Magnesian Magnesian Cements Cements Fundamental Fundamental for for Sustainability Sustainability in in the the Built Built Environment Environment Hobart, Tasmania, Australia where I live I will have to race over some slides but the presentation is always downloadable from the net if you missed something. All I ask is that you think about what I am saying. John Harrison Presentation downloadable from B.Sc. B.Ec. FCPA. 1 TecEco TecEco Cements Cements A A Blending Blending System System 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 MAGNESIA Hydration of magnesia => brucite. Carbonation of brucite => nesquehonite, lansfordite and an amorphous phase for strength, workability, dimensional stability, durability and sustainability. TecEco concretes are a system of blending reactive magnesia, Portland cement and usually a pozzolan with other materials. Presentation downloadable from
2 TecEco TecEco The materials science aspects of the technology from the direction of a geochemist. The chemistry behind the innovation and Resulting properties. The sustainability aspects of the technology from the direction of a concerned economist and scientist. If we get time a movie made by discovery channel about the technology. If we get time give the industry an invention to replace the scratch test. Is what I am going to talk about a bright new direction for masonry? Presentation downloadable from 3 TecEco Cements Presentation downloadable from 4 TecEco TecEco Cements Cements A A Blending Blending System System 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 MAGNESIA Hydration of magnesia => brucite. Carbonation of brucite => nesquehonite, lansfordite and an amorphous phase for strength, workability, dimensional stability, durability and sustainability. TecEco concretes are a system of blending reactive magnesia, Portland cement and usually a pozzolan with other materials.
Presentation downloadable from 5 TecEco TecEco Formulations Formulations Tec-cements (5-10% MgO, 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 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 (15-90% MgO, 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. Enviro-cements (15-90% MgO, 85-10% OPC) 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 6 Problems
Problems with with OPC/Lime OPC/Lime Concrete/Mortars Concrete/Mortars Talked about Strength Durability and performance Permeability and density Sulphate and chloride resistance Carbonation Corrosion of steel and other reinforcing Delayed reactions (eg alkali aggregate and delayed ettringite) Freeze-thaw The discussion should be more about fixing the mineralogy. Rheology Workability, time for and method of placing and finishing Dimensional change including shrinkage Cracking, crack control Bonding to brick and tiles Waste immobilisation and utilisation
Efflorescence Rarely discussed Sustainability issues Emissions and embodied energies Presentation downloadable from 7 Engineering Engineering Issues Issues are are Mineralogical Mineralogical Issues Issues Problems with Portland cement concretes are usually resolved by the band aid application of engineering fixes. e.g. Use of calcium nitrite, silanes, cathodic protection or stainless steel to prevent corrosion. Use of coatings to prevent carbonation. Crack control joins to mitigate the affects of shrinkage cracking. Plasticisers to improve workability, glycols to improve finishing. Mineralogical fixes are not considered We need to think outside the square. Many of the problems with Portland cement relate to the presence of Portlandite and are better fixed by removing it! Presentation downloadable from 8 Portlandite
Portlandite the the Weakness, Weakness, Brucite Brucite the the Fix Fix Portlandite (Ca(OH)2) is too soluble, mobile and reactive. It carbonates readily and being soluble can act as an electrolyte. TecEco generally remove Portlandite using the pozzolanic reaction and add reactive magnesia which hydrates forming Brucite. Brucite (Mg(OH)2) is another alkali, but much less soluble, mobile or reactive, does not act as an electrolyte or carbonate as readily. 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 9 Consequences Consequences of of the the Addition Addition of of Magnesia Magnesia The addition of magnesia Improves rheology. Uses up bleed water as it hydrates. Magnesia hydrates forming Brucite which
Fills in the pores increasing density. Reduces permeability. Adds strength. Reduces shrinkage. Provides long term pH control. In porous eco-cements Brucite carbonates Forms stronger more fibrous minerals such as lansfordite and nesquehonite. Presentation downloadable from 10 Portlandite Portlandite Compared Compared to to Brucite Brucite Property Portlandite (Lime) Brucite Density 2.23 2.9
Hardness 2.5 3 2.5 3 Solubility (cold) 1.85 g L-1 in H2O at 0 oC 0.009 g L-1 in H2O at 18 o C. Solubility (hot) .77 g L-1 in H2O at 100 oC .004 g L-1 H2O at 100 oC Solubility (moles, cold) 0.000154321 M L-1 0.024969632 M L-1 Solubility (moles, hot) 0.000685871 M L-1 0.010392766 M L-1 Solubility Product (Ksp) 5.5 X 10-6
1.8 X 10-11 Reactivity High Low Form Massive, sometime fibrous Usually fibrous Free Energy of Formation of Carbonate Gof - 64.62 kJ.mol-1 -19.55 kJ.mol-1 -119.55 kJ.mol-1(via hydrate) Presentation downloadable from 11 TecEco TecEco Technology Technology -- Simple Simple Yet Yet Ingenious? Ingenious? The TecEco 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 Dead burned magnesia is much less expansive than dead burned lime (Ramachandran V. S., Concrete Science, Heydon & Son Ltd. 1981, p 358-360 ) Reactive magnesia is essentially amorphous magnesia produced at low temperatures and finely ground. It has low lattice energy 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 Do not hydrate rapidly and cause dimensional distress. The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them. -Sir William Bragg Presentation downloadable from 12 TecEco TecEco Formulations Formulations (2) (2) OPC Tec-cements Enviro-cements Eco-cements Magnesia
Fly ash & other pozzolans Presentation downloadable from 13 Strength Strength with with Blend Blend & & Porosity Porosity 150 Tec-cement concretes Eco-cement concretes 100 50 High OPC Enviro-cement concretes STRENGTH ON ARBITARY SCALE 1-100 High Porosity 0 High Magnesia 100-150 50-100
0-50 Presentation downloadable from 14 Porosity Porosity and and Magnesia Magnesia Content Content Increasing Portland cement Increasing Magnesia Enviro-cements for toxic and hazardous waste immobilisation & CLSMs Eco cements for bricks, blocks pavers mortars, renders, tile cements, gunnites and shotcretes. Eco cements for porous pavements Tec cements (readymix concretes etc) Increasing Density Increasing Porosity TecEco eco-cements require a porous environment. Presentation downloadable from 15
Basic Basic Chemical Chemical Reactions Reactions Notice the low solubility of brucite compared to Portlandit e and that nesqueho nite adopts a more ideal habit than calcite & aragonite In Tec-Cements Magnesia We think the reactions are relatively independent. Brucite MgO + H2O Mg(OH)2 Silicates and aluminosilicates In Eco - Cements
Magnesia Amorphous Brucite Lansfordite Nesquehonite MgO + H2O Mg(OH)2 + CO2 MgCO3.nH2O + MgCO3.5H2O + MgCO3.3H2O Form: Massive-Sometimes Fibrous Often Fibrous Acicular - Needle-like crystals Hardness: 2.5 - 3.0 2.5 Solubility (mol.L-1): .00015 .01 .013 (but less in acids) Compare to the Carbonation of Portlandite Portlandite Calcite Aragonite Ca(OH)2 + CO2 CaCO3 Form: Massive Massive or crystalline
Hardness: 2.5 Solubility (mol.L-1): .024 More acicular 3.5 .00014 Presentation downloadable from 16 Problems Problems with with Portland Portland Cement Cement Fixed Fixed Strength Faster & greater strength development even with added pozzolans Water removal by magnesia as it hydrates in tec-cements results in a higher short term pH and therefore more affective pozzolanic reactions. Brucite fills pore spaces taking up mix and bleed water as it hydrates reducing voids and shrinkage
(brucite is 44.65 mass% water!). Greater density (lower voids:paste ratio) and lower permeability results in greater strength. Presentation downloadable from 17 Problems Problems with with Portland Portland Cement Cement Fixed Fixed (1) (1) Durability and Performance Permeability and Density Sulphate and chloride resistance Carbonation Corrosion of steel and other reinforcing TecEco tec - cements are Denser and much less permeable Due mainly to the removal of water by magnesia and associated volume increases Protected by brucite Which is 5 times less reactive than Portlandite
Not attacked by salts, Do not carbonate readily Protective of steel reinforcing which does not corrode due to maintenance of long term pH. Presentation downloadable from 18 Problems Problems with with Portland Portland Cement Cement Fixed Fixed (2) (2) Durability and Performance Ideal lower long term pH Delayed reactions (eg alkali aggregate and delayed ettringite) As Portlandite is removed The pH becomes governed by the pH of CSH and Brucite and Is much lower at around 10.5 -11 Stabilising many heavy metals and Allowing a wider range of aggregates to be used without AAR problems. Reactions such as carbonation are slower and The pH remains high enough to keep Fe3O4 stable for much longer.
