Concrete and chestnut trees
Greetings reuse fans,
Concrete and chestnut trees. Two materials that built America (albeit at mostly different times), one in the urban environment; the later on the more rural residential scale. I am connecting these two materials because both illustrate how we can become dependent on materials only to realize that these materials we rely on have limits and vulnerabilities. Construction Junction’s mission captures this realization with our emphasis on promoting conservation through the reuse of building materials.
Salvaged old growth chestnut barn beam.
The American Chestnut tree, at the beginning of the 20th century, accounted for 25% of all the trees in the Eastern forests of the US! It was called the “redwood” of the east and was described as “the perfect tree”. 100’ tall and 10’ wide, it was used for building homes, furniture and was an important food source. Tragically in the span of 40 years, 4 billion chestnut trees were wiped out by blight from imported chestnut trees. While the extinction of the American Chestnut tree is not a warning about the effects of overconsumption, it is a cautionary tale of how quickly an important material resource can vanish and highlight the importance of the protection of native trees.
Concrete and cement, on the other hand, is a warning of the potential negative impacts of over consumption. We are not running out of those materials per say, but we are stressing the global supply of an essential ingredient in the making of concrete, cement and glass: SAND, specifically Quartz sand. It is a supreme understatement to say that the urban built environment exists because of these materials. Sand is the most mined mineral on the planet—annually about 50 billion tons! And we are mining it faster than nature can replenish it from lakes, riverbeds, and coastlines (ocean and desert sand cannot be used to make these materials), causing destruction of habitat in many places where its extraction is unregulated. The production of concrete is estimated to be responsible for up to 8% of total greenhouse gas emissions.
Ultra high-performance concrete cladding panels.
The This Old House Clearstory podcast has some great episodes to learn more about these two building materials: “The (Second) Rise of Concrete” (Season 2, Ep.2) and “The Perfect Tree?” (Season 2, Ep. 5). I believe they will give you context on the importance of the careful stewardship of our raw materials. On a side note, CJ actively seeks out Chestnut wood. It is light weight and incredibly water resistant, perhaps if this tree had not gone extinct we would not have had to invent treated lumber! It is expensive wood because it is rare, beautiful and versatile. While we don’t recycle concrete aggregate at CJ, this material can be used in the making of new concrete. Most of the nation’s concrete is ground into aggregate for reuse, but its application in new material has limits. There are some inspiring alternatives to concrete such as hempcrete and listen to another Clearstory podcast “Plyscrapers” to see how wood is being used to replace concrete and steel in the construction of 5 to 10 story buildings!
Let’s promote more building material reuse!
