavers and mortars
etc. take a while to come to the same or greater
strength than OPC formulations but are stronger
than lime based formulations.
Chemistry of Eco-Cements
  • 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
  • The dehydration of nesquehonite to form magnesite
    is not favoured by simple thermodynamics but may
    occur in the long term under the right
  • ?Gor nesquehonite to magnesite 8.56 kJ.mol-1
  • But kinetically driven by desiccation during
  • 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.
Eco-Cement Reactions
Eco-Cement Micro-Structural Strength
  • Eco-cement is based on blending reactive
    magnesium oxide with other hydraulic cements and
    then allowing the Brucite and Portlandite
    components to carbonate in porous materials such
    as concretes blocks and mortars.
  • Magnesium is a small lightweight atom and the
    carbonates that form contain proportionally a lot
    of CO2 and water and are stronger because of
    superior microstructure.
  • The use of eco-cements for block manufacture,
    particularly in conjunction with the kiln also
    invented by TecEco (The Tec-Kiln) would result in
    sequestration on a massive scale.
  • As Fred Pearce reported in New Scientist Magazine
    (Pearce, F., 2002), There is a way to make our
    city streets as green as the Amazon rainforest.

Ancient and modern carbonating lime mortars are
based on this principle
Aggregate Requirements for Carbonation
  • The requirements for totally hydraulic limes and
    all hydraulic concretes is to minimise the amount
    of water for hydraulic strength and maximise
    compaction and for this purpose aggregates that
    require grading and relatively fine rounded sands
    to minimise voids are required
  • For carbonating eco-cements and lime mortars on
    the on the hand the matrix must breathe i.e.
    they must be porous
  • requiring a coarse fraction to cause physical air
    voids and some vapour permeability.
  • Coarse fractions are required in the aggregates

CO2 Abatement in Eco-Cements
No Capture11.25 mass reactive magnesia, 3.75
mass Portland cement, 85 mass
aggregate. Emissions.37 tonnes to the tonne.
After carbonation. approximately .241 tonne to
the tonne.
Portland Cements15 mass Portland cement, 85
mass aggregate Emissions.32 tonnes to the
tonne. After carbonation. Approximately .299
tonne to the tonne.
Capture CO211.25 mass reactive magnesia, 3.75
mass Portland cement, 85 mass
aggregate. Emissions.25 tonnes to the tonne.
After carbonation. approximately .140 tonne to
the tonne.
Capture CO2. Fly and Bottom Ash11.25 mass
reactive magnesia, 3.75 mass Portland cement, 85
mass aggregate. Emissions.126 tonnes to the
tonne. After carbonation. Approximately .113
tonne to the tonne.
For 85 wt Aggregates 15 wt Cement
Eco-cements in porous products absorb carbon
dioxide from the atmosphere. Brucite carbonates
forming lansfordite, nesquehonite and an
amorphous phase, completing the thermodynamic
Greater Sustainability
.299 gt .241 gt.140 gt.113Bricks, 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.
TecEco Cement LCA
TecEco Concretes will have a big role post Kyoto
as they offer potential sequestration as well as
waste utilisation
The TecEco LCA model is available for download
under tools on the web site
Tec-Cement Reactions
MgO H2O gt Mg(OH)2.nH2O - water consumption
resulting in greater density and higher
alkalinity. Higher alkalinity gt more reactions
involving silica alumina. Mg(OH)2.nH2O gt
Mg(OH)2 H2O slow release water for more
complete hydration of PC MgO Al H2O gt
3MgO.Al.6H2O ??? equivalent to flash set?? MgO
SO4-- gt various Mg oxy sulfates ?? yes but
more likely ettringite reaction consumes SO4--
first. MgO SiO2 gt MSH ?? Yes but high
alkalinity required. Strength??
We think the reactions are relatively independent
of PC reactions
The Form of MgO Matters - 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
  • 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 in a hydraulic binder
    (Ramachandran V. S., Concrete Science, Heydon
    Son Ltd. 1981, p 358-360 )

More Rapid and Greater Strength
DevelopmentHigher Strength Binder Ratio
  • Concretes are more often than not made to
  • The use of tec-cement results in
  • 15-30 more strength or less binder for the same
  • more rapid early strength development even with
    added pozzolans.
  • Straight line strength development for a long time

Early strength gain with less cement and added
pozzolans is of great economic and environmental
importance as it will allow the use of more
We have observed this sort of curve in over 500
cubic meters of concrete now
Tec-Cement Strength Development
Graphs above by Oxford Uni Student are for
standard 1PC3 aggregate mixes, w/c .5
WHITTLESEA SLAB (A modified 20 mpa mix) PC 180
Kg / m3MgO 15 Kg / m3Flyash 65 Kg / m3
Rate of strength development is of great interest
to engineers and constructors
Calorimetric Evidence of Faster Strength Gain
Faster Strength Development
Evolution of Less Heat
Energy associated with complexing?
Reasons for Compressive Strength Development in
  • Reactive magnesia requires considerable water to
    hydrate resulting in
  • Denser, less permeable concrete. Self compaction?
  • 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.)
  • Formation of MgAl hydrates? Similar to flash set
    in concrete but slower??
  • Formation of MSH??
  • Slow release of water from hydrated Mg(OH)2.nH2O
    supplying H2O for more complete hydration of C2S
    and C3S?