Internal delayed reactions are prevented Dry from the inside out and Have a lower long term pH Presentation downloadable from 19 Problems Problems with with Portland Portland Cement Cement Fixed Fixed (3) (3) Net shrinkage is reduced due to: Shrinkage Stoichiometric expansion of Cracking, crack control magnesium minerals, and Reduced water loss. Rheology Workability, time for and method of placing and finishing Magnesia added is around 5 micron in diameter and Acts a lubricant for the Portland cement grains. Making TecEco cements very workable. Hydration of magnesia rapidly adds early strength for finishing.
Presentation downloadable from 20 Problems Problems with with Portland Portland Cement Cement Fixed Fixed (4) (4) Improved Properties TecEco cements Can have insulating properties High thermal mass and Low embodied energy. Many formulations can be reprocessed and reused. Brucite bonds well and reduces efflorescence. Properties (contd.) Fire Retardation Brucite, hydrated magnesium carbonates are fire retardants TecEco cement products put out fires by releasing CO2 or water at relatively low temperatures. Cost No new plant and equipment are required. With economies of scale TecEco cements should be cheaper
Presentation downloadable from 21 Problems Problems with with Portland Portland Cement Cement Fixed Fixed (5) (5) Sustainability issues Tec, eco and enviro-cements Less binder is required for the same Emissions and strength embodied energies Use a high proportion of recycled materials Immobilise toxic and hazardous wastes Can use a wider range of aggregates reducing transport emissions and Have superior durability. Tec-cements Use less cement for the same strength Eco-cements reabsorb chemically released CO2. Presentation downloadable from 22 Tec-Cements-Greater Tec-Cements-Greater Strength
Strength Tec-cements can be made with around 30% or less binder for the same strength and have more rapid strength development even with added pozzolans. This is because: Reactive magnesia is an excellent plasticizer, 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 caused by the removal of water. Presentation downloadable from 23 Tec-Cements-Greater Tec-Cements-Greater Strength Strength Self compaction of brucite may add to strength. Compacted brucite is as strong as CSH (Ramachandran, Concrete Science p 358) Microstructural strength is also gained because of: More ideal particle packing (Magnesia particles at 4-5 micron are about 1/8th the size of cement grains.) Presentation downloadable from 24
Rapid Rapid Water Water Reduction Reduction Primary Observation Water is Consumption required to of water during plasticise plastic stage Voids Water concrete for placement, Paste Paste however once Binder++ Binder Variables such as % suppleme placed, the suppleme ntary hydration of mineral, ntary less water cementiti density, compaction, cementiti ous % mineral H20 etc. over the
ous materials amount materials required for Less water hydration the High water for strength for ease of better. Log time and durability placement Magnesia consumes Less water results in less shrinkage and cracking water as it and improved strength and durability. Concentration of alkalis and increased density hydrates result in greater strength. producing solid material. Presentation downloadable from Relevant Fundamental 25 Eco-Cements-Greater Eco-Cements-Greater Strength Strength Eco-cements gain early strength from the hydration of OPC, however strength also comes from the carbonation of brucite forming an amorphous phase,
lansfordite and nesquehonite that appear to add micro structural strength. More ideal particle packing (Brucite particles at 4-5 micron are about 1/8th the size of cement grains.) The natural fibrous and acicular shape of magnesium minerals which tend to lock together. Presentation downloadable from 26 Increased Increased Density Density Reduced Reduced Permeability Permeability Concretes have a high percentage (around 18%) of voids. On hydration magnesia expands 116.9 % filling voids and surrounding hydrating cement grains. Brucite is 44.65 mass% water. On carbonation to nesquehonite brucite expands 307% Nesquehonite is 243.14% water and CO 2 Lower voids:paste ratios than water:binder ratios result in little or no bleed water less permeability and greater density. Presentation downloadable from 27 Eco-Cement Eco-Cement Strength Strength and
and Bond Bond Strength Strength The growth of fibrous minerals will have profound implications for bond strength of carbonated cementitious pastes. Elongated growths of nesquehonite and lansfordite near surface, growing inwards over time. Flyash grains (red) bonding mainly by surface hydrolysis, acting as micro aggregate providing a locking key mechanism as well as filling voids. Portland clinker minerals (black). Hydration providing Imperfect structural framework Micro spaces filled with hydrating magnesia acting as a waterproof glue Presentation downloadable from
28 Reduced Reduced Permeability 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 SO4--, Cl- and CO2 TecEco tec - cement concretes are a closed system. They do not bleed as excess water is consumed by the hydration of magnesia. As a result TecEco 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 29 Tec-Cement Tec-Cement pH pH Curves Curves pH 13.7 More affective pozzolanic reactions
? HYPOTHETICAL pH CURVES OVER TIME ? 10.5 Plastic Stage OPC Concrete ? Tec Cement Concrete with 10% reactive magnesia Log Time Presentation downloadable from 30 Eco-Cement Eco-Cement pH pH Curves Curves pH 13.7 More affective pozzolanic reactions ? HYPOTHETICAL pH CURVES OVER TIME ?
