TecEco - Newsletter 25
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Keeping you informed about the TecEco cement and kiln projects.  Issue 25, 11th February 2003

Wanted – Electromagnetic Genius

We are building our kiln so we can make our own cement for quality control reasons. The kiln will be based on a new vertical flow through design with patents pending in which grinding and calcining occurs in the same vessel. An additional advantage will be that all the CO2 will be captured at source and utilized for other purposes.

If any of our readers are knowledgeable in the area of induction of dielectric heating we would appreciate them getting in contact with us as the use of these technologies is theoretically very efficient. If anybody has access to nuclear magnetic resonance (NMR) and nuclear quadrapole resonance (NQR) data please also get in touch with us.

TecEco Pour the World’s Most Sustainable Slabs

TecEco Pty. Ltd. have poured the world’s most sustainable slabs using TecEco modified Portland cement at a secret seaside location in southern Tasmania.

According to John Harrison, the managing director of TecEco Pty. Ltd., the slabs are a breakthrough in sustainable building technology for a number of reasons.  The concrete was modified by the addition of reactive magnesia and fly ash and also utilized the Tech Tendon method of pre-stressing, partial pre-stressing and reinforcing patented by a shareholder company, Tendon tech Pty. Ltd.

John said that the most noticeable feature during placement was the excellent rheology of the concrete and the fact that there was no tendency for bleeding, a phenomenon that undesirably occurs with ordinary concrete.  John also said that the “gel” phase what quite pronounced.

The high tensile steel used had a strength of around 1200 mpa which is some three times greater than ordinary reinforcing. Even at around twice the cost of conventional reinforcing the steel in the job actually cost a little over half what it would have if conventional mesh and bar chairs was used.  John said that given economies of scale the cement would also have been cheaper, but due to insufficient funding his company were still unable to produce the material at a reasonable price.

John said that the concrete used was much more durable and this factor, combined with the greater strength and thinness of the reinforcing meant that the slab could also be made thinner using less concrete.  TecEco cements are very durable because the lime is removed be reaction with a pozzolan and replaced by brucite, a much less soluble and reactive mineral.

The durability. Lower energy costs of production and the fact that less CO2 is produced as a result of using TecEco cements makes the slabs the most sustainable so far produced.

The World’s First Tech Tendon Reinforced Eco-Cement Slab.

John stressed that the ramifications for sustainability from this humble experimental beginning were huge as the concretes produced less carbon dioxide (CO2) and would last much longer.

A Short History of Current Construction Technologies and the Role of TecEco Cement Technology

The history of construction is as old as the history of mankind.  When one considers this history two relevant points emerge.

(i)         In the pre “modern” era vastly different methods of construction evolved in different social groups, ranging from the use of ice by Eskimos to dung by Africans.  Various cultures made use of what was locally available and cheap and materials used varied locally with what was available.

(ii)        In the “modern” era, timber, concrete, cement and mortars have become the singly most widely used materials for construction.  Like bricks, these materials have the advantage of being able to be formed in a plastic state and in most areas can be made from locally available materials.

The Invention of Cement and Concrete

Primitive people used clay as a cement to stop up holes in their sapling huts. The Assyrians and Babylonians had no better “cement” than this for their stone buildings. The Egyptians made a mortar of partially burned gypsum and the stones of the pyramids were held in place with this material.

The Greeks used little mortar, preferring to shape stones for their great buildings so that when placed they were held in place interlocking joints.   The Romans made a cement of slaked lime and volcanic ash and this was called pozzuolana after Pozzuoli, a town near Mount Vesuvius.  Unlike mortar, pozzuolana was a hydraulic cement, which means that it hardened under water.  The Romans used it in foundations, aqueducts, and many buildings, some of which still stand.

The knowledge of how to make the hydraulic cement used by the Romans was lost during the Middle Ages.  Lime mortar was however used in all parts of Europe during that period.

A lime based hydraulic cement was reinvented in the 1750s by John Smeaton, an English engineer.  He had been commissioned to rebuild the Eddystone lighthouse, which was subjected to wind and wave off the Cornwall coast. Smeaton made hydraulic cement of a limestone that contained considerable clay. Such a limestone is now called cement rock, and the cement made of it, natural cement.

Others began to experiment with cement rock. Because the deposits varied widely in the amounts of calcium, iron, silica, and aluminium they contained, the natural cements varied widely in quality. In 1824 Joseph Aspdin, a bricklayer from Leeds, England, invented Portland cement.  He called it "Portland" because concrete made from his cement looked like stone quarried on the Isle of Portland.  For his experiments Aspdin took limestone road surfacing that had been powdered under the wheels of heavy carts. He added varying amounts of clay to the powdered limestone until he found the proportions that when burned could be ground into a uniformly strong cement.  Aspdin's main contribution to cement making was therefore the exact proportioning of raw materials

The Advantages of Concrete

Concrete is the only major building material that can be delivered to the job site in a plastic state.  This unique quality makes concrete desirable as a building material because it can be moulded to virtually any shape or form.  Concrete provides a wide range of surface textures and colours and can be used to construct a huge variety of structures including highways and streets, bridges, dams, buildings, airport runways, irrigation structures, breakwaters, piers and docks, side walks, silos and farm buildings, homes, and even barges and ships.

Other desirable qualities of concrete as a building material are its strength, economy, and durability. Depending on the mixture of materials used, concrete will support, in compression, 703,070 or more g/sq cm (10,000 or more lb/sq in).  The tensile strength of concrete is much lower, but by using properly designed steel reinforcing, structural members can be made that are as strong in tension as they are in compression.  The problem is that the manufacture of approximately 1.8 billion tonnes of cement annually produces around 2.3 billion tonnes of CO2 (carbon dioxide)

Reinforced Concrete Construction

In about 1832 precast concrete was first made in England. Twenty-five years later Joseph Monnier of France patented reinforced concrete, and during the 19th century innovation in Europe and the United States improved concrete reinforcing, prestressing and partial pre-stressing technology.

Concrete used in most construction work is reinforced with steel.  When concrete structural members must resist extreme tensile stresses, steel supplies the necessary strength.  Steel is embedded in concrete in the form of a mesh, or roughened or twisted bars.  A bond forms between the steel and the concrete, and stresses can be transferred between both components.

Concrete is a material with great compressive strength.  It can be designed to resist a compressive load of 69 kN (kilo newtons) a square meter (10,000 lb/sq in).  Concrete, however, has little resistance to a pulling force or tension.  Steel has tensile strength and high tensile steels can have tensile strengths up to 1600 MPa or even more.  Typically high tensile steels have a strength of 1200 - 1300 MPa.  Concrete and steel are combined in reinforced, pre-stressed or partially pre-stressed concrete to take advantage of the strengths of each material. Modern reinforced concrete construction uses many steel reinforcing bars exactly shaped and placed in each structural member.

The first high-rise concrete buildings were constructions made of columns and beams similar to skeleton steel framing.  The concrete was hoisted up temporary steel towers and poured into wooden forms to shape the columns and beams.  When the concrete had set and gained sufficient strength, the forms were removed and reused.  As the concrete skeleton progressed upward, new forms were set, and the floors were poured over the beams.  The refinement of flat slab framing in the 1920s greatly reduced the weight of buildings by eliminating many of the heavy beams.  In this system the reinforced floor slabs act as a continuous beam attached to, and spanning between, columns. A more recent innovation in concrete construction is the design of exterior walls as load-bearing columns and beams.  Flat slabs span from the exterior framework to solid interior walls that act as shear panels.  This type of construction eliminates the use of a curtain wall.

Pre-Stressing

The basic function of prestressing is to greatly reduce the tensile stresses to which crucial areas of concrete structures are subjected.  Pre-stressing is accomplished by stretching high-strength steel to induce compressive stresses in concrete. The strengthening effect of compression in concrete acts like a horizontally squeezing a row of books. When you apply sufficient pressure to the books at each end, you induce compressive stresses throughout the entire row; thus, although the centre volumes are unsupported, you can lift the books and carry them horizontally. Prestressing concrete has removed many limitations on the spans and loads for which a concrete structure can be economically designed.

Although the Germans invented pre stressed concrete in the 1880's, Eugene Freycinet, a French engineer, first used it in the 1920's and 1930's.  The development of prestressing, which is the method of inducing a controlled stress in a beam before it is subjected to a load, has resulted in stronger lighter structures being possible.  This development has however evolved around the use of high tensile wire or wires because these where the first high tensile steel tendons available.

