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An Overview of Future Concretes with a Description of the Role of Reactive Magnesia Part 1 Concrete – Where are we? Drivers for Change => Opportunities.

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Presentation on theme: "An Overview of Future Concretes with a Description of the Role of Reactive Magnesia Part 1 Concrete – Where are we? Drivers for Change => Opportunities."— Presentation transcript:

1 An Overview of Future Concretes with a Description of the Role of Reactive Magnesia Part 1 Concrete – Where are we? Drivers for Change => Opportunities Barriers to Change Guides to Change Contenders with Commentary Part 2 The Role of Reactive MgO 1

2 Concrete - Where are we? The hard mineral composite we build with. Next to water the most used. – Buildings account for ~40% of the materials and ~33% of the energy consumed by the world economy. 1 – 7 billion M3 per annum 2 – 5% - 10% of CO 2 emissions depending on the authority. Concrete infrastructure expenditure a huge investment for governments at all levels A cost cutting volume business model for many players in the supply chain Already one of the most environmentally friendly building materials – significant improvements are possible however. Affect on embodied energies and emissions as well as lifetime energies significant Rees, W. E. (1999). The Built Environment and Ecosphere: A Global Perspective. Building Research and Information. British Columbia, William E Rees. 27: Wallenvik, Olafur, Carbon Footprint of High Performance Versus Conventional Vibrated Concrete

3 Drivers for Change Stakeholder demands for greater sustainability – Brungart definition and triple bottom line. – The precautionary principle & intergenerational equity – Every improvement counts but paradigm improvements really matter – If implemented!, but – Quick fixes = paradigm changes Economic Cost Benefit given – Rapidly rising energy costs – Carbon taxes Construction activities contribute over 35% of total global CO 2 emissions 3 so carbon taxes will have a big impact. > Sustainability can deliver > profit. Competition – Leed, the Green Building Council etc. Improved technical understanding and practice Government research and development as well as procurement policies 3 3 UNEP (2001). Energy and Cities: Sustainable Building and Construction Summary of Main Issues, IETC Side Event at UNEP Governing Council, Nairobi, Kenya, UNEP.

4 Sustainability? 4 Primary Production Process Build, & Manufacture Use Dispose Underlying Molecular Flows Primary Production Methane NOX & SOX Heavy Metals CO 2 etc. Embodied & Process Energy Process, Build & Manufacture NOX & SOX Heavy Metals CO 2 etc. Embodied & Process Energy Use NOX & SOX Heavy Metals CO 2 etc. Lifetime Energy Dispose or Waste Methane NOX & SOX Heavy Metals CO 2 etc. Process Energy The Techno Process These are the releases and impacts we look at with LCA and LCCA

5 Predicted Global Cement Demand and Emissions Quillin K. Low-CO2 Cements based on Calcium Sulfoaluminate [Internet]. Available from: ate_Cements_Keith_Quillin_R.ashx

6 Energy Outlook to U.S. Energy Information Administration. International Energy Outlook 2010 [Internet]. U.S. Energy Information Administration; 2010 [cited 2010 Sep 5]. Available from:

7 Global Waste – An Underestimate! 7 The challenge is to convert waste to resource.

8 Better more cost effective concrete is more sustainable Concrete is not a perfect material yet. E.g. It shrinks, it cracks, it is not as durable as we would like and has a limited range of properties. – See how we fix many these issues in Part 2 - the section on reactive MgO Better concrete is not hard to make and there are huge opportunities for change Improvements through innovation = Sustainable profit! 8 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 changes in the technical paradigm. Equilibrium shift Sustainable profit ECONOMICS Paradigm shifts ~ Lots of little shifts!

9 Examples of Huge Change Opportunities A wide variety of possible end uses with higher potential margins for which current solutions are sub-optimal. – E.g. Addressing properties affecting lifetime energy. E.g. Mineral composites with higher R value – E.g. Particle boards made with mineral binders – E.g. Exterior structural panels with insulating properties Huge opportunities for reducing the cost base and improving the properties of concretes by focusing on the process by which they are made and what they are made with. – A few tweaks to the formulations – Major changes to the process and some – Lateral thinking in relation to aggregates => Man made carbonate aggregate. De-materialization through design (Reductions in Kg CO 2 -e /MPa, see Olafur Welleviks presentation 7 ) Improvements in durability. Missing from the current analyses for sustainability 9 The use of Reactive MgO makes this possible. See Part 2 See Part 2 for the ramifications of using reactive MgO 7 Wallenvik, Olafur, Carbon Footprint of High Performance Versus Conventional Vibrated Concrete

10 Innovation – Turning Buildings the Right Way Out 10 Mineral composites with high R value can easily be made using reactive magnesia because of the polar bonding capacity (See Part 2). Hydration and carbonation products of reactive magnesia are all fire retardants. Imagine the reduction in lifetime energies if we started constructing buildings the right way out! Mineral composites with low conductance ~ high R value and fire resistance Mineral composites with high thermal capacity Conventional timber framing and plaster Mineral composites with high thermal capacity

11 Increases in Business Performance the Previous Year, by Innovation Status The technology paradigm defines what is or is not a resource

12 Barriers to Innovation and Change Out of date and inappropriate legislative restriction. – See other presentations A prescription rather than performance based standards and approvals system. – See Colin Lobo 1 and Wassim Mansour 3 and other presentations as well as what I have to say. A corrupt patent System. – Governments tend to issue patents to anyone for the money – A lack of know how in patent offices as a result of low pay Lack of transparency in relation to new products. – Secret formulations more often than not in breach of other peoples intellectual property (ip). Knowledge should be free – Wikipedia v Science Direct etc. Green wash. – See other presentations A focus on cost instead of cost effective – Little or no support for cutting edge research (See Lionel Lemays presentation 4 ) Conservatism (Goes without saying?) A low level of skills in the industry 12 Conflicting 9 Lobo, Colin, The role of Performance Based Specification in Sustainable Development 10 Mansour, Wassim, Towards Performance-based Specification – Case Studies on Construction Projects in Abu Dhabi 11 Lemay, Lionel, Life cycle Assessment of Concrete Structures

13 The Standards and Approvals Systems Far too often our standards and approvals ratings are prescription based stifling innovation and change. Even Leeds in the US and the Green Building Council in Australia make the same mistake Standards should be based on a list of metrics for properties including embodied energy and emissions, thermal capacity and conductance, strength (compressive, shear and flexural) etc. This means that many existing standards should be relegated to being codes of practice Proper audit process instead?? 13 See Colin Lobos presentation (NRMCA)

14 A Corrupt Global Patent System Patents are taken far to literally; the intent and purpose are almost irrelevant. Most patent examiners are basically incompetent – How could they be otherwise? The revenue raised is of greater importance to the grantee government than the value of the so called monopoly rights given. Patents are an invitation and challenge to others to steal ip. – Many secret formulations end up being identified as stolen ip. Governments do not protect the ip they grant they let the players fight it out in court. It follows that patents are little more than meat for dogs to fight over. – Consider geopolymers for example and my own experience. 14

15 You can Patent Anything! 15 Fierce legal competition over legal rights to intellectual property desperately needed by the world is wrong. Intelligent minds should not be trapped into such a resource consuming process as defending their intellectual property. A rethink is required as new technologies are essential for the progress of humanity and sustainability into the future AAAAEBAJ&printsec=abstract&zoom=4#v =onepage&q&f=false Is to plagiarize really to be wise?

