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Keeping you informed about the TecEco Cement and Tec-Kiln projects. Issue 38, 31st August 2004
Apart from the news and history subsections the web site has been updated at long last! There are many new documents to download, more content and a new discussion forum I will check from time to time.
Check it out
Once again John is going on a mission to spread the word about TecEco technology. As usual his schedule will be hectic. If you want to contact John whilst he is overseas email him well before. Details of his email addresss are on the TecEco web site at www.tececo.com Phone him before he goes on +61 3 62497868 or when traveling on +61 0413993911.
Saturday 11 September 2004: 16:50 Depart Sydney QF 1
Sunday 12 September 2004: 06:45 Arrive London HR
Monday 13 September 2004: Visit BRE, Imperial College, Ove Arup and anybody else who wants to see me (time permitting).
Tuesday 14 September 2004: Attend "Sustainable Waste Management and Recycling Challenges and Opportunities" conference at Kingston University
Wednesday 15 September 2004: Attend "Sustainable Waste Management and Recycling Challenges and Opportunities" conference at Kingston University."
Thursday 16 September 2004: Attend "Cement and Concrete Science (Warwick University) 2004"
Friday 17 September 2004: Attend "Cement and Concrete Science (Warwick University) 2004."
Saturday 18 September 2004: Visit See MIRO, anybody else who wants to see me (time permitting). 2230 Depart London HR BA 27
Sunday 19 September 2004: 1720 Arrive Hong Kong. 2035 Depart Hong Kong KA 870. 2245 Arrive Shanghai (PuDung Airport).
Monday 20 September 2004: Attend "SB04 - Sustainable Building 2004, China" (See http://www.jk.sh.cn/websb04/homeE.html)
Tuesday 21 September 2004: Attend "SB04 - Sustainable Building 2004, China"
Wednesday 22 September 2004: Attend "SB04 - Sustainable Building 2004, China"
Thursday 23 September 2004: 1510 Depart Shanghai KA 893.
1740 Arrive Hong Kong
1940. Depart Hong Kong QF 88
Friday 24 September 2004: 0645 Arrive Melbourne. Spend day there and return home in evening.
I often ask myself why we are a company.
The technology paradigm defines what is or is not a resource in an economic system that drives materials flows through the techno process. As a consequence new technologies that define more sustainable materials flows must result in economic benefits for the ultimate beneficiaries in a system that without inefficient regulation does not recognize externalities.
As we generally perceive ourselves to be the ultimate beneficiaries of our economic if not our entire existence then sustainable materials flows in the techno process must also be more economic.
Sustainability must be economic or is itself not sustainable.
Making sustainability economic is the challenge facing TecEco.
Around 26 billion tonnes of CO2 are released to the atmosphere annually, around 20 billion metric tonnes of which is from the burning of fossil fuels and close to a significant 2 billion tonnes from the production of Portland cement. The built environment is our footprint on the planet and huge in size. Tec-Cements reduce emissions because the same strength concretes are achievable with around 25-30% less cement than if ordinary Portland cements are used whereas Eco-Cements gain strength by sequestering carbon from the atmosphere in permeable materials.
Over two tonnes of concrete are produced per person on the planet per annum, representing an enormous opportunity to not only reduce net emissions but to utilize solid wastes including wastes for their physical property rather than chemical composition in cementitious composites with improved properties.
This paper discusses the potential impact on sustainability of the new tec and Eco-Cement technologies and goes into the as yet unclear chemistry of carbonation processes.
Tec-Cements contain around 5-15% added reactive magnesia and usually a pozzolan. Eco-Cements contain more magnesia and rely on carbonation for strength in more permeable materials.
Eco-Cements became known to the world mainly through an article on them in New Scientist Magazine (Pearce 2002) and a program shown by Discovery Channel (Carbonating Eco-Cements 2003). There have been several reasons for the intense interest – the potential lower embodied energy, the ability of Tec-Cement and Eco-Cements to benignly encapsulate a wide range of wastes, the potential for reduced emissions using Tec-Cements and in combination with TecEco Tec-Kiln technology, CO2 sequestration by Eco-Cement concretes on a massive scale.
The built environment probably accounts for around 70% of all materials flows. Current cement production of around two billion tonnes per annum is enough to make over two tonnes of concrete per person on the planet per annum. (USGS 2004). The possibility of including carbon and other wastes, particularly those containing carbon such as plastics and sawdust that would otherwise be lost to the atmosphere must be considered seriously.
Global carbon dioxide flows in tonnes CO2 are (Haughton 2004 converted from tonnes C):
Atmospheric increase = Emissions from Fossil fuels
+ Net emissions from changes in land use - Oceanic uptake - Missing carbon sink
12.07 (±0.73) = 20.152 (±0.1.83) + 5.86 (±2.56) - 7.32 (±2.93) - 6.59 (±4.39)
Unless we want to face climate change on a massive and global scale we must sequester at least 6 billion tonnes of CO2 per annum. As we are unlikely to give up the fossil fuel habit until we run out the need is urgent. Now Russia has joined the Kyoto treaty it has come into affect and countries that do not make an effort to sequester carbon will in due course face sanctions. Using TecEco technology emissions reduction is clear and definable and there are significant business opportunities particularly under the clean development mechanism of the treaty. What better way to sequester carbon and convert waste to resource than in our own built environment?
Both tec and Eco-Cements potentially contain significantly less embodied energy. Tec cements reduce emissions by requiring less CO2 emitting cement and utilizing a higher proportion of pozzolans for the same or more rapid strength development whilst Eco-Cements set by absorbing carbon dioxide from the air. This strength development has been demonstrated in several studies now including the manufacture of Tec-Cement blocks in Australia. Combined with TecEco Tec-Kiln technology which combines calcining and grinding in a closed system whereby CO2 can be captured there are very significant abatement opportunities.
The rate of carbonation of both calcium and magnesium compounds depends on the dissolution rate of Ca2+ and Mg2+ and partial pressure and transport of CO2. These in turn are influenced by the mix design, affect of aggregates on permeability and setting atmospheric conditions. Wet dry cycles appear to promote carbonation providing alternatively transport and reaction media. Well graded aggregates including a coarse fraction are essential as they are for lime mortars. Recent work by the author has demonstrated that most commercial sands specified by standards in Australia the US and Europe are unsuitable for the carbonation of mortars and that well graded sands including a coarser fraction up to 1/3 the thickness of a mortar joint are essential to allow the material to “breathe” thereby providing gas transport.
Ideal carbonation conditions are still being determined, currently coarse well graded aggregates including a coarse fraction, dry mixes and varying humidity with wet dry cycles is thought to work best. . The magnesia in Eco-Cements first hydrates forming brucite and then this carbonates forming hydrated carbonates the most important of which are an amorphous phase, nesquehonite and lansfordite. Properties are shown in Appendix 1 –Magnesium Carbonates in Eco-Cements on page 4.
XRD studies in Australia using blocks that have been allowed to carbonate both before and after HCL extraction prove complete carbonation occurs with under two years.
Both tec and Eco-Cements provide a benign environment in which significant quantities of waste can be utilized. The shear thinning properties tend to prevent segregation of materials like plastics which is a problem with Portland cements and the lower long term pH prevents internal reactions from occurring.
The current technical paradigm for recycling generates separate outputs based on chemical composition rather than class of property. Costs are incurred and waste generated in separating what is required from the balance of materials and then transporting to factories that can only use specific waste inputs.
TecEco Cements are benign low long term pH binders that can utilize wastes more on their class of property rather than chemical composition, and therefore reduce sorting problems and costs associated with recycling and provide an inherently more economic process.
In the above manner TecEco Cements change the technology paradigm redefining wastes as resources (Pilzer 1990).
Durability and many other problems of including wastes are overcome. Reasons include:
Perhaps the most pre-eminent cement chemist ever, the late great H.F.W. Taylor, predicted a need to do something about global warming and wastes in regard to cement and concrete publicly at least as far back as 1990 in his address to a Conference on Advances in Cementitious Materials (Taylor 1990). Taylor forecast many changes not only in the way cements are made but in their composition, particularly in relation to the incorporation of wastes.
TecEco Cements are a new innovation that offers sustainability in our own back yards. Tec-Cements promise greater durability than ever achieved before and stronger materials with lower embodied energies and associated emissions whilst Eco-Cements are the first construction materials that successfully use carbon dioxide and wastes.
As stated by Fred Pearce in the article on Eco-Cements that was published in the New Scientist magazine (Pearce 2002) “There is a way to make our city streets as green as the Amazon Forest. Almost every aspect of the built environment from bridges to factories to tower blocks, and from roads to sea walls, could be turned into structures that soak up carbon dioxide – the main greenhouse gas behind global warming. All we need to do it change the way we make cement.”
1. Carbonating Eco-Cements (2003). The Daily Planet.
2. Haughton, R. (2004). Understanding the Global Carbon Cycle, Wood Hole Institute, www.whrc.org/science/carbon/carbon.htm.
3. Pearce, F. (2002). "Green Foundations." New Scientist 175(2351): 39-40.
4. Pilzer, P. Z. (1990). Unlimited Wealth, The Theory and Practice of Economic Alchemy, Crown Publishers Inc.
5. USGS (2004). "Cement Year Book." http://minerals.usgs.gov/minerals/pubs/commodity/cement/cemenmcs04.pdf
The Association for the Advancement of Sustainable Materials in Construction in conjunction with RMIT University and the Center for Design will be holding their Inaugural Conference "Innovation || Materials || Sustainability" on the 18th and 19th November, 2004 at the Marriott Hotel, corner of Exhibition and Lonsdale Streets, Melbourne, Australia.
Sustainability is recognized as the major challenge facing the construction industry as we enter the 21st century. The main determinant of sustainability in the built environment is the technical paradigm in which materials play a major role as they affect embodied and lifetime energies, recyclability and affect on the planet of their net emissions and when they are wasted.
The conference is multidisciplinary and will explore the economics, legal framework, planning requirements, architectural aspects and other ramifications of innovations, developments and practical applications concerning the need for more sustainable materials within the construction industry.
An overriding theme will be the need to make sustainability an economic process and the important role of materials in redefining resources and wastages with reduced linkages to our environment.
Check out the conference when you visit the AASMIC web site at www.aasmic.org. Have a look at our conference scheduler, post your conference if you are involved in one, add a link and support the site.
A recent test at Island Block and Paver has demonstrated that a paver with
30% less Portland cement and 10% added MgO was just as strong as the control
pavers with no reduction in binder content.
Unfortunately there are some economy of scale issues in that MgO is still three times the price of OPC meaning in Australia at least it is not economic to substitute. We should be able get the same result with 5-7.5% MgO added however and if we can it will become economic and - we should become commercial without having to rely on a 30% improvement in sustainability rating.
This has been a major battle around the world but some good news at last. NZ - in spite of a lot of opposition are moving to grant.
It is all still a bit hush hush but we are talking to some large mining companies about stope back fill cements using our technology to geosythesise "concrete" using on site materials.
The good news is that we have ordered our first tonnes of MgO and tonne of fly ash with a view to making a labeled product for experimental purposes.
We thank you for your continued interest and support.
If you have any friends who would be interested in finding out about TecEco please direct them to the web site.