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1Presentation downloadable from www.tececo.com
TecEco Technology and Geopolymers TecEco Technology and Geopolymers
I will have to race over some slides but the presentation is always downloadable from the TecEco web site if you missed something. John Harrison B.Sc. B.Ec. FCPA.
It is time to deploy new technology materials like geopolymers and TecEco cement binders that offer
waste utilisation, emissions reduction, capture and
sequestration.
It is time to deploy new technology materials like geopolymers and TecEco cement binders that offer
waste utilisation, emissions reduction, capture and
sequestration.
Auguste Rodin “The Thinker”
Sustainability will be the biggest business on the planet if we want to survive the future.
Can we create more polymeric non
hydration species using Ca-Mg
cements?
2Presentation downloadable from www.tececo.com
TecEco Binder Systems and GeopolymerTecEco Binder Systems and Geopolymer
Geopolymers and TecEco binders have much in common. Both are sustainable materials with common deployment
issues e.g.– Response to the reality of carbon taxes.– Lobby groups and competition product associations e.g.
• Portland cement industry putting out information to diffuse and confuse regarding geopolymer and TecEco technology.
– Lobby groups having a disproportionate say on government committees etc.
– Research development and deployment issues. – Energy issues.– Government policy issues.– Development of standards and codes of practice?
Can we learn from each other? Can we help each other? There are also features of tec-cement chemistry that invoke
hydrolysis and more polymeric reactions.There are definitely benefits to co-operation between the two emerging technologies e.g. EU research funding.
3Presentation downloadable from www.tececo.com
The Problem – A Planet in CrisisThe Problem – A Planet in Crisis
TecEco are in the BIGGEST
Business on the Planet - Solving Sustainability
Problems Economically
TecEco are in the BIGGEST
Business on the Planet - Solving Sustainability
Problems Economically
A Planet in Crisis?
4Presentation downloadable from www.tececo.com
A Demographic Explosion A Demographic Explosion
?
Developed Countries
Undeveloped Countries
Global population, consumption per capita and our footprint on the planet is exploding.
5Presentation downloadable from www.tececo.com
Atmospheric Carbon DioxideAtmospheric Carbon Dioxide
6Presentation downloadable from www.tececo.com
Global Temperature AnomalyGlobal Temperature Anomaly
7Presentation downloadable from www.tececo.com
The Techno-ProcessThe Techno-ProcessOur linkages to the bio-geo-sphere are defined by the techno process describing and controlling the flow of matter and energy. It is these flows that have detrimental linkages to earth systems.
Detrimental affects on earth systems
Earth Systems
Atmospheric composition, climate, land cover, marine ecosystems, pollution, coastal zones, freshwater systems, salinity and global biological diversity have all been substantially affected.
Move 500-600 billion
tonnes
Use some 50 billion
tonnes
8Presentation downloadable from www.tececo.com
Ecological FootprintEcological Footprint
Our footprint is exceeding the capacity of the planet to support it. We are not longer sustainable as a species and must change our ways
9Presentation downloadable from www.tececo.com
Impact of the Largest Material Flow - Cement and ConcreteImpact of the Largest Material Flow - Cement and Concrete
Concrete made with cement is the most widely used material on earth accounting for some 30% of all materials flows on the planet and 70% of all materials flows in the built environment.– Global Portland cement production is in the order of 2
billion tonnes per annum. – Globally over 14 billion tonnes of concrete are poured
per year.– Over 2.1 tonnes per person per annum
TecEco Pty. Ltd. And the geopolymer industry both have important technologies for
improvement in sustainability and properties
TecEco Pty. Ltd. And the geopolymer industry both have important technologies for
improvement in sustainability and properties
10Presentation downloadable from www.tececo.com
Embodied Energy of Building MaterialsEmbodied Energy of Building Materials
Downloaded from www.dbce.csiro.au/ind-serv/brochures/embodied/embodied.htm (last accessed 07 March 2000)
Concrete is relatively environmentally friendly and has a relatively low embodied energy
11Presentation downloadable from www.tececo.com
Average Embodied Energy in BuildingsAverage Embodied Energy in Buildings
Downloaded from www.dbce.csiro.au/ind-serv/brochures/embodied/embodied.htm (last accessed 07 March 2000)
But because so much is used there is a huge opportunity for sustainability by reducing the embodied energy, reducing the carbon debt (net emissions) and improving properties.
