Greening Greening the the Heartland Heartland Earthship Brighton (UK) The first building utilising TecEco eco-cements I will have to race over some slides but the presentation is always downloadable from the TecEco web site if you missed something. John Harrison B.Sc. B.Ec. FCPA. Presentation downloadable from www.tececo.com 1 The The Problem Problem A A Planet Planet in in Crisis Crisis TecEco TecEco are are in in the the BIGGEST BIGGEST Business Business on on the the Planet Planet -Solving Solving Sustainability Sustainability Problems Problems Economically Economically Presentation downloadable from
www.tececo.com 2 A A Demographic Demographic Explosion Explosion ? Undeveloped Countries Develope d Countries Global population, consumption per capita and our footprint on the planet is exploding. Presentation downloadable from www.tececo.com 3 Atmospheric Atmospheric Carbon Carbon Dioxide Dioxide Presentation downloadable from www.tececo.com 4 Global Global Temperature Temperature Anomaly Anomaly Presentation downloadable from www.tececo.com
5 The The Techno-Process Techno-Process Our linkages to the biogeo-sphere are defined by the techno process describing and controlling the flow of matter and energy. It is these flows that have detrimental linkages to earth systems. Global Systems Detrimental affects on earth systems Presentation downloadable from www.tececo.com Atmospheric composition, climate, land cover, marine
ecosystems, pollution, coastal zones, freshwater systems, salinity and global biological diversity have all been substantially 6 Ecological Ecological Footprint Footprint Our footprint is exceeding the capacity of the planet to support it. We are not longer sustainable as a species and must change our ways Presentation downloadable from www.tececo.com 7 Illinois Illinois Before Before Settlement Settlement Presentation downloadable from www.tececo.com 8 Illinois Illinois Now Now Paper
Mill - Soda liquor + Cl Habitat removal Vehicles - carbon dioxide Cows - methane Cities Farming Pesticide, N &K Huge impacts Immediate and polluted water run-off. Air pollution. Carbon dioxide and other gases. Other wastes. Huge linkages. Presentation downloadable from www.tececo.com 9 Illinois Illinois with with aa Little Little Lateral Lateral Thinking Thinking & & Effort Effort TecEco technology provides ways of
sequestering carbon dioxide and utilizing wastes to create our techno - world Less paper. Other Cl free processes - no salinity Vehicles more efficient and using fuel cells Sequestration processes Cities: CO2 Cows CSIRO anti methane bred Porous pavement prevents immediate and polluted run-off. Carbon dioxide and other gases Less impacts absorbed by TecEco ecocements. Less wastes. Carbon based wastes converted to energy or mulches and returned to soils. Buildings generate own energy etc. Presentation
downloadable from www.tececo.com Evolution away from using trees paperless office Organic farming. Carbon returned to soils. Use of zeolite reduces water and fertilizer required by 2/3 10 Impact Impactof ofthe theLargest LargestMaterial MaterialFlow Flow--Cement Cementand andConcrete Concrete Concrete made with cement is the most widely used material on Earth accounting for some 30% of all materials flows on the planet and 70% of all materials flows in the built environment.
Global Portland cement production is in the order of 2 billion tonnes per annum. Globally over 14 billion tonnes of concrete are poured per year. Over 2 tonnes per person per annum TecEco TecEco Pty. Pty. Ltd. Ltd. have have benchmark benchmark technologies technologies for for improvement improvement in in sustainability sustainability and and properties properties Presentation downloadable from www.tececo.com 11 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 www.tececo.com 12 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 the carbon debt (net emissions) and improving properties. Downloaded from www.dbce.csiro.au/ind-serv/brochures/embodied/embodied.htm (last accessed 07 March 2000) Presentation downloadable from www.tececo.com 13 Emissions Emissions from
from Cement Cement Production Production Chemical Release The process of calcination involves driving off chemically bound CO2 with heat. CaCO3 CaO + CO2 Process Energy Most energy is derived from fossil fuels. Fuel oil, coal and natural gas are directly or indirectly burned to produce the energy required releasing CO2. The production of cement for concretes accounts for around 10%(1) of global anthropogenic CO2. (1) Pearce, F., "The Concrete Jungle Overheats", New Scientist, 19 July, No 2097, 1997 (page 14). Presentation downloadable from www.tececo.com 14 Cement Cement Production Production == Carbon Carbon Dioxide Dioxide Emissions Emissions M e tric 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 www.tececo.com 15 Sustainability Sustainability Sustainability is a direction not a destination. Our approach should be holistically balanced and involve Everybody, every process, every day. + + Emissions reduction Mineral Sequestration Eco-cements in cities through efficiency and + Waste utilization conversion to non fossil fuels Presentation downloadable from www.tececo.com Geologica l Sequestration 16 Converting Converting Waste Waste to to Resource
Resource Recycl Waste only e is Take only Manipulate Make Use what biodegradable renewables Reuse or can be reRe-make assimilated [ Materials ] [ Underlying molecular flows ] Materials control: How much and what we have to take to manufacture the materials we use. How long materials remain of utility, whether they are easily recycled and how and what form they are in when we eventually throw them away. What we take from the environment around us, how we manipulate and make materials out of what we take and what we waste result in underlying molecular flows that affect earth systems. Problems in the global commons today include heavy metals, halogen carbon double bond compounds, CFCs too much CO2 etc. Presentation downloadable from www.tececo.com 17 Innovative Innovative New New Materials Materials -- the the Key Key to to Sustainability Sustainability Biosphere Geosphere
Materials are the substance of the techno-process, the link between the biosphere and techno-sphere and the key to sustainability. They are everything between and define the take and waste. Techno - World The choice of materials in construction controls emissions, lifetime and embodied energies, user comfort, use of recycled wastes, durability, recyclability and the properties of wastes returned to the bio-geosphere. There is no such place as away, only a global commons Presentation downloadable from www.tececo.com 18 Sustainability Sustainability Through Through Materials Materials Innovation Innovation Problems in the global commons today can only be changed by changing the molecular flows underlying planetary anthropogenic materials flows in the techno-process so that the every day behaviors of people interacting in an economic system will deliver new more sustainable flows. This will not happen because it is the right thing to do. Pilzer's first law states that the technology paradigm defines resources. Changing the flow of materials therefore has to be economic.
