497 Main Road
Tasmania 7010 Australia
Phone: +61 3 62497868
Fax: +61 3 62730010
Mobile: +61 413993911
Our first floor slab was an eco-cement slab and used in the low carbon building. (See http://www.tececo.com/exemplar.eco-cement.earthship_brighton.php)
Since then we have mainly been using Tec-Cement Concretes containing 5-10% above standard reactive magnesium oxide because of the high proportion of pozzolans like fly ash and latently cemntitious materials like ground granulated blast furnace slag, both of which are wastes which the use of reactive magnesia makes possible to add without significant delay in setting times and a considerable improvement in wet properties.
Normally builders do not like using concretes with a high proportion of fly ash because they to not achieve sufficient set for finishing quickly and because they are difficult to work as a result of sticky, non plastic rheology. We have tested reactive magnesia against some of the most powerful rheology improving agents there are and because the magnesium ion is a very strong kosmotroph, it has a much greater improving affect on plasticity important for quickly and easily finishing slabs. The highly charged but small Mg++ ion is the cause of this and also contribues to an electrostatic "first set" that is sufficiently strong to allow finishing within normal time frames (1.5-3.5 hours after placement of a 50 - 80 slump concrete) even with high proportions of fly ash.
Dimensional stability is significantly improved for a host of reasons including less shrinkage and cracking because of the profound affect of the small but doubly charged magnesium ion. For a technical explanation as to why the magnesium oxide so profoundly affects the properties of concrete such as shrinkage and cracking as well as how the electrostatic first occurs set see http://www.tececo.com/technical.rheological_shrinkage.php.
The dimensional distress caused by shrinkage is a problem in modern high strength concretes and the problem of autogenous shrinkage is solved because when reactive magnesia hydrates it forms brucite hydrates of the general form Mg(OH)2.nH20 where n represents the degree of hydration and the additional polar bound water is available for more complete hydration of PC. For a more complete discussion on autogenous shrinkage see http://www.tececo.com/technical.autogenous_shrinkage.php
Our first Tec-Cement Concretes were high fly ash and thus greener than normal concretes. (See http://www.tececo.com/files/exemplars/WhittleseaSlab170305.pdf)
More recently we have been involved with polished ground concrete floors which are a sensible good looking alternative to timber veneers, carpets, tiles and other options. The use of reactive magnesia makes it possible to use a high proportion of fly ash without finishing problems in the same manner as for ordinary slabs with the additional advantage that the reactive magnesia lightens up the grey colour imparted by Portland cements and fly ash making a wider and more exciting range of colours possible.
The first (polish grade) concrete slab was poured using a TecEco Tec-Cement modification of a Hanson Icelandia mix containing recycled silica fume and fly ash for Rob Peagram builders.(See http://www.tececo.com/exemplar.tec-cement.hill-end.php)
Ground and polished Tec-Cement floors are a much greener option because they eliminate the carbon and dollar cost of floorcoverings including replacements and because with Tececo technology they can contain up to 60% green substitutes for Portland cement including ground granulated blast furnace slag and fly ash and still be finished on the same day.
Tec-Cement Concretes are also more sustainable because they are much more durable and when we have in place our Tec - Kiln for making magnesia without releases using non fossil fuel energy they will have even lower embodied energies and emissions.
For more information on Tec-Cements see http://www.tececo.com/products.tec-cement.php