The technology paradigm defines what is or is not a resource - Pillzer Greening Mineral Binders 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.
Under Materials Flows in the Techno-Processes are 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 environmente.g. heavy metals, cfc’s, c=halogen compounds and CO2 MoleconomicsIs 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.
Sequestration Abatement and Abatement and Sequestration • To solve sustainability problems our approach should be holistically balanced and involve • Everybody, every day • Be easy • Make money New technical paradigms are required + CarbonSafe = Sequestration and waste utilisation. Abatement = Efficiency and conversion to non fossil fuels TecEco’s Contribution
CO2 CO2 CO2 CO2 The TecEco CarbonSafe Geo-Photosynthethic Process The CarbonSafe Geo-Photosynthetic Process is TecEco’s evolving techno-process that delivers profitable outcomes whilst reversing underlying undesirable moleconomic flows from other less sustainable processes. Inputs: Atmospheric or smokestack CO2, brines,waste acid, other wastes Outputs: Potable water, gypsum, sodium bicarbonate, salts, building materials, bottled concentrated CO2 (for geo-sequestration and other uses). Solar or solar derived energy TecEcoKiln TecEco MgCO2 Cycle MgO MgCO3 Greensols Process 1.29 gm/l Mg Coal Fossil fuels Carbon or carbon compoundsMagnesium oxide CO2 Oil
The TecEco CarbonSafe Industrial Ecology InputsBrinesWaste AcidCO2 OutputsGypsum, Sodium bicarbonate, Salts, Building materials, Potable water We must design whole new technical paradigms that reverse many of our problem molecular flows
The CarbonSafe Geo-Photosynthetic Process 1.354 x 109 km3 Seawater containing 1.728 1017 tonne Mg or suitable brines from other sources Seawater Carbonation Process Waste Acid Gypsum + carbon waste (e.g. sewerage) = fertilizers Bicarbonate of Soda (NaHCO3) CO2 from power generation or industry Other salts Na+,K+, Ca2+,Cl- Gypsum (CaSO4) Sewerage compost CO2 as a biological or industrial input or if no other use geological sequestration Magnesite (MgCO3) Solar Process to Produce Magnesium Metal Magnesium Thermodynamic Cycle Simplified TecEco ReactionsTec-Kiln MgCO3 → MgO + CO2 - 118 kJ/moleReactor Process MgO + CO2 → MgCO3 + 118 kJ/mole (usually more complex hydrates) CO2 from power generation, industry or out of the air Magnesite (MgCO3) Magnesia (MgO) Hydroxide ReactorProcess Sequestration Table – Mg from Seawater CO2 Eco-CementTec-Cement Other Wastes
TecEco CO2 Capture Kiln Technology • Can run at low temperatures. • Can be powered by various non fossil fuels. • E.g. solar • 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. • Runs 25% to 30% more efficiently as use waste heat from grinding • Will result in new markets for ultra reactive low lattice energy MgO (e.g. cement, paper and environment industries)
Re - Engineering Materials – What we Build With • To solve environmental problems we need to understand more about materials in relation to the environment. • the way their precursors are derived and their degradation products re assimilated • and how we can reduce the impact of these processes • what energies drive the evolution, devolution and flow of materials • and how we can reduce these energies • how materials impact on lifetime energies • With the knowledge gained re-design materials to not only be more sustainable but more sustainable in use Environmental problems are the result of inherently flawed materials, materials flows and energy systems
CO2 CO2 Waste CO2 C Waste CO2 Huge Potential for Sustainable Materials • Reducing the impact of the take and waste phases of the techno-process. • including carbon in materialsthey are potentially carbon sinks. • including wastes forphysical properties aswell as chemical compositionthey become resources. • re – engineeringmaterials toreduce the lifetimeenergy of buildings Many wastes can contribute to physical properties reducing lifetime energies
Utilizing Carbon and Wastes (Biomimicry) • During earth's geological history large tonnages of carbon were put away as limestone and other carbonates and as coal and petroleum by the activity of plants and animals. • Sequestering carbon in magnesium binders and aggregates in the built environment mimics nature in that carbon is used in the homes or skeletal structures of most plants and animals. In eco-cement blocks and mortars the binder is carbonate and the aggregates are preferably wastes We all use carbon and wastes to make our homes! “Biomimicry”
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 2.2 billion tonnes per annum. • Globally over 15 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
Embodied Energy of Building Materials Concrete is relatively environmentally friendly and has a relatively low embodied energy Downloaded from www.dbce.csiro.au/ind-serv/brochures/embodied/embodied.htm (last accessed 07 March 2000)
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/ind-serv/brochures/embodied/embodied.htm (last accessed 07 March 2000)
Emissions 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). CO2 CO2 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.
