20.500.12556/DiRROS-18307 Thermal insulation and flammability of composite waste polyurethane foam encapsulated in geopolymer for sustainable building envelope Polyurethane foam (PUR) is a lightweight, thermally insulating, widely used, and highly flammable material that has after its use an adverse effect on the environment, i.e., PUR disposal is considered hazardous. Its flammability can be mitigated using various fire retardants, but they do not change the hazardous nature of waste PUR. Therefore, in the current study, waste PUR with and without flame retardants based on N and P was incorporated into a geopolymer, the alkali-activated material (AAM) based solely on metakaolin, to evaluate the potential recycling route of waste PUR while taking into account its flammability, so it can enter safely into the circular economy through the building industry. To enhance the mechanical properties of the composite, a fresh mixture was irradiated with microwaves. However, the irradiation of geopolymer containing PUR negatively influenced mechanical performance, which led to the evaluation of the behaviour of the complex dielectric constant of PUR and fire retardants. Materials and composites were evaluated regarding their chemistry, mineralogy, microstructure, and porosity to connect the structure with extrinsic properties like geometrical density, thermal conductivity, and fire properties. Nonetheless, positive influences of PUR being encapsulated in the geopolymer were lowered density (from 1.8 to 1.6 kg/l) and improved thermal insulation ability (from 940 to 860 mW/(m·K)) of the composites: with the inclusion of <5 % of PUR, thermal insulation improved by nearly 10 %. However, the contribution of PUR to the composite originated from its skeleton, which has more than 15 times bigger geometrical density (0.81 kg/l) compared to the density of the skeleton (0.047 kg/l). This offers an open field for further advancements of thermal properties, but would also lead to a decrease of the compressive strength, which was already lowered from 90 MPa for 30 % with <5 % of added grated PUR. Furthermore, the flammable nature of PUR and its other drawbacks can be controlled by permanent embedding in the noncombustible structure of geopolymer, making the envelope of sustainable buildings green and safer. Overall, including grated waste PUR in geopolymer represents a promising, easy, cost-effective recycling path with low energy consumption, where the composite cannot develop fire on a scale of pure PUR, even in the worst-case scenario, but only if the composite is designed in a way, that flammable materials cannot join flames during their combustion. This paper gives prospects to other flammable waste materials to be safely used in the circular economy, and to porous materials to shape properties of the composite by their intrinsic and/or extrinsic properties. waste polyurethane foam polymeric flame retardants alkali activated material metakaolin microwave irradiation thermal-fire behaviour mechanical strength odpadna poliuretanska pena polimerni zaviralci ognja alkalijsko aktivirani materiali metakaolin mikrovalovno obsevanje vpliv toplote ognja tlačna trdnost true false true Elsevier Angleški jezik Slovenski jezik © 2024 The Authors. Published by Elsevier Ltd. Neznano 2024-03-01 12:31:18 2024-03-01 12:45:50 2024-03-02 03:34:31 0000-00-00 00:00:00 2024 0 0 str. 1-25 [article no.] 141387 Vol. 446 Feb. 2024 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 2024-03-25 620.1/.2 0959-6526 10.1016/j.jclepro.2024.141387 186914819 https://www.sciencedirect.com/science/article/pii/S0959652624008345?via%3Dihub 1 d7f4b71e-d7b6-11ee-900a-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=24874 RAZ_Horvat_Barbara_2024.pdf RAZ_Horvat_Barbara_2024.pdf 1 4D2316A4F998CED3F90A2C1C2B56A978 5877ff66a251a4dc464414fa96739c44ccd88ccdcf7f465418e7304775877998 74e31b51-d7b8-11ee-900a-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=24875 RAZ_Horvat_Barbara_2024.xlsx RAZ_Horvat_Barbara_2024.xlsx 1 12EB6C0AD4C75B23A87A48FDA610E716 a25c4cd0ac11e957bb9bfd63669b1f5ea6af9c1306842ee4d0e10a0a1921ac1a 9790118e-d7b8-11ee-900a-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=24876 RAZ_Horvat_Barbara_2024.docx RAZ_Horvat_Barbara_2024.docx 1 71C9B6C3438624B16FA6AD08E72CAC2A 309378952ae61bc997fc01ee1f57907d1ee5253cb9b15fea40aa0e7e4c93fa3e 9f8f7501-d7b8-11ee-900a-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=24877 RAZ_Horvat_Barbara_2024.htm RAZ_Horvat_Barbara_2024.htm 1 95944E41954D7924B1E3E700D9890852 26ea0c0feb4fecee38ff23a680d4d379620fb11930b9a583d5a6546d2db4268d a637f11e-d7b8-11ee-900a-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=24878 Zavod za gradbeništvo Slovenije PUR in geopolymer 0 0 0