TecEco Cement Concretes Abatement, Sequestration and Waste Utilization in the Built Environment

1
TecEco Cement Concretes Abatement,
Sequestration and Waste Utilization in the Built
Environment
If we can make materials that take less than half
as much energy, last more than twice as long (are
more durable) and have a use when they are
retired as well as make them net carbon sinks
Then these materials must be sustainable.
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.
FCPA.
2
The Carbon Cycle and Emissions
The cause of the global warming problem
Source David Schimel and Lisa Dilling, National
Centre for Atmospheric Research 2003
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The TecEco Dream A More Sustainable Built
Environment
CO2
OTHERWASTES
CO2 FOR GEOLOGICAL SEQUESTRATION
PERMANENT SEQUESTRATION WASTE UTILISATION (Man
made carbonate rock incorporating wastes as a
building material)
MINING
MgO
TECECO KILN
MAGNESITE OTHER INPUTS
TECECO CONCRETES
RECYCLED BUILDING MATERIALS
We need materials that require less energy to
make them, that last much longer and that
contribute properties that reduce lifetime
energies
There is a way to make our city streets as green
as the Amazon rainforest. Fred Pearce, New
Scientist Magazine
SUSTAINABLE CITIES
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Innovative New Green Technologies

• New technologies paradigms will make the
  objectives of abatement, sequestration and waste
  utilisation economic to achieve.
• Global Warming
• Atmospheric carbon reduction is essential, but
  difficult to politically achieve by rationing.
• Innovation new ways of sequestering carbon are an
  alternative
• Waste
• potentially the second biggest problem on the
  planet after global warming
• We need to re-think many materials to solve waste
  problems

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Ramifications of TecEco Technologies

• CO2 us a waste
• We need to think about supply and waste impacts
  when we design materials not just about the
  utility phase in the middle.
• Making the built environment a repository for
  waste and huge carbon sink as proposed by TecEco
  is a politically viable and economic alternative.
• Concrete, a cementitous composite, is the single
  biggest material flow on the planet with over 2
  tonnes per person produced and a good place to
  start.
• By including carbon, materialsare potentially
  carbon sinks.
• By including wastes many problems at the waste
  end are solved.

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TecEco Technologies Provide a Profitable Solution

• 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.
  etc.)
• Tec-Kiln Technology
• Combined calcining and grinding in a closed
  system allowing the capture of CO2. Powered by
  waste heat, solar or solar derived energy.
• To be proved but simple and should work!
• Direct Scrubbing of CO2 using MgO
• Being proven by others (NETL,MIT,TNO, Finnish
  govt. etc.)
• Tec and Eco-Cement Concretes in the Built
  Environment.
• TecEco eco-cements set by absorbing CO2 and are
  as good as proven.

TecEco
More EconomicunderKyoto?
TecEco
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The TecEco Total Process
Olivine Mg2SiO4
This reaction is how most MgCO3 came to be formed
anyway so why are we not using it to also
sequester carbon?
Serpentine Mg3Si2O5(OH)4
Crushing
Crushing
CO2 from Power Generation or Industry
Grinding
Grinding
Waste Sulfuric Acid or Alkali?
Screening
Screening
Silicate Reactor Process e.g. Mg2SiO4 2CO2
gt2MgCO3 SiO2
Magnetic Sep.
Gravity Concentration
Heat Treatment
Fe, Ni, Co.
Magnesite (MgCO3)
Silicic Acids or Silica
Non Stored Energy Powered Tec-Kiln
CO2 for Geological Sequestration
Magnesium Thermodynamic Cycle
Magnesite MgCO3)
Magnesia (MgO)
Oxide Reactor Process
Other Wastes after Processing
CO2 from Power Generation, Industry or CO2
Directly From the Air
MgO for TecEco Cements and Sequestration by
Eco-Cements in the Built Environment
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The TecEco Dream A More Sustainable Built
Environment
CO2
OTHERWASTES
CO2 FOR GEOLOGICAL SEQUESTRATION
PERMANENT SEQUESTRATION WASTE UTILISATION (Man
made carbonate rock incorporating wastes as a
building material)
MINING
MgO
TECECO KILN
MAGNESITE OTHER INPUTS
TECECO CONCRETES
RECYCLED BUILDING MATERIALS
We need materials that require less energy to
make them, that last much longer and that
contribute properties that reduce lifetime
energies
There is a way to make our city streets as green
as the Amazon rainforest. Fred Pearce, New
Scientist Magazine
SUSTAINABLE CITIES
9
Benefits to the Concrete Industry of Adopting
TecEco Technology