Brucite gains weight in excess of the theoretical
increase due to MgO conversion to Mg(OH)2 in
samples cured at 98 RH. Dr Luc Vandepierre,
Cambridge University, 20 September, 2005.
Greater Tensile Strength



Mutual Repulsion
Mutual Repulsion
Ph 12 ?






Mutual Attraction
MgO Changes Surface Charge as the Ph Rises. This
could be one of the reasons for the greater
tensile strength displayed during the early
plastic phase of tec-cement concretes. The affect
of additives is not yet known
  • Concretes are said to be less durable when they
    are physically or chemically compromised.
  • Physical factors can result in chemical reactions
    reducing durability
  • E.g. Cracking due to shrinkage can allow reactive
    gases and liquids to enter the concrete
  • Chemical factors can result in physical outcomes
    reducing durability
  • E.g. Alkali silica reaction opening up cracks
    allowing other agents such as sulfate and
    chloride in seawater to enter.
  • This presentation will describe benchmark
    improvements in durability as a result of using
    the new TecEco magnesia cement technologies

Crack Collage
Alkali aggregateReaction
Settlement Shrinkage
Freeze Thaw D Cracks
Photos from PCA and US Dept. Ag Websites
Corrosion Related
Autogenous or self-desiccation shrinkage(usually
related to stoichiometric or chemical shrinkage)
  • TecEco technology can reduce if not solve
    problems of cracking
  • Related to (shrinkage) through open system loss
    of water.
  • As a result of volume change caused by delayed
  • As a result of corrosion.
  • Related to autogenous shrinkage

Causes of Cracking in Concrete
  • Cracking commonly occurs when the induced stress
    exceeds the maximum tensile stress capacity of
    concrete and can be caused by many factors
    including restraint, extrinsic loads, lack of
    support, poor design, volume changes over time,
    temperature dependent volume change, corrosion or
    delayed reactions.
  • Causes of induced stresses include
  • Restrained thermal, plastic, drying and
    stoichiometric shrinkage, corrosion and delayed
    reaction strains.
  • Slab curling.
  • Loading on concrete structures.
  • Cracking is undesirable for many reasons
  • Visible cracking is unsightly
  • Cracking compromises durability because it allows
    entry of gases and ions that react with
  • Cracking can compromise structural integrity,
    particularly if it accelerates corrosion.

Graphic Illustration of Cracking
Autogenous shrinkage has been used to refer to
hydration shrinkage and is thus stoichiometric
After Tony Thomas (Boral Ltd.) (Thomas 2005)
Cracking due to Loss of Water
Brucite gains weight in excess of the theoretical
increase due to MgO conversion to Mg(OH)2 in
samples cured at 98 RH. Dr Luc Vandepierre,
Cambridge University, 20 September, 2005.
Bucket of Water
Settlement Shrinkage
Picture from http//
We may not be able to prevent too much water
being added to concrete by fools.TecEco approach
the problem in a different way by providing for
the internal removal/storage of water that can
provide for more complete hydration of PC.
Solving Cracking due to Shrinkage from Loss of
  • In the system water plus Portland cement powder
    plus aggregates shrinkage is in the order of .05
    1.5 .
  • Shrinkage causes cracking
  • There are two main causes of Portland cements
    shrinking over time.
  • Stoichiometric (chemical) shrinkage and
  • Shrinkage through loss of water.
  • The solution is to
  • Add minerals that compensate by
    stoichiometrically expanding and/or to
  • Use less water, internally hold water or prevent
    water loss.
  • TecEco tec-cements internally hold water and
    prevent water loss.

MgO (s) H2O (l) ? Mg(OH)2.nH2O (s)
Preventing Shrinkage through Loss of Water
  • When magnesia hydrates it consumes 18 litres of
    water per mole of magnesia probably more
    depending on the value of n in the reaction
  • MgO (s) H2O (l) ? Mg(OH)2.nH2O
  • The dimensional change in the system MgO PC
    depends on
  • The ratio of MgO to PC
  • Whether water required for hydration of PC and
    MgO is coming from stoichiometric mix water (i.e.
    the amount calculated as required), excess water
    (bleed or evaporative) or from outside the
  • In practice tec-cement systems are more closed
    and thus dimensional change is more a function of
    the ratio of MgO to PC
  • As a result of preventing the loss of water by
    closing the system together with expansive
    stoichiometry of MgO reactions (see below).
  • MgO (s) H2O (l) ? Mg(OH)2.nH2O (s)
  • 40.31 18.0 ? 58.3 molar mass (at
  • 11.2 liquid ? 24.3 molar
    volumes (at least!)
  • It is possible to significantly reduce if not
    prevent (drying, plastic, evaporative and some
    settlement) shrinkage as a result of water losses
    from the system.

