Concrete modified by Łódź scientists can be used for radioactive waste disposal
Scientists from Lodz University of Technology have developed sulfur-organic copolymers that can be used to produce more durable sulphur concrete or rut resistant asphalt. Modified concrete will allow for the disposal of radioactive waste and is resistant to micro-organisms.
"These materials can be used separately as cheap polymer materials, and can be introduced as modifiers into bitumen, asphalt, rubber or concrete" - told PAP the project team leader Prof. Dariusz M. Bieliński, Vice-Dean for science and innovation, Faculty of Chemistry, Lodz University of Technology.
According to the scientist, the technology will allow better use of the Polish sulphur deposits, and utilise waste sulphur, phosphogypsum and various types of large-volume technological waste, such as ash and slag from CHPs, rubber recycling products and biomass. "We have therefore taken the initiative to use sulphur to produce new polymeric materials" - added the scientist.
At a sufficiently high temperature (159 degrees C) sulphur undergoes spontaneous polymerization, but polymeric structures of this type are energetically unstable and relatively quickly recrystallize, worsening their mechanical properties. An additive of unsaturated organic compounds that stabilizes the resulting copolymer can be used to preserve the polymeric structure of sulphur.
As part of the project, scientists from Lodz University of Technology used synthetic renewable natural substances: terpentine, furfural, furfuryl alcohol, and recycled material: waste rubber pyrolysis oil and polyolefins, alongside the most commonly used dicyclopentadiene (DCPD) to synthesise sulphur-organic copolymers. Industrial waste products, i.e. phosphogypsum, ash and slag from CHP plants were also introduced into polymer concretes with sulphur copolymers as binders.
The thermal and mechanical properties of the obtained sulphur-organic copolymers were investigated. Scientists then used these copolymers to produce of sulphur concrete and rubber, bitumen and asphlt mixtures.
"The process involves the synthesis of sulphur copolymers, that is, materials that allow sulphur to behave in a stable manner. It does not boom on the surface of the material and has stable mechanical properties. Sulphur-organic copolymers used as binders in sulphur concrete allow to obtain special concrete, resistant to micro-organisms such as fungi, moss, lichen" - he explained.
They also increase the chemical resistance of this type of materials, which allows them to be used, for example, in ports. "The addition of sulphur copolymers to concrete materials will increase their resistance to seawater" - said Prof. Bieliński.
Sulphur-organic copolymers introduced as modifiers into various types of viscous materials, bituminous materials or asphalt are expected to improve their thermal stability and resistance to permanent deformation.
"They have the advantage over the sulphur modification of asphalt that the modifier does not flush to the surface, it does not emit an unpleasant odour during the application process, and it facilitates bonding. Furthermore, the use of sulphur copolymers for asphalt modification, due to proven cross-linking of polymers and bitumen contained in asphalt, will result in modified asphalt that will be more resistant to rutting" - emphasised the scientist.
Research carried out at Lodz University of Technology also showed that sulphur concretes create opportunities for the disposal of hazardous radioactive waste. "It was tested in a laboratory at the Institute of Applied Radiation Chemistry. Radioactive waste from nuclear power plants can be safely stored in sulphur-concrete shelters, because radionuclides will not be released from such structures" - the scientist explained.
The researchers completed the first stage of the project, which involved the development of copolymers and products using these copolymers. Patent applications have been submitted for some of the solutions. Currently, they are applying for funds from The National Centre for Research and Development and the National Fund for Environmental Protection and Water Management for the development of sulphur concrete industrial technology.
"We have developed laboratory scale technology and we will try to start large, industrial scale production of these materials" - said Prof. Bieliński. In his opinion, after obtaining financial support, industrial production could be launched in two years.
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