United Arab Emirates : Recycled Tire Products Unable To Take The UAE Heat.
Used tires are often recycled to make an industrial material called crumb rubber, where scrap tires or other rubber is turned into uniform granules that is mixed with steel, fiber and other materials to achieve a desired strength and elasticity. Crumb rubber is commonly used to make products like synthetic turf, playground surfacing, landscaping products, and road surfaces and structures.
While such products have been around since the 1960s, the safety and applicability of these products has not been assessed for the UAEs extreme climate and so the research team composed of faculty from Masdar Institute and Ain Shams University of Egypt believe this oversight has led to inappropriate use in the region.
Crumb rubber product is popular because it is able to absorb impact. That is why it is used in playgrounds, landscaping, and paving around the world. However, we believe the standards applied by the American Society for Testing and Materials (ASTM) to crumb rubber regarding different size ranges of crumb rubber for playground tiles is not sufficient for the stresses that the tiles are subjected to, from the extreme temperatures common during the summer months in our region, said Dr. Isam Janajreh, Associate Professor of Mechanical and Material Engineering. He led the research from Masdar Institutes side, with Sherien Elagroudy, Associate Professor of Environmental Engineering at Ain Shams University, and Mohammed Hussain, alumnus of Masdar Institute.
To assess how crumb rubber exposed to UAE climate responds to various stressors, the team collected crumb rubber playground tiles from around Abu Dhabi. They then subjected the tiles to a number of tests that adhere to assessment of playground surface testing as per American Society for Testing and Materials (ASTM) guidelines and crumb rubber physico-chemical analysis as per the US Environment Protection Agency (EPA).
Ball drop tests, compression and dynamic tests and Scanning Electron Microscope (SEM) tests were carried out to assess the crumb rubber tiles structural characteristics whereas thermo-gravimetric tests were carried out to assess the tiles thermal stability. The results show that aged/used crumb rubber playground tiles disintegrate faster in the UAEs outdoor atmosphere and attain a condition that could be potentially dangerous to the health and safety of users.
The results are very striking. We see crumb rubber tiles in playgrounds, so if our children fall while playing, they will fall on something that absorbs the impact and will not be hurt. But if they fall on an older crumb rubber surface, our research shows that its like falling on concrete, as the rubber has lost its elasticity and is very brittle. That is dangerous, he explained.
The study also found that the rubbers binding agent sulfur was degrading faster than the crumb rubber, causing the bad condition of the tile. An elemental analysis showed the sulfur content beyond that which would be appropriate for the age of the sample due to the surface erosion of the tile. This was leading to leakage of sulfur.
The crumb rubber is also leaking its components. The sulfur used as a vulcanizing agent to give the rubber strength, resistance, and elasticity is leaking out. When sulfur starts appearing on in electron microscopy images, it shows that the bonds are breaking, and it gives a fine aggregate appearance. This means that the crumb rubber materials may also have a negative environmental impact, as sulfur can be toxic. The biggest danger is that such compounds can be carcinogenic, which is also being addressed by the U.S. Environmental Protection Agency (EPA), he added.
Given the findings, the team recommends that the crumb rubber products have a shorter recommended life cycle in very hot climates. They say there is an opportunity to find physical/chemical ways to separate crumb rubber from binding agents in such products so that the used crumb rubber can have value in processes such as pyrolysis, which can help in recycling of the material.
The research will be presented at the Eurowaste Srl 2017 conference being held from 2 to 6 October, in Sardinia, Italy.
[c] 2017 Al Bawaba (Albawaba.com) Provided by SyndiGate Media Inc. ( Syndigate.info ).
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|Date:||Sep 1, 2017|
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