https://hdl.handle.net/10259/6172 Mon, 17 Aug 2026 11:12:05 GMT 2026-08-17T11:12:05Z https://hdl.handle.net/10259/11958 Meso- and micro-analysis of the alkali resistance of concrete containing E-type GFRP-based mixed waste Hernando Revenga, Manuel; Revilla Cuesta, Víctor; Faleschini, Flora; Ortega López, Vanesa E-type Glass Fiber-Reinforced Polymer (GFRP) incorporated to concrete can degrade under alkaline environments. The alkali resistance of concrete containing 10% by volume of different fractions of wind turbine Blade Waste (BW), mainly composed of E-type GFRP, is therefore evaluated. For that, concrete mixes were immersed in a 1 N NaOH solution at temperatures of 80 °C and 300 °C, their variations in length and mechanical strength being assessed. Results revealed that BW promoted concrete expansion, although always within regulatory limits, as the maximum expansion was 0.0331% when adding BW sized lower than 1 mm. Alkali exposition also reduced strength by 10% on average. 1–2 mm BW provided the highest strength after alkali exposure, while BW larger than 2 mm provided load-bearing capacity. Scanning electron microscopy showed surface damage of BW components, which may be linked to such results. Overall, concrete containing BW showed limited expansion under alkali environments while providing proper mechanical performance. Wed, 01 Apr 2026 00:00:00 GMT https://hdl.handle.net/10259/11958 2026-04-01T00:00:00Z https://hdl.handle.net/10259/11952 Non-destructive evaluation of concrete with high contents of mixed waste from wind-turbine blades Revilla Cuesta, Víctor; Manso Morato, Javier; Hurtado Alonso, Nerea; Ortega López, Vanesa The mixed waste from wind-turbine blades, named Raw-Crushed Wind-Turbine Blade (RCWTB), contains fibers of Glass Fiber-Reinforced Polymer (GFRP) and particles of polymers and balsa wood. The performance of concrete incorporating RCWTB is altered by GFRP-fibers stitching the cementitious matrix and the low strength and stiffness of such particles acting as aggregates. This paper explores the suitability of Non-Destructive Testing (NDT) in assessing the mechanical behavior of such concrete. Regarding the variations of NDT properties, Ultrasonic Pulse Velocity (UPV) and rebound index decreased on average 0.03 km/s and 0.71 units per 1% RCWTB, respectively. Polymers and balsa wood reduced its density and surface hardness. In contrast, thermal conductivity was increased by 0.08 W/(m·K) per 1% RCWTB, although the heat insulation of GFRP and balsa wood kept values constant up to 4% RCWTB. In regression terms, flexural strength, tensile splitting strength and Poisson's coefficient could not be significantly predicted with any NDT property, either isolated or combined, due to their dependence on GFRP-fiber stitching effect. Compressive strength was successfully estimated using simple regression with any NDT property, although the highest accuracy was provided by multiple regression combining UPV and rebound index. Finally, only UPV showed a random residual distribution when developing predictive models for the modulus of elasticity. Thus, non-linear multiple-regression models for compression-related mechanical properties could be developed through conventional NDT measurements. These models had R2 coefficients above 90%, mean deviations between experimental and predicted values of 2% and safety factors of around 1.1 for the minimum expected value. Tue, 01 Sep 2026 00:00:00 GMT https://hdl.handle.net/10259/11952 2026-09-01T00:00:00Z https://hdl.handle.net/10259/11830 Fayalite slag and municipal solid waste incineration bottom ash as sand replacement in cement mortar: Physical, mechanical, and durability properties Adediran, Adeolu; Asaam, Nana; