Green Building Materials: Recycled Concrete & Recycled Steel
One of 2013’s green construction trends is the use of more recycled materials. Recycling old material into new saves natural resources, reduces pollution and uses less energy to produce. It seems like eco-friendly is the way to go this year! Recycled concrete and steel are two building materials that are getting popular.
Concrete, a mix of cement, aggregate and water, is the most energy intensive and least eco-friendly building material. The cement alone is energy intensive to produce by heating limestone with clay or sand to over 2600 degrees Fahrenheit. Aside from the heating energy, it releases CO2 emissions. Cement production is the third largest producer of greenhouse gases.
The aggregates, though, cause another problem. Sand or gravel must be mined, which means destroying the earth. Both cement and aggregates must also be transported long distances, which eats up fuel and creates more emissions and pollution.
Attempts to green up concrete over the years have been controversial. Fly ash, a coal mining by-product, is sometimes added to reduce the volume of cement instead of going to the landfill. It’s as toxic as coal with heavy metals like mercury and lead that can leach out. Eco-conscious builders will not use it, but others say it is safe.
Eco-conscious, recycled cement as a 21st century building material
Recycling old concrete is, so far, the best answer to reduce mining and energy use. Chunks of concrete have typically been hauled to the dump or used as fill in new construction. Now it can be crushed into aggregate at the job site, mixed right there and reused immediately. This reduces transportation costs and CO2 emissions and saves natural resources. Construction and energy costs are saved, which lowers the overall cost of the project.
Aggregate can also be made from recycled glass, plastics, wood and tires. Papercrete is made with waste paper. Recycled materials should be post-consumer for the least impact. This keeps material out of the landfill.
Steel as a green building material
Steel has always been recycled. It is truly a cradle-to-cradle type of material. The original raw materials are iron ore, coal and limestone, but once it is made, scrap can be recycled over and over again into new products. This saves 75% of the energy it takes to make it from raw materials, aside from saving natural resources and reducing mining.
Scrap metal comes from cars, appliances, the 100 million steel cans used in the US on a daily basis, construction materials, oil filters and aerosol cans. Old buildings can be dismantled and recycled. That reminds me of the Erector sets we had as kids!
Green building benefits of steel
There are several benefits of steel construction, It is durable and can withstand extreme weather, like high winds, hurricanes and heavy snow loads. Steel beams also allow buildings to have open and flexible floor space. LEED credit can be given for recycled steel.
Recycled steel is not new, but the eco-friendly characteristics of it are coming to light and getting popular!
All recycled materials save resources, cut down on energy use, reduce CO2 emissions and cut transportation costs and pollution.