Presentation on theme: "Implementing Sustainability"— Presentation transcript:
1 Implementing Sustainability John Harrison Presentation AASMIC ConferenceImplementing SustainabilityPresentation 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 problemsOur 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.
2 The Problem. We have a Planet in Crisis In the next 50 years it is crunch time for:Fresh WaterGlobal warmingEnergyWaste & PollutionAre you thinking about it? Do you have an answer?
3 Fresh WaterThe 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.
4 John Harrison Presentation AASMIC Conference Global WarmingJohn Harrison Presentation AASMIC ConferenceRises in the levels of carbon dioxide and other gases (methane, water vapour)ATMOSPHERIC CARBON DIOXIDEOf particular concern and therefore the most studied is the problem of CO2 in the atmosphere and the global warming that results. The level of CO2 from the burning of fossil fuels is rising too rapidly for natural processes to absorb and in the air has risen from 280 parts per million in pre-industrial times to just under 380 parts per million in 2004.Are causing a rapid rise in temperature
5 The Carbon Cycle and Emissions Emissions from fossil fuels and cement production are the cause of the global warming problemSource: David Schimel and Lisa Dilling, National Centre for Atmospheric Research 2003
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 It follows that there will be economic mayhem unless the cement and concrete industry acts now to change the energy base of their products.
7 Waste & PollutionWaste 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 commonsThere are various estimates, but we produce about million tonnes of waste each year.
8 Ecological FootprintOur 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
9 All these Problems Represent an Opportunity to Do Something About Them John Harrison Presentation AASMIC ConferenceAll these Problems Represent an Opportunity to Do Something About ThemThe built environment is made of materials and is our footprint on earth.It comprises buildings and infrastructure.Construction materials comprise70% 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 resourcesCombined 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.THE IMPORTANCE OF MATERIALSMaterials are our footprint on the planet and of first consideration in our quest to devise ways of using carbon dioxide and other wastes.Building 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.)
10 How? - The Techno-Processes & Earth Systems John Harrison Presentation AASMIC ConferenceHow? - The Techno-Processes & Earth SystemsUnderlying 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.Bio-sphereGeo-sphereEarth SystemsAtmospheric composition, climate, land cover, marine ecosystems, pollution, coastal zones, freshwater and salinity.Detrimental affects on earth systemsWasteTakeMove billion tonnes Use some 50 billion tonnesTHE TECHNO-PROCESSMost of you will have by now come to realise that there is a process often described as the “take use waste process” that I call the techno process. Unfortunately there are affects on global systems that are detrimental.Manipulate,Make and UseTechno-sphereTo 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.
11 Under Materials Flows in the Techno-Processes are Molecular Flows John Harrison Presentation AASMIC ConferenceUnder Materials Flows in the Techno-Processes are Molecular FlowsTake → 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, cfc’s, c=halogen compounds and CO2Moleconomics 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.MOLECONOMIC FLOWSUnderlying the flow of materials through the techno process is a moleconomic flow of molecules that is out of tune with the rest of the planet and causing damage to the environment. If you want to know more about the science of moleconomics please go to our web site and look under projects.
12 There are Detrimental Affects Right Through the Techno-process John Harrison Presentation AASMIC ConferenceThere are Detrimental Affects Right Through the Techno-processDetrimental Linkages that affect earth system flowsTake manipulate and make impactsEnd of lifecycle impactsMaterials are in the Techno-sphere Utility zoneThere is no such place as “away”THERE ARE DETRIMENTAL AFFECTS RIGHT THROUGH THE TECHNO PROCESSMaterials are everything between the take and wasteMaterials are everything between the take and waste and affect earth system flows.Greater UtilityLess Utility
13 We Must Learn from Nature (Biomimicry) John Harrison Presentation AASMIC ConferenceWe 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-processThere is a strong need for similar efficiency and balanceBy learning from Nature we can all live togetherBIOMIMICRYThe philosophy and chemistry of TecEco technology is backed by the greatest and longest experiment of all time – that of life on this planet.Little is wasted in nature, the waste from one living thing being the home or food for another.We must, like nature, devise ways of using carbon dioxide and other wastes.
