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Keeping you informed about the TecEco cement project. Issue 35, 15th June 2004

TecEco Web Site Update

Technical and non-technical pages on the web site have been updated with new downloads. In particular there are several new technical documents, a new business plan and a new research and development plan.

The attention of readers is drawn to a new paper on carbonation. This paper goes into the as yet unclear chemistry of carbonation processes in Eco-Cements and corrects previous incorrect assumptions made by John Harrison about the magnesium carbonates formed when Eco-Cements carbonated.

Thermodynamically hydromagnesite appears favoured and would desiccate forming magnesite. In practice however it has been found that the main minerals forming are a possibly amorphous form, lansfordite and nesquehonite.

Launch of the Association for the Advancement of Sustainable Materials in Construction (AASMIC) Web Site

In response to the growing challenge of sustainable construction, the Association for the Advancement of Sustainable Materials In Construction (AASMIC) was formed in March 2004 by a multi-disciplinary group of concerned professionals. The objective of AASMIC is to raise the profile on the importance of materials in delivering genuine environmental sustainability through workshops, conferences and general information dissemination and networking.

One of the first tasks of the AASMIC group is to run a conference on the topic of sustainability, innovation and construction materials. A number of workshops will also be run during the lead up to the conference.

It is hoped that through discussion and dissemination of ideas during workshops and conferences, a position statement will be developed which will outline a way forward for eco-efficiency and materials effectiveness within the Australian construction and construction products industries. This will then be used to inform ongoing discussions surrounding materials and the construction industry as well as act as a mandate for the ongoing activities of AASMIC.

1st Call For Papers

The first conference has been scheduled for 21st of October 2004. To find out more please visit www.aasmic.org

PhD Studentship Available - Imperial College London

An opportunity has arisen to study for a PhD at Imperial College London, so if there is anybody out there interested in doing some serious work on TecEco cement concretes please contact John Harrison.

Call for Research to Verify our Findings

TecEco and a number of other institutions are obtaining some stunning and very significant results for Tec-Cements including greater tensile strength and more rapid compressive strength development even with a high proportion of added pozzolans. Greater strength using less binder and more supplementary pozzolanic material has enormous implications for cost and sustainability. We are therefore urgently seeking third parties to independently confirm this finding.

Tec-cements (Around 5 -10% MgO, 90 - 95% PC) contain more Portland cement than reactive magnesia. Reactive magnesia hydrates in the same rate order as Portland cement forming Brucite which uses up water reducing the voids:paste ratio, increasing density and possibly raising the short term pH as reactions with pozzolans are more affective. Some magnesium silicification is also being potentially formed.

After all the Portlandite has been consumed Brucite controls the long term pH which is lower and due to its low solubility, mobility and reactivity results in greater durability.

Other benefits include improvements in density, strength and rheology, reduced permeability and shrinkage and the use of a wider range of aggregates many of which are potentially wastes without reaction problems.
Please contact us if you are interested in independently testing our cements.

Tensile Strength Results

Student - Oxford University

1 part cement :3 parts standard sand with water cement ratio 0.5
This mix was similar to what is specified by BS EN 196 - 1 and used by the British Research Establishment (BRE - see below)

Compressive Strength Results

Student - Oxford University

The same student at Oxford drew the graph on the left. The dashed line is a TecEco Tec-cement with no pfa.
1 part cement :3 parts standard sand with water cement ratio 0.5.

This mix was similar to what is specified by BS EN 196 - 1 and used by the British Research Establishment (BRE - see below)

BRE (United Kingdom)

The British Research Establishment are currently researching our concretes and reported that a mix with as much fly ash as cement in accordance with BS EN 196 1 achieved 69 mpa at 90 days and was consistently well above that of the OPC control.

2.85PC/0.15MgO/3pfa(1 part) : 3 parts sand - Compressive strength of 69MPa at 90 days. Note that there was as much pfa as Portland cement plus magnesia

TecEco Hobart

The mix was:

Portland Cement 245 Kg
Magnesia 30 Kg
Fly ash 70 Kg
Quarry Dust 215 Kg
White Sand 550 Kg
Blue metal (3 sizes) 1060 Kg
Water was 135 Kg / M3 Without plasticiser 125 Kg was required to achieve the same workability.

Unfortunately the latter mix was not tested. Normally about 380 Kgs of PC would be required for the above strength development.

Note that in all the above cases the strength development is a straight line from day 1.5 to at least ninety days!

