Recycling potential of recycled carbon fibers used in textile concrete from a technical and environmental point of view
As an important element in construction industry, cement production caused alone 2 % of total greenhouse gas emissions in Germany in 2017 and global average was even with a greater value, 8 % (WWF 2019). Considering the great impact of construction industry on the environment, Fiber reinforcement (carbon or glass) is seen as a meaningful alternative to steel reinforcement in the production of concrete. Due to their low weight, high strength and lifetime, carbon fibers have been increasingly used in construction industry. On the one hand, the use of CF reinforced concrete enables great amount of resource savings compared to conventional concrete, specifically steel reinforced concrete (Böhm et al. 2018). On the other hand, CFs have some disadvantages, such as high cost, energy intensive production process and challenging end-of-life (EOL) handling (Zhang et al. 2020).
The application of carbon fibers (CF) has been increasing in the construction industryas they allow production of lightweight concrete structures. Aside from many advantages, theend-of-life management of carbon fiber reinforced concrete remains challenging. Through thisstudy, we aimed to assess the recycling potential of recycled carbon fibers (rCF) that were usedin concrete, considering the technical and environmental aspects. To identify the separation potentialof carbon fibers from concrete, mechanical processing by means of hammer mill with differentmachine settings was conducted. In addition, a life cycle assessment was performed evaluatingtwo life cycles of carbon fibers and identifying the hotspots. From the results of mechanicalprocessing, it is seen that with the increased weight percentage of separated carbon fibers, thefine portion, which is a mix of carbon fibers and concrete, also increased. In addition, two assessedparameters, the total mass and length division of separated carbon fibers were observedto have the greatest value in two different machine settings. From an environmental point of view,virgin carbon fiber and concrete production were the highest contributors to environmental impacts.Furthermore, recycling through pyrolysis was found to be environmentally advantageous compared to virgin carbon fiber production.
| Copyright: | © Lehrstuhl für Abfallverwertungstechnik und Abfallwirtschaft der Montanuniversität Leoben | |
| Quelle: | Recy & Depotech 2022 (November 2022) | |
| Seiten: | 6 | |
| Preis inkl. MwSt.: | € 3,00 | |
| Autor: | Berfin Bayram  V. Overhage Karoline Raulf Prof. Dr. Kathrin Greiff T. Gries | |
| Artikel weiterleiten | In den Warenkorb legen
| Artikel kommentieren |
Diese Fachartikel könnten Sie auch interessieren:
Umweltbildung mit #wirfuerbio
© Witzenhausen-Institut für Abfall, Umwelt und Energie GmbH (4/2023)
#wirfuerbio ist die bundesweite Kampagne der kommunalen Abfallwirtschaft zur Reduzierung von Störstoffen im Bioabfall. Mit einer starken Bandbreite unterschiedlicher crossmedialer Kommunikationsmittel und Maßnahmen verändert sich das Verhalten der Biotonnenbenutzer. Die Störstoffquote sinkt um mehr als 50 Prozent. Die Kampagne weist einen neuen Weg in der Umweltbildung. Mit der Abfallbox und der SpieleApp „#wirfuerbio das Sortierspiel“ wird Kreislaufwirtschaft in Form von Spaß und Spiel erlebbar. Der Beitrag zeigt, wie Abfallbox und Spiele-App didaktisch funktionieren und ein Bewusstsein für Kreislaufwirtschaft und Mülltrennung entwickeln.
The AHOY-Project: Waste Wood Sorting with X-ray Technology
© Lehrstuhl für Abfallverwertungstechnik und Abfallwirtschaft der Montanuniversität Leoben (11/2022)
Waste wood is a valuable resource, but is hardly recycled despite increasing demand, predicted supply gaps (Mantau et al. 2010), and galloping wood prices since 2020 (Trading Economics 2022). In Germany alone around 10 million tons of waste wood accumulated in 2016. Only a minor part (1.7 million tons) is substantially reused in the production of chipboards. The majority (7.7 million tons) is fed into energy recovery, i.e., burned in one of the 80 German waste wood power plants (BMUV 2021), and is thus lost, while the supply of fresh wood is limited by slow growth cycles and finite acreage. In view of current environmental regulations, climate change and massive tree mortality, waste wood should be kept permanently in the circular economy as a high-quality raw material in the future.
Fundamental drying experiments with processed residual municipal solid waste materials
© Lehrstuhl für Abfallverwertungstechnik und Abfallwirtschaft der Montanuniversität Leoben (11/2022)
Waste management companies and municipalities in southwestern Hungary aim the fulfillment of the EU’s target, namely to decrease landfilling below 10 % and increase recycling above 65 % of municipal solid wastes. However selective collection is continuously improved there is still high amount of residual MSW is generated. A new mechanical RMSW processing plant (20 t/h) and an experimental RDF pyrolysis plant (200 kg/h) had been built (Faitli et al. 2020) and now extensive research is being carried out to solve the local utilization of the bio-fraction and the RDF. This is the reason why this fundamental drying research was necessary. Dryer classification and the selection of the best solid waste drying techniques vary significantly due to the vast range of waste to be dried and the inherent challenges of dealing with non-standardized systems. In general, biomass dryers may be categorized according to their heat transmission technique and the physical qualities of wet particles.
Mechanical short-term and long-term properties of PP recyclate blends
© Lehrstuhl für Abfallverwertungstechnik und Abfallwirtschaft der Montanuniversität Leoben (11/2022)
The amount of recycled material in new products should be increased in the next few years. By adding virgin material, the mechanical properties of the pure recyclate can be improved. In this work, 10 % and 40 % post-consumer recyclate was added to a virgin material and analyzed. Both raw materials were also tested. The short-term as well as the long-term properties decrease with increasing recyclate content. The recyclate has a higher influence on the young’s modulus, yield stress and slow crack growth resistance than on the notched impact toughness.
Analysis of different polypropylene waste bales – evaluation of the source
material for polypropylene recycling
© Lehrstuhl für Abfallverwertungstechnik und Abfallwirtschaft der Montanuniversität Leoben (11/2022)
In 2020 Polypropylene (PP) accounted for almost 20% of the plastic consumption in Europe, making it the second most used plastic (Plastics Europe 2021). Due to the high volume of PP used as packaging material (Plastics Europe 2021), large amounts of PP waste are generated every year. Therefore, mechanical recycling of PP waste is a crucial step towards a circular economy. Although there are already some well-established recycling techniques, the lower quality of recyclates compared to virgin materials still poses an obstacle for their use in more demanding applications. Improvements of every step of the whole recycling value chain could solve this problem, with proper and more accurate sorting techniques being particularly crucial.
