Practical Use of Tec and Eco-Cements
TecEco are in the
biggest business
on the planet –
that of solving
global warming
and waste
problems
Presentation by John
Harrison, managing director
of TecEco and inventor of tec
and eco-cements and the
CarbonSafe process.
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.
Presentation downloadable from www.tececo.com
1
The Carbon Cycle and Emissions
Emissions
from fossil
fuels and
cement
production
are the
cause of the
global
warming
problem
Units: GtC
GtC/yr
Source: David Schimel and Lisa Dilling, National Centre for Atmospheric Research 2003
Presentation downloadable from www.tececo.com
2
Techno-Processes & Earth Systems
Underlying
the technoprocess that
Earth Systems
describes and
Detrimental
Atmospheric
controls the
composition,
affects on
flow of matter
Waste
climate, land
and energy
earth
are molecular
cover, marine
systems
stocks and
Take
ecosystems,
flows. If out of
pollution,
tune with
coastal zones,
nature these
freshwater and
moleconomic
salinity.
flows have
detrimental
affects on
earth
To reduce the impact on earth systems new technical paradigms
systems.
need to be invented that result in underlying molecular flows that
mimic or at least do not interfere with natural flows.
Presentation downloadable from www.tececo.com
3
Techno-Processes Affect Underlying Molecular Flows
Take → Manipulate → Make → Use → Waste
[
[
←Materials→
]
← Underlying molecular flow → ]
If the underlying molecular flows are “out of tune” with
nature there is damage to the environment
e.g. heavy metals, cfc’s, c=halogen compounds and CO2
Moleconomics
Is 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.
Presentation downloadable from www.tececo.com
4
Changing Techno-Processes
Take => manipulate => make => use => waste
Driven by fossil fuel energy with detrimental effects on earth
systems.
Reduce
Re-use
Recycle
Eco-innovate
Reduce Re-use
Take only
renewables
Manipulate
Make
Use
Waste only what is
biodegradable or can
be re-assimilated
Recycle
If you can’t recycle based
on chemical property
Materials
Do so based on physical
properties such as weight
and strength
Presentation downloadable from www.tececo.com
5
Economically Driven Change
$ - ECONOMICS - $
New, more profitable
technical paradigms
used in the technoprocess that result in
more sustainable and
usually more efficient
moleconomic flows
that mimic or at least
do not disrupt natural
flows are required.
Presentation downloadable from www.tececo.com
6
Changing the Technical Paradigm
“By enabling us to make productive use of particular raw
materials, technology determines what constitutes a physical
resource1”
1.Pilzer, Paul Zane, Unlimited Wealth, The Theory and Practice of Economic Alchemy,
Crown Publishers Inc. New York.1990
By inventing new technical paradigms and re-engineering materials we can
change the underlying molecular flows that are damaging this planet. It is not hard
to do this and it could even be economic. All it takes is imagination.
Imagination is more important than knowledge. Knowledge is
limited. Imagination encircles the world. Albert Einstein
We can make materials that have underlying molecular
flows that mimic or at least to not disrupt natural flows, that
require less energy to make, last much longer and
contribute properties that reduce lifetime energies.
Presentation downloadable from www.tececo.com
7
Examples of Economic Changes in Technical
Paradigms that result in Greater Sustainability
Incandescent
100 watts
1700 lumens
Fluorescent
Led Light
<20 watts
25 watts
1700 lumens 1700 lumens
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.
Presentation downloadable from www.tececo.com
8
Sustainability Driven by Economics
 Our goal should be:
– To develop technical paradigms that more economically deliver
reduced moleconomic impacts and thus greater sustainability.
 To do this we need to:
– Through education to induce cultural change to increase the
demand for sustainability.
– Innovate to change the technical paradigms
– Improvements in technical paradigms will bring about changes in
demand affecting resource usage and thus underlying
moleconomic flows reducing detrimental linkages with the planet.
 TecEco tec, eco and enviro cements are innovative
sustainability enabling technologies.
Presentation downloadable from www.tececo.com
9
Sustainability = Culture + Technology
Increase in demand/price ratio for
sustainability due to educationally
induced cultural drift.
$
ECONOMICS
New Technical
Paradigms are
required that deliver
sustainability.
Equilibrium shift
Supply
Greater Value/for
impact
(Sustainability) and
economic growth
Increase in supply/price ratio for
more sustainable products due to
innovative paradigm shifts in
technology.
Demand
#
Sustainability could be considered as
where culture and technology meet.
Presentation downloadable from www.tececo.com
10
The TecEco CarbonSafe Geo-Photosynthethic Process
Inputs:
Atmospheric or smokestack CO2, brines,
waste acid, other wastes
Outputs:
The CarbonSafe Geo-Photosynthetic
Process is TecEco’s evolving technoprocess that delivers profitable
outcomes whilst reversing underlying
undesirable moleconomic flows from
other less sustainable processes.
Potable water, gypsum, sodium bicarbonate, salts, building
materials, bottled concentrated CO2 (for geo-sequestration
and other uses).