• Utilizing wastes to make materials like
  concretes.
• Tec-cements have more rapid strength development
  with fly ash, bottom ash, industrial slags etc.
  (Tec-Cements.)
• Reducing energy and emissions during the
  production of cements.
• MgO can be made using non fossil fuel energy
• Concretes containing MgO are demonstrably more
  durable.
• It makes sense to sequester carbon by allowing
  MgO to re-carbonate and thereby gain strength.

The biggest business on the planet is going to be
the sustainability business
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Concrete Industry Objectives

• PCA (USA)
• Improved energy efficiency of fuels and raw
  materials
• Formulation improvements that
• Reduce the energy of production and minimize the
  use of natural resources.
• Use of crushed limestone and industrial
  by-products such as fly ash and blast furnace
  slag.
• WBCSD
• Fuels and raw materials efficiencies
• Emissions reduction during manufacture

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TecEco Technologies Take Concrete into the Future

• More rapid strength gain even with added
  pozzolans
• 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
Eco-Cements
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More Rapid and Greater Strength
DevelopmentHigher Strength Binder Ratio

• Concretes are more often than not made to
  strength.
• The use of tec-cement results in
• 15-30 more 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

Early strength gain with less cement and added
pozzolans is of great economic and environmental
importance.
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Tec-Cement Strength Development
Graphs above by Oxford Uni Student are for
standard 1PC3 aggregate mixes, w/c .5

• 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

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
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Calorimetric Evidence of Faster Strength Gain
Faster Strength Development
Evolution of Less Heat
Energy associated with complexing?
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Reasons for Compressive Strength Development in
Tec-Cements.

• 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.
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Greater Tensile Strength










Cement

Sand
MgO









Mutual Repulsion
gt
Mutual Repulsion
Ph 12 ?


-



-


-
Cement
-
Sand
MgO


-

-
-




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
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Improved Durability
Materials that last longer need replacing less
often saving on energy and resources.

• Improved Durability
• Greater Density Lower Permeability
• Physical Weaknesses gt Chemical Attack
• Removal of Portlandite with the Pozzolanic
  Reaction.
• Removal or reactive components
• Substitution by Brucite gt Long Term pH control
• Reducing corrosion

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Greater Density Reduced Permeability

• Concretes have a high percentage (around 18
  22) of voids.
• On hydration magnesia expands gtgt116.9 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.

Reducing Physical Weaknesses
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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.
• 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.

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Removal of Portlandite with Pozzolanic Reaction

• Portlandite (Ca(OH)2) is too soluble, mobile and
  reactive. It carbonates and reacts with salts
  readily and being soluble can act as an
  electrolyte.
• TecEco generally remove Portlandite using the
  pozzolanic reaction.
• There are many consequences of removing
  Portlandite (Ca(OH)2) with the pozzolanic
  reaction and filling the voids between hydrating
  cement grains with Brucite Mg(OH)2 (and hydrated
  forms of Brucite), an insoluble alkaline mineral.
• An important consequence is improved durability.

Removing Chemical Reactants
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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 generally more acid resistant
  than Portland cement
• This is because of the relatively high acid
  resistance (?) of Lansfordite and nesquehonite
  compared to calcite or aragonite

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Substitution by Brucite gt Long Term pH control

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

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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.)

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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
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Using Wastes and Non-Traditional Aggregates to
Make TecEco Cement Concretes

• As the price of fuel rises, theuse of on site
  low embodiedenergy materials ratherthan carted
  aggregates willhave to be considered.

No longer an option?
Recent natural disasters such as the recent
tsunami and Pakistani earthquake mean we urgently
need to commercialize TecEco technologies because
they provide benign environments allowing the use
of many local materials and wastes without
delayed reactions
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Using Wastes and Non-Traditional Aggregates to
Make TecEco Cement Concretes

• Many wastes and local materials can contribute
  physical property values.
• Plastics for example are collectively light in
  weight, have tensile strength and low
  conductance.
• Tec, eco and enviro-cements will allow a wide
  range of wastes and non-traditional aggregates
  such as local materials to be used.
• Tec, enviro and eco-cements are benign binders
  that are
• low alkali reducing reaction problems with
  organic materials.
• stick well to most included wastes
• Tec, enviro and eco-cements can utilize wastes
  including carbon to increase sequestration
  preventing their conversion to methane
• There are huge volumes of concrete produced
  annually (gt2 tonnes per person per year)

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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
  cracking.
• Homogenous.
• No bleed water.

TecEco Technology - Converting Waste to Resource
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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 has a structure
comprising electronically neutral layers and is
able to accommodate a wide variety of extraneous
substances between the layers and cations of
similar size substituting for magnesium within
the layers and is known to be very suitable for
toxic and hazardous waste immobilisation.
Layers of electronically neutral brucite suitable
for trapping balanced cations and anions as well
as other substances.
Van de waals bonding holding the layers together.
Salts and other substances trapped between the
layers.
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Lower Solubility of Metal Hydroxides
There is a 104 difference
All waste streams will contain heavy metals and a
strategy for long term pH control is therefore
essential
30
Recycling Materials Reduced Embodied Energies
and Emissions
The above relationships hold true on a macro
scale, provided we can change the technology
paradigm to make the process of recycling much
more efficient economic.
31
A Post Carbon Waste Age?
We cannot get there without new technical
paradigms.
The construction industry can be uniquely
responsible for helping achieve this transition
32
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!
Biomimicry
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Utilizing Carbon as a Binder

• The concept of using carbon as a binder is not
  new.
• Ancient and modern carbonating lime mortars are
  based on this principle.
• TecEco have now taken the concept a lot further
  however with the development of eco-cement which
  is based on blending reactive magnesium oxide
  with other hydraulic cements. Eco-cements only
  carbonate in porous materials like 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.

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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.

35
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 volumetric expansion from magnesium oxide
  to lansfordite is for example volume 811.

From air and water
Mg(OH)2 CO2 ? MgCO3.5H2O
36
Eco-Cement Micro-Structural Strength
37
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.
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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)
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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)
40
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
cycle.
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.
41
TecEco Kiln Technology

• Can run at low temperatures.
• Can be powered by variable non fossil fuel
  energy.
• Runs 25 to 30 more efficiency.
• Theoretically capable of producing much more
  reactive MgO
• Even with ores of high Fe content.

• Captures CO2 for bottling and sale to the oil
  industry (geological sequestration).
• Grinds and calcines at the same time.
• Part of a major process to solve global CO2
  problems.
• Will result in new markets for ultra reactive low
  lattice energy MgO (e.g. cement, paper and
  environment industries)
• TecEco need your backing to develop the kiln

42
TecEco Technology in Practice - Whittlesea, Vic.
Australia

• On 17th March 2005 TecEco poured the first
  commercial slab in the world using tec-cement
  concrete.
• The formulation strategy was to adjust a standard
  20 MPa high fly ash (36) mix from the supplier
  as a basis of comparison.
• Strength development, and in particular early
  strength development was good.
• Shrinkage was low.
• First Eco-cement mud bricks and mortars
• Tested up twice as strong as the PC controls
• Mud brick addition rate 2.5
• Rate for mortars 18 not 13 because of molar
  ratio increase.

43
Energy On a Mass Basis
44
Energy On a Volume Basis
45
Global Abatement