Most of the embodied energy in the built environment is in concrete.
12Presentation downloadable from www.tececo.com
Emissions from Cement ProductionEmissions from Cement Production Chemical Release
– The process of calcination involves driving off chemically bound CO2 with heat.
CaCO3 →CaO + ↑CO2
Process Energy– Most energy is derived from fossil fuels.
– Fuel oil, coal and natural gas are directly or indirectly burned to produce the energy required releasing CO2.
The production of cement for concretes accounts for around 10% of global anthropogenic CO2.
– Pearce, F., "The Concrete Jungle Overheats", New Scientist, 19 July, No 2097, 1997 (page 14).
The article by Fred Pearce was based on a 1994 article by Joseph Davidovits of the Geopolymer Institute titled “Global Warming Impacts on the Cement and Aggregates Industries.” World Resources Review, pages 263-278, volume 6, number 2.
CO2
CO2
CO2
CO2
13Presentation downloadable from www.tececo.com
Cement Production = Carbon Dioxide EmissionsCement Production = Carbon Dioxide Emissions
0
500,000,000
1,000,000,000
1,500,000,000
2,000,000,000
2,500,000,000
Metric Tonnes
1926
1931
1936
1941
1946
1951
1956
1961
1966
1971
1976
1981
1986
1991
1996
2001
Year
Between geopolymers, tec, eco and enviro-cements we can provide a viable much more sustainable alternative.
14Presentation downloadable from www.tececo.com
SustainabilitySustainabilitySustainability is a direction not a
destination.Our approach should be
holistically balanced and involve– Everybody, every process, every day.
Geopolymers + TecEco Cements= Low Emissions ProductionMineral Sequestration + Waste utilization
Geological Seques-tration
Emissions reductionthrough efficiency andconversion to non fossil fuels
+ +
Common Contributions?
15Presentation downloadable from www.tececo.com
Materials Affect Underlying Molecular FlowsMaterials Affect Underlying Molecular Flows
Take only renewables
→ Manipulate → Make → Use →Waste only what is biodegradable or can be re-assimilated
ReuseRe-make
Recycle
[ ←Materials→ ] [← Underlying molecular flows →]
Materials control:
How much and what we have to take to manufacture the materials we use.How long materials remain of utility, whether they are easily recycled and how andwhat form they are in when we eventually throw them “away”.
What we take from the environment around us, how we manipulate and make materials out of what we take and what we waste result in underlying molecular flows that affect earth systems.
Problems in the global commons today include heavy metals, halogen carbon double bond compounds, CFC’s too much CO2 etc.
e.g. heavy metals, cfc’s, c=halogen compounds and CO2
16Presentation downloadable from www.tececo.com
Innovative New Materials - the Key to SustainabilityInnovative New Materials - the Key to Sustainability
Biosphere - Geosphere Techno - World
Materials are the substance of the techno-process, the link between the biosphere and techno-sphere and the key to sustainability. They are everything between and define the take and waste.
There is no such place as “away”, only a global commons
The choice of materials in construction controls emissions, lifetime and embodied energies, user comfort, use of recycled wastes, durability, recyclability and the properties of wastes returned to the bio-geo-sphere.
17Presentation downloadable from www.tececo.com
Sustainability = Culture + TechnologySustainability = Culture + TechnologyIncrease in demand/price ratio for sustainability due to educationally induced cultural drift.
#
$
Demand
Supply
Increase in supply/price ratio for more sustainable products due to innovative paradigm shifts in technology.
Equilibrium shiftECONOMICS
Greater Value/for impact (Sustainability) and economic growth
Sustainability is where Culture and Technology meet.
Demand Supply
New Technical Paradigms are required that
deliver sustainability. (TecEco and
geopolymers.)
18Presentation downloadable from www.tececo.com
Huge Potential for Sustainable Materials in the Built Environment
Huge Potential for Sustainable Materials in the Built Environment
The built environment is made of materials and is our footprint on earth.– It comprises buildings and infrastructure.
Construction materials comprise– 70% of materials flows (buildings, infrastructure etc.)– 40-45% of waste that goes to landfill (15 % of new materials going to site
are wasted.) Reducing the impact of the take and waste phases of the
techno-process.– Reducing emissions and other impacts during manufacture.– Including carbon in materials so they become carbon sinks (eco-
cements).– including wastes for
their physical properties aswell as chemical compositionso they become resources.
C
CC
C
C
Waste
Waste
19Presentation downloadable from www.tececo.com
TecEco TechnologiesTecEco Technologies Silicate → Carbonate Mineral Sequestration
– Using either peridotite, forsterite or serpentine as inputs to a silicate reactor process CO2 is sequestered and magnesite produced.
– Proven by others (NETL,MIT,TNO, Finnish govt. 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
EconomicunderKyoto?
TecEco
20Presentation downloadable from www.tececo.com
TecEco Kiln TechnologyTecEco Kiln TechnologyTec-Kiln technology will be the first non fossil
fuel industrial process.– variable energy input.– Made from geopolymers.– Suitable for the manufacture of MgO, CaO and
metakaolin. Eventually Portland cement.Grinds and calcines at the same time.Runs 25% to 30% more efficiency.Theoretically capable of producing much
more reactive MgO as well as metakaolin and other input materials for geopolymers.
21Presentation downloadable from www.tececo.com
TecEco Kiln TechnologyTecEco Kiln Technology
CO2
Captures CO2 for bottling and sale.– To the oil industry (geological
sequestration).– Coca Cola?
Can be run cyclicly as part of a major process to solve global CO2 problems.
Will result in new markets for ultra reactive low lattice energy MgO (e.g. paper and environment industries).
TecEco plan to use geopolymer materials for the kiln capable of withstanding high temperatures.
22Presentation downloadable from www.tececo.com
Drivers for TecEco & Geopolymer TechnologyDrivers for TecEco & Geopolymer Technology
Producer PushThe opportunity cost of compliant waste disposalProfitability and cost recoveryTechnical meritResource issuesRoboticsResearch objectives
Consumer PullEnvironmental sentimentFear of climate changeCostTechnical advantagesCompetition
Government Influence
Carbon Taxes
Provision of Research Funds
Environmental education
Huge Existing Markets
Cement >2 billion tonnes.
New markets e.g. Bingham mixtures for robots, kilns, fireproof materials etc.
The way forward is through solving problems in niche markets and delivering sustainability.
23Presentation downloadable from www.tececo.com
TecEco Cement ConcretesTecEco Cement Concretes
More information at www.tececo.com
24Presentation downloadable from www.tececo.com
TecEco CementsTecEco CementsSUSTAINABILITY
DURABILITY STRENGTHTECECO CEMENTS
Hydration of the various components of a hydraulic cement such as Portland cement for strength. Note that geopolymers are esp. included
Reaction of alkali with pozzolans (e.g. lime with fly ash.) for sustainability, durability and strength.
Hydration of magnesia => brucite for strength, workability, dimensional stability and durability. In Eco-cements carbonation of brucite => nesquehonite, lansfordite and an amorphous phase for sustainability.
HYDRAULIC CEMENT
+ or - POZZOLAN
MAGNESIA
25Presentation downloadable from www.tececo.com
The Magnesium Thermodynamic CycleThe Magnesium Thermodynamic Cycle
An alkaline environment in which silicates form
Thermal decomposition MgCO3 MgO + CO2 ΔH = 118.28 kJ.mol-1 ΔG = 65.92 kJ.mol-1
Carbonation Mg(OH)2 + CO2 + 2H2O MgCO3.3 H2O ΔH = -175.59 kJ.mol-1 ΔG = -38.73 kJ.mol-1
Hydration MgO + H2O Mg(OH)2 ΔH = -81.24 kJ.mol-1 ΔG = -35.74 kJ.mol-1
Reactive phase
TOTAL CALCINING ENERGY (Relative to MgCO3) Theoretical = 1480 kJ.Kg-1 With inefficiencies = 1948 kJ.Kg-1 Nesquehonite
? Representative of other hydrated mineral carbonates including an amorphous phase and lansfordite Magnesite*
Magnesia
Dehydration
CO2
Brucite*
Tec - Cements
Eco - Cements
26Presentation downloadable from www.tececo.com
TecEco FormulationsTecEco Formulations Tec-cements (Low MgO)
– contain more Portland cement than reactive magnesia. Reactive magnesia hydrates in the same rate order as Portland cement forming Brucite which uses up water reducing the voids:paste ratio, increasing density and possibly raising the short term pH.
