{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T12:08:28Z","timestamp":1789992508973,"version":"4.0.1"},"reference-count":45,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T00:00:00Z","timestamp":1789948800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>This study investigates upcycled high-density polyurethane (HD-PUR) as a substitute for conventional cement-based screed in multi-story reinforced concrete (RC) buildings. Conventional screed (\u22482400 kg\/m3) adds substantial seismic dead mass without contributing to lateral stiffness, amplifying base shear, inter-story drift, and overturning moments. HD-PUR, produced from industrial waste via mechanical re-pressing, has a density of \u2248150 kg\/m3 and thermal conductivity of 0.025 W\/m\u00b7K. It is crucial to clarify that this yields a 16-fold mass reduction specifically at the floor-screed layer level (dropping from 120 kg\/m2 to 7.5 kg\/m2). Consequently, this localized weight saving translates to an approximately 16.6% reduction in the total seismic weight (W) of the entire building. This substitution also provides near-negligible inter-story heat transfer. Three-dimensional finite element models of 5-, 10-, and 15-story moment-resisting RC frames were developed in SAP2000, with modal and response spectrum analyses performed per the Turkish Building Earthquake Code (TBEC, 2018). HD-PUR substitution reduced base shear by 10.5\u201320.0% and inter-story drift by 10.4\u201320.2% across all models. These trends were validated against an existing five-story RC building in Beyo\u011flu, Istanbul (site class ZC; PGA = 0.359 g; in situ concrete class C14), modeled in SAP2000 and STA. The fundamental period shortened from 0.888 s to 0.793 s, global base shear (FX) decreased by 10.5%, vertical base reaction (FZ) decreased by 16.6%, and the nonlinear pushover-based performance level improved from Collapse Prevention to Life Safety without any intervention on load-bearing members. Thermal calculations per TS 825 indicate an 18% reduction in the heating degree-day load associated with the floor-slab envelope interfaces (basement ceilings and roof slabs), while life-cycle assessment data reported in the literature point to appreciably lower embodied carbon, supporting circular economy objectives. In short, HD-PUR floor fillers offer a low-cost strategy that jointly improves seismic resilience, energy efficiency, and environmental performance in multi-story RC buildings.<\/jats:p>","DOI":"10.3390\/polym18182307","type":"journal-article","created":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T11:05:53Z","timestamp":1789988753000},"page":"2307","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Multi-Functional Performance of Upcycled High-Density Polyurethane Floor Fillers in Multi-Story RC Buildings: A Combined Seismic Mitigation, Thermal Insulation, and Sustainability Approach, with Field Validation on an Existing Building"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4385-4535","authenticated-orcid":false,"given":"\u00d6mer Fatih","family":"Sak","sequence":"first","affiliation":[{"name":"Department of Civil Engineering, Do\u011fu\u015f University, \u0130stanbul 34775, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,21]]},"reference":[{"key":"ref_1","unstructured":"Chopra, A.K. 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