Rise | We've Done the Research
Sustainable Construction with Concrete: Is it Possible?
Worldwide, around 4,100 million metric tons of cement were produced in 2019 alone. Joseph Aspdin patented Portland cement in 1824. Since then, experts estimate that we have made enough cement to coat our planet's entire surface with a thin layer of concrete. The Roman Empire made a more rustic type of concrete by mixing lime and volcanic rock. Today's cement industry manufactures its products through a chemical combination of calcium, silicon, aluminum, iron, and other ingredients. Despite the clear advantages that cement and concrete have brought to construction, the global cement industry has an enormous carbon footprint. As a material, it is not often associated with the sustainable building movement.
Table of Contents
How Can Concrete Be Green?
Architects and home builders are faced with a dilemma. Cement and concrete are extremely useful and practical for several elements of home construction. Still, they are also a measurable contributor to global warming. Fortunately, innovations in the cement industry are showing promises of more earth-friendly products. We will look at four ways in which the cement industry is slowly becoming more sustainable. They are:
- Recycled concrete
- Carbon negative cement
- Recycled plastic as a reinforcing agent, and
- Earth-friendly concrete made without cement.
Recycled Concrete
The United States produces around 317 million tons of construction and demolition waste each year; a large percentage of that waste is from concrete. While discarded concrete fills large amounts of landfill space, today, 38 states use recycled concrete as a sturdy road base. In Germany, 89% of concrete demolition waste is recovered and recycled. Cement cannot be separated from the concrete. But, by pulverizing concrete, it is possible to create a useful aggregate for future construction projects. Thus it will limit the need for mining other raw materials and reduce the stress on landfills around the country.
Another company, CarbonCure, based in Nova Scotia, Canada, has developed a process to inject waste carbon dioxide into concrete. This process saves that CO2 from entering the atmosphere and strengthens the concrete. Bill Gates' fund, Breakthrough Energy Ventures, has invested in them - they are already making a big difference in the industry.
Recycled Plastic as a Reinforcing Agent
The vast majority of concrete used in construction requires some reinforcing agents. Steel rebar is the most commonly used product for this purpose. Steel production is an energy-intensive process that is also responsible for large amounts of greenhouse gas emissions. In Australia, students from James Cook University came up with an alternative reinforcing product that could potentially replace the need for steel.
They manufactured recycled polypropylene fibers from industrial plastic waste into reinforcing agents mixed with Portland cement. By replacing steel with this recycled plastic product, they reportedly achieved 90 percent savings on the overall CO2 emissions associated with steel reinforcements.
Tobias Roberts
Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.