– Reactions with pozzolans are more affective. After all the Portlandite has been consumed Brucite controls the long term pH which is lower and due to it’s low solubility, mobility and reactivity results in greater durability.
– Other benefits include improvements in density, strength and rheology, reduced permeability and shrinkage and the use of a wider range of aggregates many of which are potentially wastes without reaction problems.
Eco-cements (High MgO)– contain more reactive magnesia than in tec-cements. Brucite in porous
materials carbonates forming stronger fibrous mineral carbonates and therefore presenting huge opportunities for waste utilisation and sequestration.
Enviro-cements (High MgO)– contain similar ratios of MgO and OPC to eco-cements but in non porous
concretes brucite does not carbonate readily.– Higher proportions of magnesia are most suited to toxic and hazardous waste
immobilisation and when durability is required. Strength is not developed quickly nor to the same extent.
27Presentation downloadable from www.tececo.com
TecEco Cement TechnologyTecEco Cement TechnologyPortlandite (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 water and concentrating alkalis
forming brucite which is another alkali, but much less soluble, mobile or reactive than Portlandite.
In Eco-cements brucite carbonates
The consequences of need to be considered.
28Presentation downloadable from www.tececo.com
Strength with Blend & PorosityStrength with Blend & Porosity
STRENGTH ON ARBITARY SCALE 1-100
0
50
100
150
100-15050-1000-50
High PC
Tec-cement concretes
Eco-cement concretes
Enviro-cement concretes
High Porosity
High Magnesia
Tec – cement concretes have more polymeric species because they are much more alkaline during the early plastic phase.
29Presentation downloadable from www.tececo.com
Why Add Reactive Magnesia?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
30Presentation downloadable from www.tececo.com
In the presence of water magnesium does not appear to be an important network former in silicate structures including geopolymers at room temperature and this is probably because of it’s high affinity for water which it seems to retain even when it carbonates.There are however other intriguing ramifications of adding reactive MgO.
Tec-Cements & GeopolymersTec-Cements & Geopolymers
More information at www.tececo.com
31Presentation downloadable from www.tececo.com
The Form of MgO - Overcoming DogmaThe Form of MgO - Overcoming Dogma
In 1917 the US National Bureau of Standards (now the National Bureau of standards and Technology) and the American Society for Testing Materials established a standard formula for Portland cement which excluded MgO in any form.
We now know that it is lattice energy that causes the difference between amorphous magnesia and periclase
TecEco have proved that amorphous magnesia, having no lattice energy to overcome, is safe to use in water based binder systems.
32Presentation downloadable from www.tececo.com
The Form of MgO - Lattice Energy Destroys a MythThe Form of MgO - 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 )
33Presentation downloadable from www.tececo.com
Tec-Cement Concrete Strength Gain CurveTec-Cement Concrete Strength Gain Curve
strength gain with less cement and added pozzolans is of great economic and environmental importance.
Tec – Cement Concrete with 10% reactive magnesia
OPC Concrete
HYPOTHETICAL TEC-CEMENT STRENGTH GAIN CURVE MPa
Log Days Plastic Stage
? ?
?
?
7 14 28 3
The use of tec-cement results in– 20-30% greater strength or less binder for the same strength.
– more rapid early strength development even with added pozzolans.
– Straight line strength development for a long time
We have observed this sort of curve in over 300 cubic meters of concrete now
34Presentation downloadable from www.tececo.com
Tec-Cement ReactionsTec-Cement ReactionsMgO + 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 SO4
-- first.
MgO + SiO2 => MSH ?? Yes but high alkalinity required. Strength??
We think the reactions are relatively independent of PC reactions
35Presentation downloadable from www.tececo.com
Non hydration Reactions in Tec-Cement Concretes?Non hydration Reactions in Tec-Cement Concretes?
MgO + H2O => Mg(OH)2.nH2O - water consumption– Increases density.– Raises the alkalinity during the early plastic stage.