The molar volume (L.mol-1)is equal to the molar
mass (g.mol-1) divided by the density (g.L-1).
Preventing Shrinkage through Loss of Water
  • Portland cements stoichiometrically require
    around 23 -27 water for hydration yet we add
    approximately 45 to 60 at cement batching plants
    to fluidise the mix sufficiently for placement.
  • If it were not for the enormous consumption of
    water by tri calcium aluminate as it hydrates
    forming ettringite in the presence of gypsum,
    concrete would remain as a weak mush and probably
    never set.
  • 26 moles of water are consumed per mole of tri
    calcium aluminate to from a mole of solid
    ettringite. When the ettringite later reacts with
    remaining tri calcium aluminate to form
    monosulfoaluminate hydrate a further 4 moles of
    water are consumed.
  • The addition of reactive MgO achieves water
    removal internally in a closed system in a
    similar way.

MgO (s) H2O (l) ? Mg(OH)2.nH2O (s)
Other Benefits of Preventing Shrinkage through
Loss of Water
  • Internal water consumption also results in
  • Greater strength
  • More complete hydration of PC .
  • Reduced in situ voidspaste ratio
  • Greater density
  • Increased durability
  • Higher short term alkalinity
  • More effective pozzolanic reactions.
  • More complete hydration of PC .
  • Small substitutions of PC by MgO result in water
    being trapped inside concrete as Brucite and
    Brucite hydrates which can later self desiccate
    delivering water to hydration reactions of
    calcium silicates (Preventing so called
    Autogenous shrinkage).

Bleeding is a Bad Thing
  • Bleeding is caused by
  • Lack of fines
  • Too much water
  • Bleeding can be fixed by
  • Reducing water or adding fines
  • Air entrainment or grading adjustments
  • Bleeding causes
  • Reduced pumpability
  • Loss of cement near the surface of concretes
  • Delays in finishing
  • Poor bond between layers of concrete
  • Interconnected pore structures that allow
    aggressive agents to enter later
  • Slump and plastic cracking due to loss of volume
    from the system
  • Loss of alkali that should remain in the system
    for better pozzolanic reactions
  • Loss of pollutants such as heavy metals if wastes
    are being incorporated.
  • Concrete is better as a closed system

Better to keep concretes as closed systems
Dimensional Control in Tec-Cement Concretes over
  • By adding MgO volume changes are minimised to
    close to neutral.
  • So far we have observed significantly less
    shrinkage in TecEco tec - cement concretes with
    about (8-10 substitution OPC) with or without
    fly ash.
  • At some ratio, thought to be around 15-18
    reactive magnesia there is no shrinkage.
  • The water lost by concrete as it shrinks is used
    by the reactive magnesia as it hydrates
    eliminating shrinkage.
  • Note that brucite is gt 44.65 mass water and it
    makes sense to make binders out of water!
  • More research is required to accurately establish
    volume relationships and causes for reduced

Long Term pH control
  • TecEco add reactive magnesia which hydrates
    forming brucite which is another alkali, but much
    less soluble, mobile or reactive than
  • Brucite provides long term pH control.

A pH in the range 10.5 11.2 is ideal in a
Reducing Cracking as a Result of Volume Change
caused by Delayed Reactions
An Alkali Aggregate Reaction Cracked Bridge
Photo Courtesy Ahmad Shayan ARRB
Types of Delayed Reactions
  • There are several types of delayed reactions that
    cause volume changes (generally expansion) and
  • Alkali silica reactions
  • Alkali carbonate reactions
  • Delayed ettringite formation
  • Delayed thaumasite formation
  • Delayed hydration or dead burned lime or
  • Delayed reactions cause dimensional distress,
    cracking and possibly even failure.

Reducing Delayed Reactions
  • 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.
  • Magnesia dries concrete out from the inside.
    Reactions do not occur without water.

