The Romans may have mastered the use of concrete over 2,000 years ago (just take a look at the Pantheon in Rome), but that doesn’t mean it’s the same type of material it was back then. Concrete has always combined an aggregate with a hydraulic binder to form a strong and durable substance, but concrete has come a long way over the past 2,000 years. Today, the industry is still evolving and innovating.
INNOVATIONS FOR THE FUTURE OF CONCRETE
Today’s modern concrete is most commonly made with Portland cement, highquality quarried aggregate, and innovative products and additives to make it more durable. Concrete is one of the most widely used building products in the world because of its ability to be made locally, its cost-effectiveness, and its strength and durability. Because concrete has been around for so long, it might be difficult to imagine that such a well-established material could be improved upon, but it has. New concrete products and manufacturing methods are enhancing concrete’s performance to tackle modern challenges.
In this post, we explore the different types of concrete that have developed over the past few years through various innovations.
Bendable concrete, or engineered cementitious composite (ECC), is a type of concrete with increased ductility, or ability to undergo extreme deformation before cracking or breaking, when compared to traditional concrete.
Victor C. Li of the University of Michigan, where ECC was first researched and invented, states that bendable concrete “can deform up to 3 to 5% tension before it fails, which gives it 300 to 500 times more tensile strain capacity than normal concrete.”
This ability to tolerate tensile strain makes bendable concrete an exciting development in the construction and maintenance of infrastructure where concrete is subject to harsh weather and extreme loads.
By dispersing tiny fibres throughout the concrete bendable concrete mimics nacre, a substance that coats the inside of incredibly strong abalone shells. Nacre is both hard and flexible, and held together by polymers that shift under stress rather than breaking.
Benefits of Bendable Concrete
Its ability to withstand heavy loads is only part of bendable concrete appeal.
Bendable concrete: Has self-healing capabilities. Bendable concrete keeps cracks relatively small with natural reactions within the hardened concrete that generate “healing” through carbon mineralization and continuous hydration. This process, in turn, repairs the cracks and restores the durability of the concrete.
- Is less prone to shrinkage and drying shrinkage.
- Is resistant to cracking.
- Keeps cracks from widening when they do occur.
- Gives the surface an expanded lifespan.
- Reduces costly repairs.
Applications of Bendable Concrete
Because of its ability to tolerate tensile strain and its extreme ductility, bendable concrete has a variety of potential applications:
- Roads: On roads or other surfaces that bear sustained weight, bendable concrete would crack less often and prevent weathering from road salts.
- Reinforcing elements: Because of its capacity to absorb more energy without sustaining damage, it can be used to make reinforcing elements like:
- The dampers on the Seisho Bypass Viaduct in Japan.
- Earthquake resistance for Tall buildings in Japan and Osaka.
These uses suggest that bendable concrete would also be useful in underground construction and water infrastructure.
As of now, bendable concrete is still relatively new and not widely used.
Design professionals should be aware of this product and its potential, so they don’t overlook an opportunity to utilize it in a structure that requires the ability to withstand considerable tensile strain.
ULTRA-HIGH-PERFORMANCE CONCRETE (UHPC)
A type of bendable concrete, UHPC incorporates fibres into the concrete mixture in order to improve strength and ductility along with a host of other benefits.
The manufacturer that began using UHPC states that they use “high carbon metallic fibres, stainless fibres, poly-vinyl alcohol (PVA) fibres or glass fibres” to increase the concrete’s ability to withstand tensile loads and deformation.
UHPC is less porous than conventional concrete which makes it more resistant to chlorides, acids, and sulphates. This concrete also has self-cleaning properties and has been thoroughly researched and commercialized.
Applications of UHPC
One of the most notable uses of UHPC is the Perez Art Museum in downtown Miami. One of the biggest challenges around construction of this house of modern and contemporary art is its location; built on Biscayne Bay, the museum is subject to sea air and salt. It is also at risk for tropical storms and hurricanes. An UHPC was used to produce roughly 100 16-foot-long mullions to support the world’s largest impact resistant window at the time of its construction in 2013.
This might sound like something out of the Jetsons or science fiction, but selfcleaning concrete has already made its way on to the market.
Self-cleaning concrete doesn’t just clean itself, it cleans the air around it of harmful pollutants.
Applications of Self-Cleaning Concrete
This type of concrete was first used for the curved panels on the Jubilee church (also known as the Dives in Misericordia Church) in Rome. The church used the photocatalytic cement panels for its stylistic shells. These shells were made to represent the Holy Trinity and, given their significance, it was important they remain in pristine condition. It was only natural that self-cleaning, photocatalytic concrete was used to ensure that the shells would not accumulate stains due to smog. Completed in 2003, the photocatalytic shells have notably remained clean and white, performing constant self-maintenance.
How It Works
Self-cleaning concrete is made with titanium dioxide (TiO2). TiO2 breaks down harmful pollutants in the air due to a reaction that occurs when the TiO2 is added to the cement during its production.
The cement breaks down organic and inorganic pollutants. It is intended to be used for projects in urban centres where air pollution and poor air quality are most pronounced.
An example of how TiO2 cements break down pollutants can be seen in its conversion of nitrogen dioxide (NO2), a harmful compound mostly produced by fuels in cars and trucks. NO2 causes:
- Acid rain. Smog. Respiratory problems. Building and pavement stains.
The reaction with sunlight produces hydroxyl radicals which react with NO2 to produce NO3,which is dissolved by water after reacting with the cement surface. Research data from a TiO2 cement manufacturer in the U.S. indicates that “up to 50% of these atmospheric pollutants could be reduced in some cities if only 15% of the buildings and roads were resurfaced with a TiO2 cement.”
Graphene concrete is reinforced by a single layer of carbon atoms tightly bound in a hexagonal honeycomb lattice. It is made by suspending flakes of graphene in water, then mixing that water with traditional concrete ingredients such as cement and aggregate. Layers of graphene stacked on top of each other form graphite, a naturally occurring crystalline form of carbon most used in pencils and lubricants. The layers of graphene in graphite can be separated into sheets only one atom thick.
Graphene is the thinnest compound known to man, the lightest known material and the strongest compound discovered — over 100 times stronger than steel.
Benefits of Graphene Concrete
Graphene concrete is an accessible and affordable concrete option:
- It is inexpensive.
- It is compatible with modern, large-scale manufacturing requirements.
- It is more environmentally friendly than regular concrete as it requires less cement.
- Higher strength graphene concrete can be used to produce smaller structural elements, reducing the amount of material used.
According to “Ultrahigh Performance Nanoengineered Graphene–Concrete Composites for Multifunctional Applications,” published in Advanced Functional Materials, graphene concrete impressively shows a “146% increase in compressive strength as compared to regular concrete, a 79.5% in flexural strength, and a decrease in water permeability of almost 400%.”
As the population grows, the demand for concrete will continue to grow. And as more and more environmental issues arise and the public becomes more concerned with sustainability and decreasing climate change, innovations in the buildings we use are crucial. Solutions like decreasing CO2 emissions and decreasing the carbon footprints of buildings are being explored by the use of innovative concrete. Additional concrete innovations include:
- Carbon Capture Technology.
- Self-consolidating concrete.
- Cementless concrete.
- Reinforced concrete.
The concrete industry has been evolving for thousands of years. Innovations in concrete technology will continue to lead to more sustainable products that will last longer, cut back on emissions, and use more naturally occurring elements. A combination of traditional materials and advanced technologies will help meet the physical and environmental demands of new structures in the future.
From a story posted on the Michigan Concrete Association site – Concrete Innovations: The Future of the Concrete Industry (miconcrete.org)