14 BiomimicryThe term biomimicry was popularised by the book of the same name written by Janine BenyusBiomimicry 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
15 Economically Driven Sustainability John Harrison Presentation AASMIC ConferenceEconomically Driven SustainabilityThe 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.$ - ECONOMICS - $Sustainable processes are more efficient and therefore more economic. Natural ecosystems can be 100% efficient. What is needed are new technologies that allow material and energy flows to more closely mimic natural ecosystems.Innovation will deliver these new technical paradigms.ECONOMICALLY DRIVEN SUSTAINABILITYOur approach must not only be holistic, but also economic if we are to have any hope of success.Working for sustainability market forces will make all the difference.The challenge is to move the supply and demand of resources towards more sustainable outcomes by:Stimulating and harnessing human behaviours which underlay economic demand phenomena through cultural change push by governments and other leaders and real improvement in technical and other properties.Delivery of more sustainable technologies by changing the technical paradigm to for example make carbon dioxide and other wastes resources. “By enabling us to make productive use of particular raw materials, technology determines what constitutes a physical resource”(Pilzer, P. Z., 1990).Change is itself a stimulant for economic growth and we therefore have nothing to fear from the process of change towards sustainability.Sustainable processes are more efficient and therefore more economic. What is needed are sustainable process that also deliver sustainable materials and the new TecEco technologies hold much promise of this.Sustainability will not happen by relying on people to do the right thing
16 Sustainability = Culture + Technology John Harrison Presentation AASMIC ConferenceSustainability = Culture + TechnologyIncrease in demand/price ratio for sustainability due to educationally induced cultural drift.$SupplyGreater Value/for impact (Sustainability) and economic growthEquilibrium shiftECONOMICSNew Technical Paradigms are required that deliver sustainability.DemandIncrease in supply/price ratio for more sustainable products due to innovative paradigm shifts in technology.#CULTURAL CHANGE AND PARADIGM SHIFTS IN TECHNOLOGYChanges in the market interaction of demand and supply reducing energy and resource usage and detrimental linkages with the planet can be achieved through cultural change and innovative changes in the technical paradigm.One aspect of sustainability is that it is where Culture and Technology meet.
17 Changing the Technology Paradigm 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“By enabling us to make productive use of particular raw materials, technology determines what constitutes a physical resource1”Pilzer, Paul Zane, Unlimited Wealth, The Theory and Practice of Economic Alchemy, Crown Publishers Inc. New York.1990
18 John Harrison Presentation AASMIC Conference Examples of Economic Changes in Technical Paradigms that result in Greater Sustainability100 watts 1700 lumensIncandescent25 watts 1700 lumensFluorescent<20 watts 1700 lumensLed LightLight Globes - A Recent Paradigm Shift in Technology Reducing Energy ConsumptionLight 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.Robotics - A Paradigm Shift in Technology that will fundamentally affect Building and ConstructionConstruction 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.AN EXAMPLE OF A PARADIGM SHIFT IN TECHNOLOGYAn example demonstrating that technical paradigms can be achieved is of course the common light bulb which we have improved the efficiency of five times in around ten years.
19 The TecEco CarbonSafe Industrial Ecology John Harrison Presentation AASMIC ConferenceThe TecEco CarbonSafe Industrial EcologyInputs Brines Waste Acid CO2CARBONSAFE VECTORSThe CarbonSafe process starts with either magnesium silicates or the Greensols process. In the case of silicates, magnesium carbonates are produced using proven mineral sequestration technology and then transferred to the MgCO3 cycle. The Greensols process on the other hand uses carbon dioxide from power stations and waste acid to extract magnesium carbonate and other salts from seawater or suitable brines and produces potable water as a by-product. The MgCO3 from either process is then calcined in the TecEco kiln which removes and captures carbon dioxide, ready for incorporation for example into cellulose or fuel made by genetically engineered blue green algae, and produces magnesium oxide. This magnesium oxide can either be used to make TecEco cements which in the case of eco-cement absorb more atmospheric CO2 as they harden or alternatively be used to sequester more CO2 in a hydroxide/carbonate slurry capture process.The MgCO3 produced by the hydroxide slurry process can be decarbonated and cycle around that process indefinitely as in this slide.Outputs Gypsum, Sodium bicarbonate, Salts, Building materials, Potable waterWe must design whole new technical paradigms that reverse many of our problem molecular flows
20 A Low Energy Post – Carbon & Waste Age? John Harrison Presentation AASMIC ConferenceA Low Energy Post – Carbon & Waste Age?ECO-CEMENTSThe main magnesium carbonate that form in eco-cement is nesquehonite which is 83 mass % water and CO2 – cheap binder? Lansfordite, another mineral that forms has even more water in it!Magnesium carbonates are generally fibrous and acicular and therefore add microstructural strength.The long term pH is much lower than Portland cement concretes. Combined with the fact that magnesium minerals seem to stick well to other materials the result is that a high proportion of wastes can be included.As mentioned earlier TecEco cements are generally also much more durable. Materials that last longer are much more sustainableThe construction industry can be uniquely responsible for helping achieve this transitionMaybe then we can move confidently into a more sustainable future.