Reduced Steel Corrosion Related Cracking
Rusting Causes Dimensional Distress
  • 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

Reduced Steel Corrosion
  • Brucite is less soluble and traps salts as it
    forms resulting in less ionic transport to
    complete a circuit for electrolysis and less
  • 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.)
  • As a result of the above the rusting of
    reinforcement does not proceed to the same
  • Cracking or spalling due to rust does not occur

Steel Corrosion is Influenced by Long Term pH
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 in aqueous
solution total dissolved carbonate 10-2M.
Steel corrodes below 8.9
Equilibrium pH of Brucite and of lime
Reducing Cracking Related to Autogenous Shrinkage
  • Autogenous shrinkage tends to occur in high
    performance concretes in which dense
    microstructures develop quickly preventing the
    entry of additional water required to complete
  • First defined by Lynam in 1934 (Lynam CG. Growth
    and movement in Portland cement concrete. London
    Oxford University Press 1934. p. 26-7.)
  • The autogenous deformation of concrete is defined
    as the unrestrained, bulk deformation that occurs
    when concrete is kept sealed and at a constant

Reducing Cracking Related to Autogenous Shrinkage
  • Main cause is stoichiometric or chemical
    shrinkage as observed by Le Chatelier.
  • whereby the reaction products formed during the
    hydration of cement occupy less space than the
    corresponding reactants.
  • A dense cement paste hydrating under sealed
    conditions will therefore self-desiccate creating
    empty pores within developing structure. If
    external water is not available to fill these
    empty pores, considerable shrinkage can result.

Le Chatelier H. Sur les changements de volume qui
accompagnent Ie durcissement des ciments.
Bulletin de la Societe d'Encouragement pour
I'Industrie Nationale 190054-7.
Reducing Cracking Related to Autogenous Shrinkage
  • Autogenous shrinkage does not occur in high
    strength tec-cement concretes because
  • The brucite hydrates that form desiccate back to
    brucite delivering water in situ for more
    complete hydration of Portland cement.
  • Mg(OH)2.nH2O (s) ? MgO (s) H2O (l)
  • As brucite is a relatively weak mineral
    compressed and densifies the microstructure.
  • The stoichiometric shrinkage of Portland cement
    (first observed by Le Chatelier) is compensated
    for by the stoichiometric expansion of magnesium
    oxide on hydration.
  • MgO (s) H2O (l) ? Mg(OH)2.nH2O (s)
  • 40.31 18.0 ? 58.3 molar mass (at least!)
  • 11.2 liquid ? 24.3 molar volumes (at least
    116 expansion, probably more initially before
    desiccation as above!)

Improved Durability
Materials that last longer need replacing less
often saving on energy and resources.
  • Reasons for Improved Durability
  • Greater Density Lower Permeability
  • Physical Weaknesses gt Chemical Attack
  • Removal of Portlandite with the Pozzolanic
  • Removal or reactive components
  • Substitution by Brucite gt Long Term pH control
  • Reducing corrosion

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
  • TecEco tec - cement concretes are a closed
    system. They do not bleed as excess water is
    consumed by the hydration of magnesia.
  • As a result TecEco tec - cement concretes dry
    from within, are denser and less permeable and
    therefore stronger more durable and less
    permeable. Cement powder is not lost near the
    surfaces. Tec-cements have a higher salt
    resistance and less corrosion of steel etc.

Greater Density Lower Permeability
  • Concretes have a high percentage (around 18
    22) of voids.
  • On hydration magnesia expands gt116.9 filling
    voids and surrounding hydrating cement grains gt
    denser concrete.
  • On carbonation to nesquehonite brucite expands
    307 sealing the surface.
  • Lower voidspaste ratios than waterbinder ratios
    result in little or no bleed water, lower
    permeability and greater density.

Densification During the Plastic Phase
Water is required to plasticise concrete for
placement, however once placed, the less water
over the amount required for hydration the
better. Magnesia consumes water as it hydrates
producing solid material.
Less water results in increased density and
concentration of alkalis - less shrinkage and
cracking and improved strength and durability.
Durability - Reduced Salt Acid Attack
  • Brucite has always played a protective role
    during salt attack. Putting it in the matrix of
    concretes in the first place makes sense.
  • 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

Less Freeze - Thaw Problems
  • Denser concretes do not let water in.
  • Brucite will to a certain extent take up internal
  • 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
  • 11.2 18.0 ? 24.3 molar
  • 39.20 ? 24.3 molar volumes
  • At least 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

Rosendale Concretes Proof of Durability
  • Rosendale cements contained 14 30 MgO
  • A major structure built with Rosendale cements
    commenced in 1846 was Fort Jefferson near key
    west in Florida.
  • Rosendale cements were recognized for their
    exceptional durability, even under severe
    exposure. At Fort Jefferson much of the 150
    year-old Rosendale cement mortar remains in
    excellent condition, in spite of the severe ocean
    exposure and over 100 years of neglect. Fort
    Jefferson is nearly a half mile in circumference
    and has a total lack of expansion joints, yet
    shows no signs of cracking or stress. The first
    phase of a major restoration is currently in

More information from http//www.rosendalecement.n
Solving Waste Logistics Problems
  • TecEco cementitious composites represent a cost
    affective option for
  • using non traditional aggregates from on site
    reducing transports costs and emissions
  • use and immobilisation of waste.
  • Because they have
  • 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
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