Wire was first made in early times by hammering metal into sheets, cutting thin strips, and making the strips round by hammering them. The Romans made wire by hammering heated metal rods.

Wire drawing was introduced in Germany in the 14th century.  In this process, a metal rod was pulled (drawn) through a small hole in a mould (die). Until the 19th century this was done by hand; now all wire is drawn by machine.  Metal rods are pulled through a series of progressively smaller tungsten carbide dies to produce large-diameter wire, and through diamond dies for very fine wire.  The die is funnel-shaped, with the opening smaller than the diameter of the rod.  The rod, which is pointed at one end, is coated with a lubricant to allow it to slip through the die.  Pincers pull the rod through until it can be wound round a drum.  The drum then rotates, drawing the wire through the die and winding it into a coil.

Wire with a relatively high carbon content was given tensile strength by the above process which aligned all the metal crystals.  Only in later years did other techniques for adding tensile strength develop including using different additives to steel.

There are two major types of pre-stressing.  In the first type, called pre tensioning, high-quality steel tendons are embedded in the lower portion of a beam or in areas where tension exists.  Steel tendons are placed in forms and stretched by heavy jacks; the concrete is poured into the form and allowed to set; and the jacks are then released, putting the concrete in compression.  In the other type of pre-stressing, called post tenoning, the tendons may be located in hollow tubes placed within the forms.  The concrete is poured into the forms and allowed to set; and the tendons are put in tension by screws or jacks and wedged into place against steel plates at opposite ends of whatever is being tensioned.

A recent innovation has been the tech tendon method of pre-stressing, partially pre-stressing and reinforcing in which the tendons are flat straps with up to seven times the surface area for bond. The use of this new material along with TecEco modified Portland cements and Eco-Cements will allow the manufacture of thinner lighter more durable flat and curved structures.

Precast Tilt Up and Lift Slab Construction

Two major methods have been developed to erect precast walls or floors:  tilt-up and lift-slab construction.  The labour cost of building forms and the equipment necessary to transport and place concrete in high structures are major cost items.  Concrete components formed in factories or at ground level are simpler and less expensive.  Intricate shapes and textures can be obtained in forms lined with metal, plastic, or plaster.

Tilt-up construction comprises casting wall panels in a horizontal position and, when they have gained sufficient strength, tilting them up into position by cranes.  Individual panels are either joined by poured-in-place concrete pilasters or held in place by flooring or roof framing.

Lift-slab construction is similar to tilt-up construction.  Concrete or steel columns are erected, and the ground-floor slab is cast.  The second, third, and subsequent floors are cast on top of the first floor; the final floor is the roof slab.  The roof and floor slabs are lifted into position one at a time by hydraulic jacks at a rate of 2 to 3 m/h (7 to 10 ft/h).  As each slab reaches its designated position, it is attached to the column.  Buildings more than 12 stories high have been constructed by this method.

Factory Produced Modules

In the future, building construction will be revolutionised by new technologies using preformed modular structures.  Several systems have been developed that use factory-produced modules that can be assembled to form a complete high-rise building.  In France more than 100,000 dwelling units are produced annually that use precast concrete walls and slabs in room-sized units containing all utilities.  The box-shaped units are assembled on the ground and hoisted into place in a structural steel frame by a crane.  In London many multistorey flats are now produced whose units are machine-moulded from materials reinforced with glass fibre and are hoisted into place in modular steel-framed structures.  Scandinavia has produced several industrialised building systems that are used throughout the world under licensing arrangements.  One example is the Skarne system developed in Sweden.  This system is used to construct multistorey housing units up to 25 stories high.  All components are delivered to the site prefabricated; vinyl coverings are on the floors, ceilings are painted, the partitions snap into remoulded floor and ceiling tracks, and cabinet and closet walls are pre finished.  These components are precision manufactured with tolerances of a few millimetres.  Although Europe has moved toward modular buildings, progress has been slow in the United States and Australia.

The development of better building methods such as the Tech Tendon method of prestressing patented by Tendon Tech Pty. Ltd. will overcome many of the objections to modular construction.  This method allows the manufacture of very thin and curved structures made of concrete. Combined with TecEco technology whereby durability is much greater than previously the method is ideal for the manufacture of thin architectural panels and hollow lightweight lift tilt panels and lift slabs “tailor” made in factories and erected on site very quickly.  Improvements in computer aided design (CAD) will mean that no two buildings need look the same, which was previously the principal objection to modular construction methods.  Using the Tech tendon method combined with TecEco technology will result in much more sustainable yet interesting structures.

The three major techniques of mass production developed or refined during the industrial revolution were cutting, casting and bending (or pressing).  Most mass produced products of complexity that are affordable today utilise these techniques and examples range from motor cars, to electrical goods.  The resultant material gains in our standard of living have been enormous.

A cheaper more affordable method of applying the principles of mass production to concrete manufacture and in particular building construction that is acceptable to the market will result in similar cost savings and improvement in product.

The Tech tendon method of pre-stressing, partial pre-stressing and reinforcing developed by the Tendon Tech Pty. Ltd combined with TecEco cement technology is a significant breakthrough that will make possible cheaper mass production of more sustainable concrete products with the exception of individuality through CAD design.

The Future

The potential for sustainability in relation to the built environment is enormous as according to the Australian Federal department of Industry Science and Tourism [1] buildings are responsible for some 30 % of the raw materials we use, 42 % of the energy, 25% of water used, 12% of land use, 40% of atmospheric emissions, 20% of water effluents, 25% of solid waste and 13% of other releases [2] .

Fortunately, interest in sustainability is growing. According to a Housing Industry Association (HIA, Australia) survey conducted in 1994 "builders ranked solid waste and associated environmental problems as the top emerging issue for the housing industry". The report further suggested that "this industry view reflected a wider community concern about the scale of waste and a progressive shift of attention from issues of waste management to issues of reuse and recycling and, in particular, to waste minimization. Underpinning this broader shift in attention was a growing public concern for the environment – pollution and land degradation – and a recognition that waste represents inefficiency, and thus is an avoidable cost. Pollution, in any industry, is a form of economic waste." [3]

During December 2002 and January 2003 more than 100 government representatives, building designers, engineers, planners, researchers and building surveyors attended workshops being held around Australia to discuss whether sustainability measures should be incorporated into the future Building Code of Australia.

The workshops were conducted as part of research by the Cooperative Research Centre for Construction Innovation (CRC CI) and CRC CI partner, the Australian Building Codes Board (ABCB).

Concrete produces the largest component of construction and demolition waste, estimated as being up to 67% by weight and 53% by volume [4] . Concrete and cement also emit large volumes of CO2. The manufacture of Portland cement requires a lot more energy than the production of Eco-Cements and results in between .87 [5] and 1.3 [6] tonnes of CO2 emissions per tonne of cement produced. A figure derived by Pearce [7] of 1 tonne of CO2 emitted per tonne of Portland cement produced is generally accepted and the CO2 produced accounts for between 5% [8] and 10% [9] [10] of global anthropogenic CO2 emissions. Portland cement production and hence CO2 emission is currently in the order of 1.8 billion tonnes [11] .

The firing of clay bricks also produces considerable CO2 at around .28 tonne of CO2 per tonne of bricks produced [12] . The quantity of clay bricks produced is substantial but not accurately known as the industry is much more fragmented.

Industrial wastes are even more voluminous than building industry wastes with over 600 million tonnes of fly ash waste produced annually world wide in the year 2000 [13] , low utilisation in some countries and huge stockpiles. Australia dumps around 8 million tonnes of fly ash annually. There are also huge stockpiles. Tasmania for example has some 130 [14] million tonnes of industrial wastes that have been stockpiled over the last 100 years or more.

There is broad recognition that change is required and this is even starting to infiltrate the hugely conservative cement industry. During 2003 studies will be initiated by the British Research Establishment, funded partly by the British cement industry into more sustainable cements including TecEco cements.

The TecEco innovation positively addresses durability, carbon dioxide emissions reduction, waste utilisation, recycling and cost issues and coupled with the tech tendon method of pre-stressing promises huge improvements in sustainability. As the built environment is our footprint on earth and changes advocated by TecEco bring only environmental and economic benefits, the technology represents a way forward for global sustainability.

Tree Farms Won't Halt Climate Change

On the 28 October 2002, Fred Pearce reported in the New Scientist magazine that according to the first results of CarboEurope, a Europe-wide programme that has pioneered research into the carbon budget, the Kyoto Protocol to halt climate change is based on a scientific fallacy.

According to the New Scientist “The protocol says that countries can help meet their targets for cutting emissions of greenhouse gases over the next decade by planting forests to soak up carbon dioxide. But the soil in these "Kyoto forests" will actually release more carbon than the growing trees absorb in the first 10 years.

The reason is that forest soils and the organic matter buried in them typically contain three to four times as much carbon as the vegetation above. CarboEurope's researchers have discovered that when ground is cleared for forest planting, rotting organic matter in the soil releases a surge of CO2 into the air.

According to CarboEurope this release will exceed the CO2 absorbed by growing trees for at least the first 10 years. Only later will the uptake of carbon by the trees begin to offset the losses from soils.

The New Scientists reports that the Kyoto Protocol therefore gives countries a perverse incentive to chop down existing natural forests and replace them with plantations.

Has Global Warming Aggravated Australia’s Drought?

A World Wildlife Fund (WWF) study released by former Monash University meteorology professor David Karoly claims that the current drought in Australia has substantially been caused by global warming.

Professor David Karoly said "This is the first drought in Australia where the impact of human-induced global warming can be clearly seen," in a statement released with the report.

According to the study, higher day-time temperatures in 2002, which exceeded the long-term average by 1.6 degrees Celsius (34 F), led to record evaporation levels in the Murray-Darling Basin, where 40 percent of Australia's agricultural goods are produced.

Whereas estimated evaporation rates in three previous droughts - in 1994, 1982 and 1965 - amounted to 136 mm, 120 mm and 131 mm per month in the basin town of Griffith, in 2002 the evaporation rate there reached 152 mm per month.

Dr. Kevin Hennessy, a senior research scientist at CSIRO's Atmospheric Research department, when endorsing the report said the agency predicted the Murray-Darling Basin would get between half a degree Celsius and two degrees Celsius warmer by 2030, and 10 percent drier.

According to Dr. Hennessy "The challenge is, are we growing the right crops in the right areas and if we want to continue growing those crops under dry conditions, we need to choose or breed crops that are more drought tolerant, more heat tolerant and perhaps even more disease tolerant. Or move"

JJ’s Column

Hi everybody. We have not made a lot of progress on the web site because dad is too busy trying to save the world. He has had me doing boring jobs like assembling a list of players in the world’s cement industry.



[1] Australian Federal department of Industry Science and Tourism, Environmental and Economic Life Cycle Costs of Construction, 1998 - Detailed Discussion Paper, (section 2 - page 8)

[2] The reference given by Industry Science and Tourism was Worldwatch paper 124 How Ecology and Health Concerns Are Transforming Construction Worldwatch Paper 124 by David Malin Roodman and Nicholas Lenssen

[3] Reddrop, Alan; Ryan, Chris; Housing Construction Waste – A research study by the National Key Centre for Design at RMIT for the Housing Construction Industries Branch of the Department of Industry, Science and Tourism; Department of Industry, Science and Tourism; Canberra : Australian Govt. Pub. Service, 1997

[4]   (Environmental Building News; "Cement and Concrete: Environmental Considerations"; Vol. 2, No. 2 (March/April 1993); http://www.buildinggreen.com/features/cem/cementconc.html)

[5] Hendriks C.A., Worrell E, de Jager D., Blok K., and Riemer P. Emission Reductions of Greenhouse Gases from the Cement Industry. International Energy Agency Conference Paper at www.ieagreen.org.uk.

[6] Dr Selwyn Tucker CSIRO dbce Melb, pers comm.

[7] Pearce, F., "The Concrete Jungle Overheats", New Scientist, 19 July, No 2097, 1997 (page 14).

[8] Hendriks C.A., Worrell E, de Jager D., Blok K., and Riemer P. Emission Reductions of Greenhouse Gases from the Cement Industry. International Energy Agency Conference Paper at www.ieagreen.org.uk.

[9] Davidovits, J A Practical Way to Reduce Global Warming The Geopolymer Institute info@geopolymer.org, http://www.geopolymer.org/

[10] Pearce, F., "The Concrete Jungle Overheats", New Scientist, 19 July, No 2097, 1997 (page 14).

[11] United States Government Survey (USGS) figure for 2000.

[12] Dr Selwyn Tucker CSIRO dbce Melb, pers comm.

[13] Malhotra, V.M. Making concrete greener with fly ash Concrete International, May 1999, pp61-66.

[14] A detailed list is available.