Cement Production ~= Carbon Dioxide Emissions Between Tec, Eco and Enviro-Cements TecEco can provide a viable much more sustainable alternative.
CO2 The TecEco Dream – A More Sustainable Built Environment CO2 OTHERWASTES CO2 FOR GEOLOGICAL SEQUESTRATION PERMANENT SEQUESTRATION & WASTE UTILISATION (Man made carbonate rock incorporating wastes as a building material) MINING MgO TECECO KILN MAGNESITE + OTHER INPUTS TECECO CONCRETES RECYCLED BUILDING MATERIALS We need materials that require less energy to make them, that last much longer and that contribute properties that reduce lifetime energies “There is a way to make our city streets as green as the Amazon rainforest”. Fred Pearce, New Scientist Magazine SUSTAINABLE CITIES
A Low Energy Post – Carbon & Waste Age? Maybe then we can move confidently into a more sustainable future. The construction industry can be uniquely responsible for helping achieve this transition
Concrete Industry Objectives • PCA (USA) • Improved energy efficiency of fuels and raw materials. • Formulation improvements that: • Reduce the energy of production and minimize the use of natural resources. • Use of crushed limestone and industrial by-products such as fly ash and blast furnace slag. • WBCSD • Fuels and raw materials efficiencies • Emissions reduction during manufacture
Greening the Largest Material Flow -Concrete • Scale down Production. • Untenable nonsense, especially to developing nations • Use waste for fuels • Not my area of expertise but questioned by many. • Reduce net emissions from manufacture • Increase manufacturing efficiency • Increase fuel efficiency • Waste stream sequestration using MgO and CaO • E.g. Carbonating the Portlandite in waste concrete • Given the current price of carbon in Europe this could be viable • TecEco have a mineral sequestration process that is non fossil fuel driven using MgO and the TecEco kiln Not discussed
Greening Concrete • Increase the proportion of waste materials that are pozzolanic • Using waste pozzolanic materials such as fly ash and slags has the advantage of not only extending cement reducing the embodied energy and net emissions but also of utilizing waste. • TecEco technology will allow the use of marginal pozzolans • Slow rate of strength development increased in first few hours and days • Potential long term (50 year plus) durability issues overcome using tec-cement technology • Finishing problems overcome • We could run out of fly ash as coal is phasing out. (e.g. Canada) • Replace Portland cement with viable alternatives • There are a number of products with similar properties to Portland cement • Carbonating Binders • Non-carbonating binders • The research and development of these binders needs to be accelerated
Greening Concrete • Use aggregates that extend cement • Use air as an aggregate making cement go further • Foamed Concretes work well with TecEco cements • Use for slabs to improve insulation • Aluminium use questionable • Use aggregates with lower embodied energy and that result in less emissions or are themselves carbon sinks • Other materials that be used to make concrete have lower embodied energies. • Local low impact aggregates • Waste materials • Recycled aggregates from building rubble • Glass cullet • Materials that non fossil carbon are carbon sinks in concrete • Plastics, wood etc. • Improve the performance of concrete by including aggregates that improve or introduce new properties reducing lifetime energies • Wood fibre reduces weight and conductance.
4. Increasing the Proportion of Waste Materials that are Pozzolanic • Advantages • Lower costs • More durable greener concrete • Disadvantages • Rate of strength development retarded • Potential long term durability issue due to leaching of Ca from CSH. • Resolved by presence of brucite in tec-cements • Higher water demand due to fineness. • Finishing is not as easy • Supported by WBCSD and virtually all industry associations • Driven by legislation and sentiment
Impact of TecEco Tec-Cement Technology on the use of Pozzolans • In TecEco Tec-Cements Portlandite is generally consumed by the pozzolanic reaction and replaced with brucite • Increase in rate of strength development in the first 3-4 days. • Internal consumption of water by MgO as it hydrates reducing impact of fineness demand • More pozzolanic reactions • Mg Al hydrates? • Followed by straight line development • Improved durability as brucite is much less soluble or reactive • Potential long term durability issue due to leaching of Ca from CSH resolved. • Influence of kosmotopic Mg++ • Concretes easier to finish with a strong shear thinning property • Gel up more quickly – so finishers can go home earlier even with added pozzolan • Early strength development in the first few days – previously a problem with added pozzolan • Less shrinkage and cracking
Portlandite Compared to Brucite Cement chemists in the industry should be getting their heads around the differences
Tec-Cement Concrete Strength Gain Curve We have observed this kind of curve with over 300 cubic meters of concrete The possibility of high early strength gain with added pozzolans is of great economic and environmental importance.
5.a Replacement of PC by Carbonating Binders • Lime • The most used material next to Portland cement in binders. • Generally used on a 1:3 paste basis since Roman times • Non-hydraulic limes set by carbonation and are therefore close to carbon neutral once set. CaO + H2O => Ca(OH)2 Ca(OH)2 + CO2 => CaCO3 33.22 + gas ↔ 36.93 molar volumes • Very slight expansion, but shrinkage from loss of water.
5.a Replacement of PC Carbonating Binders • Eco-Cement (TecEco) • Have high proportions of reactive magnesium oxide • Carbonate like lime • Generally used in a 1:5-1:12 paste basis because much more carbonate “binder” is produced than with lime MgO + H2O <=> Mg(OH)2 Mg(OH)2 + CO2 + H2O <=> MgCO3.3H2O 58.31 + 44.01 <=> 138.32 molar mass (at least!) 24.29 + gas <=> 74.77 molar volumes (at least!) • 307 % expansion (less water volume reduction) producing much more binder per mole of MgO than lime (around 8 times) • Carbonates tend to be fibrous adding significant micro structural strength compared to lime Mostly CO2 and water
5.b Replacement with Non Carbonating Binders • There are a number of other novel cements with intrinsically lower energy requirements and CO2 emissions than conventional Portland cements that have been developed • High belite cements • Being research by Aberdeen and other universities • Calcium sulfoaluminate cements • Used by the Chinese for some time • Magnesium phosphate cements • Proponents argue that a lot stronger than Portland cement therefore much less is required. • Main disadvantage is that phosphate is a limited resource • Geopolymers
Geopolymers • “Geopolymers” consists of SiO4 and AlO4 tetrahedra linked alternately by sharing all the oxygens. • Positive ions (Na+, K+, Li+, Ca++, Ba++, NH4+, H3O+) must be present in the framework cavities to balance the negative charge of Al3+in IV fold coordination. • Theoretically very sustainable • Unlikely to be used for pre-mix concrete or waste in the near future because of. • process problems • Requiring a degree of skill for implementation • nano porosity • Causing problems with aggregates in aggressive environments • no pH control strategy for heavy metals in waste streams
SUSTAINABILITY PORTLAND + or - POZZOLAN Hydration of the various components of Portland cement for strength. Reaction of alkali with pozzolans (e.g. lime with fly ash.) for sustainability, durability and strength. TECECO CEMENTS DURABILITY STRENGTH MAGNESIA 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. TecEco Cements TecEco concretes are a system of blending reactive magnesia, Portland cement and usually a pozzolan with other materials and are a key factor for sustainability.
The Magnesium Thermodynamic Cycle Calcination CO2 CaptureNon fossil fuel energy We think this cycle is relatively independent of other constituents
TecEco Cement Technology 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 water and concentrating alkalis forming brucite which is another alkali, but much less soluble, mobile or reactive than Portlandite. • In Eco-cements brucite carbonates
TecEco 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.
TecEco Cements – Impact on Sustainability • The CO2 released by calcined carbonates used to make binders can be captured using TecEco kiln technology. • MgO can be made using non fossil fuel energy • Tec-Cements Develop Significant Early Strength even with Added Supplementary Materials. • Eco-Cements carbonate sequestering CO2 requiring 25-75% less binder in some mixes
Benefits to the Concrete Industry of Adopting TecEco Technology • Both Tec and Eco-Cements provide a benign low pH environment for hosting large quantities of waste overcoming problems of delayed reactions: • Using acids to etch plastics so they bond with concretes. • sulphates from plasterboard etc. ending up in recycled construction materials. • heavy metals and other contaminants. • delayed reactivity e.g. ASR with glass cullet • Resolving durability issues • Indian and Chinese quality control issues • Concretes containing MgO • shrink less • are demonstrably more durable. • can incorporate wastes that contribute to physical properties reducing lifetime energies The biggest business on the planet is going to be the sustainability business
6. Using Aggregates that Extend Cement • Air used in foamed concrete is a cheap low embodied energy aggregate and has the advantage of reducing the conductance of concrete. • Concrete, depending on aggregates weighs in the order of 2350 Kg/m3 • Concretes of over 10 mp as light as 1000 Kg/m3 can be achieved. • At 1500 Kg/m3 25 mpa easily achieved. • From our experiments so far Tec-Cement formulations increase strength performance by around 5-10% for the same mass. • Claimed use of aluminium and autoclaving to make more sustainable blocks questionable
7. Use Aggregates with Lower Embodied Energy and that Result in less Emissions or that are Themselves Carbon Sinks • Use of aggregates that lower embodied energies • wastes such as recycled building rubble Tec and Eco-Cements do not have problems associated with high gypsum content • Use of other aggregates that include non fossil carbon • sawdust and other carbon based aggregates can make eco-cement concretes a net carbon sink. • Reduce transport embodied energies by using local materials such as earth • mud bricks and adobe. • our research in the UK and with mud bricks in Australia indicate that Eco-Cement formulations seem to work better than PC for this
