Browsing by Keyword "Recycled aggregates"
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Item Comprehensive study on the most sustainable concrete design made of recycled concrete, glass and mineral wool from C&D wastes(2021-03-01) Gebremariam, Abraham T.; Vahidi, Ali; Di Maio, Francesco; Moreno-Juez, J.; Vegas-Ramiro, I.; Łagosz, Artur; Mróz, Radosław; Rem, Peter; TRAZABILIDAD CIRCULAR; GENERALThis study focuses on formulating the most sustainable concrete by incorporating recycled concrete aggregates and other products retrieved from construction and demolition (C&D) activities. Both recycled coarse aggregates (RCA) and recycled fine aggregates (RFA) are firstly used to fully replace the natural coarse and fine aggregates in the concrete mix design. Later, the cement rich ultrafine particles, recycled glass powder and mineral fibres recovered from construction and demolition wastes (CDW) are further incorporated at a smaller rate either as cement substituent or as supplementary additives. Remarkable properties are noticed when the RCA (4–12 mm) and RFA (0.25–4 mm) are fully used to replace the natural aggregates in a new concrete mix. The addition of recycled cement rich ultrafines (RCU), Recycled glass ultrafines (RGU) and recycled mineral fibres (RMF) into recycled concrete improves the modulus of elasticity. The final concrete, which comprises more than 75% (wt.) of recycled components/materials, is believed to be the most sustainable and green concrete mix. Mechanical properties and durability of this concrete have been studied and found to be within acceptable limits, indicating the potential of recycled aggregates and other CDW components in shaping sustainable and circular construction practices.Item Upgrading the quality of mixed recycled aggregates from construction and demolition waste by using near-infrared sorting technology(2015-01-30) Vegas, Iñigo; Broos, Kris; Nielsen, Peter; Lambertz, Oliver; Lisbona, Amaia; GENERAL; Tecnalia Research & InnovationRecycled aggregates of high-purity, guaranteeing optimal technical and environmental performance, are required for high-grade construction applications such as concrete. The main problem constituents causing a decrease in the quality of recycled aggregates to be used in high grade applications are: organic material, gypsum and autoclaved aerated concrete (AAC). This paper studies the potential of Near Infrared (NIR) sorting technology to improve the quality of mixed recycled aggregates. Tests were carried out by using samples of mixed recycled aggregates collected in different EU countries (Germany, Sweden, Spain and Italy). Constituents, total sulphur content, acid soluble sulphates, total heavy metals and metal leaching were determined before and after the use of the NIR sorting technology. The results clearly indicate that the problematic fractions (organic material, gypsum and AAC) in the mixed recycled aggregates can be significantly reduced or even eliminated during the NIR sorting treatment, boosting a greater use of recycled aggregates in high grade applications such as concrete manufacturing.