Presentation on theme: "Presentation downloadable from www.tececo.com 1 Greening the Heartland Earthship Brighton (UK) – The first building utilising TecEco eco-cements I will."— Presentation transcript:
Presentation downloadable from 1 Greening the Heartland Earthship Brighton (UK) – The first building utilising TecEco eco-cements 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.
Presentation downloadable from 2 Relevance to Canada Help Canada meet Kyoto objectives Magnesium industry in doldrums –Collapse of the asbestos industry Export Industry? –Near USA –Close to Europe –Mg silicate minerals for sequestration in power stations. –Reactive magnesia. –MgO products with carbon credits attached?
Presentation downloadable from 3 The Problem – A Planet in Crisis TecEco are in the BIGGEST Business on the Planet - Solving Sustainability Problems Economically
Presentation downloadable from 4 A Demographic Explosion ? Developed Countries Undeveloped Countries Global population, consumption per capita and our footprint on the planet is exploding.
Presentation downloadable from 5 Atmospheric Carbon Dioxide
Presentation downloadable from 6 Global Temperature Anomaly
Presentation downloadable from 7 The Techno-Process Our 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 Global Systems Atmospheric composition, climate, land cover, marine ecosystems, pollution, coastal zones, freshwater systems, salinity and global biological diversity have all been substantially affected.
Presentation downloadable from 8 Ecological 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
Presentation downloadable from 9 Canada Before Settlement
Presentation downloadable from 10 Canada Now Paper Mill - Soda liquor + Cl Habitat removal Farming - Pesticide, N & K Cows - methane Vehicles - carbon dioxide Cities Immediate and polluted water run-off. Air pollution. Carbon dioxide and other gases. Other wastes. Huge linkages. Huge impacts
Presentation downloadable from 11 Canada with a Little Lateral Thinking & Effort Less paper. Other Cl free processes - no salinity Evolution away from using trees – paperless office Organic farming. Carbon returned to soils. Use of zeolite reduces water and fertilizer required by 2/3 Cows – CSIRO anti methane bred Vehicles – more efficient and using fuel cells Cities: Porous pavement prevents immediate and polluted run-off. Carbon dioxide and other gases absorbed by TecEco eco- cements. Less wastes. Carbon based wastes converted to energy or mulches and returned to soils. Buildings generate own energy etc. TecEco technology provides ways of sequestering carbon dioxide and utilizing wastes to create our techno - world Sequestration processes Less impacts
Presentation downloadable from 12 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 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 TecEco Pty. Ltd. have benchmark technologies for improvement in sustainability and properties
Presentation downloadable from 13 Embodied Energy of Building Materials Downloaded from serv/brochures/embodied/embodied.htm (last accessed 07 March 2000) Concrete is relatively environmentally friendly and has a relatively low embodied energy
Presentation downloadable from 14 Average Embodied Energy in Buildings Downloaded from 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.
Presentation downloadable from 15 Emissions from Cement Production Chemical Release –The process of calcination involves driving off chemically bound CO 2 with heat. CaCO 3 CaO + CO 2 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 CO 2. The production of cement for concretes accounts for around 10%(1) of global anthropogenic CO 2. (1) Pearce, F., "The Concrete Jungle Overheats", New Scientist, 19 July, No 2097, 1997 (page 14).
Presentation downloadable from 16 Cement Production = Carbon Dioxide Emissions
Presentation downloadable from 17 Sustainability Sustainability is a direction not a destination. Our approach should be holistically balanced and involve –Everybody, every process, every day. Mineral Sequestration Eco-cements in cities + Waste utilization Geological Seques- tration Emissions reduction through efficiency and conversion to non fossil fuels + +
Presentation downloadable from 18 Converting Waste to Resource Take only renewables Manipulate Make Use Waste only what is biodegradable or can be re- assimilated Reuse Re-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 and what 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, CFCs too much CO2 etc.
Presentation downloadable from 19 Innovative New Materials - the Key to Sustainability 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.