Early strength development even with added pozzolans is very important. Where will this technology take us??

More on Porous Pavements

Although the following press release from the NASA Goddard Space Flight Center is dated 2001, the importance of the issue is increasing so we thought we would reproduce it

New Satellite Maps Provide Planners with Improved Insight into Urban Sprawl

A major advance in satellite-based land surface mapping has led to the creation of more accurate and detailed maps of our cities. These maps provide urban planners with a better understanding of city growth and how rainfall runoff over paved surfaces impact regional water quality.

Maps taken from space are invaluable to city planners and state agencies monitoring water quality in urban areas, and are replacing the more expensive and time-consuming traditional aerial photography.

These space-based maps of buildings and paved surfaces, such as roads and parking lots, which are impervious to water, can indicate where large storm water runoffs occur. Concentrated amounts of runoffs lead to erosion and elevated amounts of soil and chemical discharge into rivers, streams and ground water.

Scott Goetz, Project Manager of the NASA-sponsored Mid-Atlantic Regional Earth Science Applications Center (RESAC) at the University of Maryland, presented these highly detailed surface maps today at the American Geophysical Union spring meeting, Boston, MA.

Andrew Smith, a faculty research assistant working with Goetz at the Mid-Atlantic RESAC, developed a faster and less expensive capability, utilizing Landsat 7 and Space Imaging's Ikonos satellite data, to generate accurate maps of paved surfaces. "It's a major advance in monitoring capability because aerial photo mapping can't keep up with the pace of change," Goetz said. "Our maps of counties and cities capture new development and can be repeated much more quickly than the tedious and expensive traditional photo interpretation work."

Urban sprawl results in more paved surfaces and less area for water to drain into soils.

Reduced drainage areas bring more water into fewer drainage systems at a faster rate, eroding the banks of streams and rivers, and adding more sediment into the water. "If you increase an impervious surface near a stream by creating a paved parking lot, for example, you directly affect the quality of life in the stream because of the runoff that surface will generate," Goetz said.

Smith cites previous researchers who have shown a relationship between the amounts of impervious surface cover within a watershed and the quality of surface water within that watershed. Generally, when 10 percent to 15 percent of an area is covered by impervious surfaces, the increased sediment and chemical pollutants in runoff have a measurable effect on water quality. When 15 percent to 25 percent of a watershed is paved or impervious to drainage, increased runoff leads to reduced oxygen levels and harms stream life. When more than 25 percent of surfaces are paved, many types of macro and microorganisms in streams die from concentrated runoff and sediments.

Impervious surface maps also are useful in mapping urban sprawl. Sprawl is indicated on the maps by increases in land consumption and housing construction. By monitoring an area over time, maps can show the progress of residential development. Currently, the RESAC team is working with planning departments to add the data from the maps into future urban planning models.

Smith has produced a map of the Washington-Baltimore area that quantifies how much impervious surface there is across the entire region. Baltimore and the counties that border it have at least 20 percent, and up to 40 percent, impervious surface area, indicating that pollution from runoff could be a problem. The District of Columbia and surrounding watersheds in Virginia and Maryland have levels of impervious surfaces between 20 percent and 30 percent percent. Areas between and beyond the Baltimore-Washington corridor are more "green" with levels that range from 0 percent to 20 percent impervious surface areas.

The RESAC team has provided maps to the Chesapeake Bay Program, Maryland's Departments of Planning and Natural Resources and Montgomery County Department of Environment, among others, to monitor water quality and changes in residential land use. These organizations incorporate the impervious surface area data into models that predict water quality, future land use and the potential effectiveness of various "smart growth" policies.

NASA launched Landsat 7 in April, 1999. Images are archived, processed, and distributed by the U.S. Geological Survey, which is also responsible for day-to-day operations of the satellite. This research is being conducted as part of NASA's Earth Science Enterprise, a long-term study of how natural and human-induced change affects our global environment.

For additional information regarding this release, please contact:

Lynn Chandler
Goddard Space Flight Center, Greenbelt, MD
(Phone: 301/614-5562)

How Porous Pavements Would Fix This Problem

Porous pavements filter water falling on them releasing it slowly to sub-surface drains or aquifers and finally the sea. There is little or now surface run-off to carry rubbish into drains and streams.

Water quality is purified by the sub-pavement acting as a giant biofiliter and because surface rubbish does not contaminate it.