16 Cost rather than Profit Based Business Models Most corporations in the concrete industry have business model that relies on significant turnover and cost cutting to deliver profit. – Research and development budgets that deliver innovations and potentially more profitable product are generally small. 16 If the industry believe in cutting edge research then they are going to have to practice what they preach and support innovation. In Australia there is now benchmark support for R & D and commercialisation

17 Conservatism With the exception of perhaps the architectural fraternity players in the construction industry are generally conservative There is little incentive and a lot of risk in using new materials that have reduced embodied energies and emissions and substantial impact on reducing lifetime energies. One of the reasons for this conservatism is the legal liability of designers and engineers. Perhaps prescription standards should become codes of practice and greater support given for testing of new materials. Audited procedures and less reliance on standards? 17

18 The Low Level of Skills in the Industry There is an appallingly low level of skills in the concrete industry. – Electricians and plumbers must have licenses in most countries yet concrete placers and finishers seldom have any training at all. – Most civil engineers are taught very little and understand less about the material they use every day. It is no wonder we have the attitude that all that is grey is great, all we make goes out the gate. (With affront meant to Grey Matters) – any diversion is risky! This terrible situation needs to change. – Congratulations to the NRMCA re their producer training programs but what about placers and finishers? Quality control should go beyond testing, it must include risk management through training. 18

19 Guides to Change - Abatement Potential Adapted from: Slide in presentation by Dr. John Ochsendorf, MIT Concrete Sustainability Hub (from McKinsey Consulting 1999) Paradigm Process Change??

20 Guides to Change - LCA and LCCA 20 Difficult and time consuming but arguably essential. LCCA much more relevant. Issues relating to material use. E.g. high embodied energy and emissions of aluminium could be offset by the fact that aluminium is often used to reduce lifetime energy E.g. aluminium awnings. In Aust. aluminium has around 80% recycled content

21 Embodied Energy and Emissions over Time Source: Slide in presentation by Prof Roland Pellenq, MIT Concrete Sustainability Hub

22 Summary The use of Abatement Potential and LCA and in particular LCCA should guide cost effective reductions in embodied energy and emissions Cost effective reductions in lifetime energies De materialization (reduced over design) The MIT Sustainability Hub 14 are probably the most advanced – Missing the impact of mineral composites made possible with reactive MgO with properties other than high thermal capacity such as R value – Missing is any contemplation of paradigm changes. E.g. in the way we make cements

23 Future Cement Contenders Portland Cement 23 1.http://www.tececo.com/files/spreadsheets/TecEcoCementLCA12Oct2011.xlshttp://www.tececo.com/files/spreadsheets/TecEcoCementLCA12Oct2011.xls Cements Based on Process Process CO 2 (tonnes CO 2 / tonne Compound ) Decarbonat ion CO 2 (tonnes CO 2 / tonne Compound) Emissions (if no kiln capture– tonnes CO 2 / tonne Compoun d) Emission s (kiln capture– tonnes CO 2 / tonne Compoun d) Absorpti on (tonnes CO 2 / tonne Compoun d, Assuming 100% carbonati on 1 year) Net Emissions (Sequestrat ion – No kiln Capture) (tonnes CO 2 / tonne Compound, Assuming 100% carbonatio n 1 year) Example of Cement Type Apply toComment Notes PC Current Methods None Split process lime with recapture then clinker Most dense concretes No supplementary cementitious or pozzolanic materials 1 PC Permeable Block formulation Ordinary Portland Cement Most dense concretes No supplementary cementitious or pozzolanic materials 1 PC Split Process – Lime then clinker Split process lime with recapture then clinker Most dense concretes No supplementary cementitious or pozzolanic materials 1

24 H2OH2O The Potential of CO 2 Release and Capture - Portland Cements (+/- Tec-Kiln?) 24 Split Process with Capture during Manufacture No Capture during Manufacture CO 2 in atmosphere Carbon positive. Chemical and process emissions Net sequestration less carbon from process emissions Use of non fossil fuels => Low or no process emissions Clinker H2OH2O Hydrated Cement Paste CaCO 3 + Clays CaCO 3 Hydrated Cement Paste Net Emissions (Sequestration) kg CO 2 /kg product Net Emissions (Sequestration) Kg CO 2 /Kg product CO 2 capture (e.g. N-Mg process etc.) 15 Source Data: CaO + Clays Capture during Manufacture Net Energy 3962 kJ/kg product Carbon positive. Chemical and process emissions Clinker H2OH2O Hydrated Cement Paste CaCO 3 + Clays Net Emissions (Sequestration) kg CO 2 /kg product Net Energy 3962 kJ/kg product CO 2 capture (e.g. N-Mg process etc.)

25 Future Cement Contenders - Mg Group 25 1.http://www.tececo.com/files/spreadsheets/TecEcoCementLCA12Oct2011.xlshttp://www.tececo.com/files/spreadsheets/TecEcoCementLCA12Oct2011.xls 2.http://www.tececo.com/files/newsletters/Newsletter93.phphttp://www.tececo.com/files/newsletters/Newsletter93.php Cements Based on Process Process CO 2 (tonnes CO 2 / tonne Compound) Decarbona tion CO 2 (tonnes CO 2 / tonne Compoun d) Emission s (if no kiln capture– tonnes CO 2 / tonne Compou nd) Emission s (kiln capture– tonnes CO 2 / tonne Compou nd) Absorpti on (tonnes CO 2 / tonne Compou nd, Assumin g 100% carbonati on 1 year) Net Emission s (Sequestr ation) (tonnes CO 2 / tonne Compou nd, Assumin g 100% carbonati on 1 year) Example of Cement Type Apply toComment Notes <750 o CMgCO Eco-cement concrete, pure MgO concretes. Novacem concretes TecEco, Cambridge & Novacem TecEco Eco-Cement Force carbonated pure MgO 1 <450 o CMgCO 3.3H 2 O Eco-cement concrete, pure MgO concretes. Novacem concretes? TecEco, Cambridge & Novacem N-Mg route University of Rome 1 <450 o C MgCO 3.3H 2 O Including capture during production of nesquehonite Eco-cement concrete, pure MgO concretes. Novacem concretes? TecEco, Cambridge & Novacem N-Mg route University of Rome 1 Silicate route ? NovacemAfter Klaus Lackner? Modified Ternary Blends (50% PC) Split Process – Lime (with capture) then clinker Ternary mix with MgO additive. Most dense concretes Faster setting and higher early strength 2

