1www.tececo.co

m

Mr Tharmalingam MaheswaranMr Fred Andrews-PhaedonosDr Alan Carse

Mr Greg Yorkston

Mr John Harrison

2www.tececo.co

m

New Cements Based on the Addition of Reactive Magnesia to Portland Cement With or Without

Added Pozzolan.

New Cements Based on the Addition of Reactive Magnesia to Portland Cement With or Without

Added Pozzolan.

Solving not just mitigating problems

3www.tececo.co

m

"The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them.“

-- Sir William Bragg

"Imagination has brought mankind through the dark agesto its present state of civilization.Imagination led Columbus to discover America.Imagination led Franklin to discover electricity.Imagination has given us the steam engine,the telephone the talking-machine, and the automobile,for these things had to be dreamed of before they became realities.“

-- L. Frank Baum

Imagination is more important than knowledge, knowledge is limited. -- Albert Einstein

Plasticising our MindsPlasticising our Minds

4www.tececo.co

m

Problems Remaining with Portland Type CementsProblems Remaining with Portland Type Cements Problems talked about

– Short time for placing and finishing

– Shrinkage• Cracking, crack control

– Durability and Performance• Sulphate and chloride resistance• Carbonation• Corrosion of steel and other

reinforcing• Abrasion resistance of pavement

Major problem not discussed– Sustainability

• Emissions and embodied energies

Under 1/3 of the papers presented at “Concrete in the Third Millennium Conference” Brisbane July 2003

Maybe the discussion should be more about how we may be able to overcome - not just mitigate these problems.

5www.tececo.co

m

Potential for ChangePotential for Change Globally some 2 billion tonnes of cement, lime and

magnesia are produced annually.– Consuming large amounts of energy

• Around 98% of the world’s energy is derived from fossil fuels that when burnt to produce energy they release vast amounts of CO2

• The production of Portland cement clinker, lime and magnesia all consume energy.

• The production of Portland cement, lime and reactive magnesia also result in the release of chemically bound CO2.

– Responsible between 5% and 10% of global emissions • The built environment is our footprint on earth. Buildings account for 30%

of the raw materials used, 42% of the energy, 25% of water, 12% of land use, 40% of atmospheric emissions, 20% of water effluents, 25% of solid waste and 13% of other releases. Include infrastructure and the numbers are more.

There is a huge potential to change Portland cement to improve sustainability and properties.– These days technology improvements fuel economic growth.

6www.tececo.co

m

Partially hydrated Portland cement paste [Soroos,1999 ].

Imagine the consequences of getting rid of the lime and filling all these voids as Portland cement hydrates with an almost insoluble sticky alkaline paste.

7www.tececo.co

m

TecEco CementsTecEco Cements

John Harrison B.Sc. B.Ec. FCPA.

SUSTAINABILITY

DURABILITY STRENGTH TECECO MODIFIED PORTLAND CEMENTS AND ECO-CEMENTS

Hydration of the various components of Portland cement for strength

Reaction of alkali with pozzolans (e.g. lime with fly ash.) Hydrolysis and silicification for sustainability, durability and strength

Modified Portland Cements Hydration of magnesia → brucite for plasticity, durability and sustainability. Eco-Cements Carbonation of brucite → hydromagnesite and magnesite for strength and abatement.

PORTLAND POZZOLAN

MAGNESIA

8www.tececo.co

m

TecEco Cement SummaryTecEco Cement Summary

TecEco cements are a system of blending reactive magnesia, Portland cement and usually a pozzolan.

Two main formulation groups.– TecEco modified Portland cements.

• Contain more Portland cement than reactive magnesia– The role of magnesia as it hydrates is to densify and protect.– Other benefits include improvements in rheology

– TecEco eco-cements• Contain more reactive magnesia than Portland cement.

• The brucite formed eventually carbonates – Forming stronger fibrous minerals.– Resulting in huge opportunities for abatement.

9www.tececo.co

m

Basic Chemical ReactionsBasic Chemical Reactions

Magnesia Brucite

MgO + H2O Mg(OH)2

Hardness: 3.5 4 3.5

Form: Massive-Sometimes Fibrous Often Fibrous Acicular - Needle-like crystals

Solubility (mol.L-1): .00015 .0013 .0011

Silicates and aluminosilicates

Magnesia Brucite Magnesite Hydromagnesite

MgO + H2O Mg(OH)2 + CO2 MgCO3 + Mg(OH)2.4MgO.4CO2.4H2O

In Eco - Cements

In TecEco Modified Portland Cements

10www.tececo.co

m

Understanding TecEco Modified Portland CementsUnderstanding TecEco Modified Portland Cements

The easiest way to understand TecEco modified Portland cements is to think of the ramifications of replacing lime in Portland cement with brucite (Mg(OH)2).

