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INNOVATION IN CONCRETE DESIGN FOR HAZARDOUS WASTE MANAGEMENT APPLICATIONS

Introduction

  • Promoting circular economy by using oil shale ash, an industrial waste product created in energy production in Estonia, as a supplementary cementitious material in concrete production.
  • Improving the mechanical properties of concrete by adding dispersed fibers.
  • Increasing the material's ability to shield neutrons by using basalt fibers infused with boron-oxide.
  •  Four partners:
    • Latvia - Riga Technical University
    • Lithuania - Lithuanian Energy Institute
    • Estonia - University of Tartu
    • Norway - Arctic University of Norway
  • Timeframe: 2021 - 2024

Oil shale and oil shale ash

  • Oil shale has been used for energy production in Estonia over half a century.
  • High content of mineral matter
    • Burning 1 tonne → more than 0.5 tonnes of ash.
  • Oil shale ash has found very little use.
    • Between 2014 and 2020, ca. 55 million tonnes of oil shale processing residues was created in Estonia.
      And only 1-2% were utilized.
  • Chemical composition
  • Usability in concrete production
    • ISO standard EN 197-1: 2011 allows up to 55% of clincer  replacement
      by puzzolans (siliceous and aluminous materials).
    • OSA is a promising material to be used as a barrier material to
      immobilize hazardous material (radioactive waste).

 Fiber-reinforced concrete

  • Increase of flexural tensile strength for mechanical purposes.
  • Enhancement of fire resistance.
  • Replacement of traditionally used steel rebars by structurally  dispersed fibers.
  • Reduction of early age shringage that causes crack formation  during the hardenin process.

  • Basalt microfibers
    • uniform distribution due to similar specific gravity as  the basic components of concrete
    • resistance to a high range of temperatures
    • chemical and corrosion resistance
  • Basalt-boron microfibers
    • infused with B 2 O 5
    • Improve material's neutron radiation shielding  properties

Radioactive waste management by cementation

Cementation is a standard technique in radioactive waste management.

+ Suitable for a variety of waste
+ Simple, flexible, reliable and cost effective
+ Usually accepted for storage
+ Radiation resistance
+ Compatibility with many types of
environmental conditions

+ Good actinide retention

- Increases the volume of final product.

 Funding

  • Project promoter: Riga Technical University
  • The ICONDE project is one of the Baltic Research Program's
    projects, which is financially supported by the EEA Grants of
    Iceland, Liechtenstein and Norway.
    The implementation of the
    three year project started on May 1, 2021, and will continue
    until April 30, 2024.

  • Total eligible costs: 865 661.25 €
  • Grant financing: € 735,812.06
  • National co-financing: € 129,848.19

       

Conclusion

  • The development of new concrete mixtures as part of the ICONDE project aims to offer new solutions for radioactive waste management. The long-term lack of hazardous waste storage solutions and technologies is a problem for the entire Baltic region. An example of a source of large-scale radioactive waste of all stages is the decommissioning of the Ignalina Nuclear Power Plant (NPP). It will propose a new pathway for the utilization of existing industrial waste - the oil shale ash. This supports the UN's sustainable development goals for circular material flow. Advancement of the mechanical properties is expected to be achieved by the addition of fibers. Specific interest from the viewpoint of spent nuclear fuel storage solutions is the use of basalt-boron fibers in the concrete mixture to improve shielding against neutrons.