26 The Potential of CO 2 Release and Capture - Magnesite (MgCO 3 ) Route 26 With Capture during Manufacture No Capture during Manufacture CO 2 CO 2 from atmosphere CO 2 capture (e.g. N-Mg process etc.) Carbon neutral except for carbon from process emissions Net sequestration less carbon from process emissions Use of non fossil fuels => Low or no process emissions MgO Mg(OH)2 H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O MgCO 3 Net Emissions (Sequestration) Kg CO 2 /Kg product Net Emissions (Sequestration).085 kg CO 2 /kg product 16 Source Data: MgCO 3 H2OH2O Net Energy 4084 kJ/kg product < C

27 With Capture during Manufacture No Capture during Manufacture CO 2 CO 2 from atmosphere CO 2 capture (e.g. N-Mg process etc.) Carbon neutral except for carbon from process emissions Net sequestration less carbon from process emissions Use of non fossil fuels => Low or no process emissions MgO Mg(OH)2 H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O MgCO 3.3H 2 O Net Emissions (Sequestration) Kg CO 2 /Kg product Net Emissions (Sequestration) -.399kg CO 2 /kg product 17 Source Data: MgCO 3.3H 2 O H2OH2O Net Energy 7140 kJ/kg product < C The Potential of CO 2 Release and Capture - Nesquehonite (MgCO 3.3H 2 O) Route 27

28 Gaia Engineering 28 kg CO2-e/kg product >2 kg CO2-e/kg Mg product Or similar. The annual world production of HCl is about 20 million tons, most of which is captive (about 5 million tons on the merchant market).

29 Man Made Carbonate Aggregate? 29 Source USGS: Cement Pages Assumptions - 50% non PC N-Mg mix and Substitution by Mg Carbonate Aggregate Percentage by Weight of Cement in Concrete15.00% Percentage by weight of MgO in cement6% Percentage by weight CaO in cement29% Proportion Cement Fly ash and/or GBFS50% 1 tonne Portland Cement0.867Tonnes CO2 Proportion Concrete that is Aggregate85% CO2 captured in 1 tonne aggregate1.092Tonnes CO2

30 Magnesium Carbonate Cements Magnesite (MgCO3) and the di, tri, and pentahydrates known as barringtonite (MgCO3·2H2O), nesquehonite (MgCO3·3H2O), and lansfordite (MgCO3·5H2O), respectively. Some basic forms such as artinite (MgCO3·Mg(OH)2·3H2O), hydromagnestite (4MgCO3·Mg(OH)2·4H2O) and dypingite (4MgCO3· Mg(OH)2·5H2O) also occur as minerals. We pointed out as early as 2001 that magnesium carbonates are ideal for sequestration as building materials mainly because a higher proportion of CO2 than with calcium can be bound and significant strength can be achieved. The significant strength is a result of increased density through carbonation (high molar volume increases) and the microstructure developed by some forms. 30 TecEco Eco-Cements have relatively high proportions of magnesia which in permeable materials carbonates forming lansfordite and nesquehonite adding strength and durability. Eco-Cement formulations are generally used for bricks, blocks, pavers, pervious pavements and other permeable cement based products. See

31 TecEco Non-Carbonating Tec-Cements Tec-Cement Ternary Blends 15-30% improvement in strength Fast first set & better rheology Less shrinkage – less cracking, less bleeding, greater long term durability, Solve autogenous shrinkage? 31 CriteriaGoodBad Energy Requirements and Chemical Releases, Reabsorption (Sequestration?) Use >50% replacements and still set like normal concrete! Speed and Ease of Implementation Rapid adoption possible Barriers to Deployment Permissions and rewards systems see _rewards.php Cost/Benefit Excellent until fly ash runs out! Use of Wastes? or Allow Use of Wastes? Uses GBFS and fly ash and manufactured nesquehonite based aggregate Performance Engineering Excellent all round Thermal High thermal capacity Architectural Excellent Safety No issues Tec-Cements are cement blends that comprise of a hydraulic cement such as Portland cement mixed with a relatively small proportion of reactive magnesia and optionally pozzolans and/or supplementary cementitious materials which react with Portlandite removing it and making more cement or are activated by Portland cement. They offer a solution to many of the technical problems that plague traditional cement formulations caused by the reactivity of lime (Portlandite) and have significant advantages including faster setting even with a high proportion of non PC additions. See

32 Magnesium Phosphate Cements Chemical cements that rely on the precipitation of insoluble magnesium phosphate from a mix of magnesium oxide and a soluble phosphate. Some of the oldest binders known (dung +MgO) Potentially very green – if the magnesium oxide used is made with no releases or via the nesquehonite (N- Mg route) and – a way can be found to utilise waste phosphate from intensive agriculture and fisheries e.g. feedlots. (Thereby solving another environmental problem) 32 CriteriaGoodBad Energy Requirements and Chemical Releases, Reabsorption (Sequestration?) The MgO used could be made without releasesThere is not much phosphate on the planet Speed and Ease of Implementation Rapid adoption possibleIf barrier overcome (see below) Barriers to Deployment Permissions and rewards systems see wards.php. Must find a way to extract phosphate from organic pollution. wards.php Cost/Benefit Economies of scale issue for MgO to overcome Use of Wastes? or Allow Use of Wastes? With technology could use waste phosphate reducing water pollution Performance Engineering Excellent all round Thermal High thermal capacity Architectural Safety No issues

33 Sorel Type Cements and Derivatives 33 Sorel Type Cements and Derivatives are all nano or mechano composites relying on a mix of ionic, co-valent and polar bonding. There are a very large number of permutations and combinations and thus a large number of patents CriteriaGoodBad Energy Requirements and Chemical Releases, Reabsorption (Sequestration?) The MgO used could be made without releases Speed and Ease of Implementation More could be usedIf barrier overcome (see below) Barriers to Deployment Not waterproof even with modification. Cost/Benefit Economies of scale issue for MgO to overcome Use of Wastes? or Allow Use of Wastes? Not waterproof Performance Engineering Excellent exceptNot waterpoof, salt affect metals Thermal High thermal capacity Architectural Safety No issues

34 Future Cement Contenders 34 1.http://www.tececo.com/files/spreadsheets/TecEcoCementLCA12Oct2011.xlshttp://www.tececo.com/files/spreadsheets/TecEcoCementLCA12Oct2011.xls 3.Quillin, K. and P. Nixon (2006). Environmentally Friendly MgO-based cements to support sustainable construction - Final report, British Research Establishment. Cements Based on Process Process CO 2 (tonnes CO 2 / tonne Compound) Decarbon ation CO 2 (tonnes CO 2 / tonne Compoun d) Emission s (if no kiln capture– tonnes CO 2 / tonne Compou nd) Emission s (kiln capture– tonnes CO 2 / tonne Compou nd) Absorpt ion (tonnes CO 2 / tonne Compou nd, Assumi ng 100% carbona tion 1 year) Net Emissions (Sequestr ation) (tonnes CO 2 / tonne Compoun d, Assuming 100% carbonati on 1 year) Example of Cement Type Apply toComment Notes CaOConventional Carbonating lime mortar Calera, British Lime Assn. & many others Small net sequestration with TecEco kiln 1 C3SC3SConventional?0.578>0.578? 3 C2SC2SConventional?0.511>0.511? Belite cementChinese & others 3 C3AC3AConventional?0.594>0.594? Tri calcium aluminate cement Increased proportion C4A3SC4A3SConventional?0.216>0.216?? Calcium sulfoaluminate cement Chinese & others 3

35 Future Cement Contenders 35 1.http://www.tececo.com/files/spreadsheets/TecEcoCementLCA12Oct2011.xlshttp://www.tececo.com/files/spreadsheets/TecEcoCementLCA12Oct2011.xls 4.http://www.geopolymers.com.au/science/sustainability Cements Based on Process Process CO 2 (tonnes CO 2 / tonne Compound) Decarbon ation CO 2 (tonnes CO 2 / tonne Compoun d) Emission s (if no kiln capture– tonnes CO 2 / tonne Compou nd) Emission s (kiln capture– tonnes CO 2 / tonne Compou nd) Absorpt ion (tonnes CO 2 / tonne Compou nd, Assumi ng 100% carbona tion 1 year) Net Emissions (Sequestr ation) (tonnes CO 2 / tonne Compoun d, Assuming 100% carbonati on 1 year) Example of Cement Type Apply toComment Notes Alakali Activated Ground Granulate d Blast Furnace Slag (GBFS) GBFS (slag) is a waste product from the manuf acture of iron and steel Nil to cement industry GBFS with MgO activator Many other activators Patented by TecEco Not patented 1 Geo polymers Fly ash + NaOH 0.16 Geopolymer Alliance, Geopolymer Institute, University Melbourne 6

36 CaO-Lime 36 CriteriaGoodBad Energy Requirements and Chemical Releases, Reabsorption (Sequestration?) The CaO used could be made without Speed and Ease of Implementation Easily implemented as no carbonation rooms etc. reqd. Permissions and rewards systems see rds.php. rds.php Barriers to Deployment Cost/Benefit Use of Wastes? or Allow Use of Wastes? Performance Engineering Good Thermal Engineered thermal capacity and conductivity. Architectural Safety An irritating dust Audience 1 Audience 2

37 Geopolymers 37 CriteriaGoodBad Energy Requirements and Chemical Releases, Reabsorption (Sequestration?) Low provided we do not run out of fly ash Speed and Ease of Implementation Process issues to be overcome Permissions and rewards systems see rds.php. rds.php Barriers to Deployment Cost/Benefit Use of Wastes? or Allow Use of Wastes? Performance Engineering Good but inconsistent Thermal Engineered thermal capacity and conductivity. Architectural Safety Caustic liquors Audience 1 Audience 2 Geopolymers as a future concrete suffer from two basic flaws on one very high risk Flaw. 1. The nanoporisity flaw which leads to durability problems and Flaw. 2. The fact that water is not consumed in the geopolymerisation process resulting in the almost impossible task of making them fluid enough for placement. Risk. Too much water reduces alkalinity and results in a high risk.

38 Other Contenders Slag cements a variant of Portland cement as CSH is the main product. Supersulfated cements have potential as they are made mostly from GBFS and gypsum which are wastes and only a small amount of PC or lime. The main hydration product is ettringite and they show good resistance to aggressive agents including sulphate but are slow to set. (A derivative) Calcium aluminate cements are hydraulic cements made from limestone and bauxite. The main components are monocalcium aluminate CaAl 2 O 4 (CA) and mayenite Ca 12 Al 14 O 33 (C12A7) which hydrate to give strength. Calcium aluminate cements are chemically resistant and stable to quite high temperatures. Calcium sulfoaluminate cements & belite calcium sulfoaluminate cements are low energy cements that have the potential to be made from industrial by products such as low calcium fly ash and sulphur rich wastes. The main hydration product producing strength is ettringite. Their use has been pioneered in China (A derivative) Fly ash Cements based on Class C fly ash. As this type of fly ash varies it has been difficult to produce a consistent product. 38

39 Other Contenders Belite cements can be made at a lower temperature and contains less lime than Portland cement and therefore has much lower embodied energy and emissions. Cements containing predominantly belite are slower to set but otherwise have satisfactory properties. Many early Portland type cements such as Rosendale cement were rich in belite like phases. (a variant, See PC - MgO – GBFS – fly ash blends. MgO is the most powerful new tool in hydraulic cement blends since the revelation that reactive magnesia can be blended with other hydraulic cements such as Portland cement % improvements in compressive strength and greater improvements in tensile strength, faster first set, better rheology and less shrinkage and cracking less bleeding and long term durability have been demonstrated. It is also possible autogenous shrinkage has been solved. MgO blended with other hydraulic cements, pozzolans and supplementary cementitious materials (SCMs). Amazingly very little real research has been done on optimised blends particularly with cements other than Portland cement See also: Sanjayan, Jay, Recent advances in geopolymer and other non-Portland based cements. Proc. Concrete 2011, CIA.

40 Summary –Mehtas Triangle Consume less concrete Dematerialisation 2.Consume less cement Longer period for strength, better particle packing. Etc. 2.Consume less clinker Replacement by pozzolans and SCAs 30% saving in cement 50% saving in clinker 19 Mehta, P.K., Global Concrete Industry Sustainability. Concrete International, Vol 31(2), p.4.