TecEco achieve this by removing the lime with a pozzolan and replacing it with reactive magnesia that hydrates filling in the voids.

The mean size of the reactive magnesia TecEco have been using is less than 10 micron, compared to Portland cement at around 80 micron

Highly reactive magnesia and usually a pozzolan are required to prevent dimensional distress.

11www.tececo.co

m

Understanding TecEco Eco-CementsUnderstanding TecEco Eco-Cements

The easiest way to understand eco-cements work is to think of a lime Portland mortar such as a 1:1:6-9 formulation. Replace the lime with reactive magnesia and reduce the proportion of Portland cement by around half. Add fly ash to consume the lime produced as Portland cement hydrates. The reactive magnesia will first hydrate and then carbonate as would have the lime in porous materials.

Dimensional distress is not potentially so much of a problem in porous materials such as bricks, blocks, pavers and mortars and possibly even roads and footpath pavement (which should be porous.)

12www.tececo.co

m

Overcoming Delayed Hydration.Overcoming Delayed Hydration.

Delayed hydration leads to dimensional distress. Magnesium was banned in Portland cements because

when it goes through the high temperature process of making Portland cement it becomes dead burned.

Dead burned lime is much more expansive than dead burned magnesia[1].

Reactivity of magnesia is a function of state of disorder, specific surface area and glass forming impurities. Make a particle small enough and it will react with just about anything! [2][1] Ramachandran V. S., Concrete Science, Heydon & Son Ltd. 1981, p

358-360.[2] Dr Bob Solomon – a former geology lecturer of mine at the University

of Tasmania

13www.tececo.co

m

Ramifications of Adding Reactive MagnesiaRamifications of Adding Reactive Magnesia Durability: TecEco cements include highly insoluble minerals that

last indefinitely. They will potentially maintain pH at ideal levels, protect steel reinforcing and reduce alkali aggregate reactions.

Lower Materials Cost: With economies of scale TecEco cements could reduce costs.

Easy to Use: With improved homogeneity and rheology. Fine magnesia acts as a lubricant for Portland cement and takes up bleed water as it hydrates.

Greater Strength? Less shrinkage?: A lower water cement ratio could mean greater strength and less shrinkage. Still to be examined but so far so good!

Insulating Properties / High Thermal Mass / Low Embodied Energy: Eco-cement products will be favoured for energy conserving buildings.

Waste Materials: TecEco cements and Eco-cements use a high proportion of recycled materials.

Recyclable: Eco-cement products can be reprocessed and reused, making them more attractive to many users.

A Fire Retardant: Eco-cement products put fires out by releasing CO2

Low Capital Cost: No new plant and equipment is required. Environmentally Friendly!

14www.tececo.co

m

Durability of TecEco Cement ConcretesDurability of TecEco Cement Concretes

Reducing Corrosion.– Portlandite is removed in reactions with Pozzolans.– Replacement of Portlandite which carbonates readily and being soluble can act

as an electrolyte by brucite which is much less soluble, does not act as an electrolyte or carbonate as readily.

• Portlandite - Free Energy of Formation of Carbonate Gor - 64.62 kJ.mol-1, Ksp = 5.5 X 10-6

• Brucite - Free Energy of Formation of Carbonate Gor - 19.55 kJ.mol-1, Ksp = 1.8 X 10-11

Lower More Stable pH for much Longer?– As Portlandite is removed the pH becomes governed by the solubility of brucite

and is much lower at around 10.5 -11 reducing problems such as AAR and etching, but still high enough to keep Fe and Fe3O4 stable (See Pourbaix diagram)

Increased Density– As reactive magnesia is much finer than Portland cement it tends to act as a

lubricant improving rheology even without plasticiser and lowering the water cement ratio.

– Brucite also densifies the matrix by filling in pore spaces taking up mix and bleed water as it hydrates.

15www.tececo.co

m

Eh-pH or Pourbaix DiagramEh-pH or Pourbaix Diagram

The stability fields of iron in the presence of oxygen and carbon dioxide.Source: Krauskopf K. B., Introduction to Geochemistry, McGraw Hill Book Company, 1967, page 168, after Garrels & Christ (1965), page 224.

16www.tececo.co

m

TecEco Modified Portland Cements TecEco Modified Portland Cements Improving the triple bottom line (society, the economy

and the environment )– Durability and corrosion may become problems

of the past.• Lower use of materials and energy

over time saving money and the environment.– Concretes may become easier to use with less problems.

• AAR, shrinkage, steel corrosion, fire resistance, placement and finish time are all problems that may be solved to varying extents.

– Lower Costs• Making reactive magnesia is a benign process with potential for using

waste energy.• A wider range of aggregates including wastes will be available

reducing cartage costs and emissions.– Higher Standard of Living

• More with less cost to the environment.

17www.tececo.co

m

TecEco Eco - Cements for Sustainable CitiesTecEco Eco - Cements for Sustainable Cities

RAW MATERIALS

RECYCLABLE MATERIALS

ECO-CEMENT PRODUCTS

MINING

RECYCLING CITIES

CO2

PERMANENT SEQUESTRATION (Man Made Carbonate Rock As A

Building Material)

18www.tececo.co

m

TecEco Eco-Cements - Solving Waste ProblemsTecEco Eco-Cements - Solving Waste Problems

The best thing to do with wastes isif at all possible to use them. If theycannot directly be used then they haveto be immobilised– TecEco eco-cements are ideal for utilising

hazardous wastes such as fly and bottom ash,iron slags, red mud etc.

– TecEco Modified Portland cements are excellent for toxic and hazardous waste immobilisation as they are not corrodedby ground or sea water.

– TecEco Cements are a formidable solution to toxic and hazardous waste fixation problems

19www.tececo.co

m

The Magnesium Thermodynamic CycleThe Magnesium Thermodynamic Cycle

CO2

Magnesite*

Magnesia Brucite*

An alkaline environment in which silicates form

Cementitious phases

Dolomite*

Ca++

Thermal decomposition MgCO3 MgO + CO2 ΔH = 118.28 kJ.mol-1 ΔG = 65.92 kJ.mol-1

Carbonation Mg(OH)2 + CO2 MgCO3 + H2O ΔH = -37.04 kJ.mol-1 ΔG = -19.55 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

20www.tececo.co

m

Manufacture of Portland CementManufacture of Portland Cement

CO2

Calcite and Aragonite

Quicklime Portlandite

Cementitious phases

Clay

OPC Tri calcium silicate hydrate ΔH = - 114 kJ.mol-1

+ Pozzolan

Tri calcium aluminate ΔH = - 362 kJ.mol-1 Calcium alumino ferrite

Di calcium silicate hydrate ΔH = - 43 kJ.mol-1

Rotary Kiln

Thermal decomposition CaCO3 CaO + CO2 ΔH = 178.77 kJ.mol-1 ΔG = 130.98 kJ.mol-1

Carbonation Ca(OH)2 + CO2 CaCO3 + H2O ΔH = - 69.58 kJ.mol-1 ΔG = - 64.62 kJ.mol-1

Hydration CaO + H2O Ca(OH)2 ΔH = -109.19 kJ.mol-1 ΔG = - 66.35 kJ.mol-1

Reactive phases

Portland Cement

SUMMARY

Limestone + Clay

Estimated* ΔH = 1807 kJ.kg-1 ΔG = 1287 kJ. kg-1

*Note the measure is relative to Kg as mixed molar amounts are used.

TOTAL CALCINING ENERGY. (Relative to CaCO3) Theoretical = 1807 kJ.Kg-1

With inefficiencies = 3306 kJ.Kg-1

21www.tececo.co

m

Abatement of EmissionsAbatement of Emissions

The production of Portland cement clinker, lime and magnesia all consume energy

Around 98% of the world’s energy is derived from fossil fuels that when burnt to produce energy release vast amounts of CO2

The production of Portland cement, lime and reactive magnesia also results in the release of chemically bound CO2

– Some of TecEco’s early publications on emissions were not very clear as to how they were abated and this has been compounded by the press. How CO2 releases are abated in TecEco modified Portland cements and eco-cements is discussed in detail in newsletter 28 freely available on the web.

22www.tececo.co

m

EmissionsEmissions

Total CO2 Released (tonnes/tonne) Relative to Product

Calcination Energy 100% Efficient

Calcination Energy With Inefficiencies Chemical

Total 100% Efficient

Total with Inefficiencies

MgO 0.188 0.235 1.092 1.280 1.327

Ca(OH)2 0.154 0.232 0.785 0.939 1.016

Portland Cement 0.116 0.212 0.514 0.630 0.726

23www.tececo.co

m

Abatement –TecEco Eco-CementsAbatement –TecEco Eco-Cements

85 wt% Aggregates 15 wt% Cement

No Capture 15 mass% reactive magnesia, 85 mass% aggregate.

Emissions

.37 tonnes to the tonne. After carbonation. approximately .241 tonne to the tonne.

Portland Cements 15 mass% Portland Cement, 85 mass% aggregate

Emissions

.32 tonnes to the tonne. After carbonation. Approximately .299 tonne to the tonne.

Eco – Cements

Greater Sustainability

.297 > .241 >.118>.113 Bricks, blocks, pavers, mortars and pavement made using Portland cement have 2.62 times more emissions than if they were made with TecEco eco-cements, fly and bottom ash (with capture of CO2 during manufacture of reactive magnesia)

Capture CO2 15 mass% reactive magnesia, 85 mass% aggregate

Emissions

.25 tonnes to the tonne. After carbonation. approximately .140 tonne to the tonne.

Capture CO2.

Fly and Bottom Ash 15 mass% reactive magnesia, 85 mass% fly and bottom ash

Emissions

.126 tonnes to the tonne. After carbonation. Approximately .113 tonne to the tonne.

24www.tececo.co

m

Global AbatementGlobal Abatement

No Capture CO2

Capture CO2

Units

Total Portland cement produced globally 1.800 1.800 billion tonnes

Concrete with same proportion OPC (15 mass%) 12.000 12.000 billion tonnes

Emissions Portland Cement 3.593 3.593 billion tonnes

80% substitution by eco-cements 9.600 9.600 billion tonnes

Abatement Portland Cement Emissions 2.875 2.875 billion tonnes

Emissions/Sequestration Substituted Eco-Cement 2.585 1.343 billion tonnes

Abatement/Sequestration Substituted Eco-Cement 0.289 1.532 billion tonnes

25www.tececo.co

m

Substitution (Millions of Tonnes)Substitution (Millions of Tonnes)Material Substit

utionWorld Market

Substituted Tonnes

CO2 Factors (1)

Emission From Material Before Substitution

Emission/Sequestration from Substituted Eco-Cement (Tonne for Tonne Substitution Assumed)

Net Abatement

Emissions - No Capture

Emissions - CO2 Capture

Abatement - No Capture

Abatement CO2 Capture

Bricks 85.00% 250 212.5 0.28 59.5 57.23 29.73 2.27 29.77

Steel 25.00% 840 210 2.38 499.8 56.56 29.38 443.24 470.42

Aluminium 20.00%20.5 4.1 18

73.8 1.10 0.57 72.70 73.23

TOTAL     426.6 20.66 633.1 114.89 59.68 518.21 573.42

Concretes already have low lifetime energies.

If embodied energies are improved could substitution mean greater market share?

Figures are in millons of Tonnes

26www.tececo.co

m

TecEco Kiln TechnologyTecEco Kiln TechnologyCalcining and grinding occur at the

same time.– Clastic conditions lower the state of disorder.

Heat is literally squashed into a material.

– CO2 can be captured at source.

– The heat lost through grinding is used for calcining.

• Approx 25% greater efficiency.• Much more reactive magnesia should result.

27www.tececo.co

m

TecEco’s Immediate FocusTecEco’s Immediate Focus Raise money for Research – Around 4 millions dollars

worth in the pipeline. Focus is on defined markets for low technical risk

products that require minimal research and development and for which performance based standards apply. – Carbonated products such as bricks, blocks, stabilised earth

blocks, pavers, roof tiles and mortars for the masonry industry that utilise large quantities of waste and products where sustainability, rheology or fire retardation are an issue. (Mainly eco-cement technology using fly ash).

– The immobilisation of wastes including toxic hazardous and other wastes because of the superior performance of the technology and the rapid growth of markets. (Eco-cements and modified Portland cements).

– Products where extreme durability is required.– Products for which weight is an issue.

Considerable interest is also being shown in the new TecEco kiln design and the Tech Tendon method of prestressing, partial prestressing and reinforcing.

28www.tececo.co

m

TecEco Minding the FutureTecEco Minding the Future TecEco are aware of the enormous weight of

opinion necessary before standards can bechanged globally for TecEco modified cementconcretes for general use.– TecEco already have a number of students at universities around

the world doing research

TecEco have publicly released the technology.– TecEco research documents are available from TecEco by request.

Soon they will be able to be purchased from the web site.

– Other documents by other researchers will be made available in a similar manner as they become available.

– TecEco have received huge global publicity – not all of which is correct! Technology standing on its own is not

inherently good. It still matters whether it is operating from the right value system and whether it is properly available to all people.

-- William Jefferson Clinton

29www.tececo.co

m

Manufacture of Eco-Cement ProductsManufacture of Eco-Cement Products

Caustic Magnesia Calcined using waste heat and/or sustainable energy

Flyash

Other ingredients Eco-Masonry Products e.g. Bricks & blocks

Curing, hydration & carbonation using flue cooling &/or scrubbing water & flue steam

Coal Combustion

TecEco - Cements

Magnesite Coal

Bottom ash & other wastes as aggregates

Eco-Cement – One of Many Possible Manufacturing Scenarios

Portland Cement

CO2

30www.tececo.co

m

TecEco Technology SummaryTecEco Technology Summary

Simple, Smart and Sustainable– TecEco cement technology has resulted in potential

solutions to the problem of the rusting of steel in concrete, the alkali aggregate reaction problem 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

ASR Rheology

Shrinkage Placement , Finishing