Title: TecEco Cement Concretes
1TecEco 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.
2The Carbon Cycle and Emissions
The cause of the global warming problem
Source David Schimel and Lisa Dilling, National
Centre for Atmospheric Research 2003
3The 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
4Innovative 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
5Ramifications 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.
6TecEco 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
7The 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
Tonnes CO2 Sequestered per Tonne Silicate with Various Cycles through the TecEco Process (assuming no leakage MgO to built environment i.e complete cycles) Chrysotile (Serpentinite) Billion Tonnes Forsterite (Mg Olivine) Billion 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
Total tonnes CO2 sequestered or abated per tonne mineral mined (Single calcination cycle). 1.431 1.876
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
Total tonnes CO2 sequestered or abated (Twenty calcination cycles). 11.446 15.012
MgO for TecEco Cements and Sequestration by
Eco-Cements in the Built Environment
8The 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
9Benefits 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
10Concrete 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
11TecEco 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
12More 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.
13Tec-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
14Calorimetric Evidence of Faster Strength Gain
Faster Strength Development
Evolution of Less Heat
Energy associated with complexing?
15Reasons 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.
16Greater 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
17Improved 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
18Greater 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
19Reduced 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.
20Removal 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
21Durability - 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
22Substitution 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.
23Reduced 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.)
24Steel 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
25Using 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
26Using 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)
27Solving 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
28Role 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.
29Lower 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
30Recycling 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.
31A Post Carbon Waste Age?
We cannot get there without new technical
paradigms.
The construction industry can be uniquely
responsible for helping achieve this transition
32Utilizing 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
33Utilizing 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.
34Eco-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.
35Eco-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
36Eco-Cement Micro-Structural Strength
37Chemistry 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.
38Proof 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)
39Proof 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)
40CO2 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.
41TecEco 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
42TecEco 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.
43Energy On a Mass Basis
Relative to Raw Material Used to make Cement From Manufacturing Process Energy Release 100 Efficient (MJ.tonne-1) From Manufacturing Process Energy Release with Inefficiencies (MJ.tonne-1) Relative Product Used in Cement From Manufacturing Process Energy Release 100 Efficient (MJ.tonne-1) From Manufacturing Process Energy Release with Inefficiencies (MJ.tonne-1) Relative to Mineral Resulting in Cement From Manufacturing Process Energy Release 100 Efficient (MJ.tonne-1) From Manufacturing Process Energy Release with Inefficiencies (MJ.tonne-1)
CaCO3 Clay 1545.73 2828.69 Portland Cement 1807 3306.81 Hydrated 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
44Energy On a Volume Basis
Relative to Raw Material Used to make Cement From Manufacturing Process Energy Release 100 Efficient (MJ.metre-3) From Manufacturing Process Energy Release with Inefficiencies (MJ.metre-3) Relative Product Used in Cement From Manufacturing Process Energy Release 100 Efficient (MJ.metre-3) From Manufacturing Process Energy Release with Inefficiencies (MJ.metre-3) Relative to Mineral Resulting in Cement From Manufacturing Process Energy Release 100 Efficient (MJ.metre-3) From Manufacturing Process Energy Release with Inefficiencies (MJ.metre-3)
CaCO3 Clay 4188.93 7665.75 Portland Cement 5692.05 10416.45 Hydrated 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
45Global Abatement
Without CO2 Capture during manufacture (billion tonnes) With CO2 Capture during manufacture (billion tonnes)
Total Portland Cement Produced Globally 1.80 1.80
Global mass of Concrete (assuming a proportion of 15 mass cement) 12.00 12.00
Global CO2 Emissions from Portland Cement 3.60 3.60
Mass of Eco-Cement assuming an 80 Substitution in global concrete use 9.60 9.60
Resulting Abatement of Portland Cement CO2 Emissions 2.88 2.88
CO2 Emissions released by Eco-Cement 2.59 1.34
Resulting Abatement of CO2 emissions by Substituting Eco-Cement 0.29 1.53