Presentation on theme: "Presentation downloadable from www.tececo.com 1 Implementing Sustainability Our slides are deliberately verbose as most people download and view them from."— Presentation transcript:
Presentation downloadable from www.tececo.com 1 Implementing Sustainability Our slides are deliberately verbose as most people download and view them from the net. Because of time constraints I will have to race over some slides John Harrison B.Sc. B.Ec. FCPA. Presentation by John Harrison, managing director of TecEco and inventor of Tec and Eco-Cements and the CarbonSafe process. TecEco are in the biggest business on the planet – that of solving global warming waste and water problems
Presentation downloadable from www.tececo.com 2 The Problem. We have a Planet in Crisis –Fresh Water –Global warming –Energy –Waste & Pollution In the next 50 years it is crunch time for: Are you thinking about it? Do you have an answer?
Presentation downloadable from www.tececo.com 3 Fresh Water The amount of water in the world is finite. The number of us is growing quickly and our water use is growing more quickly. A third of the world's population lives in water-stressed countries. By 2025, this is expected to rise to two-thirds. The world's supply of fresh water is running out. Already one person in five has no access to safe drinking water.
Presentation downloadable from www.tececo.com 4 Global Warming Rises in the levels of carbon dioxide and other gases (methane, water vapour) Are causing a rapid rise in temperature
Presentation downloadable from www.tececo.com 5 The Carbon Cycle and Emissions Source: David Schimel and Lisa Dilling, National Centre for Atmospheric Research 2003 Emissions from fossil fuels and cement production are the cause of the global warming problem
Presentation downloadable from www.tececo.com 6 Energy Crisis Peak Oil Production (Campell 2004) Most models of oil reserves, production and consumption show peak oil around 2010 (Campbell 2005) and serious undersupply and rapidly escalating prices by 2025. It follows that there will be economic mayhem unless the cement and concrete industry acts now to change the energy base of their products.
Presentation downloadable from www.tececo.com 7 Waste & Pollution Waste releases methane, can cause ill health in the area, leads to the contamination of land, underground water, streams and coastal waters (destroying our fisheries) and gives rise to various nuisances including increased traffic, noise, odours, smoke, dust, litter and pests. Most damaging is the release of dangerous molecules to the global commons There are various estimates, but we produce about 5-600 million tonnes of waste each year.
Presentation downloadable from www.tececo.com 8 Ecological Footprint Our footprint is exceeding the capacity of the planet to support it. We are not longer sustainable as a species and must change our ways TO SURVIVE
Presentation downloadable from www.tececo.com 9 All these Problems Represent an Opportunity to Do Something About Them The built environment is made of materials and is our footprint on earth. –It comprises buildings and infrastructure. Construction materials comprise –70% of materials flows (buildings, infrastructure etc.) –40-50% of waste that goes to landfill (15 % of new materials going to site are wasted.) Over 30 billion tonnes of building materials are used annually on a world wide basis. –Mostly using virgin natural resources –Combined in such a manner they cannot easily be separated. –And include many toxic elements. The single biggest materials flow (after water) is concrete at around 15 billion tonnes or > 2 tonnes per man, woman and child on the planet.
Presentation downloadable from www.tececo.com 10 How? - The Techno-Processes & Earth Systems Underlying the techno- process that describes and controls the flow of matter and energy are molecular stocks and flows. If out of tune with nature these moleconomic flows have detrimental affects on earth systems. Detrimental affects on earth systems Earth Systems Atmospheric composition, climate, land cover, marine ecosystems, pollution, coastal zones, freshwater and salinity. Move 500-600 billion tonnes Use some 50 billion tonnes To reduce the impact on earth systems new technical paradigms need to be invented that result in underlying molecular flows that mimic or at least do not interfere with natural flows. Take Waste
Presentation downloadable from www.tececo.com 11 Under Materials Flows in the Techno-Processes are Molecular Flows Take Manipulate Make Use Waste [ Materials ] [ Underlying molecular flow ] If the underlying molecular flows are out of tune with nature there is damage to the environment e.g. heavy metals, cfcs, c=halogen compounds and CO 2 Moleconomics Is the study of the form of atoms in molecules, their flow, interactions, balances, stocks and positions. What we take from the environment around us, how we manipulate and make materials out of what we take and what we waste result in underlying molecular flows that affect earth systems. These flows should mimic or minimally interfere with natural flows.
Presentation downloadable from www.tececo.com 12 Detrimental Linkages that affect earth system flows Takemanipulateand makeimpacts End of lifecycle impacts Greater Utility Less Utility Materials are in the Techno- sphere Utility zone Materials are everything between the take and waste and affect earth system flows. There is no such place as away There are Detrimental Affects Right Through the Techno-process
Presentation downloadable from www.tececo.com 13 We Must Learn from Nature (Biomimicry) Nature is very efficient. The waste from one plant or animal is the food or home for another. By studying Nature we learn who we are, what we are and how we are to be. (Wright, F.L. 1957:269) In nature photosynthesis balances respiration. We have nothing that balances our emissions in the techno- process There is a strong need for similar efficiency and balance By learning from Nature we can all live together
Presentation downloadable from www.tececo.com 14 Biomimicry The term biomimicry was popularised by the book of the same name written by Janine Benyus Biomimicry is a method of solving problems that uses natural processes and systems as a source of knowledge and inspiration. It involves nature as model, measure and mentor. The theory behind biomimicry is that natural processes and systems have evolved over several billion years through a process of research and development commonly referred to as evolution. A reoccurring theme in natural systems is the cyclical flow of matter in such a way that there is no waste of matter or energy. Nature is very economical about all Processes. We must also be MUCH more economical
Presentation downloadable from www.tececo.com 15 Economically Driven Sustainability The challenge is to harness human behaviours which underlay economic supply and demand phenomena by changing the technical paradigm in favour of making carbon dioxide and other wastes resources for new materials with lower take and waste impacts and more energy efficient performance. Sustainable processes are more efficient and therefore more economic. Natural ecosystems can be 100% efficient. What is needed are new technologies that allow material and energy flows to more closely mimic natural ecosystems. Innovation will deliver these new technical paradigms. $ - ECONOMICS - $ Sustainability will not happen by relying on people to do the right thing
Presentation downloadable from www.tececo.com 16 Sustainability = Culture + Technology Increase in demand/price ratio for sustainability due to educationally induced cultural drift. # $ Demand Supply Increase in supply/price ratio for more sustainable products due to innovative paradigm shifts in technology. Equilibrium shift ECONOMICS Greater Value/for impact (Sustainability) and economic growth One aspect of sustainability is that it is where Culture and Technology meet. New Technical Paradigms are required that deliver sustainability.
Presentation downloadable from www.tececo.com 17 Changing the Technology Paradigm By enabling us to make productive use of particular raw materials, technology determines what constitutes a physical resource 1 1.Pilzer, Paul Zane, Unlimited Wealth, The Theory and Practice of Economic Alchemy, Crown Publishers Inc. New York.1990 We need materials that require less energy to make them, that last much longer and that contribute properties that reduce lifetime energies. The key is to change the technology paradigm
Presentation downloadable from www.tececo.com 18 Examples of Economic Changes in Technical Paradigms that result in Greater Sustainability Robotics - A Paradigm Shift in Technology that will fundamentally affect Building and Construction Construction in the future will be largely done by robots because it will be more economic to do so. Like a color printer different materials will be required for different parts of structures, and wastes such as plastics will provide many of the properties required for the cementitious composites of the future used. A non-reactive binder such as TecEco tec-cements can supply the right rheology, and like a printer, very little will be wasted. Light Globes - A Recent Paradigm Shift in Technology Reducing Energy Consumption Light Globes in the last 10 years have evolved from consuming around 100 watts per 1700 lumens to less that 20 watts per 1700 lumens. As light globes account for around 30% of household energy this is as considerable saving. 100 watts 1700 lumens Incandescent 25 watts 1700 lumens Fluorescent <20 watts 1700 lumens Led Light
Presentation downloadable from www.tececo.com 19 The TecEco CarbonSafe Industrial Ecology Outputs Gypsum, Sodium bicarbonate, Salts, Building materials, Potable water Inputs Brines Waste Acid CO2 We must design whole new technical paradigms that reverse many of our problem molecular flows
Presentation downloadable from www.tececo.com 20 A Low Energy Post – Carbon & Waste Age? The construction industry can be uniquely responsible for helping achieve this transition Maybe then we can move confidently into a more sustainable future.
Presentation downloadable from www.tececo.com 21 Innovative New Materials - the Key to Sustainability There is no such place as away, only a global commons The choice of materials controls emissions, lifetime and embodied energies, user comfort, use of recycled wastes, durability, recyclability and the properties of wastes returned to the bio-geo-sphere.
Presentation downloadable from www.tececo.com 22 Re - Engineering Materials – What we Build With To solve environmental problems we need to understand more about materials in relation to the environment. –the way their precursors are derived and their degradation products re assimilated and how we can reduce the impact of these processes –what energies drive the evolution, devolution and flow of materials and how we can reduce these energies –how materials impact on lifetime energies With the knowledge gained re- design materials to not only be more sustainable but more sustainable in use Environmental problems are the result of inherently flawed materials, materials flows and energy systems
Presentation downloadable from www.tececo.com 23 Changing the Techno-process 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 Reduce Re-use Recycle Materials Take => manipulate => make => use => waste Driven by fossil fuel energy with detrimental effects on earth systems. Eco-innovate
Presentation downloadable from www.tececo.com 24 Huge Potential for Sustainable Materials Reducing the impact of the take and waste phases of the techno-process. –including carbon in materials they are potentially carbon sinks. –including wastes for physical properties as well as chemical composition they become resources. –re – engineering materials to reduce the lifetime energy of buildings C C C C C Waste Many wastes can contribute to physical properties reducing lifetime energies
Presentation downloadable from www.tececo.com 25 Utilizing Carbon and Wastes (Biomimicry) During earth's geological history large tonnages of carbon were put away as limestone and other carbonates and as coal and petroleum by the activity of plants and animals. Sequestering carbon in magnesium binders and aggregates in the built environment mimics nature in that carbon is used in the homes or skeletal structures of most plants and animals. We all use carbon and wastes to make our homes! Biomimicry In eco-cement blocks and mortars the binder is carbonate and the aggregates are preferably wastes
Presentation downloadable from www.tececo.com 26 Impact of the Largest Material Flow - Cement and Concrete Concrete made with cement is the most widely used material on Earth accounting for some 30% of all materials flows on the planet and 70% of all materials flows in the built environment. –Global Portland cement production is currently in the order of 2 billion tonnes per annum. –Globally over 14 billion tonnes of concrete are poured per year. –Over 2 tonnes per person per annum –Much more concrete is used than any other building material. TecEco Pty. Ltd. have benchmark technologies for improvement in sustainability and properties
Presentation downloadable from www.tececo.com 27 Embodied Energy of Building Materials Downloaded from www.dbce.csiro.au/ind- serv/brochures/embodied/embodied.htm (last accessed 07 March 2000) Concrete is relatively environmentally friendly and has a relatively low embodied energy
Presentation downloadable from www.tececo.com 28 Average Embodied Energy in Buildings Downloaded from www.dbce.csiro.au/ind- serv/brochures/embodied/embodied.htm (last accessed 07 March 2000) Because so much concrete is used there is a huge opportunity for sustainability by reducing the embodied energy, reducing the carbon debt (net emissions) and improving properties that reduce lifetime energies. Most of the embodied energy in the built environment is in concrete.
Presentation downloadable from www.tececo.com 29 Emissions from Cement Production Chemical Release –The process of calcination involves driving off chemically bound CO 2 with heat. CaCO 3 CaO + CO 2 Process Energy –Most energy is derived from fossil fuels. –Fuel oil, coal and natural gas are directly or indirectly burned to produce the energy required releasing CO 2. The production of cement for concretes accounts for around 10% of global anthropogenic CO 2. –Pearce, F., "The Concrete Jungle Overheats", New Scientist, 19 July, No 2097, 1997 (page 14). Arguments that we should reduce cement production relative to other building materials are nonsense because concrete is the most sustainable building material there is. The challenge is to make it more sustainable. CO 2 CO 2
Presentation downloadable from www.tececo.com 30 Cement Production ~= Carbon Dioxide Emissions Between tec, eco and enviro-cements TecEco can provide a viable much more sustainable alternative.
Presentation downloadable from www.tececo.com 31 TecEco Technologies Take Concrete into the Future More rapid strength gain even with added pozzolans –More supplementary materials can be used reducing costs and take and waste impacts. Higher strength/binder ratio Less cement can be used reducing costs and take and waste impacts More durable concretes –Reducing costs and take and waste impacts. Use of wastes Utilizing carbon dioxide Magnesia component can be made using non fossil fuel energy and CO 2 captured during production. Eco-Cements Tec - Cements Tec & Eco- Cements
Presentation downloadable from www.tececo.com 32 TecEco Binder Systems Hydration of the various components of Portland cement for strength. SUSTAINABILITY DURABILITYSTRENGTH TECECO CEMENTS Reaction of alkali with pozzolans (e.g. lime with fly ash.) for sustainability, durability and strength. Hydration of magnesia => brucite for strength, workability, dimensional stability and durability. In Eco-cements carbonation of brucite => nesquehonite, lansfordite and an amorphous phase for sustainability. PORTLAND POZZOLAN REACTIVE MAGNESIA TecEco concretes are a system of blending reactive magnesia, Portland cement and usually a pozzolan with other materials and are a key factor for sustainability.
Presentation downloadable from www.tececo.com 33 TecEco Formulations Tec-cements (5-15% MgO, 85-95% 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 (15-95% MgO, 85-5% 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 (5-15% MgO, 85-95% 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 www.tececo.com 34 Tec & Eco-Cement Theory Many Engineering Issues are Actually Mineralogical Issues –Problems with Portland cement concretes are usually resolved by the band aid 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. –Portlandite and water are the weakness of concrete TecEco remove Portlandite it and replacing it with magnesia which hydrates to Brucite. The hydration of magnesia consumes significant water
Presentation downloadable from www.tececo.com 35 Tec & Eco-Cement Theory Portlandite (Ca(OH) 2 ) is too soluble, mobile and reactive. –It carbonates, reacts with Cl - and SO 4 - and being soluble can act as an electrolyte. TecEco generally (but not always) remove Portlandite using the pozzolanic reaction and TecEco add reactive magnesia –which hydrates, consuming significant water and concentrating alkalis forming B rucite which is another alkali, but much less soluble, mobile or reactive than Portlandite. In Eco-Cements brucite carbonates forming hydrated compounds with greater volume
Presentation downloadable from www.tececo.com 36 Why Add Reactive Magnesia? To maintain the long term stability of CSH. –Maintains alkalinity preventing the reduction in Ca/Si ratio. To remove water. –Reactive magnesia consumes water as it hydrates to possibly hydrated forms of Brucite. To raise the early Ph. –Increasing non hydraulic strength giving reactions 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 37 Strength with Blend & Porosity High OPC High Magnesia High Porosity STRENGTH ON ARBITARY SCALE 1-100 Tec-cement concretes Eco-cement concretes Enviro-cement concretes
Presentation downloadable from www.tececo.com 38 TecEco Technology in Practice On 17th March 2005 TecEco poured the first commercial slab in the world using tec-cement concrete with the assistance of one of the larger cement and pre-mix companies. –The formulation strategy was to adjust a standard 20 MPa high fly ash (36%) mix from the company as a basis of comparison. –Strength development, and in particular early strength development was good. Interestingly some 70 days later the slab is still gaining strength at the rate of about 5 MPa a month. –Also noticeable was the fact that the concrete was not as "sticky" as it normally is with a fly ash mix and that it did not bleed quite as much. –Shrinkage was low. 7 days - 133 micro strains, 14 days - 240 micro strains, 28 days - 316 micros strains and at 56 days - 470 microstrains. => Whittlesea, Vic. Australia
Presentation downloadable from www.tececo.com 39 TecEco Technology in Practice Allow many mega litres of good fresh water to become contaminated by the pollutants on our streets and pollute coastal waterways Capture and cleanse the water for our use? Or => Porous Pavement
Presentation downloadable from www.tececo.com 40 TecEco Technology in Practice First Eco-cement mud bricks and mortars in Australia –Tested up twice as strong as the PC controls –Mud brick addition rate 2.5% –Addition rate for mortars 1:8 not 1:3 because of molar ratio volume increase with MgO compared to lime. => Whittlesea, Vic. Australia
Presentation downloadable from www.tececo.com 41 TecEco Technology in Practice 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. => Earthship Brighton, UK
Presentation downloadable from www.tececo.com 42 TecEco Technology in Practice 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. => Clifton Surf Life Saving Club
Presentation downloadable from www.tececo.com 43 TecEco Technology in Practice Mike Burdon, Builder and Plumber. I work for a council interested in sutainability and have been involved with TecEco since around 2001 in a private capacity helping with large scale testing of TecEco tec-cements at our shack. I am interested in the potentially superior strength development and sustainability aspects. To date we have poured two slabs, footings, part of a launching ramp and some tilt up panels using formulations and materials supplied by John Harrison of TecEco. I believe that research into the new TecEco cements essential as overall I have found: 1.The rheological performance even without plasticizer was excellent. As testimony to this the contractors on the site commented on how easy the concrete was to place and finish. 2.We tested the TecEco formulations with a hired concrete pump and found it extremely easy to pump and place. Once in position it appeared to gel up quickly allowing stepping for a foundation to a brick wall. 3.Strength gain was more rapid than with Portland cement controls from the same premix plant and continued for longer. 4.The surfaces of the concrete appeared to be particularly hard and I put this down to the fact that much less bleeding was observed than would be expected with a Portland cement only formulation => Mike Burdons Murdunna Works
Presentation downloadable from www.tececo.com 44 TecEco Technology in Practice Tec-Cement concretes exhibit little or no shrinkage. At 10% substitution of MgO for PC the shrinkage is less than half normal. At 18% substitution with no added pozzolan there was no measurable shrinkage or expansion. The above photo shows a tec-cement concrete topping coat (with no flyash) 20mm thick away from the door and 80 mm thick near the door. Note that there has been no tendency to push the tiles or shrink away from the borders as would normally be the case. => DJ Motors, Hobart
Presentation downloadable from www.tececo.com 45 TecEco Technology in Practice TecEco Tec and Eco- Cement blocks are now being made commercially in Tasmania and with freight equalization may be viable to ship to Victoria for your green project. Hopefully soon we will have a premix mortar available that uses eco-cement. => Island Block and Paver,Tasmania
Presentation downloadable from www.tececo.com 46 TecEco Technology in Practice BUILD LITE CELLULAR CONCRETE 4 Rosebank Ave Clayton Sth MELBOURNE AUSTRALIA 3169 PH 61 3 9547 0255 FX 61 3 9547 0266 Foamed TecEco cement concretes can be produced to about 30% weight reduction in concrete trucks using cellflow additive or to about 70% weight reduction using a foaming machine with mearlcrete additive (or equivalents) => Foamed Concretes
Presentation downloadable from www.tececo.com 47 Tec & Eco Cement Foamed Concrete Slabs BUILD LITE CELLULAR CONCRETE 4 Rosebank Ave Clayton Sth MELBOURNE AUSTRALIA 3169 PH 61 3 9547 0255 FX 61 3 9547 0266 => Foamed Concrete Slabs
Presentation downloadable from www.tececo.com 48 TecEco Technology in Practice Solutions in Steel ABN 48 103 573 039 TEL: 61 7 3271 3900 FAX: 61 7 3271 2701 80 Mica Street Carole Park 4300 Queensland Australia Imagine a conventional steel frame section with a foamed concrete panel built in adding to structural strength, providing insulation as well as the external cladding of a structure. Rigid Steel Framing have developed just such a panel and have chosen to use TecEco cement technology for the strength, ease of use and finish. Patents applied for by Rigid Steel Framing Please direct commercial enquiries to Rigid Steel Framing at rigidsteel.com.au => Foamed Concretes Panels
Presentation downloadable from www.tececo.com 49 Rear view of test panels showing tongue and groove and void for services. Interior plasterboard is fixed conventionally over gap for services. TecEco Technology in Practice => Foamed Concretes Panels
Presentation downloadable from www.tececo.com 50 Eco-Cements Eco-cements are similar but potentially superior to lime mortars because: –The calcination phase of the magnesium thermodynamic cycle takes place at a much lower temperature and is therefore more efficient. –Magnesium minerals are generally more fibrous and acicular than calcium minerals and hence add microstructural strength. Water forms part of the binder minerals that forming making the cement component go further. In terms of binder produced for starting material in cement, eco-cements are much more efficient. Magnesium hydroxide in particular and to some extent the carbonates are less reactive and mobile and thus much more durable.
Presentation downloadable from www.tececo.com 51 Eco-Cements Have high proportions of reactive magnesium oxide Carbonate like lime Generally used in a 1:5-1:12 paste basis because much more carbonate binder is produced than with lime MgO + H 2 O Mg(OH) 2 Mg(OH) 2 + CO 2 + H 2 O MgCO 3. 3H 2 O 58.31 + 44.01 138.32 molar mass (at least!) 24.29 + gas 74.77 molar volumes (at least!) 307 % expansion (less water volume reduction) producing much more binder per mole of MgO than lime (around 8 times) Carbonates tend to be fibrous adding significant micro structural strength compared to lime Mostly CO 2 and water As Fred Pearce reported in New Scientist Magazine (Pearce, F., 2002), There is a way to make our city streets as green as the Amazon rainforest.
Presentation downloadable from www.tececo.com 52 CO 2 Abatement in Eco-Cements Eco-cements in porous products absorb carbon dioxide from the atmosphere. Brucite carbonates forming lansfordite, nesquehonite and an amorphous phase, completing the thermodynamic cycle. No Capture 11.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate. Emissions.37 tonnes to the tonne. After carbonation. approximately.241 tonne to the tonne. Portland Cements 15 mass% Portland cement, 85 mass% aggregate Emissions.32 tonnes to the tonne. After carbonation. Approximately.299 tonne to the tonne..299 >.241 >.140 >.113 Bricks, blocks, pavers, mortars and pavement made using eco-cement, fly and bottom ash (with capture of CO 2 during manufacture of reactive magnesia) have 2.65 times less emissions than if they were made with Portland cement. Capture CO 2 11.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate. Emissions.25 tonnes to the tonne. After carbonation. approximately.140 tonne to the tonne. Capture CO 2. Fly and Bottom Ash 11.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate. Emissions.126 tonnes to the tonne. After carbonation. Approximately.113 tonne to the tonne. For 85 wt% Aggregates 15 wt% Cement Greater Sustainability
Presentation downloadable from www.tececo.com 53 Eco-Cement Strength Development Eco-cements gain early strength from the hydration of PC. Later strength comes from the carbonation of brucite forming an amorphous phase, lansfordite and nesquehonite. Strength gain in eco-cements is mainly microstructural because of –More ideal particle packing (Brucite particles at 4-5 micron are under half the size of cement grains.) –The natural fibrous and acicular shape of magnesium carbonate minerals which tend to lock together. More binder is formed than with calcium –Total volumetric expansion from magnesium oxide to lansfordite is for example volume 811%. Mg(OH) 2 + CO 2 MgCO 3.5H 2 O From air and water
Presentation downloadable from www.tececo.com 54 Eco-Cement Strength Gain Curve Eco-cement bricks, blocks, pavers and mortars etc. take a while to come to the same or greater strength than OPC formulations but are stronger than lime based formulations.
Presentation downloadable from www.tececo.com 55 Chemistry of Eco-Cements There are a number of carbonates of magnesium. The main ones appear to be an amorphous phase, lansfordite and nesquehonite. The carbonation of magnesium hydroxide does not proceed as readily as that of calcium hydroxide. – G o r Brucite to nesquehonite = - 38.73 kJ.mol-1 –Compare to G o r 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. G o r nesquehonite to magnesite = 8.56 kJ.mol-1 –But kinetically driven by desiccation during drying. Reactive magnesia can carbonate in dry conditions – so keep bags sealed! For a full discussion of the thermodynamics see our technical documents. TecEco technical documents on the web cover the important aspects of carbonation.
Presentation downloadable from www.tececo.com 56 Eco-Cement Reactions
Presentation downloadable from www.tececo.com 57 Eco-Cement Micro-Structural Strength
Presentation downloadable from www.tececo.com 58 Carbonation Eco-cement is based on blending reactive magnesium oxide with other hydraulic cements and then allowing the Brucite and Portlandite components to carbonate in porous materials such as concretes blocks and mortars. –Magnesium is a small lightweight atom and the carbonates that form contain proportionally a lot of CO 2 and water and are stronger because of superior microstructure. The use of eco-cements for block manufacture, particularly in conjunction with the kiln also invented by TecEco (The Tec-Kiln) would result in sequestration on a massive scale. As Fred Pearce reported in New Scientist Magazine (Pearce, F., 2002), There is a way to make our city streets as green as the Amazon rainforest. Ancient and modern carbonating lime mortars are based on this principle
Presentation downloadable from www.tececo.com 59 Aggregate Requirements for Carbonation The requirements for totally hydraulic limes and all hydraulic concretes is to minimise the amount of water for hydraulic strength and maximise compaction and for this purpose aggregates that require grading and relatively fine rounded sands to minimise voids are required For carbonating eco-cements and lime mortars on the on the hand the matrix must breathe i.e. they must be porous –requiring a coarse fraction to cause physical air voids and some vapour permeability. Coarse fractions are required in the aggregates used!
Presentation downloadable from www.tececo.com 60 CO 2 Abatement in Eco-Cements Eco-cements in porous products absorb carbon dioxide from the atmosphere. Brucite carbonates forming lansfordite, nesquehonite and an amorphous phase, completing the thermodynamic cycle. No Capture 11.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate. Emissions.37 tonnes to the tonne. After carbonation. approximately.241 tonne to the tonne. Portland Cements 15 mass% Portland cement, 85 mass% aggregate Emissions.32 tonnes to the tonne. After carbonation. Approximately.299 tonne to the tonne..299 >.241 >.140 >.113 Bricks, blocks, pavers, mortars and pavement made using eco-cement, fly and bottom ash (with capture of CO 2 during manufacture of reactive magnesia) have 2.65 times less emissions than if they were made with Portland cement. Capture CO 2 11.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate. Emissions.25 tonnes to the tonne. After carbonation. approximately.140 tonne to the tonne. Capture CO 2. Fly and Bottom Ash 11.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate. Emissions.126 tonnes to the tonne. After carbonation. Approximately.113 tonne to the tonne. For 85 wt% Aggregates 15 wt% Cement Greater Sustainability
Presentation downloadable from www.tececo.com 61 TecEco Cement LCA TecEco Concretes will have a big role post Kyoto as they offer potential sequestration as well as waste utilisation The TecEco LCA model is available for download under tools on the web site
Presentation downloadable from www.tececo.com 62 Tec-Cement Reactions MgO + H 2 O => Mg(OH) 2.nH 2 O - water consumption resulting in greater density and higher alkalinity. Higher alkalinity => more reactions involving silica & alumina. Mg(OH) 2.nH 2 O => Mg(OH) 2 + H 2 O – slow release water for more complete hydration of PC MgO + Al + H 2 O => 3MgO.Al.6H 2 O ??? – equivalent to flash set?? MgO + SO 4 -- => various Mg oxy sulfates ?? – yes but more likely ettringite reaction consumes SO 4 -- first. MgO + SiO 2 => MSH ?? Yes but high alkalinity required. Strength?? We think the reactions are relatively independent of PC reactions
Presentation downloadable from www.tececo.com 63 The Form of MgO Matters - Lattice Energy Destroys a Myth Magnesia, provided it is reactive rather than dead burned (or high density, crystalline periclase type), can be beneficially added to cements in excess of the amount of 5 mass% generally considered as the maximum allowable by standards prevalent in concrete dogma. –Reactive magnesia is essentially amorphous magnesia with low lattice energy. –It is produced at low temperatures and finely ground, and –will completely hydrate in the same time order as the minerals contained in most hydraulic cements. Dead burned magnesia and lime have high lattice energies –Crystalline magnesium oxide or periclase has a calculated lattice energy of 3795 Kj mol-1 which must be overcome for it to go into solution or for reaction to occur. –Dead burned magnesia is much less expansive than dead burned lime in a hydraulic binder (Ramachandran V. S., Concrete Science, Heydon & Son Ltd. 1981, p 358-360 )
Presentation downloadable from www.tececo.com 64 More Rapid and Greater Strength Development Higher Strength Binder Ratio Early strength gain with less cement and added pozzolans is of great economic and environmental importance as it will allow the use of more pozzolans. Concretes are more often than not made to strength. The use of tec-cement results in –15-30% more 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 We have observed this sort of curve in over 500 cubic meters of concrete now
Presentation downloadable from www.tececo.com 65 Tec-Cement Strength Development Graphs above by Oxford Uni Student are for standard 1PC:3 aggregate mixes, w/c =.5 WHITTLESEA SLAB (A modified 20 mpa mix) PC = 180 Kg / m3 MgO = 15 Kg / m3 Flyash = 65 Kg / m3 Rate of strength development is of great interest to engineers and constructors
Presentation downloadable from www.tececo.com 66 Calorimetric Evidence of Faster Strength Gain Evolution of Less Heat Faster Strength Development Energy associated with complexing?
Presentation downloadable from www.tececo.com 67 Reasons for Compressive Strength Development in Tec-Cements. Reactive magnesia requires considerable water to hydrate resulting in: –Denser, less permeable concrete. Self compaction? –A significantly lower voids/paste ratio. Higher early pH initiating more effective silicification reactions? –The Ca(OH) 2 normally lost in bleed water is used internally for reaction with pozzolans. –Super saturation of alkalis caused by the removal of water? Micro-structural strength due to particle packing (Magnesia particles at 4-5 micron are a little over ½ the size of cement grains.) Formation of MgAl hydrates? Similar to flash set in concrete but slower?? Formation of MSH?? Slow release of water from hydrated Mg(OH) 2.nH 2 O supplying H 2 O for more complete hydration of C 2 S and C 3 S? Brucite gains weight in excess of the theoretical increase due to MgO conversion to Mg(OH)2 in samples cured at 98% RH. Dr Luc Vandepierre, Cambridge University, 20 September, 2005.
Presentation downloadable from www.tececo.com 68 Greater Tensile Strength MgO Changes Surface Charge as the Ph Rises. This could be one of the reasons for the greater tensile strength displayed during the early plastic phase of tec- cement concretes. The affect of additives is not yet known + + + + + + + + + + + + + + + + + + + + Mutual Repulsion => + + + + + + + + + + + + + + - - - - - - - Ph 12 ? Cement MgO Sand MgO Mutual Repulsion Mutual Attraction
Presentation downloadable from www.tececo.com 69 Durability Concretes are said to be less durable when they are physically or chemically compromised. Physical factors can result in chemical reactions reducing durability –E.g. Cracking due to shrinkage can allow reactive gases and liquids to enter the concrete Chemical factors can result in physical outcomes reducing durability –E.g. Alkali silica reaction opening up cracks allowing other agents such as sulfate and chloride in seawater to enter. This presentation will describe benchmark improvements in durability as a result of using the new TecEco magnesia cement technologies
Presentation downloadable from www.tececo.com 70 Crack Collage TecEco technology can reduce if not solve problems of cracking: –Related to (shrinkage) through open system loss of water. –As a result of volume change caused by delayed reactions –As a result of corrosion. –Related to autogenous shrinkage Thermal Plastic Shrinkage Drying Shrinkage Corrosion Related Freeze Thaw D Cracks Structural Settlement Shrinkage Photos from PCA and US Dept. Ag Websites Autogenous or self-desiccation shrinkage (usually related to stoichiometric or chemical shrinkage) Alkali aggregate Reaction Evaporative Crazing Shrinkage
Presentation downloadable from www.tececo.com 71 Causes of Cracking in Concrete Cracking commonly occurs when the induced stress exceeds the maximum tensile stress capacity of concrete and can be caused by many factors including restraint, extrinsic loads, lack of support, poor design, volume changes over time, temperature dependent volume change, corrosion or delayed reactions. Causes of induced stresses include: –Restrained thermal, plastic, drying and stoichiometric shrinkage, corrosion and delayed reaction strains. –Slab curling. –Loading on concrete structures. Cracking is undesirable for many reasons –Visible cracking is unsightly –Cracking compromises durability because it allows entry of gases and ions that react with Portlandite. –Cracking can compromise structural integrity, particularly if it accelerates corrosion.
Presentation downloadable from www.tececo.com 72 Graphic Illustration of Cracking After Tony Thomas (Boral Ltd.) (Thomas 2005) Autogenous shrinkage has been used to refer to hydration shrinkage and is thus stoichiometric
Presentation downloadable from www.tececo.com 73 Cracking due to Loss of Water Drying Shrinkage Plastic Shrinkage Picture from: http://www.pavement.com/techserv/ACI-GlobalWarming.PDF Evaporative Crazing Shrinkage Settlement Shrinkage We may not be able to prevent too much water being added to concrete by fools. TecEco approach the problem in a different way by providing for the internal removal/storage of water that can provide for more complete hydration of PC. Brucite gains weight in excess of the theoretical increase due to MgO conversion to Mg(OH)2 in samples cured at 98% RH. Dr Luc Vandepierre, Cambridge University, 20 September, 2005. Bucket of Water Fool
Presentation downloadable from www.tececo.com 74 Solving Cracking due to Shrinkage from Loss of Water In the system water plus Portland cement powder plus aggregates shrinkage is in the order of.05 – 1.5 %. Shrinkage causes cracking There are two main causes of Portland cements shrinking over time. –Stoichiometric (chemical) shrinkage and –Shrinkage through loss of water. The solution is to: –Add minerals that compensate by stoichiometrically expanding and/or to –Use less water, internally hold water or prevent water loss. TecEco tec-cements internally hold water and prevent water loss. MgO (s) + H 2 O (l) Mg(OH) 2.nH 2 O (s)
Presentation downloadable from www.tececo.com 75 When magnesia hydrates it consumes 18 litres of water per mole of magnesia probably more depending on the value of n in the reaction below: MgO (s) + H 2 O (l) Mg(OH) 2. nH2O (s) The dimensional change in the system MgO + PC depends on: –The ratio of MgO to PC –Whether water required for hydration of PC and MgO is coming from stoichiometric mix water (i.e. the amount calculated as required), excess water (bleed or evaporative) or from outside the system. –In practice tec-cement systems are more closed and thus dimensional change is more a function of the ratio of MgO to PC As a result of preventing the loss of water by closing the system together with expansive stoichiometry of MgO reactions (see below). MgO (s) + H 2 O (l) Mg(OH) 2. nH2O (s) 40.31 + 18.0 58.3 molar mass (at least!) 11.2 + liquid 24.3 molar volumes (at least!) It is possible to significantly reduce if not prevent (drying, plastic, evaporative and some settlement) shrinkage as a result of water losses from the system. The molar volume (L.mol-1)is equal to the molar mass (g.mol-1) divided by the density (g.L-1). Preventing Shrinkage through Loss of Water
Presentation downloadable from www.tececo.com 76 Portland cements stoichiometrically require around 23 -27% water for hydration yet we add approximately 45 to 60% at cement batching plants to fluidise the mix sufficiently for placement. If it were not for the enormous consumption of water by tri calcium aluminate as it hydrates forming ettringite in the presence of gypsum, concrete would remain as a weak mush and probably never set. –26 moles of water are consumed per mole of tri calcium aluminate to from a mole of solid ettringite. When the ettringite later reacts with remaining tri calcium aluminate to form monosulfoaluminate hydrate a further 4 moles of water are consumed. The addition of reactive MgO achieves water removal internally in a closed system in a similar way. Preventing Shrinkage through Loss of Water MgO (s) + H 2 O (l) Mg(OH) 2.nH 2 O (s)
Presentation downloadable from www.tececo.com 77 Other Benefits of Preventing Shrinkage through Loss of Water Internal water consumption also results in: –Greater strength More complete hydration of PC. Reduced in situ voids:paste ratio –Greater density Increased durability Higher short term alkalinity More effective pozzolanic reactions. More complete hydration of PC. –Small substitutions of PC by MgO result in water being trapped inside concrete as Brucite and Brucite hydrates which can later self desiccate delivering water to hydration reactions of calcium silicates (Preventing so called Autogenous shrinkage).
Presentation downloadable from www.tececo.com 78 Bleeding is a Bad Thing Bleeding is caused by: –Lack of fines –Too much water Bleeding can be fixed by: –Reducing water or adding fines –Air entrainment or grading adjustments Bleeding causes: –Reduced pumpability –Loss of cement near the surface of concretes –Delays in finishing –Poor bond between layers of concrete –Interconnected pore structures that allow aggressive agents to enter later –Slump and plastic cracking due to loss of volume from the system –Loss of alkali that should remain in the system for better pozzolanic reactions –Loss of pollutants such as heavy metals if wastes are being incorporated. Concrete is better as a closed system Better to keep concretes as closed systems
Presentation downloadable from www.tececo.com 79 Dimensional Control in Tec-Cement Concretes over Time By adding MgO volume changes are minimised to close to neutral. –So far we have observed significantly less shrinkage in TecEco tec - cement concretes with about (8-10% substitution OPC) with or without fly ash. –At some ratio, thought to be around 15-18% reactive magnesia there is no shrinkage. –The water lost by concrete as it shrinks is used by the reactive magnesia as it hydrates eliminating shrinkage. Note that brucite is > 44.65 mass% water and it makes sense to make binders out of water! More research is required to accurately establish volume relationships and causes for reduced shrinkage.
Presentation downloadable from www.tececo.com 80 Long Term pH control TecEco add reactive magnesia which hydrates forming brucite which is another alkali, but much less soluble, mobile or reactive than Portlandite. Brucite provides long term pH control. A pH in the range 10.5 – 11.2 is ideal in a concrete
Presentation downloadable from www.tececo.com 81 Reducing Cracking as a Result of Volume Change caused by Delayed Reactions Photo Courtesy Ahmad Shayan ARRB An Alkali Aggregate Reaction Cracked Bridge Element
Presentation downloadable from www.tececo.com 82 Types of Delayed Reactions There are several types of delayed reactions that cause volume changes (generally expansion) and cracking. –Alkali silica reactions –Alkali carbonate reactions –Delayed ettringite formation –Delayed thaumasite formation –Delayed hydration or dead burned lime or periclase. Delayed reactions cause dimensional distress, cracking and possibly even failure.
Presentation downloadable from www.tececo.com 83 Reducing Delayed Reactions 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. –Magnesia dries concrete out from the inside. Reactions do not occur without water.
Presentation downloadable from www.tececo.com 84 Reduced Steel Corrosion Related Cracking Steel remains protected with a passive oxide coating of Fe 3 O 4 above pH 8.9. A pH of over 8.9 is maintained by the equilibrium Mg(OH) 2 Mg ++ + 2OH - for much longer than the pH maintained by Ca(OH) 2 because: –Brucite does not react as readily as Portlandite resulting in reduced carbonation rates and reactions with salts. Concrete with brucite in it is denser and carbonation is expansive, sealing the surface preventing further access by moisture, CO 2 and salts. Rusting Causes Dimensional Distress
Presentation downloadable from www.tececo.com 85 Reduced Steel Corrosion 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.) As a result of the above the rusting of reinforcement does not proceed to the same extent. Cracking or spalling due to rust does not occur
Presentation downloadable from www.tececo.com 86 Steel Corrosion is Influenced by Long Term pH Eh-pH or Pourbaix Diagram The stability fields of hematite, magnetite and siderite in aqueous solution; total dissolved carbonate = 10 -2 M. In TecEco cements the long term pH is governed by the low solubility and carbonation rate of brucite and is much lower at around 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 Fe 3 O 4 stable in reducing conditions. Steel corrodes below 8.9 Equilibrium pH of Brucite and of lime
Presentation downloadable from www.tececo.com 87 Reducing Cracking Related to Autogenous Shrinkage Autogenous shrinkage tends to occur in high performance concretes in which dense microstructures develop quickly preventing the entry of additional water required to complete hydration. –First defined by Lynam in 1934 (Lynam CG. Growth and movement in Portland cement concrete. London: Oxford University Press; 1934. p. 26-7.) The autogenous deformation of concrete is defined as the unrestrained, bulk deformation that occurs when concrete is kept sealed and at a constant temperature.
Presentation downloadable from www.tececo.com 88 Reducing Cracking Related to Autogenous Shrinkage Main cause is stoichiometric or chemical shrinkage as observed by Le Chatelier. –whereby the reaction products formed during the hydration of cement occupy less space than the corresponding reactants. A dense cement paste hydrating under sealed conditions will therefore self-desiccate creating empty pores within developing structure. If external water is not available to fill these empty pores, considerable shrinkage can result. Le Chatelier H. Sur les changements de volume qui accompagnent Ie durcissement des ciments. Bulletin de la Societe d'Encouragement pour I'Industrie Nationale 1900:54-7.
Presentation downloadable from www.tececo.com 89 Reducing Cracking Related to Autogenous Shrinkage Autogenous shrinkage does not occur in high strength tec-cement concretes because: –The brucite hydrates that form desiccate back to brucite delivering water in situ for more complete hydration of Portland cement. Mg(OH) 2.nH 2 O (s) MgO (s) + H 2 O (l) As brucite is a relatively weak mineral compressed and densifies the microstructure. –The stoichiometric shrinkage of Portland cement (first observed by Le Chatelier) is compensated for by the stoichiometric expansion of magnesium oxide on hydration. MgO (s) + H 2 O (l) Mg(OH) 2. nH 2 O (s) 40.31 + 18.0 58.3 molar mass (at least!) 11.2 + liquid 24.3 molar volumes (at least 116% expansion, probably more initially before desiccation as above!)
Presentation downloadable from www.tececo.com 90 Improved Durability Materials that last longer need replacing less often saving on energy and resources. Reasons for Improved Durability: –Greater Density = Lower Permeability Physical Weaknesses => Chemical Attack –Removal of Portlandite with the Pozzolanic Reaction. Removal or reactive components –Substitution by Brucite => Long Term pH control Reducing corrosion
Presentation downloadable from www.tececo.com 91 Reduced Permeability As bleed water exits ordinary Portland cement concretes it creates an interconnected pore structure that remains in concrete allowing the entry of aggressive agents such as SO 4 --, Cl - and CO 2 TecEco tec - cement concretes are a closed system. They do not bleed as excess water is consumed by the hydration of magnesia. –As a result TecEco tec - cement concretes dry from within, are denser and less permeable and therefore stronger more durable and less permeable. 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 92 Concretes have a high percentage (around 18% – 22%) of voids. On hydration magnesia expands >=116.9 % filling voids and surrounding hydrating cement grains => denser concrete. On carbonation to nesquehonite brucite expands 307% sealing the surface. Lower voids:paste ratios than water:binder ratios result in little or no bleed water, lower permeability and greater density. Greater Density – Lower Permeability
Presentation downloadable from www.tececo.com 93 Densification During the Plastic Phase Water is required to plasticise concrete for placement, however once placed, the less water over the amount required for hydration the better. Magnesia consumes water as it hydrates producing solid material. Less water results in increased density and concentration of alkalis - less shrinkage and cracking and improved strength and durability.
Presentation downloadable from www.tececo.com 94 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 Durability - Reduced Salt & Acid Attack
Presentation downloadable from www.tececo.com 95 Less Freeze - Thaw Problems Denser concretes do not let water in. Brucite will to a certain extent take up internal stresses When magnesia hydrates it expands into the pores left around hydrating cement grains: MgO (s) + H 2 O (l) Mg(OH) 2 (s) 40.31 + 18.0 58.3 molar mass 11.2 + 18.0 24.3 molar volumes 39.20 24.3 molar volumes At least 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 96 Rosendale Concretes – Proof of Durability Rosendale cements contained 14 – 30% MgO A major structure built with Rosendale cements commenced in 1846 was Fort Jefferson near key west in Florida. Rosendale cements were recognized for their exceptional durability, even under severe exposure. At Fort Jefferson much of the 150 year-old Rosendale cement mortar remains in excellent condition, in spite of the severe ocean exposure and over 100 years of neglect. Fort Jefferson is nearly a half mile in circumference and has a total lack of expansion joints, yet shows no signs of cracking or stress. The first phase of a major restoration is currently in progress. More information from http://www.rosendalecement.net/rosendale_natural_cement_.html
Presentation downloadable from www.tececo.com 97 Solving Waste & Logistics Problems TecEco cementitious composites represent a cost affective option for –using non traditional aggregates from on site reducing transports costs and emissions –use and immobilisation of waste. Because they have –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 98 Role of Brucite in Immobilization In a Portland cement Brucite matrix –PC derive CSH takes up lead, some zinc and germanium –Pozzolanic CSH can take up mobile cations –Brucite and hydrotalcite are both excellent hosts for toxic and hazardous wastes. –Heavy metals not taken up in the structure of Portland cement minerals or trapped within the brucite layers end up as hydroxides with minimal solubility. The Brucite in TecEco cements has a structure comprising electronically neutral layers and is able to accommodate a wide variety of extraneous substances between the layers and cations of similar size substituting for magnesium within the layers and is known to be very suitable for toxic and hazardous waste immobilisation. Layers of electronically neutral brucite suitable for trapping balanced cations and anions as well as other substances. Salts and other substances trapped between the layers. Van de waals bonding holding the layers together.
Presentation downloadable from www.tececo.com 99 Lower Solubility of Metal Hydroxides There is a 10 4 difference All waste streams will contain heavy metals and a strategy for long term pH control is therefore essential
Presentation downloadable from www.tececo.com 100 Using Wastes and Non-Traditional Aggregates to Make TecEco Cement Concretes Many wastes and local materials can contribute physical property values. –Plastics for example are collectively light in weight, have tensile strength and low conductance. Tec, eco and enviro-cements will allow a wide range of wastes and non-traditional aggregates such as local materials to be used. Tec, enviro and eco-cements are benign binders that are: –low alkali reducing reaction problems with organic materials. –stick well to most included wastes Tec, enviro and eco-cements can utilize wastes including carbon to increase sequestration preventing their conversion to methane There are huge volumes of concrete produced annually (>2 tonnes per person per year)
Presentation downloadable from www.tececo.com 101 Biomimicry - Ultimate Recyclers As peak oil looms and the price of transport is set to rise sharply –We should not just be recycling based on chemical property requiring sophisticated equipment and resources –We should be including wastes based on physical properties as well as chemical composition in composites whereby they become local resources. The Jackdaw recycles all sorts of things it finds nearby based on physical property. The bird is not concerned about chemical composition and the nest it makes could be described as a composite material. TecEco cements are benign binders that can incorporate all sort of wastes without reaction problems. We can do the same as the Jackdoor
Presentation downloadable from www.tececo.com 102 Using Wastes and Non-Traditional Aggregates to Make TecEco Cement Concretes As the price of fuel rises, the use of local or on site low embodied energy materials rather than carted aggregates will have to be considered. Recent natural disasters such as the recent tsunami and Pakistani earthquake mean we urgently need to commercialize TecEco technologies because they provide benign environments allowing the use of many local materials and wastes without delayed reactions No longer an option? The use of on site and local wastes will be made possible by the use of low reactivity TecEco mixes and a better understanding of particle packing. We hope with our new software to be able to demonstrate how adding specific size ranges can make an unusable waste such as a tailing or sludge suitable for making cementitious materials.
Presentation downloadable from www.tececo.com 103 Easier to Finish Concretes Easier to pump and finish Concretes are likely to have less water added to them resulting in less cracking
Presentation downloadable from www.tececo.com 104 Non Newtonian Rheology The strongly positively charged small Mg++ atoms attract water (which is polar) in deep layers introduce a shear thinning property affecting the rheological properties and making concretes less sticky with added pozzolan It is not known how deep these layers get Etc. Ca++ = 114, Mg++ = 86 picometres
Presentation downloadable from www.tececo.com 105 Bingham Plastic Rheology TecEco concretes and mortars are: –Very homogenous and do not segregate easily. They exhibit good adhesion and have a shear thinning property. –Exhibit Bingham plastic qualities and react well to energy input. –Have good workability. TecEco concretes with the same water/binder ratio have a lower slump but greater plasticity and workability. 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 www.tececo.com 106 Scientific approach to concrete design In the past, concrete proportioning was based on experience and estimates only. TecEco is develloping batching software, using theory from the worlds best experts theory (F. de Larrard, K. Day), to optimize mix design and particularly particle packing. Satterfield, S. G. (2001). Visualization of High Performance Concrete, National institute of standard and technology.
Presentation downloadable from www.tececo.com 107 Scientific approach to concrete design (2) TecEco sees the optimization of particle as not only a mean to improve the strength/cost ratio but to improve concrete sustainability. This is because improving packing (other parameter beiing equal) leads to an increase of: –The compressive and tensile strength –The workability –The durability And a decrease of: –The porosity –The risk of segregation –The yield stresses (easier to compact) Scientific knowledge of the concrete behaviour coupled with the use of optimization software allows concrete technologist to: -Design more sustainable concrete -Use secondary aggregate and mining waste (poor size distribution) -Dramatically reduce the number of experiment needed to design a concrete for a special application
Presentation downloadable from www.tececo.com 108 Tec-Cement Concretes Tec-Cements contain around 5-20% reactive MgO and are mainly formulated because of: –Superior thixotropic properties –Less cracking and shrinkage –Greater durability –Low reactivity Ability to incorporate a wide range of wastes. TecEco are looking for technical problems that are not being solved using conventional formulations as to us they represent niche markets.
Presentation downloadable from www.tececo.com 109 The TecEco Dream – A More Sustainable Built Environment MAGNESITE + OTHER INPUTS TECECO CONCRETES MINING SUSTAINABLE CITIES CO 2 PERMANENT SEQUESTRATION & WASTE UTILISATION (Man made carbonate rock incorporating wastes as a building material) CO 2 MgO TECECO KILN RECYCLED BUILDING MATERIALS OTHER WASTES CO 2 FOR GEOLOGICAL SEQUESTRATION We need materials that require less energy to make them, that last much longer and that contribute properties that reduce lifetime energies There is a way to make our city streets as green as the Amazon rainforest. Fred Pearce, New Scientist Magazine
Presentation downloadable from www.tececo.com 110 Sustainable Materials in the Built Environment - 2007 Technical Focus This Conference will focus on: The impacts and connectivity of different parts of the supply chain. Fabrication, performance, recycling and waste New developments in materials and processes Reviewing existing materials assessment tools Future directions in regulation Opportunities/barriers to introduction of sustainable materials and technologies in the building industry. New materials and more sustainable built environments: the evidence? Joint Venture Websites ASSMIC Website: www.aasmic.org Materials Australia Website: www.materialsaustralia.com.au