10.5 Plastic Stage OPC Concrete ? Eco Cement Concrete with 50% reactive magnesia Log Time Presentation downloadable from 31 Tec-Cement Tec-Cement Concrete Concrete Strength Strength Gain Gain Curve Curve HYPOTHETICAL STRENGTH GAIN CURVE OVER TIME (Pozzolans added) MPa Tec Cement Concrete with 10% reactive magnesia ? ? ? OPC Concrete ? 3 Plastic
Stage 7 14 28 Log Days The possibility of high early strength gain with added pozzolans is of great economic importance. Presentation downloadable from 32 Eco-Cement Eco-Cement Concrete Concrete Strength Strength Gain Gain Curve Curve HYPOTHETICAL STRENGTH GAIN CURVE OVER TIME (Pozzolans added) MPa OPC Concrete ? 7 ? Eco Cement Concrete with
50% reactive magnesia ? 3 Plastic Stage ? 14 28 Log Days 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 formualtions. Presentation downloadable from 33 A A Lower Lower More More Stable Stable Long Long Term Term pH pH In TecEco cements the long term pH 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 pH is still high enough to keep Fe3O4 stable in Eh-pH or Pourbaix Diagram reducing conditions. The stability fields of hematite, magnetite and siderite in aqueous solution; total dissolved carbonate = 10-2M. Steel corrodes below 8.9 Presentation downloadable from 34 Reduced Reduced Delayed Delayed Reactions 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 35 Reduced Reduced Delayed Delayed Reactions Reactions (2) (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 Tec-cement concretes consume unbound water from the pores inside concrete as reactive magnesia hydrates. Reactions do not occur without water. Presentation downloadable from 36 Carbonation Carbonation Carbonates are the stable phases of both calcium and magnesium. Carbonation in the built environment would result in significant sequestration because of the shear volumes involved. The formation of carbonates lowers the pH of concretes compromising the stability of the passive oxide coating on steel.
Carbonation adds considerable strength and some steel reinforced structural concrete could be replaced with fibre reinforced porous carbonated concrete. Presentation downloadable from 37 Carbonation Carbonation There are a number of carbonates of magnesium. The main ones appear to be an amorphous phase, lansfordite and nesquehonite. Gor Brucite to nesquehonite = - 38.73 kJ.mol-1 Compare to Gor Portlandite to calcite = -64.62 kJ.mol-1 The dehydration of nesquehonite to form magnesite is not favoured by simple thermodynamics but may occur in the long term under the right conditions. Gor nesquehonite to magnesite = 8.56 kJ.mol-1 But kinetically driven by desiccation during drying. 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 38 Ramifications Ramifications of of Carbonation Carbonation Magesium Carbonates. The magnesium carbonates that form at the surface of tec cement concretes expand, 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 pH. Portland Cement Concretes Carbonation proceeds relatively rapidly at the surface. ?Vaterite? followed by Calcite is the principal product and lowers the pH to around 8.2 Presentation downloadable from 39 Reduced Reduced Shrinkage Shrinkage Net shrinkage is reduced due to stoichiometric expansion of Magnesium minerals, and reduced water loss. Portland Cement Concretes Tec-Cement Concretes Drying Shrinkage Plastic Settlement Stoichiometric (Chemical) Shrinkage Stoichiometric (Chemical) Expansion Log Time, days Dimensional change such as
shrinkage results in cracking and reduced durability Presentation downloadable from 40 Cracking, the Reduced Cracking in TecEco Cement Concretes Reduced Cracking in TecEco Cementsymptomatic Concretes result of shrinkage, is Reduced in undesirable for TecEco tecmany reasons, cements but mainly because because it allows they do not entry of gases shrink. 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 After Richardson, Mark G. Fundamentals of Durable Reinforced Concrete Spon Press, 2002. page 212. concrete. Presentation downloadable from 41 Durability Durability -- Reduced Reduced Salt Salt & & Acid Acid Attack Attack Brucite has always played a protective role during salt attack. Putting it in the matrix of concretes in the first place makes sense. 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 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 Presentation downloadable from 42
Improved Improved Workability Workability Finely ground reactive magnesia acts as a plasticiser Portland cement grains Mean size 20 - 40 micron Reactive Magnesia grains Mean size 45 micron Smaller grains (eg microsilica) for even better rheology. The magnesia grains act as ball bearings to the Portland cement grains and also fill the voids densifying the whole There are also surface charge affects Presentation downloadable from 43 Improved Improved Workability Workability (2) (2) It is not known
how deep these + layers get + + Etc. O + + O - + O O + O - + + + O + + Etc. +
O - Mg++ - - O + + + The strongly positively charged small Mg++ atoms attract water which is polar in deep layers affecting the rheological properties. Ca++ = 114, Mg++ = 86 picometres Presentation downloadable from 44 Rheology Rheology Second layer low slump teccement concrete
Tech Tendons First layer low slump tec-cement concrete 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. TecEco tec-cements are potentially suitable for mortars, renders, patch cements, colour coatings, pumpable and self compacting concretes. A range of pumpable composites with Bingham plastic properties will be required in the future as buildings will be printed. Presentation downloadable from 45 Dimensionally Dimensionally Control Control Over Over Concretes Concretes During During Curing? 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 46 Volume Volume Changes Changes on on Hydration Hydration When magnesia hydrates it expands: MgO (s) + H2O (l) Mg(OH)2 (s) 40.31 + 18.0 58.3 molar mass 11.2 + liquid 24.3 molar volumes 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 47 Volume Volume Changes
Changes on on Carbonation Carbonation Consider what happens when Portlandite carbonates: Ca(OH)2 + CO2 CaCO3 74.08 + 44.01 100 molar mass 33.22 + gas 36.93 molar volumes Slight expansion. But shrinkage from surface water loss Compared to brucite forming nesquehonite as it carbonates: Mg(OH)2 + CO2 MgCO3.3H2O 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 CO2 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 48 TecEco TecEcoCement CementConcretes ConcretesDimensional DimensionalControl Control Combined Hydration and Carbonation can be manipulated to be Neutral. So far we have not observed shrinkage in TecEco 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. Brucite is 44.65 mass% water, nesquehonite is 243 mass% water and CO2. More research is required for both tec - cements and eco-cements 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 49 Tec Tec -- Cement Cement Concretes Concretes No No Dimensional Dimensional Change Change Reactive Magnesia ? +.05% +- Fly Ash? ? ? ?
? Composite Curve ? ? 28 ? 90 days -.05% Portland Cement HYDRATION THEN CARBONATION OF REACTIVE MAGNESIA AND OPC Presentation downloadable from 50 Reduced Reduced Steel Steel Corrosion Corrosion Steel remains protected with a passive oxide coating of Fe3O4 above pH 8.9. A pH of over 8.9 is maintained by the equilibrium Mg(OH)2 Mg++ + 2OHfor 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, CO2 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 51 Corrosion Corrosion in in Portland Portland Cement Cement Concretes 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. Corrosion Passive Coating Fe3O4 intact Anode: Fe Fe+++ 2eCathode: O2 + H2O +2e-
2(OH)Fe++ + 2(OH)- Fe(OH)2 + O2 Fe2O3 and Fe2O3.H2O (iron oxide and hydrated iron oxide or rust) The role of chloride in Corrosion Anode: Fe Fe+++ 2eCathode: O2 + H2O +2e- 2(OH)Fe++ +2Cl- FeCl2 FeCl2 + H2O + OH- Fe(OH)2 + H+ + 2ClFe(OH)2 + O2 Fe2O3 and Fe2O3.H2O Iron hydroxides react with oxygen to form rust. Note that the chloride is recycled in the reaction and not used up. Presentation downloadable from 52 Less Less Freeze Freeze -- Thaw Thaw Problems 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) + H2O (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! Air entrainment can also be used as in conventional concretes TecEco concretes are not attacked by the salts used on roads Presentation downloadable from
53 TecEco TecEco Enviro-Cements Enviro-Cements -- Solving Solving Waste Waste Problems Problems There are huge volumes of concrete produced annually ( 2 tonnes per person per year ) The goal should be to make cementitious 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 54 TecEco TecEco Cements Cements -- Solving Solving Waste Waste Problems Problems If wastes cannot directly be used then if they are not immobile they should be immobilised. TecEco cementitious composites represent a cost affective option for both use and immobilisation
Durability and many other problems are overcome utilizing TecEco technology. TecEco technology is more suitable than either lime, Portland cement or Portland cement lime mixes because of: Lower reactivity (less water, lower pH) Reduced solubility of heavy metals (lower pH) Greater durability Dense, impermeable and Homogenous. No bleed water Are not attacked by salts in ground or sea water Are dimensionally more stable with less cracking TecEco cements are more predictable than geopolymers. Presentation downloadable from 55 Why Why TecEco TecEco Cements Cements are are Excellent Excellent for for Toxic Toxicand and
Hazardous Hazardous Waste Waste Immobilisation Immobilisation 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 TecEco Layers of electronically neutral brucite suitable for trapping balanced cations and anions as well as other substances cements has a structure comprising electronically neutral layers and is able to accommodate a wide variety of extraneous Salts and other toxic substances between the and layers and cations of hazardous similar size substituting for substances
between the magnesium within the layers layers and is known to be very suitable for toxic and hazardous waste immobilisation. Presentation downloadable from 56 Concentration of Dissolved Metal, (mg/L) Lower Lower Solubility Solubility of of Metal Metal Hydroxides Hydroxides 10 There is a 104 difference Pb(OH) 2 Cr(OH) 3 Zn(OH) 2 10 0 Ag(OH) Cu(OH) 2 Ni(OH) 2 Cd(OH) 2
10 -2 Equilibrium pH of brucite is 10.52 (more ideal)* 10 -4 *Equilibrium pHs in pure water, no other ions present. The solubility of toxic metal hydroxides is generally less at around pH 10.52 than at higher pHs. 10 -6 6 7 8 9 10 11 12 13
14 Equilibrium pH of Portlandite is 12.35* Presentation downloadable from 57 TecEco TecEco Materials Materials are are Fire Fire Retardants 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. Lansfordite and nesquehonite releases CO2 and water and convert to magnesium oxide. 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 58 High High Performance-Lower Performance-Lower Construction
Construction Costs Costs 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 59 TecEco TecEco Concretes
Concretes -- Lower Lower Construction Construction Costs Costs (2) (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 60 TecEco TecEco Challenging Challenging the the World World
The TecEco technology is new and not yet fully characterised. The world desperately needs more sustainable building materials. Formula rather than performance based standards are preventing the development of new and better materials based on mineral binders. TecEco challenge universities governments and construction authorities to quantify performance in comparison to ordinary Portland cement and other competing materials. We at TecEco will do our best to assist. Negotiations are underway in many countries to organise supplies to allow such scientific endeavour to proceed. Presentation downloadable from 61 TecEcos TecEcos Immediate Immediate Focus Focus TecEco 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 62 TecEco TecEco Minding Minding the the Future Future TecEco are aware of the enormous weight of opinion necessary before standards can be changed globally for TecEco tec - cement concretes for general use. TecEco already have a number of institutions and universities around the world doing research. TecEco have publicly released the eco-cement technology and received huge global publicity. TecEco research documents are available from the TecEco 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 63 Summary Summary Simple, smart and sustainable? TecEco cement technology has resulted in potential solutions to a number of problems with Portland and 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. Climate Change Pollution Durability Corrosion Strength Delayed Reactions Placement , Finishing Rheology Shrinkage Carbon Taxes 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.
Presentation downloadable from 64 Characteristics Characteristics of of TecEco TecEco Cements Cements (1) (1) Portland Cement Concretes Tec-Cement Concretes Enviro-Cement Concretes Eco-Cements Typical Formulations 100 mass% PC 8 mass% OPC, 72 mass % PC, 20 mass% pozzolan 20 mass% OPC, 60 mass % PC, 20 mass% pozzolan 50 mass% OPC, 30 mass % PC, 20
mass% pozzolan Setting Main strength from hydration of calcium silicates. Main strength is from hydration of calcium silicates. Magnesia hydrates forming brucite which has a protective role. Magnesia hydrates forming brucite which protects and hosts wastes. Carbonation is not encouraged. Magnesia hydrates forming brucite then carbonates forming Lansfordite and nesquehonite. Suitability Diverse Diverse. Ready mix concrete with high
durability Toxic and hazardous waste immobilisation Brick, block, pavers, mortars and renders. Mineral Assemblage (in cement) Tricalcium silicate, di calcium silicate, tricalcium aluminate and tetracalcium alumino ferrite. Tricalcium silicate, di calcium silicate, tricalcium aluminate, tetracalcium alumino ferrite, reactive magnesia. Presentation downloadable from 65 Characteristics Characteristics of of TecEco TecEco Cements Cements (2) (2) Portland Cement Concretes
Tec-Cement Concretes Enviro-Cement Concretes Final mineral Assembla ge (in concrete) Complex but including tricalcium silicate hydrate, di calcium silicate hydrate, ettringite, monosulfoaluminat e, (tetracalcium alumino sulphate), tricalcium alumino ferrite hydrate, calcium hydroxide and calcium carbonate . Complex but including tricalcium silicate hydrate, di calcium silicate hydrate, ettringite, monosulfoaluminate, (tetracalcium alumino sulphate), tricalcium alumino ferrite hydrate, calcium hydroxide, calcium carbonate, magnesium hydroxide and magnesium carbonates. Strength Variable. Mainly dependent on the
water binder ratio and cement content. Variable. Mainly dependent on the water binder ratio and cement content. Usually less total binder for the same strength development Variable, usually lower strength because of high proportion of magnesia in mix. Eco-Cements Variable. Presentation downloadable from 66 Characteristics Characteristics of of TecEco TecEco Cements Cements (3) (3) Portland Cement Concretes Tec-Cement
Concretes Enviro-Cement Concretes Eco-Cements Rate of Strength Developm ent Variable. Addition of fly ash can reduce rate of strength development. Variable. Addition of fly ash does not reduce rate of strength development. Slow, due to huge proportion of magnesia Variable, but usually slower as strength develops during carbonation process. pH Controlled by Na+ and K+ alkalis and
Ca(OH)2 in the short term. In the longer term pH drops near the surface due to carbonation (formation of CaCO3) Controlled by Na+ and K+ alkalis and Ca(OH)2 and high in the short term. Lower in the longer term and controlled by Mg(OH) 2 and near the surface MgCO3 High in the short term and controlled by Ca(OH)2. Lower in the longer term and controlled by MgCO3 Rheology Plasticisers are required to make mixes workable. Plasticisers are not necessary. Formulations are generally much more thixotropic. Plasticisers are not necessary. Formulations are generally much more thixotropic and easier to use
for block making. Presentation downloadable from 67 Characteristics Characteristics of of TecEco TecEco Cements Cements (4) (4) Portland Cement Concretes Tec-Cement Concretes Enviro-Cement Concretes Eco-Cements Durability Lack of durability is an issue with Portland cement concretes Protected by brucite, are not attacked by salts, do not carbonate, are denser and less permeable and will last indefinitely. Density Density is reduced
by bleeding and evaporation of water. Do not bleed - water is used up internally resulting in greater density Permeabilit y Permeable pore structures are introduced by bleeding and evaporation of water. Do not bleed - water is used up internally resulting in greater density and no interconnecting pore structures Shrinkage Shrink around .05 .15 % With appropriate blending can be made dimensionally neutral as internal consumption of water reduces shrinkage through loss of water and magnesium minerals are expansive. Protected by brucite, are not attacked by salts, do not carbonate, are denser and will last indefinitely. Presentation downloadable from
68 Characteristics Characteristics of of TecEco TecEco Cements Cements (5) (5) Portland Cement Concretes Tec-Cement Concretes Enviro-Cement Concretes Eco-Cements Insulating Properties Relatively low with high thermal conductivity around 1.44 W/mK Depends on formulation but better insulation as brucite is a better insulator Thermal Mass High. Specific heat is .84 kJ/kgK Depends on
formulation but remains high Depends on formulation but remains high Embodied Energy (of concrete) Low, 20 mpa 2.7 Gj.t-1, 30 mpa 3.9 Gj.t-1 (1) Approx 15-30% lower due to less cement for same strength, lower process energy for making magnesia and high pozzolan content(2). Lower depending on formulation(2). Depends on formulation but better insulation as brucite is a better insulator and usually contains other insulating materials Depends on formulation Even lower due to lower
process energy for making magnesia and high pozzolan content(2). Presentation downloadable from 69 Characteristics Characteristics of of TecEco TecEco Cements Cements (6) (6) Portland Cement Concretes Tec-Cement Concretes Enviro-Cement Concretes Eco-Cements Recyclability Concrete can only be crushed and recycled as aggregate. Can be crushed and recycled as aggregate.
Can be crushed and fines recalcined to produce more magnesia or crushed and recycled as aggregate or both. Can be crushed and fines recalcined to produce more magnesia or crushed and recycled as aggregate or both. Fire Retardant Ca(OH)2 and CaCO3 break down at relatively high temperatures and cannot act as fire retardants Mg(OH)2 is a fire retardant and releases H2O at relatively low temperatures. Mg(OH)2 and MgCO3 are both fire retardants and release H2O or CO2 at relatively low temperatures. Presentation downloadable from
70 Characteristics Characteristics of of TecEco TecEco Cements Cements (7) (7) Portland Cement Concretes Tec-Cement Concretes Enviro-Cement Concretes Eco-Cements Sustainability A relatively low embodied energy and emissions relative to other building products. High volume results in significant emissions. Less binder for the same strength and a high proportion of supplementary cementitous materials such as fly ash and gbfs. Can
be formulated with more sustainable hydraulic cements such as high belite sulphoaluminate cements. A wider range of aggregates can be used. Greater durability. A high proportion of supplementary cementitous materials such as fly ash and gbfs. Can be formulated with more sustainable hydraulic cements such as high belite sulphoaluminate cements. A wider range of aggregates can be used. Greater durability. A high proportion of supplementary cementitous materials such as fly ash and gbfs. Carbonate in porous materials reabsorbing chemically released CO2 A wider range of aggregates can be
used. Greater durability. Carbon emissions With 15 mass% PC in concrete .32 t.t-1 After carbonation approximately .299 t.t-1 With 15 mass% PC in concrete approx.29 t.t-1 After carbonation approximately .26 t.t-1 Could be lower using supplementary cementitous materials and formulated with other low carbon cement blends. With 11.25 mass % magnesia and 3.75 mass % PC in concrete .241 t.t-1 With capture CO2 and fly ash as low as .113 t.t-1 Presentation downloadable from 71 Sustainability Sustainability Issues Issues Presentation downloadable from 72
Sustainability Sustainability Newsflash Newsflash The Guardian Wednesday July 14th 2004 at http://education.guardian.co.uk/higher/science s/story/0,12243,1260879,00.html There is more carbon dioxide in the atmosphere than for 55m years, enough to melt all the ice on the planet and submerge cities like London, New York and New Orleans, Sir David King, the government's chief scientific adviser has warned.. On current trends, cities like London, New York and New Orleans will be among the first to go. According to the article Sir David concluded by saying I am sure that climate change is the biggest problem that civilisation has had to Presentation downloadable from face in 5,000 years." 73 The The Techno Techno Process Process Our linkages to the environme nt are defined by the techno process Presentation downloadable from
74 Techno Techno Functions Functions and and Affects Affects on on the the Planet Planet Take ManipulateMakeUse Waste Detrimental Affects on Earth Systems implies moving or (transport) Presentation downloadable from 75 Earth Earth Systems 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 76 The The problem problem Population, Population, Technology Technology & & Affluence Affluence The world population reached 6 billion in 1999. Significant proportions of population increases in the developing countries have been and will be absorbed by urban areas. Recent estimates indicate an urbanization level of 61.1% for the year 2030(1). Affluence leads to greater consumption per capita. Technology can have a positive or negative affect. Impacts on the environment are by way of two major types of human activity. The resources use Wastage (1) UN-Habitat United Nations Human Settlements Program Global Urban Observatory Section web site at http://www.unchs.org/habrdd/global.html Presentation downloadable from 77 The The Techno-Process Techno-Process Take Manipulate Make Use Waste [ Materials
] What we take from the environment around us and how we manipulate and make materials out of what we take affects earth systems at both the take and waste ends of the technoprocess. The techno-process controls: How much and what we have to take to manufacture the materials we use. How long materials remain of utility and What form they are in when we eventually throw them away. Presentation downloadable from 78 There There isis no no such such place place as as Away Away The take is inefficient, well beyond what is actually used and exceeds the ability of the earth to supply. Wastage is detrimental as there is no such place as away Away means as waste back into the biospheregeosphere. Life support media within the biosphere-geosphere include water and air, both a global commons. Presentation downloadable from 79 Materials
Materials The The Key? Key? How and in what form materials are in when we waste them affects how they are reassimilated back into the natural flows of nature. If materials cannot readily, naturally and without upsetting the balances within the geospherebiosphere be reassimilated (e.g heavy metals) then they should remain within the techno-sphere and be continuously recycled as techno-inputs or permanently immobilised as natural compounds. Presentation downloadable from 80 Global Global Warming Warming the the Most Most Important? Important? rend of global annual surface temperature relative to 1951-1980 mean. Presentation downloadable from 81 Landfill Landfill The The Visible Visible Legacy Legacy Landfill is the technical term for filling large holes in the ground with waste.
Landfills release methane, can cause ill health in the area, lead to the contamination of land, underground water, streams and coastal waters and gives rise to various nuisances including increased traffic, noise, odours, smoke, dust, litter and pests. Presentation downloadable from 82 Our Our Linkages Linkages to to the the Environment Environment Must Must be be Reduced Reduced Presentation downloadable from 83 Fixing Fixing the the Techno Techno -- Function Function We need to change the
techno function to: Reuse Take lessManipulateMakeUseWaste less Manipulate Recycle Presentation downloadable from 84 Fixing Fixing the the Techno Techno -- Function Function And more desirably to: Reuse Take only ManipulateMakeUse renewables Manipulate Waste only what is biodegradable or can be reassimilated Recycle Presentation downloadable from 85 Converting Converting Waste Waste to to Resource
Resource Recycling is substantially undertaken for costly feel good political reasons and unfortunatel y not driven by sound economics Making Recycling Economic Should be a Priority Presentation downloadable from 86 The The Key Key is is To To Change Change the the Technology Technology Paradigm Paradigm Paul Zane Pilzers first law states By enabling us to make productive use of particular raw materials, technology determines what constitutes a physical resource
1.Pilzer, Paul Zane, Unlimited Wealth, The Theory and Practice of Economic Alchemy, Crown Publishers Inc. New York.1990 Presentation downloadable from 87 The The Take Take Short Use Resources Are renewable (food) or non renewable (fossil fuels). Have short use, are generally extracted modified and consumed, may (food, air, fuels) or may not (water) change chemically but are generally altered or contaminated on return back to the geosphere-biosphere (e.g food consumed ends up as sewerage, water used is contaminated on return.) Presentation downloadable from 88 The The Take Take Materials Materials == Resources Resources Long Term Use Resources or Materials Materials are the substance or substances out of which a thing is or can be made(1). Alternatively they could be viewed as the substance of which a thing is made or composed, component or constituent matter(2) Everything that lasts between the take and waste.
(1) dictionary.com at http://www.unchs.org/habrdd/global.html valid as at 24/04/04 (2)The Collins Dictionary and Thesaurus in One Volume, Harper Collins, 1992 Presentation downloadable from 89 Materials Materials == Resources Resources Materials as Resources are Characterized as follows: Some materials are renewable (wood), however most are not renewable unless recycled (metals, most plastics etc.) Materials generally have a longer cycle from extraction to return, remaining in the technosphere(1) whilst being used and before eventually being wasted. Materials may (plastics) or may not (wood) be chemically altered and are further divided into organic (e.g. wood & paper) and inorganic (e.g. metals minerals etc.) (1) The term techno-sphere refers to our footprint on the globe, our technical world of cars, buildings, infrastructure etc. Presentation downloadable from 90 Materials Materials -- the the Key Key to to Sustainability Sustainability Geosphere Biosphere Materials are the link
Technosphere between the geosphere-biosphere and techno-sphere and the key to sustainability Materials are the key to our survival on the planet. The choice of materials controls emissions, lifetime and embodied energies, maintenance of utility, recyclability and the properties of wastes returned to the geosphere-biosphere. Presentation downloadable from 91 Greatest Greatest Potential Potential == The The Built Built Environment Environment The built environment is made of materials and is our footprint on earth. It comprises buildings And infrastructure It is our footprint on the planet There are huge volumes involved. Building materials comprise 70% of materials flows (buildings, infrastructure etc.) 45% of waste that goes to landfill Improving the sustainability of materials used to create the built environment will reduce the impact of
the take and waste phases of the techno-process. A A Huge HugeOpportunity Opportunity for for Sustainability Sustainability Presentation downloadable from 92 The The Largest Largest Material Material Flow Flow -- Cement Cement and and Concrete Concrete Concrete made with cement is the most widely used material on Earth accounting for some 30% of all materials flows. 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. Thats over 2 tonnes per person per annum TecEco TecEcoPty. Pty.Ltd. Ltd.have have benchmark benchmark technologies technologies for
for improvement improvement in in sustainability sustainability and and properties properties Presentation downloadable from 93 Embodied Embodied Energy Energy of of Building Building Materials Materials Concrete is relatively environmentally friendly and has a relatively low embodied energy Downloaded from www.dbce.csiro.au/ind-serv/brochures/embodied/embodied.htm (last accessed 07 March 2000) Presentation downloadable from 94 Average Average Embodied Embodied Energy Energy in
in Buildings 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 emissions and improving properties. Downloaded from www.dbce.csiro.au/ind-serv/brochures/embodied/embodied.htm (last accessed 07 March 2000) Presentation downloadable from 95 Emissions Emissions from from Cement Cement & & Lime Lime Production Production Lime and its derivatives used in construction such as Portland cement are made from carbonates. The process of calcination involves driving off chemically bound CO2 with heat. CaCO3 CaO + CO2 Heating requires energy.
98% of the worlds energy is derived from fossil fuels. Fuel oil, coal and natural gas are directly or indirectly burned to produce the energy required releasing CO2. The production of cement for concretes accounts for around 10%(1) of global anthropogenic CO2. (1) Pearce, F., "The Concrete Jungle Overheats", New Scientist, 19 July, No 2097, 1997 (page 14). Presentation downloadable from 96 Cement Cement Production Production == Carbon Carbon Dioxide Dioxide Emissions Emissions M etric Tonne s 2,000,000,000 1,800,000,000 1,600,000,000 1,400,000,000 1,200,000,000 1,000,000,000 800,000,000 600,000,000 400,000,000 200,000,000 0 Ye ar Presentation downloadable from
97 Making Making Recycling Recycling Economic Economic Reducing, re-using and recycling is done more for feel good reasons than good economics and costs the community heaps! To get over the laws of increasing returns and economies of scale and to make the sorting of wastes economic so that wastes become low cost inputs for the techno-process new technical paradigms are required. The way forward involves at least: A new killer technology in the form of a method for sorting wastes A killer application for unsorted wastes Presentation downloadable from 98 Intelligent Intelligent Silicon Silicon in in Materials? Materials? The Cost of Silicon Chips has fallen dramatically Silicon embedded in materials from cradle to grave would not only serve to identify cost at purchase, the first owner, movement through process, but the type of material for sorting purposes on wastage. Robots will efficiently and productively be able to distinguish different types of plastic, glass, metals ceramics and so on.
Presentation downloadable from 99 A A Killer Killer Application Application for for Waste? Waste? Wastes Could be utilized depending on their class of properties rather than chemical composition? Could be utilized in vast quantities based on broadly defined properties such as light weight, tensile strength, insulating capacity, strength or thermal capacity in composites. Many if utilized would become net carbon sinks TecEco binders enable wastes to be converted to resources. Two examples: Plastics are currently hard to recycle because to be reused as inputs they cannot be mixed. Yet they would impart light weight and insulating properties to a composite bound with the new carbon dioxide absorbing TecEco eco-cements. Sawdust and wood waste is burned in the bush contributing to global CO2. If taken to the tip, methane, which is worse is the end result. Yet wood waste it light in weight, has tensile strength, captured in a mineral binder is a carbon sink and provides excellent insulation. Presentation downloadable from 100 Recycling
Recycling Materials Materials == Reduced Reduced Emissions Emissions More Recycling More = = Greater Productivity Less Process Energy = Less Less Lower Emissions More The above relationships hold true on a macro scale, provided we can change the technology paradigm to make the process of recycling much more efficient = economic. Presentation downloadable from 101 Technical Technical and and Biological
Biological Complexity Complexity Technical complexity The take and waste processes involve disassembly and reassembly Biological and geological complexity Presentation downloadable from 102 Recycling Recycling Can Can Involve Involve Remixing Remixing Technical complexity Recycling involves disassembly from waste streams and some reassembly to create saleable inputs Biological and geological
complexity e.g Blending of waste streams may be required to produce input materials below toxicity levels of various heavy metals Presentation downloadable from 103 Porous Porous Pavement Pavement A A Solution Solution for for Water Water Quality? Quality? Porous Pavements are a Technology Paradigm Change Worth Before three were cites forests and grassland covered most of our Investigating planet. When it rained much of the water naturally percolated though soils that performed vital functions of slowing down the rate of transport to rivers and streams, purifying the water and replenishing natural aquifers. Our legacy has been to pave this natural bio filter, redirecting the water that fell as rain as quickly as possible to the sea. Given global water shortages, problems with salinity, pollution, volume and rate of flow of runoff we need to change our practices so as to mimic the way it was for so many millions of years before we started making so many changes. Presentation downloadable from
104 EPR EPR Legislation Legislation ?? There is still room for taking responsibility for externalities with EPR Extended producer responsibility (EPR) incorporates negative externalities from product use and end-of-life in product prices Examples of EPR regulations include: Emissions and fuel economy standards (use stage) and product take back requirements (end of life) such as deposit legislation, and mandatory returns policies which tend to force design with disassembly in mind. Disposal costs are reflected in product prices so consumers can make more informed decisions. At the very least we need container legislation in this country as in S.A. Presentation downloadable from 105 Cementitious Cementitious Composites Composites of of the the Future Future During the gestation process of concretes: New materials have been incorporated such as fibers, fly ash and ground blast furnace slag. These new materials have introduced improved properties. Greater compressive and tensile strength as well as
improved durability. A generally recognised direction for the industry to achieve greater sustainability is to use more supplementary materials. Presentation downloadable from 106 Cementitious Cementitious Composites Composites of of the the Future Future (1) (1) The TecEco magnesian cement technology will be pivotal in bringing about changes in the energy and emissions impacts of the built environment. Tec-Cements Develop Significant Early Strength even with Added Supplementary Materials Eco-cements carbonate sequestering CO2 The CO2 released by chemical reaction from calcined materials should be captured. TecEco kiln technology provides this capability. Presentation downloadable from 107 Cementitious Cementitious Composites Composites of of the
the Future Future (2) (2) Cementitious Composite like Concrete still have a long way to improve. Diversification will result in materials more suited to specific applications required by the market. All sorts of other materials such as industrial mineral wastes, sawdust, wood fibres, waste plastics etc. could be added for the properties they impart making the material more suitable for specific applications. (e.g. adding sawdust or bottom ash in a block formulation reduces weight and increases insulation) More attention should also be paid to the micro engineering and chemistry of the material. Presentation downloadable from 108 Robotics Robotics Will Will Result Result in in Greater Greater Sustainability Sustainability Construction in the future will be largely done by robots. Like a colour printer different materials will be required for different parts of structures, and the wastes such as plastics can provide many of the properties required for
cementitious composites of the future. A nonreactive binder such as TecEco tec-cements will be required to supply the right rheology, and like a printer, very little Presentation downloadable 109 wasted from Our OurDream Dream--TecEco TecEcoCements Cementsfor forSustainable SustainableCities Cities CO2 MINING RECYCLED MATERIALS CO2 PERMANENT SEQUESTRATION (Man Made Carbonate Rock As A Building Material) CO2 MAGNESITE +
OTHER INPUTS TECECO KILN MgO TECECO CEMENT PRODUCTS RECYCLED MATERIALS RECYCLING CITIES Presentation downloadable from 110 The The Magnesium Magnesium Thermodynamic Thermodynamic Cycle Cycle CO2 TOTAL CALCINING ENERGY (Relative to MgCO3) Theoretical = 1480 kJ.Kg-1 With inefficiencies = 1948 kJ.Kg-1 Magnesite* ? Representative of other mineral carbonates including an amorphous Nesquehonite phase and lansfordite
Thermal decomposition MgCO3 MgO + CO2 H = 118.28 kJ.mol-1 G = 65.92 kJ.mol-1 Reactive phase Magnesia Carbonation Mg(OH)2 + CO2 + 2H2O MgCO3.3 H2O H = -175.59 kJ.mol-1 G = -38.73 kJ.mol-1 Brucite* Hydration MgO + H2O Mg(OH)2 H = -81.24 kJ.mol-1 G = -35.74 kJ.mol-1 An alkaline environment in which silicates form Presentation downloadable from 111 Manufacture Manufacture of of Portland Portland Cement Cement CO2 Calcite and
Aragonite TOTAL CALCINING ENERGY. (Relative to Thermal decomposition CaCO3) Carbonation Ca(OH)2 + CO2 CaCO3 + H2O H = - 69.58 kJ.mol-1 G = - 64.62 kJ.mol-1 -1 CaCO 3 CaO + CO2 Theoretical = 1807 kJ.Kg H = 178.77 kJ.mol-1 With inefficiencies = 3306 G = 130.98 kJ.mol-1 kJ.Kg-1 Quicklime Reactive phases Cementitious phases Portlandite Hydration CaO + H2O Ca(OH)2 H = -109.19 kJ.mol-1 G = - 66.35 kJ.mol-1
+ Pozzolan Clay Rotary Kiln SUMMARY Limestone + Clay OPC Estimated* H = 1807 kJ.kg-1 G = 1287 kJ. kg-1 Portland Cement Tri calcium silicate hydrate H = - 114 kJ.mol-1 Di calcium silicate hydrate H = - 43 kJ.mol-1 Tri calcium aluminate H = - 362 kJ.mol-1 Calcium alumino ferrite Presentation downloadable from *Note the measure is relative to Kg as mixed molar amounts are used. 112 CO CO22 Abatement Abatement in in Eco-Cements Eco-Cements
Eco-cements in porous products absorb carbon dioxide from the atmosphere. Brucite carbonates forming hydromagnesite and magnesite, completing the thermodynamic cycle. 85 wt% Aggregates 15 wt% Cement On the basis of the volume of building materials produced the figures are even better! Portland Cements No Capture Capture CO2 15 mass% Portland cement, 85 mass% aggregate 11.25% mass% reactive magnesia, 3.75 mass%
Portland cement, 85 mass% aggregate. 11.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate. Emissions Emissions .32 tonnes to the tonne. After carbonation. Approximately .299 tonne to the tonne. .37 tonnes to the tonne. After carbonation. approximately .241 tonne to the tonne. Emissions .25 tonnes to the tonne. After carbonation. approximately .140 tonne to the tonne. Capture CO2. 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 CO2 during manufacture of reactive magnesia) have 2.65 times less emissions than if they were made with Portland cement. Presentation downloadable from 113 TecEco TecEco Kiln Kiln Technology 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 CO2 Captures CO2 for bottling and sale to the oil industry (geological sequestration). The products CaO & MgO can be used to sequester more
CO2 and then be re-calcined. This cycle can then be repeated. Suitable for making reactive materials. Presentation downloadable from 114 Embodied Embodied Energy Energy and and Emissions Emissions 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. The new TecEco kiln technology will result in around 25% less energy being required and the capture of CO 2 during production will result in lower costs and carbon credits. The manufacture of reactive magnesia is a benign process that can be achieved with waste or intermittently available energy. Presentation downloadable from 115 Energy Energy On On aa Mass Mass Basis
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 CaCO3 + Clay
1545.73 2828.69 CaCO3 1786.09 2679.14 MgCO3 1402.75 1753.44 MgO 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 116 Energy Energy On On aa Volume Volume Basis 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) CaCO3 + Clay 4188.93 7665.75 CaCO3 6286.62 8429.93 MgCO3 4278.39 5347.99 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) Portland Cement 5692.05 10416.45 MgO 9389.63 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 117 Global
Global Abatement Abatement Without CO2 Capture during manufacture (billion tonnes) With CO2 Capture during manufacture (billion tonnes) Total Portland Cement Produced Globally 1.80 1.80 Global mass of Concrete (assuming a proportion of 15 mass% cement) 12.00 12.00 Global CO2 Emissions from Portland Cement 3.60 3.60 Mass of Eco-Cement assuming an 80% Substitution in global concrete use 9.60 9.60
Resulting Abatement of Portland Cement CO2 Emissions 2.88 2.88 CO2 Emissions released by Eco-Cement 2.59 1.34 Resulting Abatement of CO2 emissions by Substituting Eco-Cement 0.29 1.53 Presentation downloadable from 118 Abatement Abatement from from Substitution Substitution Building Material to be substituted Realisti c% Substitution 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 Concretes already have low lifetime energies. If embodied energies are improved could substitution mean greater market Bricks 85% 250 212.5
0.28 59.5 share? Emission/ Sequestration from Substituted EcoCement (Tonne for Tonne Substitution Assumed) Net Abatement Emission s - No Capture Emission s - CO2 Capture Abatem ent - No Capture Abatem ent CO2 Capture 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 119 Sustainability Sustainability Issues Issues Summary Summary We will not kick the fossil fuel habit. It will kick us when we run out of fuel. Sequestration on a massive scales is therefore essential. To reduce our linkages with the environment we must 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 CO2 to create a wide range of materials suitable for use in our built environment. Presentation downloadable from 120 Policy Policy Issues Issues Summary Summary Research and Development Funding Priorities. Materials should be prioritised Procurement policies. Government in Australia is more than 1/3 of the economy and can strongly influence change through: Life cycle purchasing policy. Funding of public projects and housing linked to sustainability such as recycling. Intervention Policies.
Building codes including mandatory adoption of performance specification. Requiring the recognition and accounting for externalities Extended producer responsibility (EPR) legislation Mandatory use of minimum standard materials that are more sustainable Mandatory eco-labelling Taxation and Incentive Policies Direct or indirect taxes, bonuses or rebates to discourage/encourage sustainable construction etc. A national system of carbon taxes. An international system of carbon trading ? Sustainability Education Presentation downloadable from 121 Policy Policy Message Message Summary Summary Governments cannot easily legislate for sustainability, it is more important that ways are found to make sustainability good business. Feel good legislation does not work. EPR Legislation works but is difficult to implement successfully. Technology can redefine materials so that they are more easily recycled or bio degraded-re-graded. It is therefore important for governments to make efforts to understand new technical paradigms that will change the techno-process and find ways of
making them work. Materials are the new frontier of technology Embedded intelligence should be globally standardized. Robotics are inevitable - we need to be prepared. Cementitious composites can redefine wastes as resources and capture CO2. The TecEco Technology Must be Developed was a finding of the recent ISOS Conference. http://www.isosconference.org.au/entry.html Presentation downloadable from 122 Policy Policy Message Message Summary Summary (2) (2) Limiting Factors to significant breakthroughs are: Credibility Issues that can only be overcome with significant funded research by TecEco and third parties. Suggestions for politically acceptable funding include: The establishment of a centre for sustainable materials in construction (preferably at the university of Tasmania near TecEco.) Including materials as a priority for ARC funding Focusing R & D support on materials on materials. Economies of scale Government procurement policies Subsidies for materials that can demonstrate clear sustainable advantages. 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 preclude Magnesium, based on historical misinformation and lack of understanding.Carbon trading may encourage
(first ending) Presentation downloadable from 123 The The Geosphere, Geosphere, Biosphere Biosphere and and Techno-sphere Techno-sphere A Few Definitions Biosphere Living organisms and the part of the earth and its atmosphere in which living organisms exist or that is capable of supporting life. (JH) Geosphere The solid earth including the continental and oceanic crust as well as the various layers of the Earth's interior. (JH) Environment The totality of physical or non-physical conditions or circumstances surrounding organisms (Dictionary.com modified by JH) Technosphere Our physical anthropogenic world. Techno refers to technology The application of science, especially to industrial or commercial objectives. (JH) Sphere A body or space contained under a single surface, which in every part is equally distant from a point within called its center e.g the earth (Dictionary.com)
Presentation downloadable from 124 There is no End with TecEco Technology Only a Beginning. Presentation downloadable from 125