Better pozzolanic reactions, surface hydrolysis and re-bonding as well as the formation of more polymeric not necessarily hydraulic species.– Resulting mineralization more similar to Roman cement
concretes that contained more Mg and more polymeric species.
36Presentation downloadable from www.tececo.com
13.7
pH
Log Time
10.5
Tec – Cement Concrete with 10% reactive magnesia (red). Ph maintained by brucite
OPC Concrete
HYPOTHETICAL pH CURVES OVER TIME (with fly ash)
Plastic Stage
? ?
?
Tec-Cement (red) - more affective pozzolanic reactions
11.2
OPC Concrete – Lower long term pH due to consumption of lime and carbonation
Surface hydrolysis and more polymeric species?
Tec-Cement pH CurvesTec-Cement pH Curves
37Presentation downloadable from www.tececo.com
ConjectureConjecture Why does Mg keep turning up in discussion
of ancient mineral systems (Egyptians, Mesopotamians and Romans)??
Maybe sepiolite (polygorskite with Al?) are carrier minerals that break down as the alkalinity rises delivering soluble and mobile SiO2 and Al2O3 for reactions forming more polymeric minerals.This idea emerged over too many drinks with Herbert Baier of PCI (part of Degussa) on the 29th June in Saint Quentin, France. It’s conjecture, interesting and not completely daft.
38Presentation downloadable from www.tececo.com
Role of Mg++ in Geopolymerism??!Role of Mg++ in Geopolymerism??!
Mg4Si6O15(OH)2.6H2O (sepiolite)+ clay + sodium or potassium salt => Geopolymer (Si-O-Al-O-Si ??) + brucite + more sepiolite??
or
Sepiolite + clay + H2O + CO2 + OH-
Geopolymer + sepiolite + salt??
Sepiolite precipitates from salty alkaline waters in arid environments and was available to the Egyptians. Does explain role of Mg in Egyptian cements.
39Presentation downloadable from www.tececo.com
Strength Development in Tec-Cements.Strength Development in Tec-Cements.
Reactive magnesia requires considerable water to hydrate resulting in:– A significantly lower voids/paste ratio i.e. denser,
less permeable concrete.
– 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?
Could the role of added reactive magnesia be to consume water like the ettringite reaction in PC concretes. This property could be useful with geopolymers to overcome the viscosity problem.
40Presentation downloadable from www.tececo.com
Water Reduction During the Plastic Phase?Water Reduction During the Plastic Phase?
Water is required to plasticise concrete for placement, however once placed, the less water over the amount required for hydration the better. Magnesia consumes water as it hydrates producing solid material.
Less water results in increased density and concentration of
alkalis - less shrinkage and cracking and improved strength and durability.
Water
Log time
Observable Characteristic
Relevant Fundamental
Voids
Binder + supplementary cementitious materials
Hydrated Binder Materials
High water for ease of placement
Less water for strength and durability
Variables such as % hydration of mineral, density, compaction, % mineral H20 etc.
Consumption of water during plastic stage
Unhydrated Binder
Ph
Water Reduction.
41Presentation downloadable from www.tececo.com
For more effective reactions in hydraulic concretes like PC and in “geopolymer concretes” high alkalinity is required.– To achieve high alkalinity it is necessary to not add too much water –
this results in higher viscosity.
– To place concretes low viscosity is required.
Tec-cement concretes achieve high alkalinity by internal water removal.– The dichotomy between viscosity and ease of placement defines much
of the current research on geopolymers and for that matter in relation to additives for PC.
Depending on the level of alkalinity reached, many of the particles of fly ash or dehydrated clay (Kandoxi) polymerise, react at the surface only (hydrolyse and re-bond) or remain as micro-aggregates.
High Alkalinity Common to Both Hydraulic and Geopolymer Systems => Better Reactions.
High Alkalinity Common to Both Hydraulic and Geopolymer Systems => Better Reactions.
42Presentation downloadable from www.tececo.com
Adding Reactive MgOAdding Reactive MgO Portland cements stoichiometrically require around 23 -25% water
for hydration yet we add approximately 45 to 50% 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 in a similar way.– Can reactive MgO be used to get over the viscosity issue in geopolymers?– Would this be cheaper than using super plasticisers?
43Presentation downloadable from www.tececo.com
Adding Reactive MgO to GeopolymersAdding Reactive MgO to Geopolymers It is not possible to add water to geopolymers. If water were add the
alkalis would be diluted, the pH would fall and the mix would not set as unlike the setting of Portland cement concretes there is no reaction that consumes water. On the contrary – water is expelled.
Reactive magnesia is a water removal tool and may be useful as an adjunct to assist with the viscosity problem.
Most people researching geopolymers seem to be trying various super, duper, hyper, blah blah plasticiser molecules to see if they can be used to fluidise the mix sufficiently.
The water removal mechanism of magnesia and its plasticising properties may be useful as a totally different approach to get over the viscosity issue. There is obviously more work to do pending funding but could it be that the best features of geopolymeric and hydraulic cements can be combined?– There are more polymeric species in Roman cements.
44Presentation downloadable from www.tececo.com
Non Newtonian RheologyNon Newtonian Rheology
O
O
O
O Mg++
+
- +
+
+
+
+
+
+
+
+
O +
+
+
+
+
+
O
O O
- -
- -
-
-
The strongly positively charged small Mg++ atoms attract water (which is polar) in deep layers affecting the rheological properties and making concretes less “sticky” with added pozzolan
It is not known how deep these layers get
Etc.
Etc.
Ca++ = 114, Mg++ = 86 picometres
45Presentation downloadable from www.tececo.com
MgO Changes Surface Charge as the Ph RisesMgO Changes Surface Charge as the Ph Rises
+
+
+
+
++
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Mutual Repulsion=
>
+
+
+
+
++
+
+
+
+
+
+
+
+
-
-
-
-
-
-
-Mutual Attraction
This could be the reason for the greater tensile strength displayed during the early plastic phase of tec-cement concretes.
Ph 12 ?
Cement
Cement
MgO Sand
SandMgO
46Presentation downloadable from www.tececo.com
Tec-Cement Tensile StrengthTec-Cement Tensile Strength
TEC - CEMENT TENSILE STRENGTH
0
1
2
3
4
5
6
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
CURING TIME (days)
ST
RE
NG
TH
(M
Pa)
OPC(100%)
OPC(90%)+ MgO(10%)
Graphs by Oxford Uni Student
Tensile strength is thought to be caused by change in surface charge on MgO particles from +ve to –ve at Ph 12 and electrostatic attractive forces
47Presentation downloadable from www.tececo.com
RheologyRheology
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.
Second layer low slump tec-cement concrete Tech Tendons
First layer low slump tec-cement concrete
A range of pumpable composites with Bingham plastic properties will be required in the future as buildings will be “printed.” (Robotics)
48Presentation downloadable from www.tececo.com
Technical Comparisons Geopolymers and Tec-Cement Concretes
Technical Comparisons Geopolymers and Tec-Cement Concretes
Tec-Cement Concretes Geopolymers
Can use a high proportion of pozzolanic materials
Use a high proportion of pozzolanic materials
Low temperature heat curing only.
Often but not always require heat curing
Low shrinkage Low shrinkage
More durable than PC concretes but not as acid resistant than Geopolymers
Durable acid and alkali resistant.
49Presentation downloadable from www.tececo.com
Technical Comparisons Geopolymers and Tec-Cement Concretes (2)
Technical Comparisons Geopolymers and Tec-Cement Concretes (2)
Tec-Cement Concretes Geopolymers
Fire retardants (Water or CO2
releases. MgO is a smoke absorbent.
Heat resistant
Higher tensile strength than PC concretes
Higher tensile strength than PC concretes
Lower heat of hydration than pure PC concretes.
Very low heat of hydration
Not attacked by sulfate and chloride.
Not attacked by sulfate and chloride.
50Presentation downloadable from www.tececo.com
Other Comparisons = Common ProblemsOther Comparisons = Common Problems
Tec-Cement Concretes GeopolymersAre a system. i.e. no single formulation ideal
Are a system. i.e. no single formulation ideal
More sustainable with reduced net emissions. (Eco-cements can be net carbon sinks)
More sustainable with reduced net emissions.
Disruption by the PC industry- Diffuse and confuse the science.- Lack of understanding => “put downs”
Disruption mentioned by Grant Lukey, Robert Temple, Davidovits and others.
Not fragmented (yet). Fragmented – too many patents
Standards ban MgO regardless of form.
Standards suit PC not geopolymers.
51Presentation downloadable from www.tececo.com
TecEco and Geopolymer GroupsTecEco and Geopolymer Groups
Mutual response to government– Changing standards to performance based.– Policy issues
• Procurement policies designed to foster new more sustainable materials technologies.
• Funding for sustainable new materials.
Mutual promotion of sustainability. Educational – the buying public Counter subversive tactics by the PC lobby
There are definitely benefits to co-operation between the two emerging technologies e.g. EU research funding.
52Presentation downloadable from www.tececo.com
TecEco and the PC Cement IndustryTecEco and the PC Cement Industry
The PC industry should:– Spend a little more money on research to move
cementitous composites into better market space.– Spend a little less on litigation, remediation and
arbitration because of the imperfect material they have.
Worth thinking about in context of carbon taxes?
53Presentation downloadable from www.tececo.com
TecEco Cement Implementation
Summary
TecEco Cement Implementation
Summary
54Presentation downloadable from www.tececo.com
High Performance-Lower Construction CostsHigh Performance-Lower Construction Costs
Less binders (OPC + magnesia) for the same strength. Faster strength gain even with added pozzolans. Elimination of shrinkage reducing
associated costs. Tolerance and consumption of water. Reduction in bleed water enables finishing of lower
floors whilst upper floors still being poured and increases pumpability.
Cheaper binders as less energy required Increased durability will result in lower
costs/energies/emissions due to less frequent replacement.
Because reactive magnesia is also an excellent plasticiser, other costly additives are not required for this purpose.
A wider range of aggregates can be utilised without problems reducing transport and other costs/energies/emissions.
Foolproof Concrete?
55Presentation downloadable from www.tececo.com
TecEco Concretes - Lower Construction Costs (2)TecEco Concretes - Lower Construction Costs (2) Homogenous, do not segregate with pumping or work. Easier placement and better finishing. Reduced or eliminated carbon taxes. Eco-cements can to a certain extent be recycled. TecEco cements utilise wastes many of which improve
properties. Improvements in insulating capacity and other properties will
result in greater utility. Products utilising TecEco cements such as masonry and
precast products can in most cases utilise conventional equipment and have superior properties.
A high proportion of brucite compared to Portlandite is water and of Lansfordite and nesquehonite compared to calcite is CO2.– Every mass unit of TecEco cements therefore produces a greater volume of
built environment than Portland and other calcium based cements. Less need therefore be used reducing costs/energy/emissions.
56Presentation downloadable from www.tececo.com
SummarySummary Simple, smart and sustainable?
– TecEco cement technology has resulted in potential solutions to a number of problems with Portland and other cements including shrinkage, durability and corrosion and the immobilisation of many problem wastes and will provides a range of more sustainable building materials.
The right technology at the right time?– TecEco cement technology addresses important triple bottom line issues
solving major global problems with positive economic and social outcomes.
Climate Change Pollution
Durability Corrosion
Strength Delayed Reactions
Placement , Finishing Rheology
Shrinkage Carbon Taxes
57Presentation downloadable from www.tececo.com
TecEco Doing Things
TecEco Doing Things
58Presentation downloadable from www.tececo.com
The Use of Eco-Cements for Building Earthship BrightonThe Use of Eco-Cements for Building Earthship BrightonBy 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.
59Presentation downloadable from www.tececo.com
Repair of Concrete Blocks. Clifton Surf ClubRepair of Concrete Blocks. Clifton Surf ClubThe 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.
60Presentation downloadable from www.tececo.com
Mike Burdon’s Murdunna WorksMike Burdon’s Murdunna WorksMike 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
61Presentation downloadable from www.tececo.com
Tec-Cement Slab Whittlesea, Vic. AustraliaTec-Cement Slab Whittlesea, Vic. Australia On 17th March 2005 TecEco
poured the first commercial slab in the world using tec-cement concrete with the assistance of one of the larger cement and pre-mix companies.
– The formulation strategy was to adjust a standard 20 MPa high fly ash (36%) mix from the company as a basis of comparison.
– Strength development, and in particular early strength development was good. Interestingly some 70 days later the slab is still gaining strength at the rate of about 5 MPa a month.
– 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.
Strength Development of Tec-Cement Concrete
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