WBCSD President Bjrn Stigson 26 November 2004 Technology is a key part of the solutions for sustainable development. Innovation and technology are tools for achieving higher Presentation downloadable from www.tececo.com resource efficiency in society. 19 Sustainability Sustainability == Culture Culture ++ Technology Technology $ Increase in demand/price ratio for sustainability due to educationally induced cultural drift. ECONOMICS Equilibrium shift Supply Greater Value/for impact (Sustainability) and economic growth
Demand Increase in supply/price ratio for more sustainable products # due to innovative paradigm shifts in technology. Sustainability is where Culture and Technology meet Demand Supply Presentation downloadable from www.tececo.com 20 Huge Huge Potential Potential for for Sustainable Sustainable Materials Materials in in the the Built Built Environment Environment The built environment is made of materials and is our footprint on earth. It comprises buildings and infrastructure. Building materials comprise 70% of materials flows (buildings, infrastructure etc.) 40-45% of waste that goes to landfill (15 % of new materials going to site are wasted.) Reducing the impact of the take and waste phases of the techno-process. By including carbon in materials they are potentially carbon sinks. By including wastes for
physical properties as well as chemical composition they become resources C C Waste C C Presentation downloadable from www.tececo.com C Waste 21 Innovative Innovative New New Materials Materials Vital Vital It is possible to achieve Kyoto targets as the UK are proving, but we need to go way beyond the treaty according to our chief scientists. Carbon rationing has been proposed as the only viable means to keep the carbon dioxide concentration in the atmosphere below 450 ppm. Atmospheric carbon reduction is essential, but difficult to politically achieve by rationing. Making the built environment not only a repository for recyclable resources (referred to as waste) but a huge carbon sink is an alternative and adjunct that is politically viable as it potentially results in economic benefits. Concrete, a cementitous composite, is the single biggest material flow on the planet with over 2.2 tonnes per person produced.
Eco-cements offer tremendous potential for capture and sequestration using cementitious composites. MgCO3 MgO + CO2 - Efficient low temperature calcination & capture MgO + CO2 + H2O MgCO3.3H2O - Sequestration as building material Presentation downloadable from www.tececo.com 22 Sustainability Sustainability Summary Summary A more holistic approach is to reduce energy consumption as well as sequester carbon. To reduce our linkages with the environment we must convert waste to resource (recycle). Sequestration and recycling have to be economic processes or they have no hope of success. We cannot stop progress, but we can change and historically economies thrive on change. What can be changed is the technical paradigm. CO2 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 www.tececo.com 23 TecEco Technology More information at www.tececo.com Presentation downloadable from
www.tececo.com 24 The TheTecEco TecEcoTotal TotalProcess Process Serpentine Mg3Si2O5(OH)4 Olivine Mg2SiO4 Crushing Grinding Screening Crushing CO2 from Power Generation or Industry Grinding Waste Sulfuric Acid or Alkali? Screening Magnetic Sep. Iron Ore. Heat Treatment Silicate Reactor Process Gravity Concentration
Silicic Acids or Silica Magnesite (MgCO3) Simplified TecEco Reactions Tec-Kiln MgCO3 MgO + CO2 - 118 kJ/mole Reactor Process MgO + CO2 MgCO3 + 118 kJ/mole (usually more complex hydrates) Solar or Wind Electricity Powered Tec-Kiln CO2 for Geological Sequestration Magnesia (MgO) Other Wastes after Processing MgO for TecEco Cements and Sequestration by Eco-Cements in the Built Environment Magnesium Thermodynamic Cycle Oxide Reactor Process Magnesite MgCO3) CO2 from Power Generation, Industry or CO2 Directly From the Air Chrysotile Forsterite (Mg Tonnes CO2 Sequestered per Tonne Silicate with Various Cycles through the TecEco Process (assuming no leakage MgO to built environment i.e complete cycles)
(Serpentinite) Billion Tonnes Olivine) Billion Tonnes Tonnes CO2 sequestered by 1 billion tonnes of mineral mined directly .4769 .6255 Tonnes CO2 captured during calcining .4769 .6255 Tonnes CO2 captured by eco-cement .4769 .6255 Total tonnes CO2 sequestered or abated per tonne mineral mined (Single calcination cycle). 1.431 1.876 Total tonnes CO2 sequestered or abated (Five calcination cycles.) 3.339 4.378 Total tonnes CO2 sequestered or abated (Ten calcination cycles).
5.723 7.506 Presentation downloadable from www.tececo.com 25 Why Why Magnesium Magnesium Compounds Compounds At 2.09% of the crust magnesium is the 8th most abundant element. Magnesium oxide is easy to make using non fossil fuel energy and efficiently absorbs CO2 Because magnesium has a low molecular weight, proportionally a much greater amount of CO2 is released or captured. CO 2 44 52% MgCO 3 84 CO 2 44 43% CaCO 3 101 A high proportion of water means that a little binder goes a long way. In terms of binder produced for starting material in cement, eco-cements are nearly six times more efficient. Presentation downloadable from www.tececo.com 26
TecEco TecEco Technologies Technologies Silicate Carbonate Mineral Sequestration Using either peridotite, forsterite or serpentine as inputs to a silicate reactor process CO2 is sequestered and magnesite produced. Proven by others (NETL,MIT,TNO, Finnish govt. etc.) Tec-Kiln Technology TecEc Combined calcining and grinding in a closed system o allowing the capture of CO2. Powered by waste heat, solar or solar derived energy. To be proved but simple and should work! Direct Scrubbing of CO2 using MgO Being proven by others (NETL,MIT,TNO, Finnish govt. etc.) Economic under Kyoto? Tec and Eco-Cement Concretes in the Built Environment. eco-cements set by absorbing CO2 and are as TecEc TecEco good as proven. o Presentation downloadable from www.tececo.com 27 TecEco
TecEco Kiln Kiln Technology Technology CO2 Grinds and calcines at the same time. Runs 25% to 30% more efficiency. Can be powered by solar energy or waste heat. Brings mineral sequestration and geological sequestration together Captures CO2 for bottling and sale to the oil industry (geological sequestration). The products CaO &/or MgO can be used to sequester more CO 2 and then be re-calcined. This cycle can then be repeated. Suitable for making reactive reactive MgO. Presentation downloadable from www.tececo.com 28 A A Post Post Carbon Carbon Age Age CO2 Recyclable Recyclable Prehistoric Classic Renaissance Industrial Revolution Contemporary Post Carbon Age Wattle & daub Stone Mud brick Etc.
Stone Stone Brick Concrete Concrete Steel Aluminium Eco-cements e all use carbon and wastes to make our home Biomimicry Presentation downloadable from www.tececo.com 29 Drivers Drivers for for TecEco TecEco Technology Technology Government Influence Carbon Taxes Provision of Research Funds TecEco kiln technology could be the first non fossil fuel powered industrial process Environmental education Consumer Pull Producer Push The opportunity cost of compliant waste disposal
Profitability and cost recovery Environmental sentiment Cost and technical advantages? Competition? Huge Markets Cement 2 billion tonnes. Bricks 130,000 million tonnes Technical merit Resource issues Robotics Research objectives TecEco cements are the only binders capable of utilizing very large quantities of wastes based on physical property rather than chemical composition overcoming significant global disposal problems, and reducing the impact of landfill taxes. TecEco eco-cements can sequester CO2 on a large scale and will therefore provide carbon accounting advantages. Presentation downloadable from www.tececo.com 30 Drivers Drivers for for Change Change Robotics Robotics Using Robots to print buildings is all quite simple from
a software, computer hardware and mechanical engineering point of view. The problem is in developing new construction materials with the right flow characteristics so they can be squeezed out like toothpaste, yet retain their shape until hardened Once new materials suitable for the way robots work have been developed economics will drive the acceptance of robots for construction Concretes for example will need to evolve from being just a high strength grey material, to a smorgasbord of composites that can be squeezed out of a variety of nozzles for use by a robotic workforce for the varying requirements of a structure TecEco cement concretes have the potential of achieving the right shear thinning characteristics required Presentation downloadable from www.tececo.com 31 TecEco Cements More More information slides onat www.tececo.com web site Presentation downloadable from www.tececo.com 32 TecEco TecEco Cements Cements SUSTAINABILITY
PORTLAN D Hydration of the various components of Portland cement for strength. DURABILITY + or POZZOLAN Reaction of alkali with pozzolans (e.g. lime with fly ash.) for sustainability, durability and strength. TECECO CEMENTS STRENGTH TecEco concretes are a system of MAGNESIA blending reactive Hydration of magnesia => brucite for magnesia, Portland strength, workability, dimensional stability cement and usually and durability. In Eco-cements carbonation of a pozzolan with brucite => nesquehonite, lansfordite and an other materials and amorphous phase for sustainability. are a key factor for Presentation downloadable from 33 sustainability.
www.tececo.com The The Magnesium Magnesium Thermodynamic Thermodynamic Cycle Cycle CO2 Eco - Cements TOTAL CALCINING ENERGY (Relative to MgCO3) Theoretical = 1480 kJ.Kg-1 With inefficiencies = 1948 kJ.Kg-1 ? Magnesite* Thermal decomposition MgCO3 MgO + CO2 H = 118.28 kJ.mol-1 G = 65.92 kJ.mol-1 Reactive phase Representative of other hydrated mineral carbonates including an amorphous phase and Nesquehonite lansfordite Dehydration Carbonation Mg(OH)2 + CO2 + 2H2O MgCO3.3 H2O H = -175.59 kJ.mol-1 G = -38.73 kJ.mol-1
Brucite* Magnesia Hydration Tec - Cements 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 www.tececo.com 34 TecEco TecEco Cement Cement Sustainability Sustainability TecEco technology will be pivotal in bringing about sustainability in the built environment. The CO2 released by calcined carbonates used to make binders can be captured using TecEco kiln technology. Tec-Cements Develop Significant Early Strength even with Added Supplementary Materials. Around 25 = 30% less total binder is required for the same strength. Eco-cements carbonate sequestering CO2 Both tec and eco=cements provide a benign low pH environment for hosting large quantities of waste overcoming problems of: Using acids to etch plastics so they bond with concretes. sulphates from plasterboard etc. ending up in recycled construction materials. heavy metals and other contaminants. delayed reactivity e.g. ASR with glass cullet Durability issues Presentation downloadable from www.tececo.com
35 TecEco TecEco Formulations Formulations Tec-cements (Low MgO) contain more Portland cement than reactive magnesia. Reactive magnesia hydrates in the same rate order as Portland cement forming Brucite which uses up water reducing the voids:paste ratio, increasing density and possibly raising the short term pH. Reactions with pozzolans are more affective. After all the Portlandite has been consumed Brucite controls the long term pH which is lower and due to its low solubility, mobility and reactivity results in greater durability. Other benefits include improvements in density, strength and rheology, reduced permeability and shrinkage and the use of a wider range of aggregates many of which are potentially wastes without reaction problems. Eco-cements (High MgO) contain more reactive magnesia than in tec-cements. Brucite in porous materials carbonates forming stronger fibrous mineral carbonates and therefore presenting huge opportunities for waste utilisation and sequestration. Enviro-cements (High MgO) contain similar ratios of MgO and OPC to eco-cements but in non porous concretes brucite does not carbonate readily. Higher proportions of magnesia are most suited to toxic and hazardous waste immobilisation and when durability is required. Strength is not developed quickly nor to the same extent. Presentation downloadable from www.tececo.com 36 TecEco TecEco Cement Cement Technology Technology Portlandite (Ca(OH)2) is too soluble, mobile and
reactive. It carbonates, reacts with Cl- and SO4- and being soluble can act as an electrolyte. TecEco generally (but not always) remove Portlandite using the pozzolanic reaction and TecEco add reactive magnesia which hydrates forming brucite which is another alkali, but much less soluble, mobile or reactive than Portlandite. In Eco-cements brucite carbonates The consequences of need to be considered. Presentation downloadable from www.tececo.com 37 Why Why Add Add Reactive Reactive Magnesia? Magnesia? To maintain the long term stability of CSH. Maintains alkalinity preventing the reduction in Ca/Si ratio. To remove water. Reactive magnesia consumes water as it hydrates to possibly hydrated forms of brucite. To reduce shrinkage. The consequences of putting brucite through the matrix of a concrete in the first place need to be considered. To make concretes more durable Because significant quantities of carbonates are produced in porous substrates which are affective binders.
Reactive MgO is a new tool to be understood with profound affects on most properties Presentation downloadable from www.tececo.com 38 What WhatisisReactive ReactiveMgO? MgO?or or Lattice LatticeEnergy EnergyDestroys DestroysaaMyth Myth Magnesia, provided it is reactive rather than dead burned (or high density, crystalline periclase type), can be beneficially added to cements in excess of the amount of 5 mass% generally considered as the maximum allowable by standards prevalent in concrete dogma. Reactive magnesia is essentially amorphous magnesia with low lattice energy. It is produced at low temperatures and finely ground, and will completely hydrate in the same time order as the minerals contained in most hydraulic cements. Dead burned magnesia and lime have high lattice energies Crystalline magnesium oxide or periclase has a calculated lattice energy of 3795 Kj mol-1 which must be overcome for it to go into solution or for reaction to occur. Dead burned magnesia is much less expansive than dead burned lime (Ramachandran V. S., Concrete Science, Heydon & Son Ltd. 1981, p 358-360 ) Presentation downloadable from www.tececo.com
39 Summary Summary of of Reactions Reactions Involved Involved Notice the low solubility of brucite compared to Portlandit e and that nesqueho nite adopts a more ideal habit than calcite & aragonite We think the reactions are relatively independent. In Tec-Cements Magnesia Brucite MgO + H2O Mg(OH)2 M3A + 6H + M3AH6 (or similar ?) Silicates and aluminosilicates In Eco - Cements
Magnesia Amorphous Brucite Lansfordite Nesquehonite MgO + nH2O Mg(OH)2.nH2O + 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 Hardness: Solubility (mol.L-1): Massive or crystalline 2.5 .024
Presentation downloadable from www.tececo.com More acicular 3.5 .00014 40 Strength Strength with with Blend Blend & & Porosity Porosity 150 Tec-cement concretes Eco-cement concretes 100 50 High Porosity High OPC Enviro-cement concretes STRENGTH ON ARBITARY SCALE 1-100 100-150 50-100 0-50 Presentation downloadable from www.tececo.com
0 High Magnesia 41 Tec-Cement Tec-Cement Concrete Concrete Strength Strength Gain Gain Curve Curve Concretes are more often than not made to strength. The use of tec-cement results in 20-30% greater strength or less binder for the same strength. more rapid early strength development even with added pozzolans. Straight line strength development for a long time MPa HYPOTHETICAL TEC-CEMENT STRENGTH GAIN CURVE Tec Cement Concrete with 10% reactive magnesia ? ? ? ? Plastic Stage 3 OPC Concrete 7 14 28
Presentation downloadable from www.tececo.com Log Days strength gain with less cement and added pozzolans is of great economic and environment al importance. 42 Reasons Reasons for for Strength Strength Development Development in in Tec-Cements. Tec-Cements. Reactive magnesia requires considerable water to hydrate resulting in: Denser, less permeable concrete. A significantly lower voids/paste ratio. Higher early pH initiating more effective silicification reactions? The Ca(OH)2 normally lost in bleed water is used internally for reaction with pozzolans. Super saturation of alkalis caused by the removal of water? Micro-structural strength due to particle packing (Magnesia particles at 4-5 micron are a little over the size of cement
grains.) Slow release of water from hydrated Mg(OH)2.nH2O supplying H2O for more complete hydration of C2S and C3S? Formation of MgAl hydrates? Similar to flash set in concrete but slower?? Presentation downloadable from www.tececo.com 43 Water Water Reduction Reduction During During the the Plastic Plastic Phase Phase Observable Characteristic Water Binder + supplemen tary cementitio us materials High water for ease of placement Consumption of water during plastic stage Relevant Fundamental Voids Hydrated Binder
Materials Variables such as % hydration of mineral, density, compaction, % mineral H20 etc. Log time Unhydrated Binder Less water for strength and durability Less water results in less shrinkage and cracking and improved strength and durability. Concentration of alkalis and increased density result in greater strength. Presentation downloadable from www.tececo.com 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. 44 Tec-Cement Tec-Cement Compressive Compressive Strength Strength 3 14.365 18.095 19.669 5.516STRENGTH TEC-CEMENT COMPRESSIVE STRENGTH ( MPa) 40 3 9 9 9 21 21 21 35 30 25 20 16.968 19.466 24.248 29.03 24.54 28.403 32.266
19.44 20.877 24.408 27.939 35.037 36.323 37.609 20.196 13.39 15.39 17.39 25.493 28.723 31.953 15 6.656 3.417 4.434 5.451 11.992 13.933 15.874 OPC(100%) 10 OPC(90%)+MgO(10%) 5 0 0 2 4
6 8 10 12 14 16 18 20 22 24 CURING TIME (days) Graphs by Oxford Uni Student Presentation downloadable from www.tececo.com 45 STRENG TH (M Pa) Tec-Cement Tec-Cement Tensile Tensile Strength Strength TEC - CEMENT TENSILE STRENGTH 6 5 4 3
OPC(100%) 2 OPC(90%)+ MgO(10%) 1 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 CURING TIME (days) Graphs by Oxford Uni Student Tensile strength is thought to be caused by change in surface charge on MgO particles from +ve to ve at Ph 12 and electrostatic attractive forces Presentation downloadable from www.tececo.com 46 Other Other Strength Strength Testing Testing to
to Date Date BRE (United Kingdom) 2.85PC/0.15MgO/3pfa(1 part) : 3 parts sand - Compressive strength of 69MPa at 90 days. Note that there was as much pfa as Portland cement plus magnesia. Strength development was consistently greater than the OPC control Large Cement Company Strength Development of Tec-Cement Concrete 60 30 40 20 Strength, MPa MPa TecEco Sam ple 1 Sam ple 2 0 17 30 56 89 25 20
Compressive Strength 15 10 5 0 0 5 Days 10 15 20 25 30 Days w ater cured Modified 20 MPa mix Presentation downloadable from www.tececo.com 47 Increased Increased Density Density Reduced Reduced Permeability Permeability Concretes have a high percentage (around 18% 25%) of voids. On hydration magnesia expands 116.9 % filling voids and surrounding hydrating cement grains and compensates for the shrinkage of Portland cement.
Brucite is 44.65 mass% water. Lower voids:paste ratios than water:binder ratios result in little or no bleed water less permeability and greater density. Compare the affect to that of vacuum dewatering. Presentation downloadable from www.tececo.com 48 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. Consequences: Tec - cement concretes tend to dry from within, are denser and less permeable and therefore stronger more durable and more waterproof. Cement powder is not lost near the surfaces. Tec-cements have a higher salt resistance and less corrosion of steel etc. Presentation downloadable from www.tececo.com 49 Tec-Cement Tec-Cement pH
pH Curves Curves Tec-Cement (red) - more affective pozzolanic reactions pH HYPOTHETICAL pH CURVES OVER TIME (with fly ash) ? 13.7 Tec Cement Concrete with 10% reactive ? ? magnesia (red). Ph maintained by brucite 11.2 OPC Concrete 10.5 OPC Concrete Lower long term pH due to consumption of lime and carbonation Log Time Plastic Stage Presentation downloadable from www.tececo.com 50 Lower LowerMore MoreStable StableLong LongTerm TermpH pHwith withLess LessCorrosion Corrosion 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 www.tececo.com 51 Reduced Reduced Steel Steel Corrosion Corrosion Steel remains protected with a passive oxide coating of Fe 3O4 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 www.tececo.com 52 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 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)
Passive Coating Fe3O4 intact 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 www.tececo.com 53 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 www.tececo.com 54 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 the reactive magnesia in Tec-cement concretes consumes unbound water from the pores inside concrete, probably holding it for slow release to extended hydration reactions of Ca silicates. Magnesia dries concrete out from the inside. Reactions do not occur without water. Presentation downloadable from www.tececo.com 55 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 introduces considerable durability. Brucite does not react with salts because it is a least 5 orders of magnitude less soluble, mobile or reactive. Ksp brucite = 1.8 X 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 www.tececo.com
56 Bingham Bingham Plastic Plastic Rheology Rheology Finely ground reactive magnesia consumes water but also acts as a plasticiser Portland cement grains Mean size 10 - 15 micron Reactive Magnesia grains Mean size 5 6 micron Smaller grains (eg microsilica. 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 www.tececo.com 57 Bingham Bingham Plastic Plastic Rheology Rheology It is
not known how deep these + layers get + The strongly positively + Etc. charged small O Mg++ atoms + + + attract water O + + (which is polar) O O O in deep layers + Mg++ + affecting the O O rheological + + + O properties and + + making +
concretes less sticky with Etc. added pozzolan Ca++ = 114, Mg++ = 86 Presentation picometres downloadable from www.tececo.com 58 Rheology Rheology Tech Tendons Second layer low slump teccement concrete 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. 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 59 Reduced Reduced Shrinkage Shrinkage Net shrinkage is reduced due
to stoichiometric expansion of Magnesium minerals, and reduced water loss. Legend 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 www.tececo.com 60 Reduced Reduced Shrinkage Shrinkage Less Less Cracking Cracking Large Cement Company Test Age (days) Microstrain 7 133 14
240 28 316 56 470 Cracking, the symptomatic result of shrinkage, is undesirable for many reasons, but mainly because it allows entry of gases and ions reducing durability. Cracking can be avoided only if the stress induced by the free shrinkage strain, reduced by creep, is at all times less than the tensile strength of the concrete. Tec-cements also have greater tensile strength. Tec-cements exhibit higher tensile strength and less shrinkage and therefore less cracking Presentation downloadable from www.tececo.com 61 Volume Volume Changes Changes on on Hydration Hydration When magnesia hydrates it expands:
MgO (s) + H2O (l) Mg(OH)2.nH2O (s) 40.31 + 18.0 58.3 (minimum) molar mass 11.2 + liquid 24.3 (minimum) 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 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 62 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 www.tececo.com 63 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 www.tececo.com 64 TecEco TecEco Cement Cement Concretes Concretes Dimensional Dimensional Control Control Combined Hydration and Carbonation can be manipulated to be close to neutral. So far we have not observed significant shrinkage in
TecEco tec - cement concretes (5% -10% substitution OPC) also containing fly ash. At some ratio, thought to be around 10% reactive magnesia and 90% PC volume changes are optimised as higher additions of MgO reduce strength. The water lost by Portland cement as it shrinks is used by reactive magnesia as it hydrates also reducing shrinkage. Presentation downloadable from www.tececo.com 65 Tec Tec--Cement CementConcretes ConcretesLess Lessor orno noDimensional DimensionalChange Change Reactive Magnesia ? +.05% +- Fly Ash? ? ? ? ? Composite Curve ?
? 28 ? 90 days Tec-Cement Concrete -.05% Portland Cement HYDRATION THEN CARBONATION OF REACTIVE MAGNESIA AND OPC It may be possible to engineer a particle with slightly delayed expansion to counterbalance the expansion and then shrinkage concretes containing gbfs. Presentation downloadable from www.tececo.com 66 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 www.tececo.com 67 Eco-Cements Eco-Cements Eco-cements are similar but potentially superior to lime mortars because: The calcination phase of the magnesium thermodynamic cycle takes place at a much lower temperature and is therefore more efficient. Magnesium minerals are generally more fibrous and acicular than calcium minerals and hence add microstructural strength. Water forms part of the binder minerals that forming making the cement component go further. In terms of binder produced for starting material in cement, eco-cements are nearly six times more efficient. Magnesium hydroxide in particular and to some extent the carbonates are less reactive and mobile and thus much more durable. Presentation downloadable from www.tececo.com 68 Eco-Cement Eco-Cement pH pH Curves Curves pH HYPOTHETICAL pH CURVES OVER TIME ?
13.7 Eco Cement Concrete with 75% reactive magnesia ? ? (red). Ph maintained by brucite and hydrated carbonates 11.2 OPC Concrete 10.5 PC Concrete Ph maintained by lime and calcite (Ca(OH)2 carbonates more readily.) Log Time Plastic Stage Presentation downloadable from www.tececo.com 69 Eco-Cement Eco-Cement Strength Strength Development Development Eco-cements gain early strength from the hydration of PC. Later strength comes from the carbonation of brucite forming an amorphous phase, lansfordite and nesquehonite. Strength gain in eco-cements is mainly microstructural because of More ideal particle packing (Brucite particles at 4-5 micron are under half the size of cement grains.) The natural fibrous and acicular shape of magnesium carbonate minerals which tend to lock together. More binder is formed than with calcium Total volumentric expansion from magnesium oxide to lansfordite is for example 473 volume %. Presentation downloadable from www.tececo.com
70 Eco-Cement Eco-Cement Concrete Concrete Strength Strength Gain Gain Curve Curve HYPOTHETICAL STRENGTH GAIN CURVE OVER TIME (Pozzolans added) MPa ? OPC Concrete ? ? Eco Cement Concrete with 50% reactive magnesia ? 3 Plastic Stage 7 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 formulations. Presentation downloadable from www.tececo.com 71 Eco-Cement Eco-Cement Micro-Structural Micro-Structural Strength Strength Elongated growths of lansfordite and nesquehonite near the surface, growing inwards over time and providing microstructural strength. Flyash grains (red) reacting with lime producing more CSH and if alkaline enough conditions bonding through surface hydrolysis. Also acting as micro aggregates. Presentation downloadable from www.tececo.com Portland clinker minerals (black). Hydration providing Imperfect structural framework. Micro spaces filled with hydrating magnesia (brucite) acting as a waterproof glue Mysterious amorphous
phase? 72 Carbonation Carbonation Because magnesium has a low molecular weight, proportionally a greater amount of CO2 is captured. Carbonation results in significant sequestration because of the shear volumes involved. Carbonation adds strength. Carbonates are the stable phases of both calcium and magnesium. The formation of carbonates lowers the pH of concretes compromising the stability of the passive oxide coating on steel. Some steel reinforced structural concrete could be replaced with fibre reinforced porous carbonated concrete. Presentation downloadable from www.tececo.com 73 Chemistry Chemistry of of Carbonation Carbonation There are a number of carbonates of magnesium. The main ones appear to be an amorphous phase, lansfordite and nesquehonite. The carbonation of magnesium hydroxide does not proceed as readily as that of calcium hydroxide. Gor Brucite to nesquehonite = - 38.73 kJ.mol-1 Compare to Gor Portlandite to calcite = -64.62 kJ.mol-1 The dehydration of nesquehonite to form magnesite is not favoured by simple thermodynamics but may occur in the long term under the right conditions.
Gor nesquehonite to magnesite = 8.56 kJ.mol-1 But kinetically driven by desiccation during drying. Reactive magnesia can carbonate in dry conditions so keep bags sealed! For a full discussion of the thermodynamics see our technical documents. TecEco technical documents on the web cover the important aspects of carbonation. Presentation downloadable from www.tececo.com 74 Ramifications Ramifications of of Carbonation Carbonation Magnesium Carbonates. The magnesium carbonates that form at the surface of tec cement concretes expand significantly thereby sealing off further carbonation. Lansfordite and nesquehonite are stronger and more acid resistant than calcite or aragonite. The curing of eco-cements in a moist - dry alternating environment seems to encourage carbonation. Portland Cement Concretes Carbonation proceeds relatively rapidly at the surface. Vaterite followed by Aragonite and Calcite is the principal product and lowers the pH to around 8.2 Presentation downloadable from www.tececo.com 75 Proof Proofof
ofCarbonation Carbonation--Minerals MineralsPresent PresentAfter After18 18Months Months XRD showing carbonates and other minerals before removal of carbonates with HCl in a simple Mix (70 Kg PC, 70 Kg MgO, colouring oxide .5Kg, sand unwashed 1105 Kg) Presentation downloadable from www.tececo.com 76 Proof Proofof ofCarbonation Carbonation--Minerals MineralsPresent PresentAfter After18 18Months Monthsand and Acid AcidLeaching Leaching XRD Showing minerals remaining after their removal with HCl in a simple mix (70 Kg PC, 70 Kg MgO, colouring oxide .5Kg, sand unwashed 1105 Kg)
Presentation downloadable from www.tececo.com 77 TecEco TecEco Binders Binders -- Solving Solving Waste Waste Problems Problems There are huge volumes of concrete produced annually ( 2 tonnes per person per year.) An important objective should be to make cementitous composites that can utilise wastes. TecEco cements provide a benign environment suitable for waste immobilisation Many wastes such as fly ash, sawdust , shredded plastics etc. can improve a property or properties of the cementitious composite. There are huge materials flows in both wastes and building and construction. TecEco technology will lead the world in the race to incorporate wastes in cementitous composites Presentation downloadable from www.tececo.com 78 TecEco TecEcoBinders Binders--Solving SolvingWaste WasteProblems Problems(2) (2) TecEco cementitious composites represent a cost affective option for both use and immobilisation of waste.
Lower reactivity less water lower pH Reduced solubility of heavy metals less mobile salts Greater durability. Denser. Impermeable (tec-cements). Dimensionally more stable with less shrinkage and cracking. Homogenous. No bleed water. TecEco Technology Converting Waste to Resource Presentation downloadable from www.tececo.com 79 Role Role of of Brucite Brucite in in Immobilization Immobilization In a Portland cement brucite matrix PC takes up lead, some zinc and germanium Brucite and hydrotalcite are both excellent hosts for toxic and hazardous wastes. Heavy metals not taken up in the structure of Portland cement minerals or trapped within the brucite layers end up as hydroxides with minimal solubility. The brucite in TecEco Layers of electronically neutral brucite
suitable for trapping balanced cations and anions as well as other substances. Van der waals bonding holding the layers together. Salts and other substances trapped between the layers. Presentation downloadable from www.tececo.com 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. 80
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 www.tececo.com 81 TecEco TecEco Materials Materials as as 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. Mg(OH)2 MgO + H2O Lansfordite and nesquehonite releases CO2 and water and convert to magnesium oxide. MgCO3.nH2O MgO + CO2 + H2O 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 www.tececo.com 82 TecEco Cement Implementation Summary Presentation downloadable from www.tececo.com 83 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 Foolproof associated costs. Tolerance and consumption of water. Concrete?
Reduction in bleed water enables finishing of lower floors whilst upper floors still being poured and increases pumpability. Cheaper binders as less energy required Increased durability will result in lower costs/energies/ emissions due to less frequent replacement. Because reactive magnesia is also an excellent plasticiser, other costly additives are not required for this purpose. A wider range of aggregates can be utilised without problems reducing transport and other costs/energies/emissions. Presentation downloadable from www.tececo.com 84 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 www.tececo.com 85 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 shrinkage, durability and corrosion 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 www.tececo.com 86 TecEco Doing Things Presentation downloadable from www.tececo.com 87 The TheUse Useof ofEco-Cements Eco-Cementsfor forBuilding BuildingEarthship EarthshipBrighton Brighton By Taus Larsen, (Architect, Low Carbon Network Ltd.) The Low Carbon Network (www.lowcarbon.co.uk) was established to raise awareness of the links between buildings, the working and living patterns they create, and global warming and aims to initiate change through the application of innovative ideas and approaches to construction. Englands first Earthship is currently under construction in southern England outside Brighton at Stanmer Park and TecEco technologies have been used for the floors and some walling. Earthships are exemplars of low-carbon design, construction and living and were invented and developed in the USA by Mike Reynolds over 20 years of practical building exploration. They are autonomous earth-sheltered buildings independent from mains electricity, water and waste systems and have little or no utility costs.
For information about the Earthship Brighton and other projects please go to the TecEco web site. Presentation downloadable from www.tececo.com 88 Repair Repair of of Concrete Concrete Blocks. Blocks. Clifton Clifton Surf Surf Club Club The Clifton Surf Life Saving Club was built by first pouring footings, On the footings block walls were erected and then at a later date concrete was laid in between. As the ground underneath the footings was sandy, wet most of the time and full of salts it was a recipe for disaster. Predictably the salty water rose up through the footings and then through the blocks and where the water evaporated there was strong efflorescence, pitting, loss of material and damage. The TecEco solution was to make up a formulation of eco-cement mortar which we doctored with some special chemicals to prevent the rise of any more moisture and salt. The solution worked well and appears to have stopped the problem. Presentation downloadable from www.tececo.com 89
Mike Mike Burdons Burdons Murdunna Murdunna Works Works Mike Burdon, Builder and Plumber. I work for a council interested in sutainability and have been involved with TecEco since around 2001 in a private capacity helping with large scale testing of TecEco tec-cements at our shack. I am interested in the potentially superior strength development and sustainability aspects. 1. To date we have poured two slabs, footings, part of a launching ramp and some tilt up panels using formulations and materials supplied by John Harrison of TecEco. I believe that research into the new TecEco cements essential as overall I have found: The rheological performance even without plasticizer was excellent. As testimony to this the contractors on the site commented on how easy the concrete was to place and finish. 2. We tested the TecEco formulations with a hired concrete pump and found it extremely easy to pump and place. Once in position it appeared to gel up quickly allowing stepping for a foundation to a brick wall. 3. Strength gain was more rapid than with Portland cement controls from the same premix plant and continued for longer.
4. The surfaces of the concrete appeared to be particularly hard and I put this down to the fact that much less bleeding was observed than would be expected with a Portland cement only formulation Presentation downloadable from www.tececo.com 90 Tec-Cement Tec-Cement Slab Slab Whittlesea, Whittlesea, Vic. Vic. Australia Australia On 17th March 2005 TecEco poured the first commercial slab in the world using teccement concrete with the assistance of one of the larger cement and pre-mix companies. Strength Development of Tec-Cement Concrete 30 Strength, MPa The formulation strategy was to adjust a standard 20 MPa high fly ash (36%) mix from the company as a basis of comparison. Strength development, and in particular early strength development was good. Interestingly some 70 days later the slab is still gaining strength at the rate of about 5 MPa a month.
Also noticeable was the fact that the concrete was not as "sticky" as it normally is with a fly ash mix and that it did not bleed quite as much. Shrinkage was low. 7 days - 133 micro strains, 14 days - 240 micro strains, 28 days - 316 micros strains and at 56 days - 470 microstrains. 25 20 Compressive Strength 15 10 5 0 0 Presentation downloadable from www.tececo.com 5 10 15 20 25 30 Days w ater cured 91
Embodied Energies and Emissions Presentation downloadable from www.tececo.com 92 CO CO22 Abatement Abatement in in Eco-Cements Eco-Cements For 85 wt % Aggregat es 15inwt% Eco-cements Cement porous products absorb carbon dioxide from the atmosphere. Brucite carbonates forming lansfordite, nesquehonite and an amorphous phase, completing the thermodynamic cycle. Portlan d Cement s 15 mass% Portland cement, 85 mass%
aggregate Emissions .32 tonnes to the tonne. After carbonatio n. Approximat ely .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. approximate ly .241 tonne to the tonne. Capture CO2 11.25% mass % reactive magnesia, 3.75 mass%
Portland cement, 85 mass% aggregate. Emissions .25 tonnes to the tonne. After carbonation. approximatel y .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 ecocement, 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 93 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 www.tececo.com 94 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 Presentation downloadable from www.tececo.com 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 95 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 www.tececo.com 96 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 www.tececo.com