41 Harrisons Table 41 CriteriaDescriptionPlayers Drivers BarriersGuides Dematerialisation Innovative architecture and engineering. More durable concretes. Architects & Engineers Economic cost/benefit, Sustainability, Leed, GBC, R & D & Procurement Policies. Prescription standards and approvals systems (see m/sustainability.permission s_rewards.php.)http://www.tececo.co m/sustainability.permission s_rewards.php Design codes, LCA & LCCA Optimisation Appropriate particle packing, better admixtures and use of brucite hydrates to release water for more complete hydration Cement technologists Economic cost/benefit, sustainability. Conservatism, inappropriate software. Prescription standards and approvals systems (see m/sustainability.permission s_rewards.php.)http://www.tececo.co m/sustainability.permission s_rewards.php Mix design methods. LCA & LCCA. New better software. Replacement of cement by pozzolans and SCAs Blended cements that contain a high volume of replacement materials such as fly ash, slag cement (gbfs), pozzolans, silica fume, rice husk ash etc. High replacement cement concretes often have improved properties such as rheology, less shrinkage, greater durability etc. The use of reactive MgO makes the use of higher proportions possible. Cement technologists Economic cost/benefit, Sustainability, Leed, GBC, R & D & Procurement Policies. Conservatism, out dated software. Prescription standards and approvals systems (see m/sustainability.permission s_rewards.php.)http://www.tececo.co m/sustainability.permission s_rewards.php Mix design methods. LCA & LCCA. New better software. Alternative processes of manufacture Cements that involve calcination can be made without releases. One option is to split the process, another is to use closed system kilnsScientists Sustainability, carbon taxes. Inability to think outside the box. Fear of changeCommon sense! Alternative product Mineral composites other than concrete with just stone aggregate would be useful. E.g. composites with a high R value Materials scientists Economic cost/benefit Inability to think outside the box. Fear of change Standards, LCA & LCCA Alternative emphasis An emphasis other than on the binder to improve sustainability. E.g. Use of man made carbonate aggregate.Scientists Sustainability, Economic cost/benefit. Technical merit Inability to think outside the box. Fear of change. Technical issues (?).Common sense!

42 Part2 The Role of Reactive MgO – An Update on TecEco Technology An update on recent advances in Tec and Eco- Cements including the use of high proportions of fly ash and SCMS with added reactive magnesia 42 Reactive Magnesia is the most powerful new tool in cement chemistry

43 TecEco Patents Reactive magnesia (calcined at less than about C) included in a hydraulic composition with or without added pozzolans. They may or may not carbonate. We define in most jurisdictions hydraulic cements according to the ASTM C definition as a cement that sets and hardens by chemical interaction with water and that is capable of doing so under water We include slag cements as hydraulic and notice the American Slag Association think likewise. Beware of imitators and charlatans 43

44 TecEco Cements Eco-Cements have relatively high proportions of magnesia which in permeable materials carbonates adding strength and durability. Eco-Cement formulations are generally used for bricks, blocks, pavers, pervious pavements and other permeable cement based products. See Enviro-Cements are made using large quantities of reactive magnesia which reacts to form brucite. Brucite is unique to TecEco Cements and is an ideal mineral for trapping toxic and hazardous wastes due to its layered structure, equilibrium pH level, durability and low solubility. See Tec-Cements are cement blends that comprise of a hydraulic cement such as Portland cement mixed with a relatively small proportion of reactive magnesia and optionally pozzolans and/or supplementary cementitious materials which react with Portlandite removing it and making more cement or are activated by Portland cement. They offer a solution to many of the technical problems that plague traditional cement formulations caused by the reactivity of lime (Portlandite) and have significant advantages including faster setting even with a high proportion of non PC additions. See 44

45 Magnesium Minerals 45 MineralFormulaClassMolar volume Hard ness HabitReference for Habit BruciteMg(OH) 2 Brucite24.40 Blocky pseudo hexagonal crystals. Platy or foliated masses and rosettes - fibrous to massive sting.shtml Notes 1, 2, 3 Brucite Hydrates Mg(OH) 2.nH 2 Obrucite hydrates ?2.5 Not much known about them!http://webmineral.com/Alphabetical_Li sting.shtml PokrovskiteMg 2 (CO 3 )(OH) 2 ·0.5(H 2 O)Basic Brown radiating tufts.http://mineralbliss.blogspot.com/2010/ 03/different-pokrovskite-habits- possible.html ArtiniteMg 2 (CO3)(OH) 2 3(H 2 O)Basic Bright, white acicular sprays Forms crusts of acicular crystals, elongated [010]. Also botryoidal masses of silky fibres; spherical aggregates of radiating fibers; cross- fibre veinlets. sting.shtml Hydromagn esite Mg5(CO3)4(OH) 2.4H 2 OBasic Include acicular, lathlike, platy and rosette forms Crystals small, occurring as tufts, rosettes, or crusts of acicular or bladed crystals elongated [001] and flattened {100}. Massive, chalky. sting.shtml 979&ld=1 DypingiteMg5(CO3)4(OH) 2. 5H 2 OBasic Numerous individual crystals or clusters. Globular - Spherical, or nearly so, rounded forms (e.g. wavellite).

46 Magnesium Minerals 46 MineralFormulaClassMolar volume Hard ness HabitReference for Habit GiorgiositeMg 5 (CO 3 ) 4 (OH) 2.5-6H 2 O Basic Fibrous and spherulitic, admixed with other species in powdery masses html MagnesiteMgCO3Normal or self setting Usually massive Crystals usually rhombohedral {1011}, also {0112}; prismatic rare [0001] with {1120} and {0001}, or tabular {0001}. Scalenohedral rare. Massive, coarse- to fine-granular, very compact and porcelainous; earthy to rather chalky; lamellar; coarsely fibrous isting.shtml html BarringtoniteMgCO3·2H 2 ONormal or self setting Glassy blocky crystalshttp://webmineral.com/Alphabetical_L isting.shtml NesquehoniteMgCO3·3H 2 ONormal or self setting Acicular prismatic needles Crystals prismatic, elongated along [010], {001}, {010}, {011}, {101}. {110} deeply striated parallel to [010]. Forms radial sprays and coatings, also botryoidal. isting.shtml html LansforditeMgCO3·5H 2 ONormal or self setting Glassy blocky crystals Minute short-prismatic crystals [001]; also stalactitic. isting.shtml isting.shtml html

47 The N-Mg Process for MgO Cement and Aggregate Production 47 kg CO2-e/kg product > 2 kg CO2-e/kg Mg product Or similar. The annual world production of HCl is about 20 million tons, most of which is captive (about 5 million tons on the merchant market).

48 The N-Mg Process 48 Tec-Kiln NH 3 and a small amount of CO 2 MgCO 3.3H 2 O MgO Mg(OH) 2 CO 2 H2OH2O Steam NH 4 Cl and a small amount of NH 4 HCO 3 Filter Mg rich water Ammoniacal Mg rich water MgCO 3.3H 2 O HCl The N-Mg Process - A Modified Solvay Process for Nesquehonite

49 Gaia Engineering 49 MgCO 3.3H 2 O N-Mg Process NH4Cl or HCl Industrial CO 2 MgO TecEco Tec-Kiln Eco- Cements Building components & aggregates TecEco Cement Manufacture CaO Clays Portland Cement Manufacture Brine, Sea water, Oil Process water, De Sal Waste Water etc. Tec- Cements Other wastes Fresh Water GBFS Fly ash

50 The TecEco Tec-Kiln 50 An obvious future requirement will be to make cements without releases so TecEco are developing a top secret kiln for low temperature calcination of alkali metal carbonates and the pyro processing and simultaneous grinding of other minerals such as clays. The TecEco Tec-Kiln makes no releases and is an essential part of TecEco's plan to sequester massive amounts of CO2 as man made carbonate in the built environment. The TecEco Tec-Kiln has the following features: Operates in a closed system and therefore does not release CO2 or other volatiles substances to the atmosphere Can be powered by various potentially cheaper non fossil sources of energy such as intermittent solar or wind energy. Grinds and calcines at the same time thereby running 25% to 30% more efficiently. Produces electricity as a by-product. Can be integrated into an industrial ecology producing solid fuel Produces more precisely definable product. (Secret as disclosure would give away the design) The CO2 produced can be sold or re-used in for example the N-Mg process. Cement made with the Tec-Kiln will be eligible for carbon offsets. To further develop the Tec-Kiln, TecEco require not only additional funding but also partners able to provide expertise.

51 TecEco Tec-Kiln, N-Mg route 51 The calcination of nesquehonite has a relatively high enthalpy but there is significant scope for reducing energy using waste heat and for co- generation from expansive gas emissions. Initial weight loss below C consists almost entirely of water (1.3 molecules per molecule of nesquehonite). Between 100 and C volatilization of further water is associated with a small loss of carbon dioxide (~3-5 %). From C to C, the residual water content varies between 0-6 and 0-2 molecules per molecule of MgC03. Above C, loss of carbon dioxide becomes appreciable and is virtually complete by C, leaving MgO with a small residual water content. Energy could be saved using a two stage calcination process using waste energy for the first stage. 1 Dell, R. M. and S. W. Weller (1959). "The Thermal Decomposition of Nesquehonite MgCO3.3H20 And Magnesium Ammonium Carbonate MgCO3 (NH4)2CO3 4H2O." Trans Faraday Soc 55(10):

52 TecEco Eco-Cements 52 Left: Recent Eco-Cement blocks made, transported and erected in a week. Laying and Eco-Cement floor. Eco-Cement mortar & Eco-cement mud bricks. Right: Eco-Cement permeacocretes and foamed concretes Eco-Cements are blends of one or more hydraulic cements and relatively high proportions of reactive magnesia with or without pozzolans and supplementary cementitious additions. They will only carbonate in gas permeable substrates forming strong fibrous minerals such as lansfordite and nesquehonite. Water vapour and CO2 must be available for carbonation to ensue. Eco-Cements can be used in a wide range of products from foamed concretes to bricks, blocks and pavers, mortars renders, grouts and pervious concretes such as our own permeacocrete. Somewhere in the vicinity of the Pareto proportion (80%) of conventional concretes could be replaced by Eco-Cement. Light colour = low albido

53 Forced Carbonation ~ Optimisation 53 Forced Carbonation (Cambridge)Kinetic Optimisation (TecEco) StepsMultistep processLess steps = lower costs RateVariable Varying on weather conditions (wet dry best and gas permeability) % Carbonation in 6 months 70% (reported, could be more if permeable) 100% Ease of general implementation Require point sources CO 2 Can be implemented very quickly Can use large quantities of fine wastes Can use large quantities of fine wastes like fly ash that are not necessarily pozzolanic Fine wastes tend to reduce gas permeability SafetyAre carbonation rooms safe?No issues Key requirementsSpecial carbonation roomsOptimal kinetics including gas permeability Physical rate considerations Doubling the concentration of CO2 doubles the rate of carbonation. Doubling the pore size quadruples the rate of carbonation. Other issues Able to be sealed with paint etc. as pre carbonated Some sealing paints will slow down carbonation Forced carbonation of silicate phases as promoted by some is nonsense 2 According to ECN "The CO 2 concentration in power station flue gas ranges from about 4% (by volume)for natural gas fired combined cycle plants to about 14% for pulverised coal fired boilers." At 10% the rate increase over atmospheric could be expected to be 10/.038 = 263 times provided other kinetic barriers such as the delivery of water do not set in. Ref: accessed 24 Mar 08.

54 Carbonation Optimisation Dissolution of MgO – Gouging salts e.g. MgSO 4, MgCl 2 and NaCl (Not used by TecEco) – Various catalysing cations e.g. Ca ++ and Pb ++ and ligands EDTA, acetate, oxalate citrate etc. (Not used by TecEco) – Low temperature calcination = Low lattice energy = high proportion of unsaturated co-ordination sites = rapid dissolution. See Carbonation – High concentration of CO 3 -- at high pH as a result of OH - from Portlandite Possible catalysis and nucleation by polar surface of calcium silicate hydrate at high pH Wet dry conditions. Wet for through solution carbonation, dry for gas transport. Gas permeability Carbonate shape is important (next slides) 54

55 Particle Packing – Percolation and Porosity ~ Permeability 55 Shape effects particle packing (Olafur Wallevik presentation 3 ) and the angle of repose (Bagnold 4 ). The latter is therefore a proxy guide to shape. Eco-Cements are deliberately not perfectly packed. Whereas in Tec- Cements the opposite occurs 3 Wallenvik, Olafur, Carbon Footprint of High Performance Versus Conventional Vibrated Concrete 4 Bagnold, Ralph A, The Physics of Blown Sand and Desert Dunes

56 Why Nesquehonite as a Binder in Eco-Cements / Aggregate? Significant molar volume expansion. Excellent morphology. Nesquehonite has an ideal shape that contributes strength to the microstructure of a concrete Forms readily at moderate and high pH in the presence of CSH. (Catalytic nucleation mechanism?) Can be manufactured using the N-Mg Process Can be agglomerated Light albido Stable over a wide PT range (See Ferrinis work) The hydration of PC => alkalinity dramatically increasing the CO 3 -- levels that are essential for carbonation. Captures more CO 2 than Calcium Ideal wet dry conditions are easily and cheaply provided. Forced carbonation is not required (Cambridge uni and others) 56 XRD Pattern Nesquehonite 3H 2 O + CO Mg ++ => MgCO 3 ·3H 2 O Nesquehonite courtesy of Vincenzo Ferrini, university of Rome. We have to ask ourselves why we are still digging holes in the ground. The industry would encounter far less bureaucratic blocking, make more money and go a long way towards solving global warming by manufacturing out of Mg, thin air and water its own inputs! pH dependent speciation

57 Economics of Magnesium Carbonate Binder Based Masonry Products 57 What this embedded spread sheet demonstrates is that Magnesium Carbonate Block formulations are uneconomic unless the price of reactive MgO approaches that of PC or there is a high price for carbon or alternatively less MgO can be used! Because of molar volume growth less can be used but we must still address supply chain issues. This embedded spread sheet looks only at the binder price and assumes all other factors remain the same

58 Permeacocretes Permeacocretes are an example of a product where the other advantages of using reactive MgO overcome its high cost. The use of MgO gives an ideal rheology which makes it possible to make permeacocrete pervious pavements using conventional road laying equipment therefore substantially reducing labour costs. There are many other advantages of pervious pavements see rence%20presentations/TecEcoPres entationSGA25Mar2010.ppt rence%20presentations/TecEcoPres entationSGA25Mar2010.ppt 58

59 Tec-Cements Tec-Cements (5-20% MgO, 80-95% OPC) – contain more Portland cement than reactive magnesia. Reactive magnesia hydrates in the same rate order as Portland cement forming Brucite which uses up excess water reducing the voids:paste ratio, increasing density and possibly raising the short term pH. – Reactions with pozzolans are more affective. After much of the Portlandite has been consumed Brucite tends to control 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. 59

60 Water – Fundamental to Concretes 60 Polar Bonding Diagrammatic representation of a water molecule having polar covalent bonds between the Oxygen atom and the Hydrogen atoms. (Note the angle is o C) In a polar covalent bond, the electrons shared by the atoms spend a greater amount of time, on average, closer to the oxygen nucleus than the hydrogen nucleus. This is because of the geometry of the molecule and the great electronegativity difference between the hydrogen atom and the oxygen atom. The result of this pattern of unequal electron association is a charge separation in the molecule, where one part of the molecule, the oxygen end, has a partial negative charge and the hydrogen's have a partial positive charge. H+H+ O -- H+H+ -- These drawings are subject to copyright by TecEco

61 The Electrostatic Nature of Cements made with Water The surface tension of water is 73 dynes per cm at 18 o C compared to ethyl alcohol at 24 dynes per cm. Hydrogen bonding is attributed to the ability of water to adhere to or wet most surfaces; such substances are said to be hydrophilic (water-loving). Hydrogen bonding is only about 10 per cent of the strength of the covalent bond, but it is responsible for most of the unusual properties of water (high freezing and boiling points, high heat capacity, high heats of fusion and evaporation, solvency, and high surface tension). Water has an exceptionally large dipole moment (1.87 x e.s.u.) relative to most other inorganic compounds. Dipole moment is the product of the distance between the charges multiplied by the magnitude of the charge in electrostatic units (e.s.u.) Refer: Labbe, Christophe, Nonat, Andre, 2007, The Cement Cohesion: An Affair of Electrostatics, Lutam Symposium on Swelling and Shrinkage of Porous Materials, Petropolis, Brazil

62 Wet Stage Properties of Tec-Cement Concretes Water has cohesivity due to a network of extensive three-dimensional hydrogen bonding and this property is strengthened both by Brucite surfaces and the strongly kosmotropic Mg ++ ion and other species in solution. The strong polar bonding – Affects all wet stage properties Improving rheology markedly (all formulations) Reducing early age shrinkage Contributing to dissolution of clinker, gbfs etc. Contributing to high early strength Reducing bleed water thereby retaining alkali Making the mixes highly thixotropic – Significantly brings forward the onset of first set with high replacement mixes. Increases the wet sand effect effect. MgO goes negative – Helps deliver high early strength 62 Ca ++ = 114 picometres Mg ++ = 86 picometres

63 Dissolution – By Proton Wrenching? 63 According to Pellenq from MIT water dissociates and the protons formed move in a Grotthus like way (i.e. by proton hopping) penetrating the crystal structure of alite and play a role in breaking it apart. Belite has a different crystal structure and this does not occur to the same extent. Pellenq suggests change Belite structure using aluminium. We mention that aluminium works in our patents at length so have the prior art however Pellenq et. al. add understanding as to possibly why. We suggest changing the nature of water by adding Mg ++. (See later, note both methods work well together) Magnesium is mainly present as Mg2+ (aq.) in water, but also as MgOH+ (aq.) and Mg(OH)2 (aq.) and other species. The strong electron pull of magnesium may also play a role in dissolution as we have noticed a much faster early setting rate and can make cements with pure gbfs for example. i.e Mg++ and associated aqueous species probably play a role in dissolution processes. 6 Image Source: Slide in a presentation by Prof Roland Pellenq, MIT Concrete Sustainability Hub Dissolution of alite by proton wrenching

64 The Effect of a Strong Kosmotrope such as Mg The charge distribution on water is strongly influenced by the presence of a kosmotropic cation such as Mg ++ which has a strong polar bonding affinity for the oxygen end of water. This propagates and may cause more rapid dissolution of clinker, GBFS and other hydraulic cements leading to earlier more complete reaction and thus early strength. H+H+ H+H+ H+H+ Mg ++ O -- H+H+ H+H+ H+H+ Polar covalent bonds O -- These drawings are subject to copyright by TecEco Polar bond

65 Setting – An Electrostatic Affair? 65 The Wet Beach affect Sand is largely silica that has broken into small grains. At the atomic scale, silica consists of a three-dimensional network of covalently bonded silicon and oxygen atoms. Typically, silica surfaces contain mostly oxygen atoms, many of which are covalently bonded to hydrogen atoms. The surface contains many polar bonds and can hydrogen-bond to water molecules. Therefore water is attracted to silica surfaces, which are said to be hydrophilic (water loving).

