While waste management is a subject the entire world is grappling with, at the same time use of alternate sustainable material for building infrastructure is another area of concern for governments across the world. Conventional methods of waste management like landfills etc and infrastructure development pose a big threat to the environment.
Now RMIT University in Australia has found a unique solution that would mitigate the risks posed by these issues. As per the researchers at RMIT, the solution to prevent the environmental damage caused due to poor waste management methods and use of conventional material for infrastructure development is use of recycled waste materials.
Out of the world’s total waste produced annually, almost 50% is contributed by the building debris, which is a result of construction, renovation or demolition. While the waste is being generated at a faster pace, its efficient management is an area that is lagging behind.
Another interesting fact – almost 1 billion units of scrap tyres are generated annually worldwide.
Similar kind of situation was faced by Australian government. In Australia, only 16% of scrap tyres are domestically recycled. About 3.15 million tons of processed building rubble – known as recycled concrete aggregate (RCA) – is added to stockpiles each year rather than being reused.
This coupled with government decision to ban the export of certain waste materials in order to build Australia’s capacity to produce high value recycled products, put a lot of pressure on researchers to come out with an innovative solution to this problem, which was becoming an environmental hazard.
To address this problem, RMIT researchers developed a new material that is produced by mixing the recycled building debris and the old scrap tyres. The blending happens in specific proportions such that the new material is precisely optimized to meet road engineering safety standards. Designed to be used for base layers, the recycled blend is more flexible than standard materials, making roads less prone to cracking. Thus this new material has the potential to deliver both the environmental and engineering benefits.
Roads are typically made of four layers – a subgrade, base and sub-base, with asphalt on top. While as an alternative to the conventional material, RCA can very well be used as base layer, however adding rubber to RCA in right proportions would increase it strength and flexibility manifolds. This will enable the road to withstand the weight and pressure of heavy vehicles effectively without developing any cracks or getting deformed. Not only has this material been tested for stress, but it has been found to be acid and water resistant, with low shrinkage.
Researchers used special machinery to assess the blended material’s performance under frictional force, or shear stress, and compared different types of crumb rubber (fine and coarse) mixed into the RCA at different ratios.
The team identified an optimal mixture – 0.5% fine crumb rubber to 99.5% RCA – that delivered on shear strength while maintaining good cohesion between the two materials.
Now the real value can only be derived from this new invention, by scaling up its production and usage in infrastructure development. This is not the end of the road, as this alone may not be sufficient to mitigate the waste problem. We need to make relentless efforts in this direction to evolve new materials and advance recycling techniques, and make further contribution to circular economy.