Using Wastes and Non-Traditional Aggregates to Make TecEco Cement Concretes • As the price of fuel rises, theuse of local or on site lowembodied energy materialsrather than carted aggregateswill have to be considered. No longer an option? The use of on site and local wastes will be made possible by the use of low reactivity TecEco mixes and a better understanding of particle packing. We hope with our new software to be able to demonstrate how adding specific size ranges can make an unusable waste such as a tailing or sludge suitable for making cementitious materials. Recent natural disasters such as the recent tsunami and Pakistani earthquake mean we urgently need to commercialize technologies like TecEco’s because they provide benign environments allowing the use of many local materials and wastes without delayed reactions
8. Improve the Performance of Concrete by Including Aggregates that Improve or Introduce New Properties Reducing Lifetime Energies • Rather than be taken to landfill many wastes can be used to improve properties of concrete that reduce lifetime energies. • For example paper and plastic have in common reasonable tensile strength, low mass and low conductance and can be used to make cementitious composites that assume these properties
Biomimicry - Ultimate Recyclers • As peak oil looms and the price of transport is set to rise sharply • We should not just be recycling based on chemical property requiring sophisticated equipment and resources • We should be including wastes based on physical properties as well as chemical composition in composites whereby they become local resources. The Jackdaw recycles all sorts of things it finds nearby based on physical property. The bird is not concerned about chemical composition and the nest it makes could be described as a composite material. TecEco cements are benign binders that can incorporate all sort of wastes without reaction problems. We can do the same as the Jackdoor
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. • Easier to finish even with added pozzolans • The stickiness concretes with added fly ash is retarding use • Higher strength/binder ratio • Less cement can be used reducing costs and take and waste impacts • More durable concretes • Reducing costs and take and waste impacts. • Use of wastes • Utilizing carbon dioxide • Magnesia component can be made using non fossil fuel energy and CO2 captured during production. Tec -Cements Tec & Eco-Cements Eco-Cements Contact: John Harrison, TecEco Pty. Ltd. www.tececo.com
Eco-Cements • Eco-cements are similar but potentially superior to lime mortars because: • The calcination phase of the magnesium thermodynamic cycle takes place at a much lower temperature and is therefore more efficient. • Magnesium minerals are generally more fibrous and acicular than calcium minerals and hence add microstructural strength. • Water forms part of the binder minerals that forming making the cement component go further. In terms of binder produced for starting material in cement, eco-cements are much more efficient. • Magnesium hydroxide in particular and to some extent the carbonates are less reactive and mobile and thus much more durable.
From air and water Mg(OH)2 + CO2 MgCO3.5H2O Eco-Cement Strength Development • Eco-cements gain early strength from the hydration of PC. • Later strength comes from the carbonation of brucite forming an amorphous phase, lansfordite and nesquehonite. • Strength gain in eco-cements is mainly microstructural because of • More ideal particle packing (Brucite particles at 4-5 micron are under half the size of cement grains.) • The natural fibrous and acicular shape of magnesium carbonate minerals which tend to lock together. • More binder is formed than with calcium • Total volumetric expansion from magnesium oxide to lansfordite is for example volume 811%.
Eco-Cement Strength Gain Curve 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.
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.
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 Tec-Kiln) would result in sequestration on a massive scale. • As Fred Pearce reported in New Scientist Magazine (Pearce, F., 2002), “There is a way to make our city streets as green as the Amazon rainforest”. Ancient and modern carbonating lime mortars are based on this principle
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 relative mono grading so that particle packing is imperfect causing physical air voids and some vapour permeability.
CO2 Abatement in Eco-Cements For 85 wt% Aggregates 15 wt% Cement Capture CO211.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate. Emissions.25 tonnes to the tonne. After carbonation. approximately .140 tonne to the tonne. Portland Cements15 mass% Portland cement, 85 mass% aggregate Emissions.32 tonnes to the tonne. After carbonation. Approximately .299 tonne to the tonne. No Capture11.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate. Emissions.37 tonnes to the tonne. After carbonation. approximately .241 tonne to the tonne. Capture CO2. Fly and Bottom Ash11.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate. Emissions.126 tonnes to the tonne. After carbonation. Approximately .113 tonne to the tonne. Eco-cements in porous products absorb carbon dioxide from the atmosphere. Brucite carbonates forming lansfordite, nesquehonite and an amorphous phase, completing the thermodynamic cycle. Greater Sustainability .299 > .241 >.140 >.113Bricks, blocks, pavers, mortars and pavement made using eco-cement, fly and bottom ash (with capture of CO2 during manufacture of reactive magnesia) have 2.65 times less emissions than if they were made with Portland cement.