Poured in place concrete is generally made from Portland cement, lime, oxides of calcium silicon, aluminum and iron. Other materials, such as diatomaceous earth, volcanic ash, pumicites and fly ash can sometimes be used as well.

Concrete is commonly considered an inert material once it is cured. Healthier water-based, zero- or low-VOC additives have been developed and are readily available for the cement mixture. Be sure to have this discussion with your local supplier or installer to ensure that your choice is the most sustainable.
Unsealed concrete produces a very fine dust during use. Clear or colored sealers and coatings are available to finish off the concrete and prevent this fine dusting. Attention must be paid to ensure that additive materials are compatible with the finish materials you choose for the top of the cured concrete. For example, a coating of sodium silicate (also called water glass) does not adhere properly with most finishing paints or sealers.
Sustainability issues can include the mining of the raw materials used in concrete, which can produce soil erosion, pollutant runoff and habitat loss. Depletion of resources in some locations is another concern as is the energy-intensive production process. Many facilities have made improvements by replacing traditional fuel with waste materials as fuel (such as tires) for their kilns and by reducing their levels of CO2.
Excess concrete can often be returned to the supplier. Retardants have been developed so that concrete from incomplete jobs can be brought back to the ready mix plant and reactivated after a day or two. Concrete is a recyclable material that can be crushed and reused, often in pavement or as aggregate in concrete manufacturing. Despite its re-use potential, over 50% of concrete ends up as landfill.
Sometimes hazardous materials have been recycled into concrete. Although GreenSage supports recycling, consideration needs to be made regarding recycled hazardous materials with respect to reuse and recyclability.