An Opportunity for the Concrete Industry Earthship Brighton
An Opportunity for the Concrete Industry Earthship Brighton (UK) – The first building utilising Tec. Eco ecocements I will have to race over some slides but the presentation is always downloadable from the Tec. Eco web site if you missed something. John Harrison B. Sc. B. Ec. FCPA. Presentation downloadable from www. tececo. com and www. aasmic. org 1
The Built Environment is Where we Can Solve the Problem Ü The built environment is our footprint, a major proportion of the techno-sphere and our lasting legacy on the planet. – It comprises buildings and infrastructure Ü Huge flows are involved – 70% of all materials flows. – Buildings account for 40% of the materials and about a third of the energy consumed by the world economy. – Construction activities contributed over 35% of total global CO 2 emissions in 1999. – In Australia 40% of waste going to landfill Presentation downloadable from www. tececo. com and www. aasmic. org 2
There is no End with Tec. Eco Technology – Only a Beginning. More slides on web site Presentation downloadable from www. tececo. com and www. aasmic. org 3
Tec. Eco Cements SUSTAINABILITY PORTLAND POZZOLAN Hydration of the various components of Portland cement for strength. DURABILITY Reaction of alkali with pozzolans (e. g. lime with fly ash. ) for sustainability, durability and strength. TECECO CEMENTS STRENGTH Tec. Eco concretes are a system of blending MAGNESIA reactive magnesia, Hydration of magnesia => brucite fo strength, Portland cement and workability, dimensional stability and durability. In usually a pozzolan Eco-cements carbonation of brucite => nesquehonite, with other materials lansfordite and an amorphous phase for sustainability. and are a key factor for sustainability. Presentation downloadable from www. tececo. com and www. aasmic. org 4
Eco-Cements and The Magnesium Thermodynamic Cycle Presentation downloadable from www. tececo. com and www. aasmic. org 5
Tec. Eco Formulations Ü Tec-cements (5 -10% Mg. O, 90 -95% OPC) – contain more Portland cement than reactive magnesia. Reactive magnesia hydrates in the same rate order as Portland cement forming Brucite which uses up water reducing the voids: paste ratio, increasing density and possibly raising the short term p. H. – Reactions with pozzolans are more affective. After all the Portlandite has been consumed Brucite controls the long term p. H 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. Ü Eco-cements (15 -90% Mg. O, 85 -10% OPC) – contain more reactive magnesia than in tec-cements. Brucite in porous materials carbonates forming stronger fibrous mineral carbonates and therefore presenting huge opportunities for waste utilisation and sequestration. Ü Enviro-cements (15 -90% Mg. O, 85 -10% OPC) – contain similar ratios of Mg. O and OPC to eco-cements but in non porous concretes brucite does not carbonate readily. – Higher proportions of magnesia are most suited to toxic and hazardous waste immobilisation and when durability is required. Strength is not developed quickly nor to the same extent. Presentation downloadable from www. tececo. com and www. aasmic. org 6
Strength with Blend & Porosity Tec-cement concretes Eco-cement concretes High Porosity High OPC Enviro-cement concretes High Magnesia STRENGTH ON ARBITARY SCALE 1 -100 Presentation downloadable from www. tececo. com and www. aasmic. org 7
Consequences of replacing Portlandite with Brucite Ü Portlandite (Ca(OH)2) is too soluble, mobile and reactive. It carbonates readily and being soluble can act as an electrolyte. Ü Tec. Eco generally remove Portlandite using the pozzolanic reaction and add reactive magnesia which hydrates forming brucite which is another alkali, but much less soluble, mobile or reactive than Portlandite. The consequences of removing Portlandite (Ca(OH)2 with the pozzolanic reaction and filling the voids between hydrating cement grains with Brucite Mg(OH)2, an insoluble alkaline mineral, need to be considered. Presentation downloadable from www. tececo. com and www. aasmic. org 8
Why Reactive Magnesia? Ü One of the most important variables in concretes affecting most properties is water. – The addition of reactive magnesia has profound affects on both the fluid properties of water and the amount of water remaining in the mix during setting. Ü Corrosion texts describe the protective role of brucite. – The consequences of putting brucite through the matrix of a concrete in the first place need to be considered. Reactive Mg. O is a new tool to be understood with profound affects on most properties Presentation downloadable from www. tececo. com and www. aasmic. org 9
Tec. Eco Technology - Simple Yet Ingenious? Ü The Tec. Eco technology demonstrates that magnesia, provided it is reactive rather than “dead burned” (or high density, periclase type), can be beneficially added to cements in excess of the amount of 5 mass% generally considered as the maximum allowable by standards – Note that dead burned magnesia is much less expansive than dead burned lime (Ramachandran V. S. , Concrete Science, Heydon & Son Ltd. 1981, p 358 -360 ) Ü 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. Ü Dead burned magnesia and lime have high lattice energies – Do not hydrate rapidly and – cause dimensional distress. Presentation downloadable from www. tececo. com and www. aasmic. org 10
Summary of Reactions Involved We think the reactions are relatively independent. Notice the low solubility of brucite compared to Portlandite and that nesquehonite adopts a more ideal habit than calcite & aragonite Presentation downloadable from www. tececo. com and www. aasmic. org 11
Tec-Cements-Less Binder for the Same Strength. Ü Concretes are more often than not made to strength. Ü The use of tec-cement results in – 20 -30% greater strength or less binder for the same strength. – more rapid strength development even with added pozzolans. Presentation downloadable from www. tececo. com and www. aasmic. org 12
Reasons for Strength Development in Tec-Cements. Ü Reactive magnesia requires considerable water to hydrate resulting in: – Denser, less permeable concrete. – A significantly lower voids/paste ratio. Ü Higher early p. H 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? Ü Micro-structural strength due to particle packing (Magnesia particles at 4 -5 micron are about 1/8 th the size of cement grains. ) Ü Slow release of water from around highly charged Mg++ ion? Presentation downloadable from www. tececo. com and www. aasmic. org 13
Water Reduction During the Plastic Phase Less water results in less shrinkage and cracking and improved strength and durability. Concentration of alkalis and increased density result in greater strength. 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. Presentation downloadable from www. tececo. com and www. aasmic. org 14
Tec-Cement Compressive Strength Graphs by Oxford Uni Student Presentation downloadable from www. tececo. com and www. aasmic. org 15
Tec-Cement Tensile Strength Graphs by Oxford Uni Student Presentation downloadable from www. tececo. com and www. aasmic. org 16
Other Strength Testing to Date BRE (United Kingdom) 2. 85 PC/0. 15 Mg. O/3 pfa(1 part) : 3 parts sand - Compressive strength of 69 MPa at 90 days. Note that there was as much pfa as Portland cement plus magnesia. Strength development was consistently greater than the OPC control Tec. Eco The mix was: Portland cement 245 Kg 10. 88% Magnesia 30 Kg 1. 39% Fly ash 70 Kg 3. 24% Quarry dust 215 Kg 9. 55% White sand 550 Kg 25. 46% Dolerate aggregate 1060 Kg 49. 07% Presentation downloadable from www. tececo. com and www. aasmic. org 12. 29% 17
Tec-Cement Concrete Strength Gain Curve The possibility of strength gain with less cement and added pozzolans is of great economic and environmental importance. Presentation downloadable from www. tececo. com and www. aasmic. org 18
A Few Warnings About Trying to Repeat Tec. Eco Findings with Tec-Cements Ü Mg. O is a fine powder and like other fine powders has a high water demand so the tendency is to add too much water. As for other concretes this significantly negatively impacts on strength. Ü Mg++ when it goes into solution is a small atom with a high charge and tends to affect water molecules which are polar. The result is a Bingham plastic quality which means energy is required to introduce a shear thinning to allow placement. Ü Do not use the slump test! – With ordinary Portland cement concretes as rheology prior to placement is observed in the barrel of a concrete truck whilst energy is applied by the revolving barrel. – Is what is done in practice more accurate that the slump test anyway? Presentation downloadable from www. tececo. com and www. aasmic. org 19
Eco-Cement Strength Development Ü Eco-cements gain early strength from the hydration of OPC. Later strength comes from the carbonation of brucite forming an amorphous phase, lansfordite and nesquehonite. Ü Strength gain is mainly microstructural because of – More ideal particle packing (Brucite particles at 4 -5 micron are about 1/8 th the size of cement grains. ) – The natural fibrous and acicular shape of magnesium carbonate minerals which tend to lock together. Presentation downloadable from www. tececo. com and www. aasmic. org 20
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 www. tececo. com and www. aasmic. org 21
Eco-Cement Micro-Structural Strength Presentation downloadable from www. tececo. com and www. aasmic. org 22
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 Mg. O, colouring oxide. 5 Kg, sand unwashed 1105 Kg) Presentation downloadable from www. tececo. com and www. aasmic. org 23
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 Mg. O, colouring oxide. 5 Kg, sand unwashed 1105 Kg) Presentation downloadable from www. tececo. com and www. aasmic. org 24
A Few Warnings About Trying to Repeat Tec. Eco Findings with Eco-Cements Ü Eco-cements will only gain strength in materials that are sufficiently porous to allow the free entry of CO 2. Ü Testing in accordance with standards designed for hydraulic cements is irrelevant. Ü There appears to be a paucity of standards that apply to carbonating lime mortars however we understand the European Lime project will rectify this. Ü Most knowledge of carbonating materials is to be found amongst the restoration fraternity. Ü Centuries of past experience and good science dictate well graded aggregates with a coarser fraction for sufficient porosity. These are generally found in concrete blocks made to today’s standards but not in mortars. Presentation downloadable from www. tececo. com and www. aasmic. org 25
Increased Density – Reduced Permeability Ü Concretes have a high percentage (around 18%) of voids. Ü On hydration magnesia expands 116. 9 % filling voids and surrounding hydrating cement grains. Ü Brucite is 44. 65 mass% water. Ü On carbonation to nesquehonite brucite expands 307% Ü Nesquehonite is 71 mass% water and CO 2! Lansfordite is 77 mass% water and CO 2! – Cheap binder!? ? !! Ü 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. Presentation downloadable from www. tececo. com and www. aasmic. org 26
Reduced Permeability Ü 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 --, Cland CO 2 Ü Tec. Eco tec - cement concretes are a closed system. They do not bleed as excess water is consumed by the hydration of magnesia. – As a result Tec. Eco tec - cement concretes 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 www. tececo. com and www. aasmic. org 27
Tec-Cement p. H Curves Presentation downloadable from www. tececo. com and www. aasmic. org 28
Eco-Cement p. H Curves Presentation downloadable from www. tececo. com and www. aasmic. org 29
A Lower More Stable Long Term p. H In Tec. Eco cements the long term p. H is governed by the low solubility and carbonation rate of brucite and is much lower at around 10. 5 -11, allowing a wider range of aggregates to be used, reducing problems such as AAR and etching. The p. H is still high enough to keep Fe 3 O 4 stable in reducing conditions. Eh-p. H or Pourbaix Diagram The stability fields of hematite, magnetite and siderite in aqueous solution; total dissolved carbonate = 10 -2 M. Steel corrodes below 8. 9 Presentation downloadable from www. tececo. com and www. aasmic. org 30
Reduced Delayed Reactions Ü 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. Ü Delayed reactions cause dimensional distress and possible failure. Presentation downloadable from www. tececo. com and www. aasmic. org 31
Reduced Delayed Reactions (2) Ü Delayed reactions do not appear to occur to the same extent in Tec. Eco cements. – A lower long term p. H 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 Teccement concretes consumes unbound water from the pores inside concrete. – Magnesia dries concrete out from the inside. Reactions do not occur without water. Presentation downloadable from www. tececo. com and www. aasmic. org 32
Carbonation Ü Carbonates are the stable phases of both calcium and magnesium. Ü Carbonation in the built environment would result in significant sequestration because of the shear volumes involved. Ü The formation of carbonates lowers the p. H of concretes compromising the stability of the passive oxide coating on steel. Ü Carbonation adds considerable strength and some steel reinforced structural concrete could be replaced with fibre reinforced porous carbonated concrete. Presentation downloadable from www. tececo. com and www. aasmic. org 33
Carbonation (2) Ü There a number of carbonates of magnesium. The main ones appear to be an amorphous phase, lansfordite and nesquehonite. – Gor Brucite to nesquehonite = - 38. 73 k. J. mol-1 – Compare to Gor Portlandite to calcite = -64. 62 k. J. mol-1 Ü The dehydration of nesquehonite to form magnesite is not favoured by simple thermodynamics but may occur in the long term under the right conditions. Ü Gor nesquehonite to magnesite = 8. 56 k. J. mol-1 – But kinetically driven by desiccation during drying. Ü Reactive magnesia can carbonate in dry conditions – so keep bags sealed! Ü For a full discussion of thermodynamics see our technical documents. Tec. Eco technical documents on the web cover the important aspects of carbonation. Presentation downloadable from www. tececo. com and www. aasmic. org 34
Ramifications of Carbonation Ü Magesium Carbonates. – The magnesium carbonates that form at the surface of tec – cement concretes expand significantly thereby sealing off further carbonation. – Lansfordite and nesquehonite are formed in porous eco-cement concrete as there are no kinetic barriers. 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 via Lansfordite and nesquehonite. – Carbonation results in a fall in p. H. Ü Portland Cement Concretes – Carbonation proceeds relatively rapidly at the surface. ? Vaterite? followed by Calcite is the principal product and lowers the p. H to around 8. 2 Presentation downloadable from www. tececo. com and www. aasmic. org 35
Eco-Cement compared to Carbonating Lime Mortar. Ü The underlying chemistry is very similar however eco-cements are potentially superior to lime mortars because: Ü The calcination phase of the magnesium thermodynamic cycle takes place at a much lower temperature Ü Magnesium minerals are generally more fibrous and acicular than calcium minerals and hence a lot stronger. Ü Water forms part of the binder minerals that forming making the cement component go further. Ü Magnesium hydroxide in particular and to some extent the carbonates are less reactive and mobile and thus much more durable. Ü A less reactive environment with a lower long term p. H. (around 10. 5 instead of 12. 35) Ü Because magnesium has a low molecular weight, proportionally a much greater amount of CO 2 is captured. Presentation downloadable from www. tececo. com and www. aasmic. org 36
Reduced Shrinkage Net shrinkage is reduced due to stoichiometric expansion of Magnesium minerals, and reduced water loss. Dimensional change such as shrinkage results in cracking and reduced durability Presentation downloadable from www. tececo. com and www. aasmic. org 37
Reduced Shrinkage – Less Cracking Reduced in Tec. Eco teccements. After Richardson, Mark G. Fundamentals of Durable Reinforced Concrete Spon Press, 2002. page 212. 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. Teccements may also have greater tensile strength. Presentation downloadable from www. tececo. com and www. aasmic. org 38
Durability - Reduced Salt & Acid Attack Ü Brucite has always played a protective role during salt attack. Putting it in the matrix of concretes in the first place makes sense. Ü Brucite does not react with salts because it is a least 5 orders of magnitude less soluble, mobile or reactive. – Ksp brucite = 1. 8 X 10 -11 – Ksp Portlandite = 5. 5 X 10 -6 Ü Tec. Eco cements are more acid resistant than Portland cement – This is because of the relatively high acid resistance (? ) of Lansfordite and nesquehonite compared to calcite or aragonite Presentation downloadable from www. tececo. com and www. aasmic. org 39
Improved Workability Finely ground reactive magnesia acts as a plasticiser There also surface charge affects Presentation downloadable from www. tececo. com and www. aasmic. org 40
Bingham Plastic Rheology It is not known how deep these layers get Etc. The strongly positively charged small Mg++ atoms attract water which is polar in deep layers affecting the rheological properties. Etc. Ca++ = 114, Mg++ = 86 picometres Presentation downloadable from www. tececo. com and www. aasmic. org 41
Rheology Ü Tec. Eco 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. Ü Tec. Eco concretes with the same water/binder ratio have a lower slump but greater plasticity and workability. Ü Tec. Eco tec-cements are potentially suitable for mortars, renders, patch cements, colour coatings, pumpable and self compacting concretes. Ü A range of pumpable composites with Bingham plastic properties will be required in the future as buildings will be “printed. ” Presentation downloadable from www. tececo. com and www. aasmic. org 42
Dimensionally Control Over Concretes During Curing? Ü Portland cement concretes shrink around. 05%. Over the long term much more (>. 1%). – Mainly due to plastic and drying shrinkage. Ü The use of some wastes as aggregates causes shrinkage e. g. wood waste in masonry units, thin panels etc. Ü By varying the amount and form of magnesia added dimensional control can be achieved. Presentation downloadable from www. tececo. com and www. aasmic. org 43
Volume Changes on Hydration ÜWhen magnesia hydrates it expands: Mg. O (s) + H 2 O (l) ↔ Mg(OH)2 (s) 40. 31 + 18. 0 ↔ 58. 3 molar mass 11. 2 + liquid ↔ 24. 3 molar volumes Ü Up to 116. 96% solidus expansion depending on whether the water is coming from stoichiometric mix water, bleed water or from outside the system. In practice much 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). Presentation downloadable from www. tececo. com and www. aasmic. org 44
Volume Changes on Carbonation Ü Consider what happens when Portlandite carbonates: Ca(OH)2 + CO 2 Ca. CO 3 74. 08 + 44. 01 ↔ 100 molar mass 33. 22 + gas ↔ 36. 93 molar volumes – Slight expansion. But shrinkage from surface water loss Ü Compared to brucite forming nesquehonite as it carbonates: Mg(OH)2 + CO 2 Mg. CO 3. 3 H 2 O 58. 31 + 44. 01 ↔ 138. 32 molar mass 24. 29 + gas ↔ 74. 77 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 www. tececo. com and www. aasmic. org 45
Tec. Eco Cement Concretes –Dimensional Control Ü Combined – Hydration and Carbonation can be manipulated to be close to neutral. – So far we have not observed shrinkage in Tec. Eco tec - cement concretes (5% -10% substitution OPC) also containing fly ash. – At some ratio, thought to be around 5% -10% reactive magnesia and 90 – 95% OPC volume changes cancel each other out. – The water lost by Portland cement as it shrinks is used by the reactive magnesia as it hydrates eliminating shrinkage. Ü Note that brucite is 44. 65 mass% water, nesquehonite is 71 mass% water and CO 2 – It makes sense to make binders out of CO 2 and water!. Ü More research is required for both tec - cements and ecocements to accurately establish volume relationships. 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 www. tececo. com and www. aasmic. org 46
Tec - Cement Concretes – No Dimensional Change Presentation downloadable from www. tececo. com and www. aasmic. org 47
Reduced Steel Corrosion Ü Steel remains protected with a passive oxide coating of Fe 3 O 4 above p. H 8. 9. – A p. H of over 8. 9 is maintained by the equilibrium Mg(OH)2 ↔ Mg++ + 2 OHfor much longer than the p. H maintained by Ca(OH)2 because: – Brucite does not react as readily as Portlandite resulting in reduced carbonation rates and reactions with salts. Ü Concrete with brucite in it is denser and carbonation is expansive, sealing the surface preventing further access by moisture, CO 2 and salts. Ü Brucite is less soluble and traps salts as it forms resulting in less ionic transport to complete a circuit for electrolysis and less corrosion. Ü 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 www. tececo. com and www. aasmic. org 48
Corrosion in Portland Cement Concretes 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. Passive Coating Fe 3 O 4 intact Corrosion Anode: Fe → Fe+++ 2 e. Cathode: ½ O 2 + H 2 O +2 e- → 2(OH)Fe++ + 2(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+++ 2 e. Cathode: ½ O 2 + H 2 O +2 e- → 2(OH)Fe++ +2 Cl- → Fe. Cl 2 + H 2 O + OH- → Fe(OH)2 + H+ + 2 Cl. 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 www. tececo. com and www. aasmic. org 49
Less Freeze - Thaw Problems Ü Denser concretes do not let water in. Ü Brucite will to a certain extent take up internal stresses Ü When magnesia hydrates it expands into the pores left around hydrating cement grains: Mg. O (s) + H 2 O (l) ↔ Mg(OH)2 (s) 40. 31 + 18. 0 ↔ 58. 3 molar mass 11. 2 + 18. 0 ↔ 24. 3 molar volumes 39. 20 ↔ 24. 3 molar volumes 38% air voids are created in space that was occupied by magnesia and water! Ü Air entrainment can also be used as in conventional concretes Ü Tec. Eco concretes are not attacked by the salts used on roads Presentation downloadable from www. tececo. com and www. aasmic. org 50
Tec. Eco Binders - Solving Waste Problems Ü There are huge volumes of concrete produced annually ( 2 tonnes person per year ) Ü The goal should be to make cementitious composites that can utilise wastes. Ü Tec. Eco cements provide a benign environment suitable for waste immobilisation Ü 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. Tec. Eco technology will lead the world in the race to incorporate wastes in cementitous composites Presentation downloadable from www. tececo. com and www. aasmic. org 51
Tec. Eco Binders - Solving Waste Problems (2) ÜTec. Eco cementitious composites represent a cost affective option for both use and immobilisation of waste. – – – – – Lower reactivity (less water, lower p. H). Reduced solubility of heavy metals (lower p. H). Greater durability. Dense. Impermeable (tec-cements). Homogenous. No bleed water. Are not attacked by salts in ground or sea water. Are dimensionally more stable with less cracking. Tec. Eco Technology Converting Waste to Resource Presentation downloadable from www. tececo. com and www. aasmic. org 52
Role of Brucite in Immobilisation Ü In a Portland cement brucite matrix – OPC 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 Tec. Eco cements has a structure comprising electronically neutral layers and is able to accommodate a wide variety of extraneous substances between the layers and cations of similar size substituting for magnesium within the layers and is known to be very suitable for toxic and hazardous waste immobilisation. Presentation downloadable from www. tececo. com and www. aasmic. org 53
Lower Solubility of Metal Hydroxides There is a 104 difference Presentation downloadable from www. tececo. com and www. aasmic. org 54
Tec. Eco Materials are Fire Retardants Ü The main phase in Tec. Eco tec - cement concretes is Brucite. Ü The main phases in Tec. Eco eco-cements are Lansfordite and nesquehonite. Ü Brucite, Lansfordite and nesquehonite are excellent fire retardants and extinguishers. Ü At relatively low temperatures – Brucite releases water and reverts to magnesium oxide. – Lansfordite and nesquehonite releases CO 2 and water and convert to magnesium oxide. Ü Fires are therefore not nearly as aggressive resulting in less damage to structures. Ü Damage to structures results in more human losses that direct fire hazards. Presentation downloadable from www. tececo. com and www. aasmic. org 55
Slides About Concrete Sustainability Presentation downloadable from www. tececo. com and www. aasmic. org 56
Materials – The Key to Sustainability Presentation downloadable from www. tececo. com and www. aasmic. org 57
Materials – The Key to Sustainability Ü Materials are the lasting substances that flow through the techno-process. They are the link between the bio-geo-sphere and techno-sphere and hence everything between and defining the take and waste. Ü The choice of materials in construction has a huge impact on many properties including weight, embodied energies, fuel related and chemical emissions, lifetime energies, user comfort and health, use of recycled wastes, durability, recyclability and the properties of wastes returned to the biogeo-sphere. Presentation downloadable from www. tececo. com and www. aasmic. org 58
Innovative New Materials Vital Ü We need to think at the supply and waste end when we design building materials – not just about the materials utility phase in the middle Ü 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. Ü Concrete, a cementitous composite, is the single biggest material flow on the planet with over 2 tonnes person produced and a C good place to start. C Ü By including carbon, materials C are potentially carbon sinks. C Ü By including wastes many problems at C C the waste end are solved. C Eco-cement example Δ Mg. CO 3 → Mg. O + ↓CO 2 - Efficient low temperature calcination & capture Mg. O + ↓CO 2 + H 2 O → Mg. CO 3. 3 H 2 O - Sequestration as building material Presentation downloadable from www. tececo. com and www. aasmic. org 59
Focus on Materials Ü The choice of materials in a structure profoundly affects many properties relevant to sustainability including weight, embodied energies, fuel related and chemical emissions, lifetime energies, user comfort and health, use of recycled wastes, durability, recyclability and the properties of wastes returned to the bio-geo-sphere. Ü Materials need to economically become more sustainable, utilising more wastes and at the same time reducing net emissions or better still sequester carbon. Presentation downloadable from www. tececo. com and www. aasmic. org 60
Embodied Energy of Building Materials Concrete is relatively environmentally friendly and has a relatively low embodied energy Downloaded from www. dbce. csiro. au/indserv/brochures/embodied. htm (last accessed 07 March 2000) Presentation downloadable from www. tececo. com and www. aasmic. org 61
The Largest Material Flow - Cement and Concrete Ü Concrete made with cement is the most widely used material on Earth accounting for some 30% of all materials flows on the planet and 60 - 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. – That’s over 2 tonnes person per annum Tec. Eco Pty. Ltd. have benchmark technologies for improvement in sustainability and properties Presentation downloadable from www. tececo. com and www. aasmic. org 62
Cement Production = Carbon Dioxide Emissions Presentation downloadable from www. tececo. com and www. aasmic. org 63
Emissions from Cement Production Ü Portland cement used in construction is made from carbonate. Ü The process of calcination involves driving off chemically bound CO 2 with heat. Ca. CO 3 →Ca. O + ↑CO 2 ∆ Ü Heating also requires energy. – 94% of energy is still derived from fossil fuels. – Fuel oil, coal and natural gas are directly or indirectly burned to produce the energy required releasing CO 2. Ü 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 www. tececo. com and www. aasmic. org 64
Average Embodied Energy in Buildings Most of the embodied energy in the built environment is in concrete. 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. Downloaded from www. dbce. csiro. au/indserv/brochures/embodied. htm (last accessed 07 March 2000) Presentation downloadable from www. tececo. com and www. aasmic. org 65
Utilising Wastes Ü An important objective should be to make cementitious composites that can utilise wastes. Ü Tec. Eco cements provide a benign environment suitable for waste immobilisation. Ü 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. Tec. Eco technology leads the world in the race to incorporate wastes in cementitous composites Presentation downloadable from www. tececo. com and www. aasmic. org 66
Making Concrete, the Main Material Used in Construction More Sustainable Ü As the biggest single material flow on the planet and certainly the biggest in construction, cementitious composites like Portland cement concrete present huge challenges and opportunities for improvement. Ü Technical issues: – Portland cement concretes are not very durable because of the lime content and are generally not considered to last more than 50 to 100 years. – The addition of pozzolan like fly ash to initiate the pozzolanic reaction may leave use with a CSH (the main mineral in cement) stability issue. Ü These durability issues can be overcome with the adoption of Tec. Eco technology whereby brucite, a much more stable alkali replaces Portlandite. Durable concretes are more sustainable. Presentation downloadable from www. tececo. com and www. aasmic. org 67
Making Concrete, the Main Material Used in Construction More Sustainable (2) Ü Opportunities: – Change towards sustainability should be embraced by the industry as an opportunity to make money by • grabbing market share as legislative and cultural change induces change in demand patterns and by • being more efficient. (Note that efficiency implies sustainability. ) – Economics must drive sustainability There is no security in this life, only opportunity. (General Douglas Macarthur) Presentation downloadable from www. tececo. com and www. aasmic. org 68
A Killer Application for Waste? Ü Wastes – Utilizing wastes based on their chemical composition involves energy consuming transport. – Wastes could be utilized as resources depending on their class of properties rather than chemical composition. • in vast quantities based on broadly defined properties such as light weight, tensile strength, insulating capacity, strength or thermal capacity in composites. • Many wastes contain carbon and if utilized would result in net carbon sinks. Ü Tec. Eco binders enable many wastes to be converted to resources. Two examples: – Plastics – Sawdust and wood waste Presentation downloadable from www. tececo. com and www. aasmic. org 69
Sustainability Ü The Current Technical Direction – Reduce the amount of total binder. – Use more supplementary materials • Pfa, gbfs, industrial pozzolans etc. – Use of recycled aggregates. Enhanced by using reactive Mg. O • Including aggregates containing carbon Ü The use of Mg. O potentially overcomes: – Problems using acids to etch plastics so they bond with concretes. – Problem of sulphates from plasterboard etc. ending up in recycled construction materials. – Problems with heavy metals and other contaminants. – Problems with delayed reactivity e. g. ASR with glass cullet Ü Eco-cements further provide carbonation of the binder component. Ü Possibility of easy capture of CO 2 during the manufacturing process. Presentation downloadable from www. tececo. com and www. aasmic. org 70
The Impact of Tec. Eco Technology Ü Tec. Eco magnesian cement technology will be pivotal in bringing about sustainability in the built environment. – Tec-Cements Develop Significant Early Strength even with Added Supplementary Materials. Around 25 = 30% less binder is required for the same strength. – Eco-cements carbonate sequestering CO 2 – Both tec and eco=cements provide a benign low p. H environment for hosting large quantities of waste Ü The CO 2 released by calcined carbonates used to make binders can be captured using Tec. Eco kiln technology. Presentation downloadable from www. tececo. com and www. aasmic. org 71
Comparative Sustainability of Various Concretes Compound CO 2 released through decarbonation in producing 1 tonne (tonnes CO 2/tonne produced) CO 2 potentially recaptured in a porous concrete or mortar Net Emission s (if no capture) Net Emissions (if capture for Mg. O and Ca. O only) Example of Cement Type Mg. O 1. 09 0 -1. 09 (net sequestration) Eco-cement mortar Ca. O 0. 78 0 -. 78 (net sequestration) Carbonating lime mortar C 3 S 0. 578 . 289 Not feasible technically yet Alite cement C 2 S 0. 511 . 255 . 256 Not feasible technically yet Belite cement C 3 A 0. 594 0 0. 594 Not feasible technically yet Tri calcium aluminate cement PC 0. 54 . 27 (variable) . 27 Not feasible technically yet Portland Cement 1 PC: 2 Mg. O 0. 99 . 817 . 173 -. 817 (net sequestration) Eco-cement with no pfa 1 PC: 2 Mg. O: 3 pfa 0. 445 . 367 . 077 -. 367 (net sequestration) Eco-cement with pfa 1 PC: 2 pfa 8 . 27 . 137 Only feasible for the Mg. O component Very high fly ash cement . 05 Mg. O: . 95 PC: 2 pfa 8 . 18 . 092 Only feasible for the Mg. O component Tec-cement assuming 1/3 (. 334%) less binder required. 0. 216 0 . 216 Not feasible technically yet Calcium sulfoaluminate cement [1] C 4 A 3 s Presentation downloadable from www. tececo. com and www. aasmic. org 72
Tec. Eco Cement Summary Presentation downloadable from www. tececo. com and www. aasmic. org 73
High Performance-Lower Construction Costs Ü Ü Ü Ü Less binders (OPC + magnesia) for the same strength. Faster strength gain even with added pozzolans. Elimination of shrinkage reducing associated costs. Elimination of 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. Presentation downloadable from www. tececo. com and www. aasmic. org 74
Tec. Eco Concretes - Lower Construction Costs (2) Ü Ü Ü 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. Tec. Eco cements utilise wastes many of which improve properties. Improvements in insulating capacity and other properties will result in greater utility. Ü Products utilising Tec. Eco cements such as masonry and precast products can in most cases utilise conventional equipment and have superior properties. Ü 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 Tec. Eco cements therefore produces a greater volume of built environment than Portland other calcium based cements. Less need therefore be used reducing costs/energy/emissions. Presentation downloadable from www. tececo. com and www. aasmic. org 75
Tec. Eco Challenging the World Ü The Tec. Eco technology is new and not yet fully characterised. Ü Tec. Eco cement technology offers – a new tool – sustainability in the built environment not previously considered possible. Ü The world desperately needs a way of sequestering large volumes of CO 2 such as made possible by eco-cements. Ü Formula rather than performance based standards are preventing the development of new and better materials based on mineral binders. Ü Tec. Eco challenge universities governments and construction authorities to quantify performance in comparison to ordinary Portland cement and other competing materials. Ü We at Tec. Eco will do our best to assist. Ü Negotiations are underway in many countries to organise supplies to allow such scientific endeavour to proceed. Presentation downloadable from www. tececo. com and www. aasmic. org 76
Tec. Eco’s Immediate Focus Ü Tec. Eco will concentrate on: – Killer applications that use a lot of cement, are easy to manage and that will initiate and achieve volume production. – low technical risk products that require minimal research and development and for which performance based standards apply. • Niche products for which our unique technology excels. • Carbonated products such as bricks, blocks, stabilised earth blocks, pavers, roof tiles pavement and mortars that utilise large quantities of waste. • Products where sustainability, rheology or fire retardation are required. (Mainly eco-cement technology using fly ash). • Products such as oil well cement, gunnites, shotcrete, tile cements, colour renders and mortars where excellent rheology and bond strength are required. – The immobilisation of wastes including toxic hazardous and other wastes because of the superior performance of the technology and the rapid growth of markets. (enviro and tec - cements). – Controlled low strength materials e. g. mud bricks. – Solving problems not adequately resolved using Portland cement • Products where extreme durability is required (e. g. bridge decking. ) • Products for which weight is an issue. Presentation downloadable from www. tececo. com and www. aasmic. org 77
Tec. Eco Minding the Future Ü Tec. Eco are aware of the enormous weight of opinion necessary before standards can be changed globally for Tec. Eco tec - cement concretes for general use. – Tec. Eco already have a number of institutions and universities around the world doing research. Ü Tec. Eco have publicly released the eco-cement technology and received huge global publicity. – Tec. Eco research documents are available from the Tec. Eco web site by download, however a password is required. 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. 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 Presentation downloadable from www. tececo. com and www. aasmic. org 78
A Few Other Comments Ü Research – Tec. Eco have found that in house research is difficult due to the high cost of equipment and lack of credibility of the results obtained. – Although a large number of third party research projects have been initiated, the work has been slow due to inefficiencies and a lack of understanding of the technology. We are doing our best to address this with a new web site and a large number of papers and case histories that are being posted to it. – Tec. Eco are always keen to discuss research projects provided they are fair and the proposed test regime is appropriate. Ü Business – There are significant business opportunities that are emerging. – Tec. Eco are shifting the focus to tec-cement concretes due to economy of scale issues likely only to be overcome with the adoption of Tec. Eco kiln technology and introduction of the superior Nichromet process (www. nichromet. com) to the processing of minerals containing Mg. – Watch the development of robotic construction and placement without formwork as these new developments will require the use of binders with Bingham plastic qualities such as provided by Tec. Eco technology. – Tec. Eco technology gives Mineral sequestration real economic relevance. Presentation downloadable from www. tececo. com and www. aasmic. org 79
Limiting Factors for Development of Tec. Eco Technology Ü Credibility Issues that can only be overcome with significant funded research by Tec. Eco and third parties. Ü Economies of scale – Government procurement policies – Subsidies for materials that can demonstrate clear sustainable advantages. – Carbon taxes/credits. Ü Formula rather than performance based standards – Formula based standards enshrine mediocrity and the status quo. – A legislative framework enforcing performance based standards is essential. – For example cement standards excluding magnesium are based on historical misinformation and lack of understanding. Presentation downloadable from www. tececo. com and www. aasmic. org 80
Summary Ü Simple, smart and sustainable? – Tec. Eco cement technology has resulted in potential solutions to a number of problems with Portland other cements including durability and corrosion, the alkali aggregate reaction problem and the immobilisation of many problem wastes and will provides a range of more sustainable building materials. üClimate Change üPollution üDurability üCorrosion üStrength üDelayed Reactions üPlacement , Finishing üRheology üShrinkage üCarbon Taxes Ü The right technology at the right time? – Tec. Eco cement technology addresses important triple bottom line issues solving major global problems with positive economic and social outcomes. Presentation downloadable from www. tececo. com and www. aasmic. org 81
Tec. Eco Doing Things Presentation downloadable from www. tececo. com and www. aasmic. org 82
The Use of Eco-Cements for Building Earthship Brighton By Taus Larsen, (Architect, Low Carbon Network Ltd. ) The Low Carbon Network (www. lowcarbon. co. uk) was established to raise awareness of the links between buildings, the working and living patterns they create, and global warming and aims to initiate change through the application of innovative ideas and approaches to construction. England’s first Earthship is currently under construction in southern England outside Brighton at Stanmer Park and Tec. Eco 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 Tec. Eco web site. Presentation downloadable from www. tececo. com and www. aasmic. org 83
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 effloresence, pitting, loss of material and damage. The Tec. Eco solution was to make up a formulation of eco-cement mortar which we doctored with some special chemicals to prevent the rise of any more moisture and salt. The solution worked well and appears to have stopped the problem. Presentation downloadable from www. tececo. com and www. aasmic. org 84
Mike Burdon’s Murdunna Works Mike Burdon, Builder and Plumber. I work for a council interested in sutainability and have been involved with Tec. Eco since around 2001 in a private capacity helping with large scale testing of Tec. Eco teccements 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 Tec. Eco. I believe that research into the new Tec. Eco 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 Tec. Eco formulations with a hired concrete pump and found it extremely easy to pump and place. Once in position it appeared to “gel up” quickly allowing stepping for a foundation to a brick wall. 3. Strength gain was more rapid than with Portland cement controls from the same premix plant and continued for longer. 4. The surfaces of the concrete appeared to be particularly hard and I put this down to the fact that much less bleeding was observed than would be expected with a Portland cement only formulation Presentation downloadable from www. tececo. com and www. aasmic. org 85
Sustainability Presentation downloadable from www. tececo. com and www. aasmic. org 86
Drivers Presentation downloadable from www. tececo. com and www. aasmic. org 87
Drivers for Change – Robotics Ü Using Robots to print buildings is all quite simple from a software, computer hardware and mechanical engineering point of view. Ü 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 Ü Tec. Eco cement concretes have the potential of achieving the right shear thinning characteristics required Presentation downloadable from www. tececo. com and www. aasmic. org 88
Robotics Will Result in Greater Sustainability Construction in the future will be largely achieved using robots. Like a color printer different materials will be required for different parts of structures, and wastes such as plastics will provide many of the properties required for the cementitious composites used. A non-reactive binder such as Tec. Eco teccements will supply the right rheology and environment, and as with a printer, there will be very little waste. Presentation downloadable from www. tececo. com and www. aasmic. org 89
Other than Economics -What’s in the Way? Ü The main inhibiter to innovation in the industry is the formula-based approach to standards which grew out of the industrial environment of the early twentieth century. Ü Performance based standards make much more sense. Ü Other restrictions to change: – Expensive manufacturing infrastructure. – Low margin product. – Industry dogmatism and culture tied to the belief that "it has always been done this way". Presentation downloadable from www. tececo. com and www. aasmic. org 90
The Solution must be Economic. Ü With record energy prices the argument of Hawken and Lovins in the book Natural Capitalism that sustainability makes good business sense has never been more vindicated Ü Moves towards ensuring a sustainable future by changing the materials we use have to be more economic than not changing them. – Otherwise, given human nature, they will not happen Presentation downloadable from www. tececo. com and www. aasmic. org 91
Economically Driven Sustainability The challenge is to harness human behaviours which underlay economic supply and demand phenomena by changing the technical paradigm in favour of making carbon dioxide and other wastes resources. ECONOMICS Sustainable processes are more efficient and therefore more economic. What is needed are sustainable process that also deliver sustainable materials and innovation will deliver these new technical paradigms. Presentation downloadable from www. tececo. com and www. aasmic. org 92
Cultural Change and Paradigm Shifts in Technology Increase in demand/price ratio for sustainability due to educationally induced cultural drift. $ ECONOMICS Equilibrium shift Supply Greater Value/for impact (Sustainability ) Demand Increase in supply/price ratio for # more sustainable products due to innovative changes in the technical paradigm. Presentation downloadable from www. tececo. com and www. aasmic. org 93
To Make Carbon and Wastes Resources the Key is To Change the Technology Paradigm “By enabling us to make productive use of particular raw materials, technology determines what constitutes a physical resource 1” 1. Pilzer, Paul Zane, Unlimited Wealth, Theory and Practice of Economic Alchemy, Crown Publishers Inc. New York. 1990 Changing the technical paradigm will affect the supply of and demand for more sustainable materials Presentation downloadable from www. tececo. com and www. aasmic. org 94
Paradigm Shifts in Technology Ü Paradigm shifts in technologies that define resources and thus the molecular flows that underlay their movement through the economy are essential. Changes in molecular flows towards sustainability by definition mean less pollutants, less take and less waste. Ideally they also mean less output of CO 2 and other harmful gases. – Such change will stimulate a major new round of economic growth. Like the computer industry or mobile phone industry this will be a technology led economic revolution of substantial proportions. Ü New materials with low embodied energies and emissions that deliver more than just strength or durability are urgently required. Many of these will be composites combining properties previously considered mutually exclusive such as thermal capacity and insulating ability. Presentation downloadable from www. tececo. com and www. aasmic. org 95
Economies of Scale and Other Economic Barriers Ü Arguably economies of scale are as large a barrier as the formula based standards that support the status quo. – To nurture new technologies a level playing field or even incentives are required and as it is the role of governments to govern for the common good providing such business conditions is their prerogative. Ü Even though governments through policy can introduce change that brings about economies of scale it is important that building technologies that seek sustainability are also fundamentally economic in the long run. Presentation downloadable from www. tececo. com and www. aasmic. org 96
The Tec-Kiln Technology Presentation downloadable from www. tececo. com and www. aasmic. org 97
Tec. Eco Kiln Technology Ü Grinds and calcines at the same time. Ü Runs 25% to 30% more efficiency. Ü Can be powered by solar energy or waste heat. Ü Brings mineral sequestration and geological sequestration together Ü Captures CO 2 for bottling and sale to the oil industry (geological sequestration). Ü The products – Ca. O &/or Mg. O can be used to sequester more CO 2 and then be re-calcined. This cycle can then be repeated. Ü Suitable for making reactive Mg. O. Presentation downloadable from www. tececo. com and www. aasmic. org 98
The Tec. Eco Process for Saving the Planet The new Tec. Eco binder technologies interface ideally with mineral sequestration. Using either forsterite or serpentine as inputs the tec-kiln technology previously shown provides a calcining method whereby the magnesium carbonate produced can be calcined with the capture of the CO 2 released using solar derived intermittent energy or waste energy from other sources. The magnesium oxide (Mg. O) produced can be used to directly sequester more CO 2 in a scrubbing process or to sequester carbon as hydrated magnesium carbonates in the built environment Presentation downloadable from www. tececo. com and www. aasmic. org 99
The Tec. Eco Process Ü Silicate → Carbonate Mineral Sequestration – Using either 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. Tec. Eco etc. ) Ü Tec-Kiln Technology – Combined calcining and grinding in a closed system allowing the capture of CO 2. Powered by waste heat, solar or solar derived energy. – To be proved but simple and should work! Economic under Kyoto? Ü Direct Scrubbing of CO 2 using Mg. O Tec. Eco – Being proven by others (NETL, MIT, TNO, Finnish govt. etc. ) Ü Eco-Cement Concretes in the Built Environment. – Tec. Eco eco-cements are as good as proven. Presentation downloadable from www. tececo. com and www. aasmic. org 100
Sustainability Requires a Holistic Approach Ü Carbon trading ? Ü Sequestration on a massive scale is politically easiest to implement and could potentially be an economic process given changes in the technology paradigm (e. g. those advocated by Tec. Eco. ) Ü Every direction and everybody from the take to the waste. Geological Sequestration Eco-cements in cities Presentation downloadable from www. tececo. com and www. aasmic. org 101
Eco-Cements We all use carbon to make our homes! Presentation downloadable from www. tececo. com and www. aasmic. org 102
Why Mangesium Compounds Ü Because magnesium has a low molecular weight, proportionally a much greater amount of CO 2 is released or captured. Ü This, together with the high proportion of water in the binder is what makes construction the built environment out of CO 2 and water so exciting. Ü Imagine the possibilities if CO 2 could be captured during the manufacture of eco-cement! Presentation downloadable from www. tececo. com and www. aasmic. org 103
CO 2 Abatement in Eco-Cements For 85 wt% Aggregates 15 wt% Cement Eco-cements in porous products absorb carbon dioxide from the atmosphere. Brucite carbonates forming hydromagnesite and magnesite, completing thermodynamic cycle. Portland Cements 15 mass% Portland cement, 85 mass% aggregate Emissions. 32 tonnes to the tonne. After carbonation. Approximatel y. 299 tonne to the tonne. No Capture 11. 25% mass% reactive magnesia, 3. 75 mass% Portland cement, 85 mass% aggregate. Emissions. 37 tonnes to the tonne. After carbonation. approximately. 241 tonne to the tonne. Capture CO 2 11. 25% mass% reactive magnesia, 3. 75 mass% Portland cement, 85 mass% aggregate. Emissions. 25 tonnes to the tonne. After carbonation. approximately. 140 tonne to the tonne. Capture 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. Greater Sustainability. 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. Presentation downloadable from www. tececo. com and www. aasmic. org 104
Embodied Energies and Emissions Presentation downloadable from www. tececo. com and www. aasmic. org 105
Embodied Energy and Emissions Ü Energy costs money and results in emissions and is the largest cost factor in the production of mineral binders. – Whether more or less energy is required for the manufacture of reactive magnesia compared to Portland cement or lime depends on the stage in the utility adding process it is measured. – Utility is greatest in the finished product which is concrete. The volume of built material is more relevant than the mass and is therefore more validly compared. On this basis the technology is far more sustainable than either the production of lime or Portland cement. Ü The new Tec. Eco kiln technology will result in around 25% less energy being required and the capture of CO 2 during production will result in less energy, lower costs and carbon credits. Ü The manufacture of reactive magnesia is a benign process that can be achieved with waste or intermittently available energy. Presentation downloadable from www. tececo. com and www. aasmic. org 106
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 Portlan d Cemen t Ca. CO 3 + Clay 1545. 73 2828. 69 Ca. CO 3 1786. 09 2679. 14 Mg. CO 3 1402. 75 1753. 44 Mg. O From Manufacturi ng Process Energy Release 100% Efficient (MJ. tonne-1) 1807 2934. 26 From Manufacturi ng Process Energy Release with Inefficienci es (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) 3306. 81 Hydrated OPC 1264. 90 2314. 77 Ca(OH)2 2413. 20 3619. 80 Mg(OH)2 2028. 47 2535. 59 3667. 82 Presentation downloadable from www. tececo. com and www. aasmic. org 107
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 Portland Cement Ca. CO 3 + Clay 4188. 93 7665. 75 Ca. CO 3 6286. 62 8429. 93 Mg. CO 3 4278. 39 5347. 99 Mg. O From Manufacturi ng Process Energy Release 100% Efficient (MJ. metre-3) 5692. 05 9389. 63 From Manufacturin g Process Energy Release with Inefficiencies (MJ. metre-3) 10416. 45 11734. 04 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) Hydrate d OPC 3389. 93 6203. 58 Ca(OH)2 5381. 44 8072. 16 Mg(OH)2 4838. 32 6085. 41 Presentation downloadable from www. tececo. com and www. aasmic. org 108
Global Abatement Without CO 2 Capture during manufacture (billion tonnes) With CO 2 Capture during manufacture (billion tonnes) Total Portland Cement Produced Globally 1. 80 Global mass of Concrete (assuming a proportion of 15 mass% cement) 12. 00 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 2. 59 1. 34 Resulting Abatement of CO 2 emissions by Substituting Eco-Cement 0. 29 1. 53 Presentation downloadable from www. tececo. com and www. aasmic. org 109
Abatement from Substitution Building Material to be substituted Realisti c% Substitution by Tec. Eco technol ogy Size of World Market (millio n tonnes Substit uted Mass (million tonnes) CO 2 Fact ors (1) Emission From Material Before Substituti on Concretes already have low lifetime energies. If embodied energies are improved could substitution mean greater market share? Emission/Sequestrati on from Substituted Eco-Cement (Tonne for Tonne Substitution Assumed) Net Abatement Emission s - No Capture Emission s - CO 2 Capture Abatem ent - No Capture Abatem ent CO 2 Capture Bricks 85% 250 212. 5 0. 28 59. 5 57. 2 29. 7 2. 3 29. 8 Steel 25% 840 210 2. 38 499. 8 56. 6 29. 4 443. 2 470. 4 Aluminium 20% 20. 5 4. 1 18. 0 73. 8 1. 1 0. 6 72. 7 73. 2 426. 6 20. 7 633. 1 114. 9 59. 7 518. 2 573. 4 TOTAL Figures are in millions of Tonnes Presentation downloadable from www. tececo. com and www. aasmic. org 110
- Slides: 110