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Sayı: 83 - Temmuz / Ağustos 2023

Summaries


STEEL RE-USE AND CIRCULAR ECONOMY

European Convention for Constructional Steelwork (ECCS) Advocacy Manager Carlos Del Castillo wrote about the reuse of steel and its importance in the circular economy.

Construction is a key economic activity, being responsible for near 9.5 % of the EU GPD, over 20 million jobs and 3.1 million enterprises, 90% of them SME´s.

However, construction is also responsible for 40% of energy consumption, 36% of CO2 emissions, 50% of raw materials consumption, 33% of waste and 33% water used in the EU.

Therefore, construction must undergo a deep transformation to achieve carbon neutrality and implement circular economy by 2050. This transition must be accomplished without committing cost efficiency, durability, and safety.

Circular economy will; on the one hand reduce the construction and demolition wastes, and on the other hand will significantly reduce the resources consumption and therefore raw materials, water and carbon footprint. Moreover, the transition to a circular construction models will generate new supply chains and revenue streams that will positively impact local economies and societies.

Steel is currently a profitable and consolidated example of circular economy. Scrap based steel saves both primary resources and energy and steel quality is not affected using scrap instead of iron ores. In addition, the use of renewable energy in Electric Arc Furnaces allows to reach carbon footprint values in the range of those claimed by engineered wood products.

The next step in steel circular economy is re-use. Only steel exposed to radioactivity, fire, severe corrosion, severe fatigue loads or plastic deformation cannot be re-used. In these cases, recycling will be the recommended End of Life (E.o.L) option. Construction technology was not seen to hinder the reuse of steel components, but rather the lack of established practices and therefore the adoption of steel as a common E.o.L practice must be promoted. Nowadays, 93% of the recovered steel is recycled with a minimum share of reuse (6%) and landfilling (1%).

The main driver for the re-use of steel is cost; steel is only re-used when reclaimed steel is easily available and implies cost savings. However, re-used steel offers important environmental values, re-used steel is a near zero carbon material, and re-use may result into higher yield factors compared to recycling operations (1 vs 0.9).

Design for re-use or what is the same, reuse as E.o.L option will allow to capitalize the benefits of re-use in primary materials through Module in LCA (in those cases in which Module D benefits are accounted e.g following a Whole Life Cycle Approach). In this direction, the new EPBD version refers to circular economy as an opportunity to decarbonize construction and current EN 15978 drafts include separate fraction for re-use and recycling scrap.

The benefits of re-use versus recycling can also be extended to most construction materials. Steel is also called to play a key role in other materials circular economy as re-use. Steel frames and precast concrete panels can work in composite action connected by reversible bolted connections. Cladding and envelopes can be connected in a reversible way to minimal steel secondary structures to simplify deinstallation and renovation operations as well to meet design for adaptability requirements.

The reuse of structural steel from existing buildings is currently possible due to clause 5.1 of EN 1090-2: this clause allows use of constituent products not covered by harmonized standards although specification of material properties is requested.

There are many examples of the successful re-use of structural steel, from complete structures to constituent products. The project PROGRESS includes 11 real examples of steel re-use. In order to provide the specifications of material properties, different Industry standards and the recommendations from projects are available:
Swedish guidance for structural steel reuse (MVR 2021) can be currently followed.
PROGRESS project.
STRUCTURAL STEEL REUSE ASSESSMENT, TESTING AND DESIGN PRINCIPLES (SCI)
Some member states are also working on the development of national standards on steel reuse. However, there is a need for developing a family of harmonized standards at EU level.

Particularly, the re-use of constituent products from EXC1 and EXC2 buildings when certificates are available can be considered as a safe and conservative practice for existing buildings. On the contrary, the re-use of elements that commit safety or cost efficiency must be avoided.

While reclaiming steel from existing buildings will be limited by; available information, the fact that buildings have not be designed for re-use and the difficulties to recover steel elements without damaging these elements, for new buildings available digital passports, optimized deinstallation procedures as well as design for re-use and the buildings as bank of materials concept define an optimal scenario for the adoption of re-use as E.o.L.

To create the foundations for the massive adoption of re-use in new buildings and maximize the potential of re-use in existing buildings, it is necessary a whole supply chain collaboration. All supply chain actors must work in coordinated way to develop the necessary tools to implement re-use for both existing and new buildings and to consolidate a robust and consistent regulatory and standardization framework.

Assuming that in 2050 50 to 70% of steel production will be based on scrap, re-use may be the simpler and shorter route to cost efficient and locally available near zero carbon steel.
Çelik Yapılar - Sayı: 83 - Temmuz / Ağustos 2023

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