Presentation downloadable from 20 Sustainability Through Materials Innovation Problems in the global commons today can only be changed by changing the molecular flows underlying planetary anthropogenic materials flows in the techno-process so that the every day behaviors of people interacting in an economic system will deliver new more sustainable flows. This will not happen because it is the right thing to do. Pilzer's first law states that the technology paradigm defines resources. Changing the flow of materials therefore has to be economic. WBCSD President Björn Stigson 26 November 2004 Technology is a key part of the solutions for sustainable development. Innovation and technology are tools for achieving higher resource efficiency in society.
Presentation downloadable from 21 Sustainability = Culture + Technology Increase 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 shift ECONOMICS Greater Value/for impact (Sustainability) and economic growth Sustainability is where Culture and Technology meet. DemandSupply
Presentation downloadable from 22 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. Building 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. –By including carbon in materials they are potentially carbon sinks. –By including wastes for physical properties as well as chemical composition they become resources C C C C C Waste
Presentation downloadable from 23 Innovative New Materials Vital It is possible to achieve Kyoto targets as the UK are proving, but we need to go way beyond the treaty according to our chief scientists. Carbon rationing has been proposed as the only viable means to keep the carbon dioxide concentration in the atmosphere below 450 ppm. Atmospheric carbon reduction is essential, but difficult to politically achieve by rationing. Making the built environment not only a repository for recyclable resources (referred to as waste) but a huge carbon sink is an alternative and adjunct that is politically viable as it potentially results in economic benefits. Concrete, a cementitous composite, is the single biggest material flow on the planet with over 2.2 tonnes per person produced. Eco-cements offer tremendous potential for capture and sequestration using cementitious composites. MgCO 3 MgO + CO 2 - Efficient low temperature calcination & capture MgO + CO 2 + H 2 O MgCO 3.3H 2 O - Sequestration as building material
Presentation downloadable from 24 Sustainability Summary A more holistic approach is to reduce energy consumption as well as sequester carbon. To reduce our linkages with the environment we must convert waste to resource (recycle). Sequestration and recycling have to be economic processes or they have no hope of success. We cannot stop progress, but we can change and historically economies thrive on change. What can be changed is the technical paradigm. CO 2 and wastes need to be redefined as resources. New and better materials are required that utilize wastes including CO 2 to create a wide range of materials suitable for use in our built environment.
Presentation downloadable from 25 TecEco Technology More information at
Presentation downloadable from 26 The TecEco Total Process Iron Ore. Silicate Reactor Process Silicic Acids or Silica Solar or Wind Electricity Powered Tec-Kiln CO 2 for Geological Sequestration Oxide Reactor Process CO 2 from Power Generation, Industry or CO 2 Directly From the Air Magnesite MgCO 3 ) Crushing Grinding Screening Magnetic Sep. Heat Treatment Serpentine Mg 3 Si 2 O 5 (OH) 4 Crushing Grinding Screening Gravity Concentration Olivine Mg 2 S i O 4 Magnesia (MgO) MgO for TecEco Cements and Sequestration by Eco-Cements in the Built Environment Other Wastes after Processing Tonnes CO2 Sequestered per Tonne Silicate with Various Cycles through the TecEco Process (assuming no leakage MgO to built environment i.e complete cycles) Chrysotile (Serpentinite) Billion Tonnes Forsterite (Mg Olivine) Billion Tonnes Tonnes CO2 sequestered by 1 billion tonnes of mineral mined directly Tonnes CO2 captured during calcining Tonnes CO2 captured by eco-cement Total tonnes CO2 sequestered or abated per tonne mineral mined (Single calcination cycle) Total tonnes CO2 sequestered or abated (Five calcination cycles.) Total tonnes CO2 sequestered or abated (Ten calcination cycles) Simplified TecEco Reactions Tec-Kiln MgCO3 MgO + CO kJ/mole Reactor Process MgO + CO 2 MgCO kJ/mole (usually more complex hydrates) Magnesite (MgCO 3 ) CO 2 from Power Generation or Industry Magnesium Thermodynamic Cycle Waste Sulfuric Acid or Alkali?
Presentation downloadable from 27 Why Magnesium Compounds At 2.09% of the crust magnesium is the 8th most abundant element. Magnesium oxide is easy to make using non fossil fuel energy and efficiently absorbs CO 2 Because magnesium has a low molecular weight, proportionally a much greater amount of CO 2 is released or captured. A high proportion of water means that a little binder goes a long way. In terms of binder produced for starting material in cement, eco-cements are nearly six times more efficient.
