What is Concrete? A simple AI inquiry reveals a concise answer:
Concrete is a composite material used in construction, made by mixing cement, aggregates (like sand and gravel), and water. The cement acts as a binder, hardening when mixed with water (hydration) to bind the aggregates together, creating a durable, stone-like material.
Beyond what concrete is (manufactured rock) so many heavier questions abound. How did it come to be such a wide-spread construction material? How has it altered the physical world? What are its environmental impacts? Is there a value to recycling concrete and asphalt? What does it say about modern ambitions to conquer the natural world? How can we restrain our species from paving the planet? All of these questions were prompted by a recent visit to a concrete and asphalt crusher.
While concrete dates back many hundreds of years, it became central to construction in the 20th century, especially reinforced concrete. Concrete found wide-spread use in bridges, buildings, dams and roads. Heavy equipment led the way in the clearing of forests and filling wetlands. And concrete followed, paving the path. Today, the ubiquitous nature of concrete, along with asphalt, makes it impossible to avoid on any road and sidewalk. When I lived in New York City for many years, most of the earth that wasn’t built on was paved over. The impermeable surfaces made for easier travel, but the trek is hard on human bodies and psyches. In addition, the pavement collects thermal energy raising temperatures often by 10-15 degrees, not to mention polluted water run-off into underground drainage.
As with all natural materials extracted and turned into products and profits, concrete found its way in into the recycling stream. Giant machines, called Concrete Crushers, take large chunks of concrete and breaks them up into aggregate to be used in roads, buildings and landscaping. With over 25 billion tons of concrete used in construction worldwide, 90 million tons of waste seems small by comparison. And 100 tons of concrete recycled in the United States seems even smaller, considering 1 cubic yard of concrete aggregate weighs around 2,600 lbs.
On a recent trip to a Concrete Crushers at a Recycling Facility, I learned that Rockland County circulates concrete from construction and demolition sites back into the county road construction. This is commendable and many of our education facilities tout the success of these efforts. Yet when you consider the environmental impact that concrete weighs on the planet, you must wonder what the alternative might be for the use of such humongous amounts of man-made rock.
Often unknowingly, we pave and build in concrete and asphalt and significantly alter or destroy the natural habitat in which wildlife (like humans) evolved to survive. Paved roads allow access for people, cars, trucks to remote places. (And, not incidentally, water run-off.) Today, cars prevail over pedestrians, with paved roadways taking up about one-fifth of the total built up land area in the United States. And approximately 0.8% of the earth’s land surface is covered by concrete, asphalt and other man-made materials. While seemingly a small percentage, it represents a significant alteration to the earth’s surface.
Concrete recycling can be profitable. Recycling concrete, particularly by crushing it into recycled aggregate, can significantly reduce costs associated with material disposal and new aggregate purchases, and diverts concrete from the landfill saving tipping fees and transportation costs.
As I witness a concrete crusher, I wonder are we saving natural resources and helping the environment or providing more access so we can extract more resources, build more buildings? How can we understand the equation? Perhaps, we need to envision human ingenuity in a different way. Let’s take our skills at growing economies and technologies, constructing factories and cities, and building weapons, and transfer more of our human energy into preserving our natural world and our quality of life on a finite planet.
A quote by the late Donella Meadows, stands out as a simple reminder that we need to take stock of our growth and look for more sustainable alternatives.
“We know it is impossible to go on finding, moving and wasting oil, leveling forests, paving roads, dumping toxins and multiplying our numbers. A new way of life, a new set of thoughts must be found.”
Some days, I feel empowered to understand what’s happening to our planet. Other days, I want to stop the world and step off.