Solar or solar
derived energy
CO2
CO2
CO2
MgO
TecEco
MgCO2
Cycle
TecEco
Kiln
MgCO3
Coal
Carbon or carbon compounds
Magnesium oxide
Fossil fuels
CO2
Oil
Presentation downloadable from www.tececo.com
CO2
Greensols
Process
1.29 gm/l
Mg
11
TecEco CarbonSafe Vectors
Inputs
Brines
Waste Acid
CO2
Outputs
Gypsum, Sodium
bicarbonate, Salts,
Building materials,
Potable water
Presentation downloadable from www.tececo.com
12
The CarbonSafe Geo-Photosynthetic Process
Waste
Acid
Seawater
Carbonatio
n Process
CO2 from power
generation or industry
Other salts
Na+,K+,
Ca2+,Cl-
Magnesite (MgCO3)
Solar Process to Produce
Magnesium Metal
Simplified TecEco Reactions
Tec-Kiln MgCO3 → MgO + CO2 - 118 kJ/mole
Reactor Process MgO + CO2 → MgCO3 + 118
kJ/mole (usually more complex hydrates)
CO
2
Other Wastes
1.354 x 109 km3 Seawater containing 1.728 10 17
tonne Mg or suitable brines from other sources
Magnesia
(MgO)
Eco-Cement
Tec-Cement
Gypsum +
carbon waste
(e.g.
sewerage) =
fertilizers
Bicarbonate
of Soda
(NaHCO3)
Gypsum
(CaSO4)
Sewerage compost
CO2 as a biological or
industrial input or if no
other use geological
sequestration
Magnesium
Thermodynamic
Magnesite
Cycle
(MgCO3)
Hydroxid
e
Reactor
Process
CO2 from power
generation, industry
or out of the air
Sequestration Table – Mg from Seawater
Tonnes CO2 sequestered per tonne magnesium with various cycles
through the TecEco Tec-Kiln process. Assuming no leakage MgO to built
environment (i.e. complete cycles).
Billion
Tonnes
Tonnes CO2 sequestered by 1 billion tonnes of Mg in seawater
1.81034
Tonnes CO2 captured during calcining (same as above)
1.81034
Tonnes CO2 captured by eco-cement
1.81034
Total tonnes CO2 sequestered or abated per tonne Mg in seawater
(Single calcination cycle).
3.62068
Total tonnes CO2 sequestered or abated (Five calcination cycles.)
18.1034
Total tonnes CO2 sequestered or abated (Ten calcination cycles).
36.20
Presentation downloadable from www.tececo.com
13
The MgCO2 Process (Magnesium Thermodynamic Cycle)
The magnesium thermodynamic
cycle is very important for sequestration and is used
for the formation of valuable building product
CO2
Calcination
CO2 Capture
Non fossil fuel energy
Magnesite
Eco-Cements
Dehydration
MgCO3 MgO + CO2
ΔH = 118.28 kJ.mol-1
ΔG = 65.92 kJ.mol-1
Calcination
TOTAL CALCINING ENERGY
Representative of other
hydrated mineral
carbonates including an
amorphous phase and
lansfordite
Magnesia
Nesquehonite
Carbonation
Carbonation
Mg(OH)2.nH2O + CO2 + 2H2O MgCO3.3 H2O
ΔH = -175.59 kJ.mol-1
ΔG = -38.73 kJ.mol-1
Brucite
(Relative to MgCO3)
Theoretical = 1480 kJ.Kg-1
With inefficiencies = 1948
kJ.Kg-1
Hydration
MgO + H2O  Mg(OH)2.nH2O
ΔH = -81.24 kJ.mol-1
ΔG = -35.74 kJ.mol-1
Tec and Enviro-Cements
Presentation downloadable from www.tececo.com
14
The TecEco Dream – A More Sustainable Built Environment
OTHER
WASTES
CO2
CO2 FOR
GEOLOGICAL
SEQUESTRATION
CO2
MINING
MAGNESITE
+ OTHER
INPUTS
“There is a way to
make our city streets
as green as the
Amazon rainforest”.
Fred Pearce, New
Scientist Magazine
TECECO
KILN
MgO
PERMANENT
SEQUESTRATION &
WASTE
UTILISATION (Man
made carbonate
rock incorporating
wastes as a
TECECO CONCRETES building material)
RECYCLED
BUILDING
MATERIALS
SUSTAINABLE CITIES
We need materials that
require less energy to
make them, that last
much longer and that
contribute properties
that reduce lifetime
energies
Presentation downloadable from www.tececo.com
15
TecEco CO2 Capture Kiln Technology
 Can run at low temperatures.
 Can be powered by various
non fossil fuels.
 Runs 25% to 30% more
efficiently.
 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)
Presentation downloadable from www.tececo.com
16
Why Magnesium Carbonates for Sequestration?
 Because of the low molecular weight of magnesium,
magnesium oxide which hydrates to magnesium hydroxide
and then carbonates, is ideal for scrubbing CO2 out of the
air and sequestering the gas into the built environment:
 More CO2 is captured than in calcium systems as the
calculations below show.
CO2
44

 52%
MgCO 3 84
CO 2
44

 43%
CaCO3 101
 An area 10km by 10m by 150m deep of magnesium
carbonate will sequester all the excess CO2 we release to
the atmosphere in a year.
 At 2.09% of the crust magnesium is the 8th most abundant
element
 Magnesium minerals are potential low cost. New kiln
technology from TecEco will enable easy low cost simple
non fossil fuel calcination of magnesium carbonate with
CO2 capture for geological sequestration.
Presentation downloadable from www.tececo.com
17
Reduction Global CO2 from CarbonSafe Process
Mass of CO2 (Gt)
Global CO2 in the Atmosphere
3,500
3,300
3,100
2,900
2005
2010
2015
2020
2025
M ass CO2 in the atmosphere without "CarbonSafe"
sequestration (Gt)
M ass CO2 in the atmosphere with "CarbonSafe"
sequestration (Gt)
Upper CO2 limit (Gt)
Presentation downloadable from www.tececo.com
18
Mimicking Natural Processes - Biomimicry
Since we now dominate this planet we need to evolve
technical paradigms that result in techno-processes
that mimic nature.
 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.
Presentation downloadable from www.tececo.com
19
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.
We all use carbon and wastes to
make our homes! “Biomimicry”
In eco-cement blocks
and mortars the
binder is carbonate
and the aggregates
are preferably wastes
Presentation downloadable from www.tececo.com
20
A Post – Carbon & Waste Age?
New techno-process are required that mimic
nature and do not change global system flows
Presentation downloadable from www.tececo.com
21
Materials in the Built Environment
 The built environment is made of materials and is
our footprint on earth.