66 MgO has a Bar Magnet Effect 66 The Change in the Surface Charge of Metal Oxides with pH. 7 Source:Small, R.J. et al., Using a buffered rinse solution to minimize metal contamination after wafer cleaning. MicroMagazine.com. Available at:

67 High and Total Replacement Cements TecEco recently announced a way forward to greater sustainability for the Portland cement industry. Up to 30% or more strength at all stages with high & very high replacement ternary mixes. (GBFS +- fly ash replacing PC.) Total replacement with class C fly ash and gbfs is possible Finishers can go home early using >50% replacement mixes removing the remaining barrier to their implementation. Brilliant rheology, low shrinkage and little or no cracking. Excellent durability. A solution to autogenous shrinkage? Mixes with MgO can tolerate carbon in fly ash and clays to some extent. Mg++ combines with chloride or sulphate immobilising these cations 67

68 Example Results for TecEco 68 Date of Trial Mix 30/10/ MPa 3/12/ MPa ConstituentsKg % % GP PC, kg/m Fly ash, kg/m Slag, kg/m Reactive Magnesia, kg/m MgO relative to PC8.7 20mm, kg/m mm, kg/m Total Coarse Aggregate Manufactured Sand, kg/m Fine Sand, kg/m Total Fine Aggregate WR (WRDA PN), ml/100kg Water, lt/m Design Slump, mm80100 Actual Slump, mm80100 Strength20 MPa32MPa 3 Day Day Day Day Shrinkage20 MPa32MPa 1 week week week week week NB. Our patents in all countries define the minimum added % MgO as being >5% of hydraulic cement components or hydraulic cement components + MgO

69 A Tec-Cement Modified Ternary Mix 69

70 Tec-Cement Mixes 70 Ordinary MixesTecEco Tec-Cement MixesNotes Reactive MgO as definedNoneUsually 8 to 10% / PC added1 PozzolanShould be usedRecommended. Supplementary cementitious materials (SCMs) Should be usedRecommended.2 Limit on additions pozzolans + SCMs Limited by standards that are increasingly exceeded > 50% recommended especially if a ternary blend Rheology Usually sticky, especially with fly ash. Hard to finish. Slippery and creamy. Easy to finish. Setting timeSlow. Especially with fly ash only. Much faster. Blends with a high proportion Pos. and SCMs set like ordinary PC concrete. Shrinkage and crackingSignificantMuch less AdditivesUsually usedNot necessary Durability Without additions of Pozzolans and SCMs questionable. Excellent especially with additions of Pozzolans and SCMs 28 day Strength (20 MPA mix)<.20 MPa/Kg PC/m 3 >.27 MPa/Kg PC/m 3 $ Cost Binder/MPa at 28 days (20 & 32 MPa mixes) > ($2.30-$2.50)< ($1.50-$1.90)3 Notes 1. See % is relative to PC and in addition to amount already in PChttp://www.tececo.com/technical.reactive_magnesia.php 2. To keep our patents simple we included supplementary cementitious materials as pozzolans in our specification 3. See economics pages following We recommend using both Pozzolans and SCMs together

71 Why Put Brucite in Concretes? Improved rheology (see l_shrinkage.php) l_shrinkage.php Prevents shrinkage and cracking (see l_shrinkage.php) l_shrinkage.php Provides low shrinkage and pH and eH control. Reduced corrosion. Stabilises CSH when Ca ++ consumed by the pozzolanic reaction (Encouraged) Relinquishes polar bound water for more complete hydration of PC thereby preventing autogenous shrinkage? Solves the carbon in fly ash, sulfate, chloride and clay in aggregate problems. 71 Pourbaix diagram steel reinforcing Equilibrium pH brucite

72 Durability (Important for Sustainability) Durability is related to – How easy is it for an aggressive agent to get into the concrete matrix This depends on the density which depends on the voids and specific gravity of the minerals present. – The number and size of voids depends on the particle packing and water added. – If the number and size of voids causes percolation points to be exceeded then the material is permeable and thus not likely to be durable depending on the Eh-pH – Strength is not the cause of strength but a bad proxy for permeability. – What the aggressive agent can do once in there Depends on the Eh-pH conditions inside the matrix – Ideally reducing Eh and pH above about 9.5 depending on the Eh. – Brucite the hydration product of reactive MgO stabilises the pH in concrete. The equilibrium pH of Brucite is around – Reactive MgO will also remove chloride and sulfate by reacting with them. – The electro coupling present e.g. steel – chloride 72 Durability is badly understood. Many text books get their chemistry 101 facts incorrect especially in relation to rheo bar.

73 Dry Stage Properties of Tec-Cement Concretes Significantly increased tensile strength Increased compressive strength (especially early strength) particularly with high replacement mixes containing significant amounts of GBFS compacting factor Reduced shrinkage and cracking Improved durability Higher tensile strain capacity? Greater creep Less permeable? Lighter albido Solves autogenous shrinkage problems May solve other delayed reaction problems 73 8 Recommended Reading: Du C. A Review of Magnesium Oxide in Concrete - A serendipitous discovery leads to new concrete for dam construction. Concrete International. 2005;(December 2005):

74 Solving Autogenous Shrinkage to Reduce Emissions 74 Brucite consists of polar bound layers of ionically bound atoms Strongly differentially charged surfaces and polar bound water account for many of the properties of brucite Brucite hydrates consist of polar bound layers of ionically bound atoms NB. We think this loosely bound polar water is available for the more complete hydration of PC. In most concrete 18-23% of the PC used never hydrates. If all the PC used could be made to hydrate less could be used saving on emissions be around 20%. 2C 3 S+7H => C 3 S 2 H 4 + 3CH 2C 2 S+5H => C 3 S 2 H 4 + CH

75 Economics of Tec-Cements 75 This embedded spread sheet looks only at the binder price and assumes all other factors remain the same Binder Prices Only

76 Agglomeration of Carbonates, Fly ash and other Wastes Sand and stone aggregate are in short supply in some areas. Nesquehonite is an ideal micro aggregate so why not agglomerate it and/or other magnesium carbonates to make man made manufactured aggregate? MgO binders will be suitable for this purpose and TecEco are seeking funding to demonstrate the technology. TecEco can already agglomerate fly ash and nesquehonite without additional energy. We just cant tell you how as we have not had the money to pursue a patent. 76

77 Man Made Carbonate Aggregate? 77 Source USGS: Cement Pages Assumptions - 50% non PC N-Mg mix and Substitution by Mg Carbonate Aggregate Percentage by Weight of Cement in Concrete15.00% Percentage by weight of MgO in cement6% Percentage by weight CaO in cement29% Proportion Cement Fly ash and/or GBFS50% 1 tonne Portland Cement0.867Tonnes CO2 Proportion Concrete that is Aggregate85% CO2 captured in 1 tonne aggregate1.092Tonnes CO2 With carbon trading think of the potential for sequestration (=money with carbon credits) making man made carbonate aggregate

78 A final Note re TecEco Technology 78 In this presentation we have given you so some insights into why reactive MgO is the most powerful new tool in cement chemistry. The ramifications of the effect of the Mg++ ion on water chemistry will go beyond hydraulic cements but we are a small company and do not have the money to patent other applications we are aware of. In relation to hydraulic cements including by definition gbfs in some of our applications we would appreciate that you honour our intellectual property. For the good of all we are working now to produce reactive MgO cheaply from brines rich in Mg++ such as oil and gas or de-sal process water. If you are interested further please contact us.


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