21 Innovative New Materials - the Key to Sustainability 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.There is no such place as “away”, only a global commons
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 assimilatedand how we can reduce the impact of these processeswhat energies drive the evolution, devolution and flow of materialsand how we can reduce these energieshow materials impact on lifetime energiesWith the knowledge gained re-design materials to not only be more sustainable but more sustainable in useEnvironmental problems are the result of inherently flawed materials, materials flows and energy systems
23 Changing the Techno-process John Harrison Presentation AASMIC ConferenceChanging the Techno-processTake => manipulate => make => use => wasteDriven by fossil fuel energy with detrimental effects on earth systems.Reduce Re-use RecycleEco-innovateINDUSTRIAL ECOLOGY – CHANGING THE TECHNO-PROCESSIndustrial ecology, the idea that the waste output of one kind of activity can be resource input for another, is most easily achieved in cities.The materials used determine many properties including weight, embodied energies, fuel related and chemical emissions, lifetime energies, user comfort and health, use of recycled wastes, durability, recyclability and the properties of wastes returned to the bio-geo-sphere.There is huge scope for sequestration and conversion of waste to resource given the massive size of the materials flows involved in the built environment. With the right materials technology, because of its sheer size, the built environment could reduce the take from the bio-geo-sphere and utilise many different wastes including carbon dioxideMaterialsImproving the sustainability of materials used to create the built environment will reduce the impact of the take and waste phases of the techno-process
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 buildingsMany wastes can contribute to physical properties reducing lifetime energiesCWaste
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.In eco-cement blocks and mortars the binder is carbonate and the aggregates are preferably wastesWe all use carbon and wastes to make our homes! “Biomimicry”
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 annumMuch more concrete is used than any other building material.TecEco Pty. Ltd. have benchmark technologies for improvement in sustainability and properties
27 Embodied Energy of Building Materials Concrete is relatively environmentally friendly and has a relatively low embodied energyDownloaded from (last accessed 07 March 2000)
28 Average Embodied Energy in Buildings Most of the embodied energy in the built environment is in concrete.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.Downloaded from (last accessed 07 March 2000)
29 Emissions from Cement Production Chemical ReleaseThe process of calcination involves driving off chemically bound CO2 with heat.CaCO3 →CaO + ↑CO2Process EnergyMost 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% of global anthropogenic CO2.Pearce, F., "The Concrete Jungle Overheats", New Scientist, 19 July, No 2097, 1997 (page 14).CO2 CO2Arguments 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.
30 Cement Production ~= Carbon Dioxide Emissions Between tec, eco and enviro-cements TecEco can provide a viable much more sustainable alternative.
31 TecEco Technologies Take Concrete into the Future More rapid strength gain even with added pozzolansMore supplementary materials can be used reducing costs and take and waste impacts.Higher strength/binder ratioLess cement can be used reducing costs and take and waste impactsMore durable concretesReducing costs and take and waste impacts.Use of wastesUtilizing carbon dioxideMagnesia component can be made using non fossil fuel energy and CO2 captured during production.Tec -CementsTec & Eco-CementsEco-Cements
32 John Harrison Presentation AASMIC Conference TecEco Binder SystemsSUSTAINABILITYPORTLANDPOZZOLANHydration of the various components of Portland cement for strength.Reaction of alkali with pozzolans (e.g. lime with fly ash.) for sustainability, durability and strength.TECECO CEMENTSDURABILITYSTRENGTHTECECO BINDER SYSTEMSI am now going to talk just a little about are binder systems which are basically a blending system between Portland and other hydraulic cement, reactive magnesia and, as required, a pozzolanTecEco concretes are a system of blending reactive magnesia, Portland cement and usually a pozzolan with other materials and are a key factor for sustainability.REACTIVE MAGNESIAHydration of magnesia => brucite for strength, workability, dimensional stability and durability. In Eco-cements carbonation of brucite => nesquehonite, lansfordite and an amorphous phase for sustainability.
33 John Harrison Presentation AASMIC Conference TecEco FormulationsTec-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 it’s low solubility, mobility and reactivity results in greater durability.Other benefits include improvements in density, strength and rheology, reduced permeability and shrinkage and the use of a wider range of aggregates many of which are potentially wastes without reaction problems.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.TECECO FORMULATIONSWe have three main formulations to date, Tec-Cements which are really pre-mix concretes, Eco-Cements which have much more magnesia in them and set by carbonation in porous substrates and Enviro-Cements which are relatively weak as they do not carbonate, they are however potentially suitable for toxic and hazardous wastes.
