Concrete is to the construction industry what silicon is to tech. With approximately 22 billion tons of concrete produced each year, concrete is the most produced product by volume behind clean water. As such a critical component of modern day construction, it has never been more important for construction professionals to understand the inherent challenges concrete poses to our infrastructure long-term.
At the turn of the 20th century, some proposed that reinforced concrete structures might last up to 1,000 years. Today, this prediction could be generously described as over-optimistic. Besides being a major contributor to greenhouse gas emissions, it turns out that most modern concrete structures will only last for 50-150 years, making the continual use of concrete an important ecological and economical question that construction industry professionals must take seriously.
Fortunately, cutting-edge science is looking to address inherent problems with the material and create a new concrete solution for the 21st century. New concrete solutions are promising better ways to combat extreme weather conditions and create sustainable production processes which can help to prevent these climate conditions from getting worse in the first place.
An engineer at the University of New York at Buffalo has added carbon fibers to concrete in order to create a new composite material. The idea is simple: carbon fibers conduct electricity, which turns concrete into an active sensor by allowing it to have measurable electrical resistance change in response to damage or defamation. This way, new faults in the structural integrity of concrete structures can self-report for repairs automatically rather than relying on human observation. In the long run, smart concrete’s ability to self-report could empower teams to work on repairs even before such damages can be detected by the human eye, thus preventing further deterioration and saving resources.
Self - healing concrete
What if innovators could develop a way for concrete to repair itself automatically as it develops cracks? Scientists today are aiming to accomplish just that with new self-healing concrete formulas. These new formulas contain micro-pods of healing material that release once cracks appear and repair structural deficiencies from within.
Researchers at UCLA’s Laboratory for the Chemistry of Construction Materials have developed an exciting new technology which harnesses CO2 emissions from power plants to create a brand new 3D-printed building material. Dubbed CO2NCRETE, this concrete alternative can take unprocessed CO2 and turn it into a high-caliber construction material on site. Best of all, CO2NCRETE’s results exceed the industry standards of Portland cement while producing 50-70% less carbon dioxide.
Why Conventional Concrete Still Reigns
Concrete has become ubiquitous in the construction industry for many reasons. Comprising of a simple foundation of water, cement and aggregate, the primary advantage concrete brings as a construction material is that it is cheap to produce relative to its application potential. Before it hardens, concrete is also very malleable, which gives it the ability to be poured in a variety of environments and shapes. In the short term, builders can produce massive amounts of concrete to erect large, tall and even complicated structures at an overall low material cost.
In other words: concrete is easy to work with and provides a lot of bang for your buck. This has established concrete as a go-to construction resource worldwide, especially when a job needs to be completed quickly or under budget.
You might expect such an inexpensive solution to come with overt pitfalls, but concrete is surprisingly resilient when implemented correctly by an expert. For example, structures like the Pantheon in Rome were created using concrete over 2,000 years ago and remain standing today. Due to concrete’s innate ability to withstand earthquakes and water damage, concrete has proven to be highly reliable, versatile and economical by comparison to other building materials barring major complications, such as poor workmanship.
Far From Perfect
Concrete isn’t complex like organic chemistry or rocket science, yet its basic formula can be tough to nail down for the inexperienced — especially under certain conditions like extreme temperatures. Improperly placed, cured or proportioned concrete can cause defects like shrinkage, curling, cracking and disintegration, thus reducing the lifespan of a structure.
These cracks and defects can compound on each other to create additional issues with structural integrity. For example, we often frame modern concrete around rebar for extra support, which is prone to corrosion over time as the surrounding concrete deteriorates. Once the iron rebar becomes exposed and oxidizes, it can expand up to nine times its original size. This expansion, also known as ‘concrete cancer’, often leads to further deterioration of the structure. As the iron rod expands, it increases the amounts of cracks and deformations in the concrete, and will ultimately result in structural collapse if left unrepaired.
Furthermore, concrete is among the top carbon dioxide emitters and contributes to about one third of all landfill waste. According to CNN, Portland cement - the primary binding agent in concrete - is created by baking lime in a kiln which “emits approximately one ton of CO2 for every ton of cement.” As a result, concrete is responsible for over 5% of all man-made greenhouse gas emissions.
All of this begs the question as to how sustainable concrete is as the construction industry’s go-to building material. Faced with climate change and extreme weather phenomena, builders are now asking how we can prepare for increased rains, winds, fires and extreme temperatures which will only increase the pressure placed on existing concrete structures in the coming years.
[Photo courtesy of Annawaldl]