It is all around us. But most of the time, you cant see it. And there is a good reason why scientists are currently focusing their research efforts on it.
Concrete is one of the most commonly used construction materials in the world, says Enzo Martinelli, a civil engineer at the University of Salerno. In Europe alone, we produce the equivalent of one cubic meter of concrete per inhabitant each year.
At the University of Salerno in southern Italy, scientists working on the European research project EnCoRe (Environmentally-friendly solutions for Concrete with Recycled and natural components) are mixing what looks like ordinary concrete. But there is one added ingredient: the standard recipe including water, cement and aggregates has been improved by adding recycled industrial fibers to produce a greener, more sustainable concrete.
What we are trying to assess is how we can reduce the quantity of industrial fibers added to the concrete and replace them with recycled industrial fibers. Were trying to understand how much recycled fiber we can add to the concrete while preserving its quality and resilience, says Enzo Martinelli.
This experimental concrete, enriched with recycled materials, then undergoes a tough series of tests. It is bended, compressed, stretched and split to see how it reacts to extreme conditions.
Weve realised that the main problem with industrial recycled fibers is their geometry. As they have already been used for other applications, their geometry isnt regular or smooth. So they dont mix in so well with cement, says civil engineer Antonio Caggiano from Buenos Aires University.
But new industrial fibers mix in better. Which means we could produce a concrete that has more homogenous mechanical properties, and which is therefore more reliable, he adds.
In addition to the mechanical tests, researchers carry out computer simulations in order to see what happens inside the concrete when its submitted to extreme conditions.
There are several parameters, including the rigidity of each component inside the concrete, its internal shape, its chemistry, its inner temperature, its hydration level
how much fiber it contains, and what kind of fibers. All of this is translated into parameters that help us understand the behavior of the concrete, says José Guillermo Etse, a civil engineer at the University of Tucumán in Argentina.
Scientists hope their research will soon prove that green concrete can be produced on an industrial scale. Managers at Calcestruzzi Irpini S.p.A, which produces 60.000 cubic metres of green concrete each year, say they are ready for a more sustainable alternative under one condition:
We already use 100 percent recycled water in our concrete. And we would be delighted to use recycled aggregates as well if we can ensure that the final product lives up to national and international quality standards, says Quality Manager Mauro Mele.
According to Enzo Martinelli, there are various areas where green concrete could be used:
Green concrete enriched with vegetable fiber can be used to reinforce existing buildings, like historical monuments. It would be a good, sustainable alternative, because it would be produced from materials with a low environmental impact, and could be reversible: since its not being used for structural purposes, it could be replaced with another kind of concrete if its use is not appropriate.
Apart from using recycled industrial and natural fibers, researchers hope they will soon develop high quality green concrete by using tyres and even recycled plastic.