Concrete, What’s Next and Why It Isn’t Likely to Go Away in the near Future
Currently the world is consuming tons of concrete. According to Bill Gates, enough to build a city the size of New York City every month for the next 40 years. So, it is not surprising to learn that after water, concrete is the most used resource on the planet. Although research is being conducted on alternative materials, it doesn’t look like this concrete consumption trend will change anytime soon.
As cities, states and communities aim to fulfill this construction demand it presents us with two major challenges:
- The production of cement, the “glue” used to bind concrete together, accounts globally for nearly 10% of all carbon dioxide greenhouse gas.
- The specific type of sand that is required to make concrete is a limited resource that is running out at an ever-increasing pace.
If we wish to cater to the construction demands of the future, we must change how we are producing construction materials, search for alternatives, and consider how to use these materials as efficiently as possible.
One approach is to reduce the amount of carbon dioxide created during cement production. To produce cement, limestone (calcium carbonate) mixed with clay is ground down and heated to temperatures as high as 1450°C (2640°F) where the chemical bonds of the raw materials are broken down, releasing carbon dioxide molecules and forming calcium oxide. From the total carbon dioxide incurred during the process, approximately 40% comes from the energy required to heat the limestone while the remaining 60% comes from the chemical change.
To tackle the amount of greenhouse gas produced, companies such as CarbonCure are investigating the possibility of injecting carbon dioxide back into the concrete/cement. Other approaches focus on reducing the energy required for the chemical process by tapping into sources of green energy. Heliogen embraces a machine learning based method to control a multitude of mirrors that can focus enough solar energy toward a single point to achieve the required temperature for cement production.
A more drastic approach is to rid concrete of cement all together as is the case with the ETH Zurich spin-off Oxara. The spin-off’s ultimate goal is to make use of onsite excavation material which is usually an unwanted byproduct of construction. Oxara’s advantage lies in its organic additives that turn materials that could be used for laborious rammed earth into a stabile product that can be easily cast into a mold; in a similar fashion to concrete but without the need for cement. Oxara claims that its product can perform to approximately 25% that of concrete, making it an ideal substitute for low-rise buildings but not for more permanent and performative structures. A two-story proof of concept building in Portugal is currently in the making and should debut in 2020. Astonishingly, Oxara’s earth concrete can be mixed in such a way that it can be easily recycled by only applying water and, if reused, the performance of the material increases in performance with every iteration.
Composites on the other hand promise to create seemingly magical material properties that can outperform conventional construction materials. This is especially true when coupled with digital fabrication, enabling graded material properties such as illustrated in the research conducted by the University of Stuttgart’s Institute of Computational Design and Construction (ICD) and Institute of Building Structures and Structural Design (ITKE). However, applying the adage ‘if it’s too good to be true it usually is’, reveals one considerable drawback with composites is their inability to be recycled and separated into their core materials at their end of life.
Timber is proving to be a promising alternative to cement based concrete in a multitude of cases but for the foreseeable future concrete is here to stay.
Infrastructure is the largest and one of the most important yet overlooked essential technologies to ensure a bright future. Most infrastructure is and will continue to be made from concrete due to its price, endurance to harsh conditions, structural performance, and ability to be applied at scale. The American Society of Civil Engineers estimates that the U.S. needs to invest over $2 trillion by 2025 to address critical deficiencies in the nation’s roads, railroads, waterways, water systems, dams, airports, electrical grids and waste management systems.
At Toggle we are focused on addressing the needs of the built world by prefabricating structural components using methods of digital planning and fabrication, be it architecture or infrastructure. Currently we are working with steel rebar for reinforced cement concrete however, our process is material agnostic so we are also closely following developments of eco-friendly cements and new materials in academia and industry.
We are eager to collaborate with other innovative groups focused on creating a better and more sustainable building environment. In a following post we will explain how our process can actually make construction more efficient and performative.