– It comprises buildings and infrastructure.
 Building materials comprise
– 70% of materials flows (buildings, infrastructure etc.)
– 40-50% of waste that goes to landfill (15 % of new materials
going to site are wasted.)
 At 1.5% of world GDP Annual Australian production of
building materials likely to be in the order 300 million
tonnes or over 15 tonnes per person.
 Over 20 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 separated.
– Include many toxic elements.
Presentation downloadable from www.tececo.com
22
Huge Potential for More Sustainable Construction Materials
Reducing the impact of the take and
waste phases of the techno-process.
– including carbon in materials
they are potentially carbon sinks.
– including wastes for
physical properties as
well as chemical composition
C
they become resources.
– re – engineering
Waste
materials to
reduce the lifetime
energy of buildings C
Many wastes can
contribute to
physical
properties
reducing lifetime
energies
C
C
Waste
C
Presentation downloadable from www.tececo.com
23
Impact of the Largest Material Flow - Cement and Concrete
 Concrete made with cement is the most widely
used material on Earth accounting for some
30% of all materials flows on the planet and 70%
of all materials flows in the built environment.
– Global Portland cement production is 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
Presentation downloadable from www.tececo.com
24
Embodied Energy of Building Materials
Concrete is
relatively
environmentally
friendly and has a
relatively low
embodied energy
Downloaded from www.dbce.csiro.au/indserv/brochures/embodied/embodied.htm (last accessed 07 March 2000)
Presentation downloadable from www.tececo.com
25
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 www.dbce.csiro.au/indserv/brochures/embodied/embodied.htm (last accessed 07 March 2000)
Presentation downloadable from www.tececo.com
26
Emissions from Cement Production
 Chemical Release
– The process of calcination involves driving off chemically bound
CO2 with heat.
CaCO3 →CaO + ↑CO2
CO2
 Process Energy
– Most energy is derived from fossil fuels.
CO2
– 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.
Presentation downloadable from www.tececo.com
27
Cement Production ~= Carbon Dioxide Emissions
Metric Tonnes
2,500,000,000
2,000,000,000
1,500,000,000
1,000,000,000
500,000,000
2001
1996
1991
1986
1981
1976
1971
1966
1961
1956
1951
1946
1941
1936
1931
1926
0
Year
Between tec, eco and enviro-cements TecEco can provide a
viable much more sustainable alternative.
Presentation downloadable from www.tececo.com
28
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
Tec Cements
– Reducing costs and take and waste impacts.
 Use of wastes
 Utilizing carbon dioxide
Tec & EcoEco-Cements Cements
 Magnesia component can be made using non
fossil fuel energy and CO2 captured during
production.
Presentation downloadable from www.tececo.com
29
TecEco Binder Systems
SUSTAINABILITY
PORTLAND
POZZOLAN
Hydration of the
various components
of Portland cement
for strength.
DURABILITY
Reaction of alkali with
pozzolans (e.g. lime with
fly ash.) for sustainability,
durability and strength.
TECECO CEMENTS
STRENGTH
TecEco concretes are
a system of blending
REACTIVE MAGNESIA
reactive magnesia,
Hydration of magnesia => brucite for strength, workability, Portland cement and
dimensional stability and durability. In Eco-cements
usually a pozzolan
carbonation of brucite => nesquehonite, lansfordite and
with other materials
an amorphous phase for sustainability.
and are a key factor
for sustainability.
Presentation downloadable from www.tececo.com
30
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 voids:paste ratio, increasing density and
possibly raising the short term pH.
– Reactions with pozzolans are more affective. After all the Portlandite has
been consumed Brucite controls the long term pH which is lower and due to
it’s low solubility, mobility and reactivity results in greater durability.
– Other benefits include improvements in density, strength and rheology,
reduced permeability and shrinkage and the use of a wider range of
aggregates many of which are potentially wastes without reaction problems.
 Eco-cements (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
sequestration.
 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.
Presentation downloadable from www.tececo.com
31
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 corrosion.
• 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 concrete
• TecEco remove Portlandite it and replacing it with magnesia
which hydrates to Brucite.
• The hydration of magnesia consumes significant water
Presentation downloadable from www.tececo.com
32
Tec & Eco-Cement Theory
 Portlandite (Ca(OH)2) is too soluble, mobile and
reactive.
– It carbonates, reacts with Cl- and SO4- and being soluble
can act as an electrolyte.
 TecEco generally (but not always) remove
Portlandite using the pozzolanic reaction and
 TecEco add reactive magnesia
– which hydrates, 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
Presentation downloadable from www.tececo.com
33
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 reactions
 To reduce shrinkage.
– The consequences of putting brucite through the matrix of a
concrete in the first place need to be considered.
 To make concretes more durable
 Because significant quantities of carbonates are
produced in porous substrates which are affective
binders.
Reactive MgO is a new tool to be understood
with profound affects on most properties
Presentation downloadable from www.tececo.com
34
Strength with Blend & Porosity
150
Tec-cement concretes
Eco-cement concretes
100
50
High OPC
Enviro-cement
concretes
STRENGTH ON
ARBITARY SCALE 1-100
100-150
50-100
0-50
Presentation downloadable from www.tececo.com
0 High Porosity
High Magnesia
35
Ramifications of TecEco Eco-Cement Technologies
 CO2 is a waste.
 Making the built environment a repository for waste
and a huge carbon sink as proposed by TecEco is a
technically feasible, politically viable and economic
alternative.
 By capturing carbon during manufacture and
including it in concretes they become carbon sinks.
C
C
 By including wastes many
Waste
problems at the waste
Waste
end are solved.
C
Eco-cements
Δ
Waste
C
C
MgCO3 → MgO + ↓CO2 - Efficient low temperature calcination & capture
MgO + ↓CO2 + H2O → MgCO3.3H2O - Sequestration as building material
Presentation downloadable from www.tececo.com
36
TecEco Technology in Practice - 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.