Presentation downloadable from 28 TecEco Technologies Silicate Carbonate Mineral Sequestration –Using either peridotite, forsterite or serpentine as inputs to a silicate reactor process CO 2 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 CO 2 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 Economic under Kyoto? TecEco
Presentation downloadable from 29 TecEco Kiln Technology Grinds and calcines at the same time. Runs 25% to 30% more efficiency. Can be powered by solar energy or waste heat. Brings mineral sequestration and geological sequestration together Captures CO 2 for bottling and sale to the oil industry (geological sequestration). The products – CaO &/or MgO can be used to sequester more CO 2 and then be re-calcined. This cycle can then be repeated. Suitable for making reactive reactive MgO.
Presentation downloadable from 30 A Post – Carbon Age We all use carbon and wastes to make our homes! Biomimicry
Presentation downloadable from 31 Drivers for TecEco Technology Producer Push The opportunity cost of compliant waste disposal Profitability and cost recovery Technical merit Resource issues Robotics Research objectives Consumer Pull Environmental sentiment Cost and technical advantages? Competition? Government Influence Carbon Taxes Provision of Research Funds Environmental education Huge Markets Cement 2 billion tonnes. Bricks 130,000 million tonnes TecEco cements are the only binders capable of utilizing very large quantities of wastes based on physical property rather than chemical composition overcoming significant global disposal problems, and reducing the impact of landfill taxes. TecEco eco-cements can sequester CO2 on a large scale and will therefore provide carbon accounting advantages. TecEco kiln technology could be the first non fossil fuel powered industrial process
Presentation downloadable from 32 Drivers for Change – Robotics Using Robots to print buildings is all quite simple from a software, computer hardware and mechanical engineering point of view. The problem is in developing new construction materials with the right flow characteristics so they can be squeezed out like toothpaste, yet retain their shape until hardened –Once new materials suitable for the way robots work have been developed economics will drive the acceptance of robots for construction –Concretes for example will need to evolve from being just a high strength grey material, to a smorgasbord of composites that can be squeezed out of a variety of nozzles for use by a robotic workforce for the varying requirements of a structure TecEco cement concretes have the potential of achieving the right shear thinning characteristics required
Presentation downloadable from 33 TecEco Cements More slides on web siteMore information at
Presentation downloadable from 34 TecEco Cements SUSTAINABILITY DURABILITYSTRENGTH TECECO CEMENTS 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. 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. PORTLAND + or - POZZOLAN MAGNESIA 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.
Presentation downloadable from 35 The Magnesium Thermodynamic Cycle
Presentation downloadable from 36 TecEco Cement Sustainability TecEco technology will be pivotal in bringing about sustainability in the built environment. –The CO 2 released by calcined carbonates used to make binders can be captured using TecEco kiln technology. –Tec-Cements Develop Significant Early Strength even with Added Supplementary Materials. Around 25 = 30% less total binder is required for the same strength. –Eco-cements carbonate sequestering CO 2 –Both tec and eco=cements provide a benign low pH environment for hosting large quantities of waste overcoming problems of: 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 Durability issues
Presentation downloadable from 37 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 its 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.
Presentation downloadable from 38 TecEco Cement Technology Portlandite (Ca(OH) 2 ) is too soluble, mobile and reactive. –It carbonates, reacts with Cl - and SO 4 - 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 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.
Presentation downloadable from 39 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 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 40 What is Reactive MgO? or 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 (Ramachandran V. S., Concrete Science, Heydon & Son Ltd. 1981, p )
Presentation downloadable from 41 Summary of Reactions Involved Notice the low solubility of brucite compared to Portlandite and that nesquehoni te adopts a more ideal habit than calcite & aragonite We think the reactions are relatively independent.
Presentation downloadable from 42 Strength with Blend & Porosity High OPC High Magnesia High Porosity STRENGTH ON ARBITARY SCALE Tec-cement concretes Eco-cement concretes Enviro-cement concretes
Presentation downloadable from 43 Tec-Cement Concrete Strength Gain Curve strength gain with less cement and added pozzolans is of great economic and environmental importance. Concretes are more often than not made to strength. 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
Presentation downloadable from 44 Reasons for Strength Development in Tec-Cements. Reactive magnesia requires considerable water to hydrate resulting in: –Denser, less permeable concrete. –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.) Slow release of water from hydrated Mg(OH) 2.nH 2 O supplying H 2 O for more complete hydration of C 2 S and C 3 S? Formation of MgAl hydrates? Similar to flash set in concrete but slower??
Presentation downloadable from 45 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 less shrinkage and cracking and improved strength and durability. Concentration of alkalis and increased density result in greater strength.
Presentation downloadable from 46 Tec-Cement Compressive Strength Graphs by Oxford Uni Student
Presentation downloadable from 47 Tec-Cement Tensile Strength 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
Presentation downloadable from 48 Other Strength Testing to Date 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 TecEcoLarge Cement Company Modified 20 MPa mix
Presentation downloadable from 49 Concretes have a high percentage (around 18% - 25%) of voids. On hydration magnesia expands % filling voids and surrounding hydrating cement grains and compensates for the shrinkage of Portland cement. Brucite is mass% water. Lower voids:paste ratios than water:binder ratios result in little or no bleed water less permeability and greater density. –Compare the affect to that of vacuum dewatering. Increased Density – Reduced Permeability
Presentation downloadable from 50 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 SO 4 --, Cl - and CO 2 TecEco tec - cement concretes are a closed system. They do not bleed as excess water is consumed by the hydration of magnesia. Consequences: –Tec - cement concretes tend to dry from within, are denser and less permeable and therefore stronger more durable and more waterproof. Cement powder is not lost near the surfaces. –Tec-cements have a higher salt resistance and less corrosion of steel etc.
Presentation downloadable from 51 Tec-Cement pH Curves
Presentation downloadable from 52 Lower More Stable Long Term pH with Less Corrosion Eh-pH or Pourbaix Diagram The stability fields of hematite, magnetite and siderite in aqueous solution; total dissolved carbonate = M. In TecEco cements the long term pH is governed by the low solubility and carbonation rate of brucite and is much lower at around , allowing a wider range of aggregates to be used, reducing problems such as AAR and etching. The pH is still high enough to keep Fe 3 O 4 stable in reducing conditions. Steel corrodes below 8.9
Presentation downloadable from 53 Reduced Steel Corrosion Steel remains protected with a passive oxide coating of Fe 3 O 4 above pH 8.9. –A pH of over 8.9 is maintained by the equilibrium Mg(OH) 2 Mg OH - 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, CO 2 and salts. Brucite is less soluble and traps salts as it forms resulting in less ionic transport to complete a circuit for electrolysis and less corrosion. Free chlorides and sulfates originally in cement and aggregates are bound by magnesium –Magnesium oxychlorides or oxysulfates are formed. ( Compatible phases in hydraulic binders that are stable provided the concrete is dense and water kept out.)
Presentation downloadable from 54 Corrosion in Portland Cement Concretes Passive Coating Fe 3 O 4 intact Both carbonation, which renders the passive iron oxide coating unstable or chloride attack (various theories) result in the formation of reaction products with a higher electrode potential resulting in anodes with the remaining passivated steel acting as a cathode. Corrosion Anode: Fe Fe e- Cathode: ½ O 2 + H 2 O +2e - 2(OH) - Fe (OH) - Fe(OH) 2 + O 2 Fe 2 O 3 and Fe 2 O 3.H 2 O (iron oxide and hydrated iron oxide or rust) The role of chloride in Corrosion Anode: Fe Fe e- Cathode: ½ O 2 + H 2 O +2e - 2(OH) - Fe ++ +2Cl - FeCl 2 FeCl 2 + H 2 O + OH - Fe(OH) 2 + H + + 2Cl - Fe(OH) 2 + O 2 Fe 2 O 3 and Fe 2 O 3.H 2 O Iron hydroxides react with oxygen to form rust. Note that the chloride is recycled in the reaction and not used up.
Presentation downloadable from 55 Reduced Delayed Reactions A wide range of delayed reactions can occur in Portland cement based concretes –Delayed alkali silica and alkali carbonate reactions –The delayed formation of ettringite and thaumasite –Delayed hydration of minerals such as dead burned lime and magnesia. Delayed reactions cause dimensional distress and possible failure.
Presentation downloadable from 56 Reduced Delayed Reactions (2) 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, probably holding it for slow release to extended hydration reactions of Ca silicates. –Magnesia dries concrete out from the inside. Reactions do not occur without water.
Presentation downloadable from 57 Brucite has always played a protective role during salt attack. Putting it in the matrix of concretes in introduces considerable durability. 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 –Ksp Portlandite = 5.5 X 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 Durability - Reduced Salt & Acid Attack
Presentation downloadable from 58 Bingham Plastic Rheology Finely ground reactive magnesia consumes water but also acts as a plasticiser There are also surface charge affects
Presentation downloadable from 59 Bingham Plastic Rheology 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. Ca++ = 114, Mg++ = 86 picometres
Presentation downloadable from 60 Rheology 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. A range of pumpable composites with Bingham plastic properties will be required in the future as buildings will be printed.
Presentation downloadable from 61 Reduced Shrinkage Dimensional change such as shrinkage results in cracking and reduced durability Net shrinkage is reduced due to stoichiometric expansion of Magnesium minerals, and reduced water loss.
Presentation downloadable from 62 Reduced Shrinkage – Less Cracking Cracking, the symptomatic result of shrinkage, is undesirable for many reasons, but mainly because it allows entry of gases and ions reducing durability. Cracking can be avoided only if the stress induced by the free shrinkage strain, reduced by creep, is at all times less than the tensile strength of the concrete. Tec-cements also have greater tensile strength. Test Age (days)Microstrain Large Cement Company Tec-cements exhibit higher tensile strength and less shrinkage and therefore less cracking
Presentation downloadable from 63 When magnesia hydrates it expands: MgO (s) + H 2 O (l) Mg(OH) 2.nH 2 O (s) (minimum) molar mass liquid 24.3 (minimum) molar volumes Up to % solidus expansion depending on whether the water is coming from stoichiometric mix water, bleed water or from outside the system. In practice less as the water comes from mix and bleed water. The molar volume (L.mol-1)is equal to the molar mass (g.mol-1) divided by the density (g.L-1). Volume Changes on Hydration
Presentation downloadable from 64 Volume Changes on Carbonation Consider what happens when Portlandite carbonates: Ca(OH) 2 + CO 2 CaCO molar mass gas molar volumes –Slight expansion. But shrinkage from surface water loss Compared to brucite forming nesquehonite as it carbonates: Mg(OH) 2 + CO 2 MgCO 3.3H 2 O molar mass gas molar volumes –307 % expansion (less water volume reduction) and densification of the surface preventing further ingress of CO 2 and carbonation. Self sealing? The molar volume (L.mol-1)is equal to the molar mass (g.mol-1) divided by the density (g.L-1).
Presentation downloadable from 65 Dimensionally Control Over Concretes During Curing? Portland cement concretes shrink around.05%. Over the long term much more (>.1%). –Mainly due to plastic and drying shrinkage. The use of some wastes as aggregates causes shrinkage e.g. wood waste in masonry units, thin panels etc. By varying the amount and form of magnesia added dimensional control can be achieved.
Presentation downloadable from 66 TecEco Cement Concretes –Dimensional Control Combined – Hydration and Carbonation can be manipulated to be close to neutral. –So far we have not observed significant shrinkage in TecEco tec - cement concretes (5% -10% substitution OPC) also containing fly ash. –At some ratio, thought to be around 10% reactive magnesia and 90% PC volume changes are optimised as higher additions of MgO reduce strength. –The water lost by Portland cement as it shrinks is used by reactive magnesia as it hydrates also reducing shrinkage.
Presentation downloadable from 67 Tec - Cement Concretes – Less or no Dimensional Change It may be possible to engineer a particle with slightly delayed expansion to counterbalance the expansion and then shrinkage concretes containing gbfs.
Presentation downloadable from 68 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) + H 2 O (l) Mg(OH) 2 (s) molar mass molar volumes molar volumes 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 69 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 nearly six times more efficient. –Magnesium hydroxide in particular and to some extent the carbonates are less reactive and mobile and thus much more durable.
Presentation downloadable from 70 Eco-Cement pH Curves
Presentation downloadable from 71 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 volumentric expansion from magnesium oxide to lansfordite is for example 473 volume %.
Presentation downloadable from 72 Eco-Cement Concrete 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.
Presentation downloadable from 73 Eco-Cement Micro-Structural Strength
Presentation downloadable from 74 Carbonation Because magnesium has a low molecular weight, proportionally a greater amount of CO 2 is captured. Carbonation results in significant sequestration because of the shear volumes involved. Carbonation adds strength. Carbonates are the stable phases of both calcium and magnesium. The formation of carbonates lowers the pH of concretes compromising the stability of the passive oxide coating on steel. Some steel reinforced structural concrete could be replaced with fibre reinforced porous carbonated concrete.
Presentation downloadable from 75 Chemistry of Carbonation There are a number of carbonates of magnesium. The main ones appear to be an amorphous phase, lansfordite and nesquehonite. The carbonation of magnesium hydroxide does not proceed as readily as that of calcium hydroxide. – G o r Brucite to nesquehonite = kJ.mol-1 –Compare to G o r Portlandite to calcite = 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. G o r 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 76 Ramifications of Carbonation Magnesium Carbonates. –The magnesium carbonates that form at the surface of tec – cement concretes expand significantly thereby sealing off further carbonation. –Lansfordite and nesquehonite are stronger and more acid resistant than calcite or aragonite. –The curing of eco-cements in a moist - dry alternating environment seems to encourage carbonation. Portland Cement Concretes –Carbonation proceeds relatively rapidly at the surface. Vaterite followed by Aragonite and Calcite is the principal product and lowers the pH to around 8.2
Presentation downloadable from 77 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 78 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 79 TecEco Binders - Solving Waste Problems There are huge volumes of concrete produced annually ( 2 tonnes per person per year.) An important objective should be to make cementitous composites that can utilise wastes. TecEco cements provide a benign environment suitable for waste immobilisation Many wastes such as fly ash, sawdust, shredded plastics etc. can improve a property or properties of the cementitious composite. There are huge materials flows in both wastes and building and construction. TecEco technology will lead the world in the race to incorporate wastes in cementitous composites
Presentation downloadable from 80 TecEco Binders - Solving Waste Problems (2) TecEco cementitious composites represent a cost affective option for both use and immobilisation of waste. –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 81 Role of Brucite in Immobilization In a Portland cement brucite matrix –PC takes up lead, some zinc and germanium –Brucite and hydrotalcite are both excellent hosts for toxic and hazardous wastes. –Heavy metals not taken up in the structure of Portland cement minerals or trapped within the brucite layers end up as hydroxides with minimal solubility. The brucite in TecEco cements has a structure comprising electronically neutral layers and is able to accommodate a wide variety of extraneous substances between the layers and cations of similar size substituting for magnesium within the layers and is known to be very suitable for toxic and hazardous waste immobilisation. Layers of electronically neutral brucite suitable for trapping balanced cations and anions as well as other substances. Salts and other substances trapped between the layers. Van der waals bonding holding the layers together.
Presentation downloadable from 82 Lower Solubility of Metal Hydroxides There is a 10 4 difference
Presentation downloadable from 83 TecEco Materials as Fire Retardants The main phase in TecEco tec - cement concretes is Brucite. The main phases in TecEco eco-cements are Lansfordite and nesquehonite. Brucite, Lansfordite and nesquehonite are excellent fire retardants and extinguishers. At relatively low temperatures –Brucite releases water and reverts to magnesium oxide. Mg(OH) 2 MgO + H 2 O –Lansfordite and nesquehonite releases CO 2 and water and convert to magnesium oxide. MgCO 3.nH 2 O MgO + CO 2 + H 2 O Fires are therefore not nearly as aggressive resulting in less damage to structures. Damage to structures results in more human losses that direct fire hazards.
Presentation downloadable from 84 TecEco Cement Implementation Summary
Presentation downloadable from 85 High 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?
Presentation downloadable from 86 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 CO 2. –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.
Presentation downloadable from 87 Summary 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
Presentation downloadable from 88 TecEco Doing Things
Presentation downloadable from 89 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. Englands 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 90 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 91 Mike Burdons 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 92 Tec-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 micro strains, 14 days micro strains, 28 days micros strains and at 56 days microstrains.
Presentation downloadable from 93 Embodied Energies and Emissions
Presentation downloadable from 94 CO 2 Abatement in Eco-Cements Eco-cements in porous products absorb carbon dioxide from the atmosphere. Brucite carbonates forming lansfordite, nesquehonite and an amorphous phase, completing the thermodynamic cycle. 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. Portland Cements 15 mass% Portland cement, 85 mass% aggregate Emissions.32 tonnes to the tonne. After carbonation. Approximately.299 tonne to the tonne..299 >.241 >.140 >.113 Bricks, blocks, pavers, mortars and pavement made using eco-cement, fly and bottom ash (with capture of CO 2 during manufacture of reactive magnesia) have 2.65 times less emissions than if they were made with Portland cement. Capture CO % 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 CO 2. 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. For 85 wt% Aggregates 15 wt% Cement Greater Sustainability
Presentation downloadable from 95 Energy – On a Mass Basis Relative to Raw Material Used to make Cement From Manufacturi ng Process Energy Release 100% Efficient (MJ.tonne -1 ) From Manufacturin g Process Energy Release with Inefficiencies (MJ.tonne -1 ) Relative Product Used in Cement From Manufacturi ng Process Energy Release 100% Efficient (MJ.tonne -1 ) From Manufacturin g Process Energy Release with Inefficiencies (MJ.tonne -1 ) Relative to Mineral Resulting in Cement From Manufacturi ng Process Energy Release 100% Efficient (MJ.tonne -1 ) From Manufacturi ng Process Energy Release with Inefficienci es (MJ.tonne -1 ) CaCO 3 + Clay Portlan d Cemen t Hydrated OPC CaCO Ca(OH) MgCO MgO Mg(OH)
Presentation downloadable from 96 Energy – On a Volume Basis Relative to Raw Material Used to make Cement From Manufacturi ng Process Energy Release 100% Efficient (MJ.metre -3 ) From Manufacturin g Process Energy Release with Inefficiencies (MJ.metre -3 ) Relative Product Used in Cement From Manufacturi ng Process Energy Release 100% Efficient (MJ.metre -3 ) From Manufacturin g Process Energy Release with Inefficiencies (MJ.metre -3 ) Relative to Mineral Resulting in Cement From Manufacturi ng Process Energy Release 100% Efficient (MJ.metre -3 ) From Manufacturin g Process Energy Release with Inefficiencies (MJ.metre -3 ) CaCO 3 + Clay Portland Cement Hydrate d OPC CaCO Ca(OH) MgCO MgO Mg(OH)
Presentation downloadable from 97 Global Abatement Without CO2 Capture during manufacture (billion tonnes) With CO2 Capture during manufacture (billion tonnes) Total Portland Cement Produced Globally 1.80 Global mass of Concrete (assuming a proportion of 15 mass% cement) Global CO 2 Emissions from Portland Cement 3.60 Mass of Eco-Cement assuming an 80% Substitution in global concrete use 9.60 Resulting Abatement of Portland Cement CO 2 Emissions 2.88 CO 2 Emissions released by Eco-Cement Resulting Abatement of CO 2 emissions by Substituting Eco-Cement
Presentation downloadable from 98 Abatement from Substitution Figures are in millions of Tonnes Building Material to be substituted Realisti c % Subst- itution by TecEco technol ogy Size of World Market (millio n tonnes Substit uted Mass (million tonnes) CO2 Fact ors (1) Emission From Material Before Substituti on Emission/Sequestrati on from Substituted Eco-Cement (Tonne for Tonne Substitution Assumed) Net Abatement Emission s - No Capture Emission s - CO2 Capture Abatem ent - No Capture Abatem ent CO2 Capture Bricks85% Steel25% Aluminium20% TOTAL Concretes already have low lifetime energies. If embodied energies are improved could substitution mean greater market share?