The concrete we have chosen to use, 'Ecomax', is a more environmentally friendly option because it contains a portion of fly ash as a substitute for some of the normal cement content.
Fly Ash is a by product from coal burning power stations. Briefly, it is the powder that is left behind in the exhaust gases from the combustion chambers of the boilers. Although it comes from coal burning stations, this is not local fly ash, as Victorian fly ash has a higher level of soluble salts which makes it unsuitable for use in concrete.
Fly ash reacts with lime in order to form a cement product. By using a proportion of fly ash in our slab (around 30% according to our supplier) not only are we reusing a waste product from power generation, but we are also cutting down on the embodied energy required to make cement. Embodied energy comprises all energy required in the production process including that used in the mining of the minerals, processing of the product and actual manufacturing, so we are cutting down on CO2 emissions as well.
Additionally, our concrete supplier also uses recycled water in the production of their concrete, so it's nice to know that mains water supply is being reduced too.
Hope this all makes sense!