34 Tec & Eco-Cement Theory Many Engineering Issues are Actually Mineralogical IssuesProblems 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 concreteTecEco remove Portlandite it and replacing it with magnesia which hydrates to Brucite.The hydration of magnesia consumes significant water
35 Tec & Eco-Cement Theory John Harrison Presentation AASMIC ConferenceTec & Eco-Cement TheoryPortlandite (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 andTecEco add reactive magnesiawhich hydrates, consuming significant water and concentrating alkalis forming Brucite which is another alkali, but much less soluble, mobile or reactive than Portlandite.In Eco-Cements brucite carbonates forming hydrated compounds with greater volume
36 Why Add Reactive Magnesia? John Harrison Presentation AASMIC ConferenceWhy 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 reactionsTo 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 durableBecause 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
37 Strength with Blend & Porosity Tec-cement concretesEco-cement concretesHigh PorosityEnviro-cement concretesHigh OPCHigh MagnesiaSTRENGTH ON ARBITARY SCALE 1-100
38 TecEco Technology in Practice John Harrison Presentation AASMIC ConferenceTecEco Technology in Practice=> Whittlesea, Vic. AustraliaOn 17th March 2005 TecEco poured the first commercial slab in the world using tec-cement concrete with the assistance of one of the larger cement and pre-mix companies.The formulation strategy was to adjust a standard 20 MPa high fly ash (36%) mix from the company as a basis of comparison.Strength development, and in particular early strength development was good. Interestingly some 70 days later the slab is still gaining strength at the rate of about 5 MPa a month.Also noticeable was the fact that the concrete was not as "sticky" as it normally is with a fly ash mix and that it did not bleed quite as much.Shrinkage was low. 7 days micro strains, 14 days micro strains, 28 days micros strains and at 56 days microstrains.TECECO TECHNOLOGY IN PRACTICEI will now flick through a number of slides just to let you know that we are trying to get as much experience as possible as quickly as possible in all sorts of applications.
39 TecEco Technology in Practice => Porous PavementAllow many mega litres of good fresh water to become contaminated by the pollutants on our streets and pollute coastal waterwaysOrCapture and cleanse the water for our use?
40 TecEco Technology in Practice John Harrison Presentation AASMIC ConferenceTecEco Technology in Practice=> Whittlesea, Vic. AustraliaFirst Eco-cement mud bricks and mortars in AustraliaTested up twice as strong as the PC controlsMud 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.WHITTLESEAAt Whittlesea, shown on this and the previous slide, we have been responsible for all cementitious materials including the slab, mortars, mud bricks, renders etc.
41 TecEco Technology in Practice John Harrison Presentation AASMIC ConferenceTecEco Technology in Practice=> Earthship Brighton, UKBy Taus Larsen, (Architect, Low Carbon Network Ltd.)The Low Carbon Network (www.lowcarbon.co.uk) was established to raise awareness of the links between buildings, the working and living patterns they create, and global warming and aims to initiate change through the application of innovative ideas and approaches to construction. England’s first Earthship is currently under construction in southern England outside Brighton at Stanmer Park and TecEco technologies have been used for the floors and some walling.EARTHSHIP BRIGHTONThis slide shows the interior and exterior of Earthship Brighton in the UK which was the first building we were ever involved in.At Brighton we mainly used Eco-CementsEarthships 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.
42 TecEco Technology in Practice John Harrison Presentation AASMIC ConferenceTecEco Technology in Practice=> Clifton Surf Life Saving ClubThe 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 CLUBThe 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.We are able to remedy the problem with 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.
43 TecEco Technology in Practice John Harrison Presentation AASMIC ConferenceTecEco Technology in Practice=> Mike Burdon’s Murdunna WorksMike 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: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.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.Strength gain was more rapid than with Portland cement controls from the same premix plant and continued for longer.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 formulationMIKE BURDON’S MURDUNNA WORKSMike is a plumber and a friend of mine.We have built footings, two slabs and some tilt ups at his shack. All were significantly better than controls on the same site.
44 TecEco Technology in Practice John Harrison Presentation AASMIC ConferenceTecEco Technology in Practice=> DJ Motors, HobartTec-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.SHRINK AND CRACKPROOF CONCRETEAt the new DJ motors in Hobart we poured some very difficult topping coats that were low or zero shrinkage.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.
45 TecEco Technology in Practice John Harrison Presentation AASMIC ConferenceTecEco Technology in Practice=> Island Block and Paver,TasmaniaTecEco 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.BLOCK MAKINGIsland Block and Paver Pty. Ltd. are a shareholder in TecEco and have made both Tec and Eco-Cement blocks successfully for us.
46 TecEco Technology in Practice John Harrison Presentation AASMIC ConferenceTecEco Technology in Practice=> Foamed ConcretesFoamed 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 CONCRETESWe are working with Buildlite cellular concrete making foamed concretes where the huge mass and volume increase of magnesia as it hydrates become of value.BUILD LITE CELLULAR CONCRETE 4 Rosebank Ave Clayton Sth MELBOURNE AUSTRALIA 3169 PH FX
47 Tec & Eco Cement Foamed Concrete Slabs John Harrison Presentation AASMIC ConferenceTec & Eco Cement Foamed Concrete Slabs=> Foamed Concrete SlabsFOAMED CONCRETE SLABSFoamed concrete slabs, useful for insulation, are made stronger with TecEco technologyBUILD LITE CELLULAR CONCRETE 4 Rosebank Ave Clayton Sth MELBOURNE AUSTRALIA 3169 PH FX
48 TecEco Technology in Practice John Harrison Presentation AASMIC ConferenceTecEco Technology in Practice=> Foamed Concretes PanelsImagine 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 FramingSolutions in SteelABNTEL: FAX: Mica Street Carole Park 4300 Queensland AustraliaFOAMED CONCRETES IN ACTIONRigid steel are using our Tec-Cement foam formulations to make a rather interesting panel.Please direct commercial enquiries to Rigid Steel Framing at rigidsteel.com.au
49 TecEco Technology in Practice John Harrison Presentation AASMIC ConferenceTecEco Technology in Practice=> Foamed Concretes PanelsRIGID STEEL FRAMINGThe panels fit together forming the outside cladding of a building as you put together the frame.Rear view of test panels showing tongue and groove and void for services. Interior plasterboard is fixed conventionally over gap for services.
50 John Harrison Presentation AASMIC Conference Eco-CementsEco-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.ECO-CEMENTS COMPARED TO CARBONATING LIME MORTARSThe underlying chemistry is very similar however eco-cements are potentially superior to lime mortars because:The calcination phase of the magnesium thermodynamic cycle takes place at a much lower temperatureMagnesium minerals are generally more fibrous and acicular than calcium minerals and hence a lot stronger.Water forms part of the binder minerals that forming making the cement component go further.Magnesium hydroxide in particular and to some extent the carbonates are less reactive and mobile and thus much more durable.A less reactive environment with a lower long term pH. (around 10.5 instead of 12.35)Because magnesium has a low molecular weight, proportionally a much greater amount of CO2 is captured.
51 Eco-Cements Have high proportions of reactive magnesium oxide Carbonate like limeGenerally used in a 1:5-1:12 paste basis because much more carbonate “binder” is produced than with limeMgO + H2O <=> Mg(OH)2Mg(OH)2 + CO2 + H2O <=> MgCO3.3H2O<=> molar mass (at least!)gas <=> 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 limeMostly CO2 and waterAs 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”.
52 CO2 Abatement in Eco-Cements John Harrison Presentation AASMIC ConferenceCO2 Abatement in Eco-CementsFor 85 wt% Aggregates15 wt% CementPortland Cements 15 mass% Portland cement, 85 mass% aggregateEmissions .32 tonnes to the tonne. After carbonation. Approximately .299 tonne to the tonne.No Capture 11.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate.Emissions .37 tonnes to the tonne. After carbonation. approximately .241 tonne to the tonne.Capture CO % mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate.Emissions .25 tonnes to the tonne. After carbonation. approximately 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.Eco-cements in porous products absorb carbon dioxide from the atmosphere. Brucite carbonates forming lansfordite, nesquehonite and an amorphous phase, completing the thermodynamic cycle.Greater SustainabilityCO2 ABATEMENT IN AN ECO-CEMENT BLOCKThis slide shows that for an eco-cement concrete in a block which is 15% eco-cement if the eco-cement contains 75% reactive magnesia and with capture of CO2 during the manufacturing process net emissions are less than a third as much..299 > .241 >.140 >.113 Bricks, blocks, pavers, mortars and pavement made using eco-cement, fly and bottom ash (with capture of CO2 during manufacture of reactive magnesia) have 2.65 times less emissions than if they were made with Portland cement.
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 ofMore 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 calciumTotal volumetric expansion from magnesium oxide to lansfordite is for example volume 811%.Mg(OH)2 + CO2 MgCO3.5H2OFrom air and water
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.
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.Gor Brucite to nesquehonite = kJ.mol-1Compare to Gor Portlandite to calcite = kJ.mol-1The 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-1But 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.
58 CarbonationEco-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 CO2 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
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 requiredFor carbonating eco-cements and lime mortars on the on the hand the matrix must “breathe” i.e. they must be porousrequiring a coarse fraction to cause physical air voids and some vapour permeability.Coarse fractions are required in the aggregates used!
60 CO2 Abatement in Eco-Cements John Harrison Presentation AASMIC ConferenceCO2 Abatement in Eco-CementsFor 85 wt% Aggregates15 wt% CementPortland Cements 15 mass% Portland cement, 85 mass% aggregateEmissions .32 tonnes to the tonne. After carbonation. Approximately .299 tonne to the tonne.No Capture 11.25% mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate.Emissions .37 tonnes to the tonne. After carbonation. approximately .241 tonne to the tonne.Capture CO % mass% reactive magnesia, 3.75 mass% Portland cement, 85 mass% aggregate.Emissions .25 tonnes to the tonne. After carbonation. approximately 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.Eco-cements in porous products absorb carbon dioxide from the atmosphere. Brucite carbonates forming lansfordite, nesquehonite and an amorphous phase, completing the thermodynamic cycle.Greater SustainabilityCO2 ABATEMENT IN AN ECO-CEMENT BLOCKThe above slide shows that for an eco-cement concrete in a block which is 15% eco-cement if the eco-cement contains 75% reactive magnesia and with capture of CO2 during the manufacturing process and the use of a pozzolan after carbonation net emissions are less than a third as much..299 > .241 >.140 >.113 Bricks, blocks, pavers, mortars and pavement made using eco-cement, fly and bottom ash (with capture of CO2 during manufacture of reactive magnesia) have 2.65 times less emissions than if they were made with Portland cement.
61 John Harrison Presentation AASMIC Conference TecEco Cement LCATecEco Concretes will have a big role post Kyoto as they offer potential sequestration as well as waste utilisationTECECO LCA MODELFor more information on the contribution our Tec and Eco-Cements can make to the global carbon balance please consult our LCA model under tools on the web site.The TecEco LCA model is available for download under “tools” on the web site
62 Tec-Cement ReactionsMgO + H2O => Mg(OH)2.nH2O - water consumption resulting in greater density and higher alkalinity.Higher alkalinity => more reactions involving silica & alumina.Mg(OH)2.nH2O => Mg(OH)2 + H2O – slow release water for more complete hydration of PCMgO + Al + H2O => 3MgO.Al.6H2O ??? – equivalent to flash set??MgO + SO4-- => various Mg oxy sulfates ?? – yes but more likely ettringite reaction consumes SO4-- first.MgO + SiO2 => MSH ?? Yes but high alkalinity required. Strength??We think the reactions are relatively independent of PC reactions
63 The Form of MgO Matters - Lattice Energy Destroys a Myth John Harrison Presentation AASMIC ConferenceThe Form of MgO Matters - Lattice Energy Destroys a MythMagnesia, 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, andwill completely hydrate in the same time order as the minerals contained in most hydraulic cements.Dead burned magnesia and lime have high lattice energiesCrystalline 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 )
64 More Rapid and Greater Strength Development Higher Strength Binder Ratio Concretes are more often than not made to strength.The use of tec-cement results in15-30% 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 timeEarly strength gain with less cement and added pozzolans is of great economic and environmental importance as it will allow the use of more pozzolans.We have observed this sort of curve in over 500 cubic meters of concrete now
65 Tec-Cement Strength Development Graphs above by Oxford Uni Student are for standard 1PC:3 aggregate mixes, w/c = .5WHITTLESEA SLAB (A modified 20 mpa mix)PC = 180 Kg / m3 MgO = 15 Kg / m3 Flyash = 65 Kg / m3Rate of strength development is of great interest to engineers and constructors
66 Calorimetric Evidence of Faster Strength Gain Faster Strength DevelopmentEvolution of Less HeatEnergy associated with complexing?
67 Reasons for Compressive Strength Development in Tec-Cements. John Harrison Presentation AASMIC ConferenceReasons 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.nH2O supplying H2O for more complete hydration of C2S and C3S?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.
68 Greater Tensile Strength ++++++++Cement++MgO+Sand+++++++++Mutual RepulsionPh 12 ?=>Mutual Repulsion+++-+-+++Cement+-MgO-Sand+--+++-++Mutual AttractionMgO 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
69 DurabilityConcretes are said to be less durable when they are physically or chemically compromised.Physical factors can result in chemical reactions reducing durabilityE.g. Cracking due to shrinkage can allow reactive gases and liquids to enter the concreteChemical factors can result in physical outcomes reducing durabilityE.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
70 Crack Collage Alkali aggregate Reaction Evaporative Crazing Shrinkage Drying ShrinkageThermalSettlement ShrinkageFreeze Thaw D CracksStructuralPlastic ShrinkagePhotos from PCA and US Dept. Ag WebsitesCorrosion RelatedAutogenous or self-desiccation shrinkage (usually related to stoichiometric or chemical shrinkage)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 reactionsAs a result of corrosion.Related to autogenous shrinkage
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 reasonsVisible cracking is unsightlyCracking compromises durability because it allows entry of gases and ions that react with Portlandite.Cracking can compromise structural integrity, particularly if it accelerates corrosion.
72 Graphic Illustration of Cracking Autogenous shrinkage has been used to refer to hydration shrinkage and is thus stoichiometricAfter Tony Thomas (Boral Ltd.) (Thomas 2005)
73 Cracking due to Loss of Water 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.Drying ShrinkageFoolPlastic ShrinkageEvaporative Crazing ShrinkageBucket of WaterSettlement ShrinkagePicture from: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.
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 crackingThere are two main causes of Portland cements shrinking over time.Stoichiometric (chemical) shrinkage andShrinkage through loss of water.The solution is to:Add minerals that compensate by stoichiometrically expanding and/or toUse less water, internally hold water or prevent water loss.TecEco tec-cements internally hold water and prevent water loss.MgO (s) + H2O (l) ↔ Mg(OH)2.nH2O (s)
75 Preventing Shrinkage through Loss of Water 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) + H2O (l) ↔ Mg(OH)2.nH2O (s)The dimensional change in the system MgO + PC depends on:The ratio of MgO to PCWhether 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 PCAs a result of preventing the loss of water by closing the system together with expansive stoichiometry of MgO reactions (see below).↔ molar mass (at least!)liquid ↔ 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).
76 Preventing Shrinkage through Loss of Water Portland cements stoichiometrically require around % 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.MgO (s) + H2O (l) ↔ Mg(OH)2.nH2O (s)
77 Other Benefits of Preventing Shrinkage through Loss of Water Internal water consumption also results in:Greater strengthMore complete hydration of PC .Reduced in situ voids:paste ratioGreater densityIncreased durabilityHigher short term alkalinityMore effective pozzolanic reactions.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).
78 Bleeding is a Bad Thing Better to keep concretes as closed systems Bleeding is caused by:Lack of finesToo much waterBleeding can be fixed by:Reducing water or adding finesAir entrainment or grading adjustmentsBleeding causes:Reduced pumpabilityLoss of cement near the surface of concretesDelays in finishingPoor bond between layers of concreteInterconnected pore structures that allow aggressive agents to enter laterSlump and plastic cracking due to loss of volume from the systemLoss of alkali that should remain in the system for better pozzolanic reactionsLoss of pollutants such as heavy metals if wastes are being incorporated.Concrete is better as a closed systemBetter to keep concretes as closed systems
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 > 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.
80 Long Term pH controlTecEco 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
81 Reducing Cracking as a Result of Volume Change caused by Delayed Reactions An Alkali Aggregate Reaction Cracked Bridge ElementPhoto Courtesy Ahmad Shayan ARRB
82 Types of Delayed Reactions There are several types of delayed reactions that cause volume changes (generally expansion) and cracking.Alkali silica reactionsAlkali carbonate reactionsDelayed ettringite formationDelayed thaumasite formationDelayed hydration or dead burned lime or periclase.Delayed reactions cause dimensional distress, cracking and possibly even failure.
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.
84 Reduced Steel Corrosion Related Cracking Rusting Causes Dimensional DistressSteel remains protected with a passive oxide coating of Fe3O4 above pH 8.9.A pH of over 8.9 is maintained by the equilibrium Mg(OH)2 ↔ Mg++ + 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, CO2 and salts.
85 Reduced Steel Corrosion John Harrison Presentation AASMIC ConferenceReduced Steel CorrosionBrucite 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 magnesiumMagnesium 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
86 Steel Corrosion is Influenced by Long Term pH John Harrison Presentation AASMIC ConferenceSteel Corrosion is Influenced by Long Term pHIn TecEco cements the long term pH is governed by the low solubility and carbonation rate of brucite and is much lower at around , allowing a wider range of aggregates to be used, reducing problems such as AAR and etching. The pH is still high enough to keep Fe3O4 stable in reducing conditions.Eh-pH or Pourbaix Diagram The stability fields of hematite, magnetite and sideritein aqueous solution; total dissolved carbonate = 10-2M.Steel corrodes below 8.9Equilibrium pH of Brucite and of lime
87 Reducing Cracking Related to Autogenous Shrinkage John Harrison Presentation AASMIC ConferenceReducing Cracking Related to Autogenous ShrinkageAutogenous 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; p )The autogenous deformation of concrete is defined as the unrestrained, bulk deformation that occurs when concrete is kept sealed and at a constant temperature.
88 Reducing Cracking Related to Autogenous Shrinkage John Harrison Presentation AASMIC ConferenceReducing Cracking Related to Autogenous ShrinkageMain 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.
89 Reducing Cracking Related to Autogenous Shrinkage John Harrison Presentation AASMIC ConferenceReducing Cracking Related to Autogenous ShrinkageAutogenous 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.nH2O (s) ↔ MgO (s) + H2O (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) + H2O (l) ↔ Mg(OH)2.nH2O (s)↔ molar mass (at least!)liquid ↔ molar volumes (at least 116% expansion, probably more initially before desiccation as above!)
90 Improved DurabilityMaterials that last longer need replacing less often saving on energy and resources.Reasons for Improved Durability:Greater Density = Lower PermeabilityPhysical Weaknesses => Chemical AttackRemoval of Portlandite with the Pozzolanic Reaction.Removal or reactive componentsSubstitution by Brucite => Long Term pH controlReducing corrosion
91 Reduced PermeabilityAs 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 CO2TecEco 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.
92 Greater Density – Lower Permeability 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.
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.
94 Durability - Reduced Salt & Acid Attack Brucite has always played a protective role during salt attack. Putting it in the matrix of concretes in the first place makes sense.Brucite does not react with salts because it is a least 5 orders of magnitude less soluble, mobile or reactive.Ksp brucite = 1.8 X 10-11Ksp Portlandite = 5.5 X 10-6TecEco cements are more acid resistant than Portland cementThis is because of the relatively high acid resistance (?) of Lansfordite and nesquehonite compared to calcite or aragonite
95 Less Freeze - Thaw Problems Denser concretes do not let water in.Brucite will to a certain extent take up internal stressesWhen magnesia hydrates it expands into the pores left around hydrating cement grains:MgO (s) + H2O (l) ↔ Mg(OH)2 (s)↔ molar mass↔ molar volumes↔ molar volumesAt least 38% air voids are created in space that was occupied by magnesia and water!Air entrainment can also be used as in conventional concretesTecEco concretes are not attacked by the salts used on roads
96 Rosendale Concretes – Proof of Durability Rosendale cements contained 14 – 30% MgOA 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
97 Solving Waste & Logistics Problems TecEco cementitious composites represent a cost affective option forusing non traditional aggregates from on site reducing transports costs and emissionsuse and immobilisation of waste.Because they havelower reactivityless waterlower pHReduced solubility of heavy metalsless mobile saltsgreater durability.denser.impermeable (tec-cements).dimensionally more stable with less shrinkage and cracking.homogenous.no bleed water.TecEco Technology - Converting Waste to Resource
98 Role of Brucite in Immobilization In a Portland cement Brucite matrixPC derive CSH takes up lead, some zinc and germaniumPozzolanic CSH can take up mobile cationsBrucite 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.
99 Lower Solubility of Metal Hydroxides There is a 104 differenceAll waste streams will contain heavy metals and a strategy for long term pH control is therefore essential
100 John Harrison Presentation AASMIC Conference Using Wastes and Non-Traditional Aggregates to Make TecEco Cement ConcretesMany 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 wastesTec, enviro and eco-cements can utilize wastes including carbon to increase sequestration preventing their conversion to methaneThere are huge volumes of concrete produced annually (>2 tonnes per person per year)CONVERTING WASTES TO RESOURCEMany wastes and local materials can contribute physical property values.Tec, Eco and Enviro-Cements will allow a wide range of wastes and non-traditional aggregates such as local materials to be used.
101 Biomimicry - Ultimate Recyclers John Harrison Presentation AASMIC ConferenceBiomimicry - Ultimate RecyclersAs peak oil looms and the price of transport is set to rise sharplyWe should not just be recycling based on chemical property requiring sophisticated equipment and resourcesWe 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
102 John Harrison Presentation AASMIC Conference Using Wastes and Non-Traditional Aggregates to Make TecEco Cement ConcretesAs 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.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.DUE TO RISING FUEL PRICES WE WILL HAVE TO RECONSIDER USING LOCAL MATERIALSThe 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.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
103 Easier to Finish Concretes Easier to pump and finish Concretes are likely to have less water added to them resulting in less cracking
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 pozzolanIt is not known how deep these layers getEtc.Etc.Ca++ = 114, Mg++ = 86 picometres
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.”
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 world’s 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.
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 strengthThe workabilityThe durabilityAnd a decrease of:The porosityThe risk of segregationThe 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 concreteUse secondary aggregate and mining waste (poor size distribution)Dramatically reduce the number of experiment needed to design a concrete for a special application
108 Tec-Cement ConcretesTec-Cements contain around 5-20% reactive MgO and are mainly formulated because of:Superior thixotropic propertiesLess cracking and shrinkageGreater durabilityLow reactivityAbility 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.
109 The TecEco Dream – A More Sustainable Built Environment John Harrison Presentation AASMIC ConferenceThe TecEco Dream – A More Sustainable Built EnvironmentCO2OTHERWASTESCO2 FOR GEOLOGICAL SEQUESTRATIONCO2PERMANENT SEQUESTRATION & WASTE UTILISATION (Man made carbonate rock incorporating wastes as a building material)MININGMgOTECECO KILNMAGNESITE + OTHER INPUTSTECECO CONCRETESRECYCLED BUILDING MATERIALSWe 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 MagazineSUSTAINABLE CITIES
110 Sustainable Materials in the Built Environment - 2007 Technical FocusThis Conference will focus on:The impacts and connectivity of different parts of the supply chain.Fabrication, performance, recycling and wasteNew developments in materials and processesReviewing existing materials assessment toolsFuture directions in regulationOpportunities/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: Materials Australia Website: