Posted on September 12, 2019
American infrastructure has been deteriorating at a shocking pace. Just last year, the State of Pennsylvania received a low rating of ‘C-‘ in the infrastructure report card by the American Society of Civil Engineers.
To address this problem, researchers have been testing different materials, and ways of enhancing the performance of concrete for decades. We are now finally close to developing the perfect replacement for ordinary concrete, i.e., Bendable Concrete.
What Is Bendable Concrete?
Bendable Concrete, also known as Engineered Cementations Composites (ECC), was first developed in the 1990s by Victor C. Li, a professor at the University of Michigan. His research was largely inspired by the production of the inner nacre (mother of pearl) in abalone shells, leading to a better and stronger alternative to ordinary concrete.
According to senior research associate at Louisiana State University’s Department of Construction Management, Gabriel Arce, "ECC material has about 300 times more deformation capacity, more than two times the flexural strength, and a higher compressive strength."
Unfortunately, mass production was not an economical option. The materials needed for the mix were expensive and drove the cost to more than 4 times that of conventional concrete.
The original bendable concrete was made with micro silica and polyvinyl alcohol (PVA) fiber. Not only is silica extremely difficult to mine, but both of these materials are too expensive to import.
Added to this, supply chain concerns and other technical factors combined to halt the journey of ECC from the lab to the construction industry.
However, new developments from Arce have given rise to the possibility of bendable concrete becoming a viable alternative. The research associate started a multi-year project in May 2017 in the hopes of discovering a cost effective technique of producing bendable concrete.
The team experimented with various locally sourced materials, including fine grain sand from around the Mississippi River, and fly ash. While these substances are not inexpensive, they can be used to cut down the cost of production by half.
Although ECC would still be more expensive than usual concrete, when you consider factors like reduced upkeep and half the material required for building structures, the gap in costs becomes negligible. "
When you factor in the possibility of building pavements at half the thickness and the enhanced construction productivity due to the ability to construct pavements without joints, the cost of pavements with our ECC material should be comparable to that of traditional concrete," explains Acre.
The Creation of Bendable Concrete
Initially, bendable concrete was made with nacre, an iridescent substance found on the insides of abalone shells which is also called the mother of pearl. The mollusks make nacre from a natural form of calcium carbonate known as aragonite.
While aragonite is delicate, it is also very ductile because of its nanoscale structure, which is built like a brick wall. The so-called bricks are extremely thin layers of aragonite platelets, with the elastic polymer “mortar” between them.
The polymer has dual functions, i.e. holding together the rigid aragonite brick wall, and allowing the individual layers to slip from side to side when placed under stress. The resulting material is tough, yet extremely flexible – making it ideal for use as a building material.
New Way of Producing Bendable Concrete
Concrete is composed of a mixture of gravel and sand, bound together with cement. To introduce ductility into concrete, researchers added tiny fibers into its structure. These interact with the cement to produce the same effect as that of the nacre’s brickwork.
The resulting material is ductile, or bendable concrete that can deform up to 5% in tension before cracks form, with a tensile strain capacity of 300 – 500 times as that of normal concrete.
Benefits of ECC
ECC, or bendable concrete, solves many of the issues associated with using traditional concrete. Here are some of its benefits:
- It stops roads and buildings from fracturing or forming wide cracks. These cracks, commonly formed with traditional concrete, allow the penetration of water and other aggressive agents into the structure that attack the reinforcing steel.
- It allows structures to absorb energy, making tall buildings more resilient to earthquake shocks.
- Intelligent use of the material and an efficient supply chain will make this type of concrete optimal for construction work. Not only does it perform better, but it will also be more cost effective once mass production is initiated.
- Bendable concrete is self-healing; unlike traditional concrete, with cracks only getting worse with increased exposure to natural elements, any hairline fractures in ECC are healed upon contact with water and air.
- ECC can adjust its thermal capacity in accordance with the outside temperature. Unlike traditional concrete that reflects heat, the bendable variant can store it, thus keeping homes cool during hot, summer days.
Currently, researchers are working on infusing ECC with the ability to neutralize contaminants around us, to help clean out our environments. Experts have embedded nano-titanium into the composition of ECC, which will break down these contaminants into harmless substances.
The large-scale use of bendable concrete is also predicted to accelerate our move to the future – or more specifically, the creation of ‘smart cities’ with advanced, eco-friendly infrastructure.
Overall, the use of bendable concrete as an alternative to the traditional building material can alleviate many problems such as decaying and poorly maintained infrastructure – thus, making buildings, roads, towers etc. more durable and safer.