Strength Development of Tec-Cement Concrete
30
Strength, MPa
– 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.
25
20
Compressive
Strength
15
10
5
0
0
5
10
15
20
25
30
Days w ater cured
Presentation downloadable from www.tececo.com
37
TecEco Technology in Practice - Whittlesea,
Vic. Australia
First Eco-cement mud
bricks and mortars in
Australia
– Tested up twice as
strong as the PC
controls
– Mud brick addition rate
2.5%
– Addition rate for mortars
1:8 not 1:3 because of
molar ratio volume
increase with MgO
compared to lime.
Presentation downloadable from www.tececo.com
38
The Use of Eco-Cements for Building Earthship Brighton
By Taus Larsen, (Architect, Low Carbon Network Ltd.)
The Low Carbon Network (www.lowcarbon.co.uk) was established to raise awareness of the links between
buildings, the working and living patterns they create, and global warming and aims to initiate change
through the application of innovative ideas and approaches to construction. England’s first Earthship is
currently under construction in southern England outside Brighton at Stanmer Park and TecEco
technologies have been used for the floors and some walling.
Earthships are exemplars of low-carbon design, construction and living and were invented and developed in the USA
by Mike Reynolds over 20 years of practical building exploration. They are autonomous earth-sheltered buildings
independent from mains electricity, water and waste systems and have little or no utility costs.
For information about the Earthship Brighton and other projects please go to the TecEco web site.
Presentation downloadable from www.tececo.com
39
Repair of Concrete Blocks. Clifton Surf Club
The Clifton Surf Life Saving Club was built by first
pouring footings, On the footings block walls were
erected and then at a later date concrete was laid in
between.
As the ground underneath the footings was sandy, wet
most of the time and full of salts it was a recipe for
disaster.
Predictably the salty water rose up through the footings
and then through the blocks and where the water
evaporated there was strong efflorescence, pitting, loss
of material and damage.
The TecEco solution was to make up a
formulation of eco-cement mortar which we
doctored with some special chemicals to prevent
the rise of any more moisture and salt.
The solution worked well and appears to have
stopped the problem.
Presentation downloadable from www.tececo.com
40
Mike Burdon’s Murdunna Works
Mike Burdon, Builder and Plumber.
I work for a council interested in sutainability and
have been involved with TecEco since around
2001 in a private capacity helping with large
scale testing of TecEco tec-cements at our
shack.
I am interested in the potentially superior
strength development and sustainability aspects.
To date we have poured two slabs, footings, part
of a launching ramp and some tilt up panels
using formulations and materials supplied by
John Harrison of TecEco. I believe that research
into the new TecEco cements essential as
overall I have found:
1.
The rheological performance even without plasticizer was excellent. As testimony to this the contractors on the site
commented on how easy the concrete was to place and finish.
2.
We tested the TecEco formulations with a hired concrete pump and found it extremely easy to pump and place. Once in
position it appeared to “gel up” quickly allowing stepping for a foundation to a brick wall.
3.
Strength gain was more rapid than with Portland cement controls from the same premix plant and continued for longer.
4.
The surfaces of the concrete appeared to be particularly hard and I put this down to the fact that much less bleeding was
observed than would be expected with a Portland cement only formulation
Presentation downloadable from www.tececo.com
41
Non Shrink Concrete
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.
Presentation downloadable from www.tececo.com
42
Block Making with TecEco Cements
TecEco tec and ecocement 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 eco-cement.
Presentation downloadable from www.tececo.com
43
Teco Blocks Made Using Tec and Eco-Cements
Channel Plate
Block Locator
End Cap
Teco Blocks
from Liquid
Frame
System Using
TecEco
Cements.
Please direct
commercial
enquiries to
liquidframesy
stem.com.au/
4 Rosebank Ave.
Clayton South, Victoria, Australia
3169. Ph 03 95470277
Presentation downloadable from www.tececo.com
44
TecEco Cement Teco Blocks Being Laid
Presentation downloadable from www.tececo.com
45
Tec & Eco Cement Foamed Concretes
BUILD LITE CELLULAR CONCRETE
4 Rosebank Ave Clayton Sth
MELBOURNE AUSTRALIA 3169
PH 61 3 9547 0255 FX 61 3 9547 0266
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)
Presentation downloadable from www.tececo.com
46
Tec & Eco Cement Foamed Concrete Slabs
BUILD LITE CELLULAR CONCRETE
4 Rosebank Ave Clayton Sth
MELBOURNE AUSTRALIA 3169
PH 61 3 9547 0255 FX 61 3 9547 0266
Presentation downloadable from www.tececo.com
47
Lightweight Tec-Cement Steel Braced
Foamed Concrete 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.
Solutions in Steel
ABN 48 103 573 039
TEL: 61 7 3271 3900
FAX: 61 7 3271 2701
80 Mica Street
Carole Park 4300
Queensland
Australia
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
Please direct commercial enquiries to
Rigid Steel Framing at rigidsteel.com.au
Presentation downloadable from www.tececo.com
48
Lightweight Tec-Cement Steel Braced
Foamed Concrete Panels
Rear view of test panels showing tongue and groove and void for services.
Interior plasterboard is fixed conventionally over gap for services.
Presentation downloadable from www.tececo.com
49
Eco-Cement Porous Pavement – A Solution for Water Quality?
Porous Pavements are a
Technology Paradigm
Change Worth Investigating
Before three were cites forests and grassland covered most of our planet.
When it rained much of the water naturally percolated though soils that
performed vital functions of slowing down the rate of transport to rivers and
streams, purifying the water and replenishing natural aquifers.
Our legacy has been to pave this natural bio filter, redirecting the water that
fell as rain as quickly as possible to the sea. Given global water shortages,
problems with salinity, pollution, volume and rate of flow of runoff we need
to change our practices so as to mimic the way it was for so many millions
of years before we started making so many changes.
Presentation downloadable from www.tececo.com
50
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, ecocements are much more efficient.
 Magnesium hydroxide in particular and to some extent the
carbonates are less reactive and mobile and thus much
more durable.
Presentation downloadable from www.tececo.com
51
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
From air and water
is for example volume 811%.
Mg(OH)2 + CO2  MgCO3.5H2O
Presentation downloadable from www.tececo.com
52
Eco-Cement Strength Gain Curve
HYPOTHETICAL STRENGTH
GAIN CURVE OVER TIME
(Pozzolans added)
MPa
?
OPC Concrete
?
Eco – Cement Concrete with
50% reactive magnesia
?
?
3
Plastic
Stage
7
14
28
Log Days
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.
Presentation downloadable from www.tececo.com
53
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 kJ.mol-1
 The dehydration of nesquehonite to form magnesite is not
favoured by simple thermodynamics but may occur in the long
term under the right conditions.
 Gor nesquehonite to magnesite = 8.56 kJ.mol-1
– But kinetically driven by desiccation during drying.
 Reactive magnesia can carbonate in dry conditions – so keep
bags sealed!
 For a full discussion of the thermodynamics see our technical
documents.
TecEco technical documents on the web
cover the important aspects of carbonation.
Presentation downloadable from www.tececo.com
54
Eco-Cement Reactions
In Eco - Cements
Magnesia
Amorphous Lansfordite
Brucite
Nesquehonite
MgO + nH2O  Mg(OH)2.nH2O + CO2  MgCO3.nH2O + MgCO3.5H2O + MgCO3.3H2O
Form: Massive-Sometimes Fibrous Often Fibrous Acicular - Needle-like
crystals
Hardness:
2.5 - 3.0
2.5
Solubility (mol.L-1): .00015
.01
.013 (but less in acids)
Compare to the Carbonation of Portlandite
Portlandite
Calcite
Aragonite
Ca(OH)2 + CO2  CaCO3
Form: Massive
Massive or crystalline
Hardness:
Solubility (mol.L-1):
More acicular
2.5
.024
3.5
.00014
Presentation downloadable from www.tececo.com
55
Eco-Cement Micro-Structural Strength
Elongated growths of
lansfordite and
nesquehonite near the
surface, growing inwards
over time and providing
microstructural strength.
Flyash grains (red)
reacting with lime
producing more CSH and
if alkaline enough
conditions bonding
through surface
hydrolysis. Also acting as
micro aggregates.
Portland clinker minerals
(black). Hydration
providing Imperfect
structural framework.
Micro spaces filled with
hydrating magnesia
(→brucite) – acting as a
“waterproof glue”
Mysterious amorphous
phase?
Presentation downloadable from www.tececo.com
56
Carbonation
 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 TecKiln) 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
Presentation downloadable from www.tececo.com
57
CO2 Abatement in Eco-Cements
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.
Portland
Cements
15 mass%
Portland
cement, 85
mass%
aggregate
Emissions
.32 tonnes to
the tonne.
After
carbonation.
Approximately
.299 tonne to
the tonne.
No
Capture
11.25% 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.
Capture
CO2
11.25% 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 Ash
11.25% 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.
Greater Sustainability
.299 > .241 >.140 >.113
Bricks, blocks, pavers, mortars and pavement made using eco-cement, fly
and bottom ash (with capture of CO2 during manufacture of reactive
magnesia) have 2.65 times less emissions than if they were made with
Portland cement.
Presentation downloadable from www.tececo.com
58
Proof of Carbonation - Minerals Present After 18 Months
XRD showing carbonates and
other minerals before removal of
carbonates with HCl in a simple
Mix (70 Kg PC, 70 Kg MgO,
colouring oxide .5Kg, sand
unwashed 1105 Kg)
Presentation downloadable from www.tececo.com
59
Proof of Carbonation - Minerals Present After 18 Months
and Acid Leaching
XRD Showing minerals remaining
after their removal with HCl in a
simple mix (70 Kg PC, 70 Kg
MgO, colouring oxide .5Kg, sand
unwashed 1105 Kg)
Presentation downloadable from www.tececo.com
60
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 used!
Presentation downloadable from www.tececo.com
61
Roman Specifications
 The oldest record: Book II, chapter IV of the Ten Books of
Architecture by Vitruvius Pollio.
– According to Vitruvius “the best (sand) will be found to be that which
crackles when rubbed in the hand, while that which has much dirt in it
will not be sharp enough. Again: throw some sand upon a white
garment and then shake it out; if the garment is not soiled and no dirt
adheres to it, the sand is suitable” Vitruvious was talking about gritty
sand with no fines.
 The 16th century architect Andrea Palladio is renowned for
"The Four Books of Architecture“
– translated into English in the early 18th century
– used as a principal reference for building for almost two centuries
(Palladio, Isaac Ware translation, 1738).
– In the first book Palladio says, "the best river sand is that which is
found in rapid streams, and under water-falls, because it is most
purged". In other words, it is coarse. Compare this with most sand for
use in mortar today.
 The conclusion form history is that a coarse gritty sand that
is not graded for minimum paste is required.
Presentation downloadable from www.tececo.com
62
Using Wastes and Non-Traditional Aggregates to
Make TecEco Cement Concretes
 As the price of fuel rises, the
use of on site low embodied
energy materials rather
than carted aggregates will
have 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
Presentation downloadable from www.tececo.com
63
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
(>2 tonnes per person per year)
Presentation downloadable from www.tececo.com
64
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
Presentation downloadable from www.tececo.com
65
Recycling Materials = Reduced Embodied Energies and Emissions
More
Recycling
More
=
=
Greater
Productivity
Less Process Energy
=
Less
Less
Lower Emissions
More
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.
Presentation downloadable from www.tececo.com
66
Tec-Cement Reactions
MgO + H2O => Mg(OH)2.nH2O - water consumption
resulting in greater density and higher alkalinity.
Higher alkalinity => more reactions involving silica & alumina.
Mg(OH)2.nH2O => Mg(OH)2 + H2O – slow release water
for more complete hydration of PC
MgO + Al + H2O => 3MgO.Al.6H2O ??? – equivalent to
flash set??
MgO + SO4-- => various Mg oxy sulfates ?? – yes but
more likely ettringite reaction consumes SO 4-- first.
MgO + SiO2 => MSH ?? Yes but high alkalinity required.
Strength??
We think the reactions are relatively
independent of PC reactions
Presentation downloadable from www.tececo.com
67
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
energies
– Crystalline magnesium oxide or periclase has a calculated lattice
energy of 3795 Kj mol-1 which must be overcome for it to go
into solution or for reaction to occur.
– Dead burned magnesia is much less expansive than dead burned
lime in a hydraulic binder (Ramachandran V. S., Concrete
Science, Heydon & Son Ltd. 1981, p 358-360 )
Presentation downloadable from www.tececo.com
68
More Rapid and Greater Strength Development
Higher 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.
Early strength
– Straight line strength development for a long time
gain with less
We have
cement and
HYPOTHETICAL TEC-CEMENT STRENGTH GAIN CURVE
MPa
observed
added
Tec – Cement Concrete with
this sort of
?
10% reactive magnesia
pozzolans is of
curve in over
great
?
500 cubic
?
meters of
economic and
?
concrete
OPC Concrete
environmental
now
importance as
Log Days
28
3
7
14
Plastic Stage
it will allow the
use of more
pozzolans.
Presentation downloadable from www.tececo.com
69
Tec-Cement Strength Development
3
14.365
18.095
19.669
5.516STRENGTH
TEC-CEMENT
COMPRESSIVE
3
9
9
9
21
21
21
35
30
25
16.968
19.466
24.248
29.03
24.54
28.403
32.266
19.44
20.877
24.408
27.939
35.037
36.323
37.609
20.196
13.39
15.39
17.39
25.493
28.723
31.953
WHITTLESEA SLAB
6.656
3.417
4.434
5.451
11.992
13.933
15.874
30
Strength, MPa
STRENGTH ( MPa)
40
20
15
OPC(100%)
10
OPC(90%)+MgO(10%)
5
25
20
Compressive
Strength
15
10
5
0
0
0
0
2
4
6
8
10
12
14
16
18
CURING TIME (days)
20
22
24
5
10
15
20
25
30
Days w ater cured
Graphs above by Oxford Uni Student are for standard 1PC:3 aggregate mixes, w/c = .5
MPa
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.
WHITTLESEA SLAB (A modified
20 mpa mix)
TECECO
60
PC = 180 Kg / m3
MgO = 15 Kg / m3
Flyash = 65 Kg / m3
40
20
Sam ple 1
Sam ple 2
0
17
30
56
89
Days
Rate of strength development
is of great interest to
engineers and constructors
Presentation downloadable from www.tececo.com
70
Calorimetric Evidence of Faster Strength Gain
Faster Strength
Development
HEAT OF HYDRATION
Evolution of Less
Heat
32
31
30
29
TEMP.( C)
28
27
Energy associated
with complexing?
26
25
24
23
22
21
20
19
18
17
OPC
16
15
OPC+PFA(10%)
0
120
240
360
480
600
720
840
TIME (min)
960 1080 1200 1320 1440
OPC+MgO(10%)
OPC(80%)+PFA(10%)+MgO(10%
)
Presentation downloadable from www.tececo.com
71
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.
Presentation downloadable from www.tececo.com
72
+
+
+ +
+ Cement + +
MgO
+
+ + +
+
Mutual Repulsion
=>
+
Ph
12 ?
+ + +
Sand +
+
+
+ +
Mutual Repulsion
+ +
+ - +
+
Cement + MgO Sand
+
+
+
- + +
+
+
Mutual Attraction
STRENGTH (MPa)
Greater Tensile Strength
6
5
4
3
OPC(100%)
2
OPC(90%)+ MgO(10%)
1
0
0
2
4
6
8 10 12 14 16 18 20 22 24 26 28 30
CURING TIME (days)
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 teccement concretes. The affect of additives is not yet known
Presentation downloadable from www.tececo.com
73
Durability
 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
Presentation downloadable from www.tececo.com
74
Crack Collage
Thermal
Freeze Thaw
D Cracks
Alkali aggregate
Reaction
Evaporative
Crazing
Shrinkage
Drying
Shrinkage
Settlement
Shrinkage
Structural
Plastic
Shrinkage
Corrosion Related
Photos from PCA and
US Dept. Ag Websites
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 reactions
As a result of corrosion.
Related to autogenous shrinkage
Presentation downloadable from www.tececo.com
75
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 Portlandite.
– Cracking can compromise structural integrity, particularly if it
accelerates corrosion.
Presentation downloadable from www.tececo.com
76
Graphic Illustration of Cracking
Combined Effect of Concrete Volume Change (Example Only)
200
150
Max Tensile Strain
Temperature effect
100
Drying Shrinkage
Autogenous Shrinkage
Total Srain Induced
50
Total Strain Less Creep
0
Tim e since Cast (Hrs)
120
108
96
84
72
60
48
36
24
12
-50
0
Shrinkage/(Expansion) Microstrain
250
Autogenous
shrinkage has
been used to refer
to hydration
shrinkage and is
thus stoichiometric
After Tony Thomas (Boral Ltd.) (Thomas 2005)
Presentation downloadable from www.tececo.com
77
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.
Fool
Drying
Shrinkage
Plastic
Shrinkage
Bucket of Water
Evaporative
Crazing
Shrinkage
Settlement
Shrinkage
Picture from: http://www.pavement.com/techserv/ACI-GlobalWarming.PDF
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.
Presentation downloadable from www.tececo.com
78
Solving Cracking due to Shrinkage from
Loss of Water
 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)
Presentation downloadable from www.tececo.com
79
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 below:
MgO (s) + H2O (l) ↔ Mg(OH)2.nH2O (s)
 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 system.
– 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 least!)
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
The molar volume (L.mol-1)is equal to the molar
losses from the system.
mass (g.mol-1) divided by the density (g.L-1).
Presentation downloadable from www.tececo.com
80
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)
Presentation downloadable from www.tececo.com
81
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 voids:paste 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).
Presentation downloadable from www.tececo.com
82
Bleeding is a Bad Thing
 Bleeding is caused by:
– Lack of fines
– Too much water
 Bleeding can be fixed by:
Better to keep
concretes as
closed systems
– 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
Presentation downloadable from www.tececo.com
83
Dimensional Control in Tec-Cement
Concretes over Time
 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 8 - 12% reactive
magnesia and 90 – 95% OPC volume changes cancel each
other out.
– The water lost by concrete as it shrinks is used by the
reactive magnesia as it hydrates eliminating shrinkage.
 Note that brucite is > 44.65 mass% water and it
makes sense to make binders out of water!
 More research is required to accurately establish
volume relationships.
Presentation downloadable from www.tececo.com
84
Balancing Time Dependent Dimensional
Change
Reactive Magnesia
?
+.05%
+- Fly Ash?
?
?
?
?
Composite Curve
?
?
28
?
90 days
-.05%
Portland Cement
HYDRATION THEN CARBONATION OF REACTIVE MAGNESIA AND OPC
Presentation downloadable from www.tececo.com
85
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.
Tec-Cement (red) - more affective
pozzolanic reactions
Surface hydrolysis and more polymeric species?
pH
13.7
11.2
10.5
HYPOTHETICAL pH CURVES
OVER TIME (with fly ash)
?
Tec – Cement Concrete with 10% reactive
?
? magnesia (red). Ph maintained by brucite
OPC Concrete
OPC Concrete – Lower long term pH due
to consumption of lime and carbonation
Log Time
Plastic
Stage
Presentation downloadable from www.tececo.com
A pH in
the
range
10.5 –
11.2 is
ideal in a
concrete
86
Reducing Cracking as a Result of Volume
Change caused by Delayed Reactions
An Alkali Aggregate Reaction Cracked Bridge Element
Photo Courtesy Ahmad Shayan ARRB
Presentation downloadable from www.tececo.com
87
Types of Delayed Reactions
 There are several types of delayed reactions
that cause volume changes (generally
expansion) and cracking.
–
–
–
–
–
Alkali silica reactions
Alkali carbonate reactions
Delayed ettringite formation
Delayed thaumasite formation
Delayed hydration or dead burned lime or
periclase.
Delayed reactions cause dimensional
distress, cracking and possibly even
failure.
Presentation downloadable from www.tececo.com
88
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.
Presentation downloadable from www.tececo.com
89
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
salts.
Presentation downloadable from www.tececo.com
90
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 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.)
 As a result of the above the rusting of
reinforcement does not proceed to the same
extent.
 Cracking or spalling due to rust does not occur
Presentation downloadable from www.tececo.com
91
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
Presentation downloadable from www.tececo.com
92
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 hydration.
– 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 temperature.
Presentation downloadable from www.tececo.com
93
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 1900:54-7.
Presentation downloadable from www.tececo.com
94
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 is 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!)
Presentation downloadable from www.tececo.com
95
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 => Chemical Attack
– Removal of Portlandite with the Pozzolanic Reaction.
• Removal or reactive components
– Substitution by Brucite => Long Term pH control
• Reducing corrosion
Presentation downloadable from www.tececo.com
96
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--, Cland 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. Teccements have a higher salt resistance and
less corrosion of steel etc.
Presentation downloadable from www.tececo.com
97
Greater Density – Lower Permeability
 Concretes have a high percentage (around 18% –
22%) of voids.
 On hydration magnesia expands >=116.9 % filling
voids and surrounding hydrating cement grains =>
denser concrete.
 On carbonation to nesquehonite brucite expands
307% sealing the surface.
 Lower voids:paste ratios than water:binder ratios
result in little or no bleed water, lower permeability
and greater density.
Presentation downloadable from www.tececo.com
98
Densification During the Plastic Phase
Observable
Characteristic
Water
Binder +
supplemen
tary
cementitio
us
materials
High water
for ease of
placement
Consumption
of water during
plastic stage
Variables such as %
hydration of mineral,
density, compaction,
% mineral H20 etc.
Log time
Relevant
Fundamental
Voids
Hydrated
Binder
Materials
Unhydrated
Binder
Less water
for strength
and durability
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.
Presentation downloadable from www.tececo.com
99
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
Presentation downloadable from www.tececo.com
100
Less Freeze - Thaw Problems
 Denser concretes do not let water in.
 Brucite will to a certain extent take up internal stresses
 When magnesia hydrates it expands into the pores left around
hydrating cement grains:
MgO (s) + H2O (l) ↔ Mg(OH)2 (s)
40.31 + 18.0 ↔ 58.3 molar mass
11.2 + 18.0 ↔ 24.3 molar volumes
39.20 ↔ 24.3 molar volumes
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
Presentation downloadable from www.tececo.com
101
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 progress.
More information from http://www.rosendalecement.net/rosendale_natural_cement_.html
Presentation downloadable from www.tececo.com
102
Using Wastes and Non-Traditional Aggregates to
Make TecEco Cement Concretes
 As the price of fuel rises, the
use of on site low embodied
energy materials rather
than carted aggregates will
have 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
Presentation downloadable from www.tececo.com
103
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
(>2 tonnes per person per year)
Presentation downloadable from www.tececo.com
104
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
Presentation downloadable from www.tececo.com
105
Role of Brucite in Immobilization
 In a Portland cement Brucite matrix
– PC derive CSH takes up lead, some zinc and germanium
– Pozzolanic CSH can take up mobile cations
– 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.
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.
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.
Presentation downloadable from www.tececo.com
106
Concentration of Dissolved Metal, (mg/L)
Lower Solubility of Metal Hydroxides
There is a 104 difference
10
Pb(OH)
2
Cr(OH) 3
Zn(OH) 2
100
Ag(OH)
Cu(OH) 2
Ni(OH) 2
Cd(OH) 2
10 -2
Equilibrium pH of brucite
is 10.52 (more ideal)*
10 -4
10 -6
6
7
8
9
10
Equilibrium pH of PC
CSH is 11.2
11
12
13
*Equilibrium
pH’s in pure
water, no
other ions
present. The
solubility of
toxic metal
hydroxides is
generally less
in the range
pH 10.52 11.2 than at
higher pH’s.
14
Equilibrium pH of
Portlandite is 12.35
All waste streams will contain heavy metals and a
strategy for long term pH control is therefore essential
Presentation downloadable from www.tececo.com
107
Easier to Finish Concretes
Easier to pump and finish
Concretes are likely to have less
water added to them resulting in
less cracking
Presentation downloadable from www.tececo.com
108
Non Newtonian Rheology
It is not
known
how
deep
these +
layers
+
get
Etc.
+
O
+
+
O
-
+
O
O +
O - +
+
+
O
O
+
+
Etc.
+
-
Mg++
-
-
O
+
+
+
The strongly
positively charged
small Mg++ atoms
attract water
(which is polar) in
deep layers
introduce a shear
thinning property
affecting the
rheological
properties and
making concretes
less “sticky” with
added pozzolan
Ca++ = 114, Mg++ = 86 picometres
Presentation downloadable from www.tececo.com
109
Bingham Plastic Rheology
Tech Tendons
Second layer low slump teccement concrete
First layer low slump tec-cement
concrete
 TecEco concretes and mortars are:
– Very homogenous and do not segregate easily. They exhibit good adhesion and
have a shear thinning property.
– Exhibit Bingham plastic qualities and react well to energy input.
– Have good workability.
 TecEco concretes with the same water/binder ratio have a lower
slump but greater plasticity and workability.
 TecEco tec-cements are potentially suitable for mortars, renders,
patch cements, colour coatings, pumpable and self compacting
concretes.
 A range of pumpable composites with Bingham plastic properties will
be required in the future as buildings will be “printed.”
Presentation downloadable from www.tececo.com
110
Problems with Portland Cement Fixed
Strength
Faster & greater
strength
development
even with added
pozzolans
Water removal by magnesia as it
hydrates in tec-cements results in a
higher short term pH and therefore
more affective pozzolanic reactions.
Brucite hydrate fills pore spaces taking
up mix and bleed water as it hydrates
reducing voids and shrinkage (brucite
hydrate is > 44.65 mass% water!).
Greater density (lower voids:paste ratio)
and lower permeability results in greater
strength.
Possible formation of Mg Al hydrates.
Strength from self compaction
Presentation downloadable from www.tececo.com
111
Problems with Portland Cement Fixed (1)
Durability and
Performance
Permeability and
Density
Sulphate and
chloride
resistance
Carbonation
Corrosion of
steel and other
reinforcing
TecEco tec - cements are
• Denser and much less permeable
• Due mainly to the removal of
water by magnesia and
associated volume increases
• Protected by brucite
• Which is 5 times less reactive
than Portlandite
• Not attacked by salts,
• Do not carbonate readily
• Protective of steel reinforcing
which does not corrode
• due to maintenance of long term
pH.
Presentation downloadable from www.tececo.com
112
Problems with Portland Cement Fixed (2)
Durability and
Performance
Ideal lower long term
pH
Delayed reactions
(eg alkali aggregate
and delayed
ettringite)
As Portlandite is removed
• The pH becomes governed by the pH of
CSH and Brucite and
• Is much lower at around 10.5 -11
• Stabilising many heavy metals and
• Allowing a wider range of aggregates to
be used without AAR problems.
• Reactions such as carbonation are
slower and
• The pH remains high enough to keep
Fe3O4 stable for much longer.
Internal delayed reactions are prevented
• Dry from the inside out and
• Have a lower long term pH
Presentation downloadable from www.tececo.com
113
Problems with Portland Cement Fixed (3)
Net shrinkage is reduced due to:
Shrinkage
• Stoichiometric expansion of
Cracking, crack control
magnesium minerals, and
• Reduced water loss.
Rheology
Workability, time for
and method of placing
and finishing
The Mg++ ion adds a shear thinning
making TecEco cements very
workable.
Hydration of magnesia rapidly adds
early strength for finishing.
Presentation downloadable from www.tececo.com
114
Problems with Portland Cement Fixed (4)
Improved Properties
TecEco cements
• Can have insulating properties
• High thermal mass and
• Low embodied energy.
Many formulations can be reprocessed and
reused.
Brucite bonds well and reduces
efflorescence.
Properties (contd.)
Fire Retardation
Brucite, hydrated magnesium carbonates
are fire retardants
TecEco cement products put out fires by
releasing CO2 or water at relatively low
temperatures.
Cost
No new plant and equipment are required.
With economies of scale TecEco cements
should be cheaper
Presentation downloadable from www.tececo.com
115
Problems with Portland Cement Fixed (5)
Sustainability
issues
Emissions and
embodied
energies
Tec, eco and enviro-cements
• Less binder is required for the same
strength
• Use a high proportion of recycled
materials
• Immobilise toxic and hazardous
wastes
• Can use a wider range of
aggregates reducing transport
emissions and
• Have superior durability.
Tec-cements
• Use less cement for the same
strength
Eco-cements reabsorb chemically
released CO2.
Presentation downloadable from www.tececo.com
116