Environmental issues and green products are hot topics in this day and age. Protecting our planet is not only the “hip” thing to do but it’s the right thing to do. It is every vendor, manufacturer and businessperson’s obligation to understand the ecological impact of his or her business.
In trying to determine whether concrete is truly a green product, one of the first pieces of the puzzle for me was that the material itself is organic in the sense that it derives from natural products. Concrete has been around for centuries. It was used in ancient times and is the foundational material for the Roman aqueducts, and was used in the Coliseum and the Pantheon. The basic mix of sand, stone and cement is still the basis of today’s concrete.
The actual manufacturing of concrete is not what one would deem planet friendly as it begins with the blasting of limestone in quarries to make cement, the material that binds concrete. The cement powder mixes with water which allows it to bind with sand or gravel. The combination of mining, manufacturing and transporting the materials to the concrete factory and then transporting it to jobsites does not fit into what would be considered a good ecological pattern. On a positive note, concrete uses local resources which minimizes fuel requirements for handling and transportation, but on the other hand there are concerns to be addressed with the alkalinity of the wash-out water used for production of cement and concrete.
Once used in construction, concrete tends to last and even strengthen in time and offers significant energy savings throughout a building or pavement’s lifetime. Concrete’s thermal mass, along with insulating materials, affords high insulation factors and moderates temperature swings by storing and releasing energy needed for heating and cooling, therefore using less energy to heat or cool a building. The durability of concrete conserves resources by reducing maintenance and the need for reconstruction. My final step was to look at the recycling of existing concrete. Concrete is a main
ingredient in new construction, but it also plays an important role in renovation and beautification of existing residential and commercial sites. The old concrete is recycled but cannot be recycled into new concrete. It is can be crushed for use as aggregate in new concrete or as fill or base materials for roads, sidewalks and concrete slabs. Concrete’s recyclability is limited because its chemical properties change over time and with each processing. In North Carolina it is easy to find recycling centers to sell the old material to.
As stated in http://www.greenconcrete.info: “The concrete industry also uses industrial waste byproducts such as fly ash (from coal combustion) and blast furnace slag (created in iron manufacture) to constitute a portion of the cement used in producing concrete. Use of such byproducts in concrete prevents 15 million metric tons a year of these waste materials from entering landfills. Utilizing these “supplemental cementitious materials” as a replacement for cement improves the strength and durability of concrete and also further reduces the CO2 embodied in concrete by as much as 70%, with typical values ranging from 15% to 40%.”
In summary, when I ask myself if concrete is a green product, it is in the sense that it lasts with little maintenance for many years, that it is a building product that can be re-used, and that its resources derive from local areas. An example of concrete in its greenest form is a building in Berkeley, CA that received the highest LEED certification and used “concrete with slag to significantly reduce CO2 and cement content, and to increase strength.” There are many issues that need to be resolved to make concrete a more eco-friendly product, but it also appears that the industry is sensitive to environmental matters and is trying to improve its track record.
As a consumer you should consult with your concrete contractor to address any concerns about the environmental impact of your concrete products.
By Sara Abrams
Contact: Mo Sandoval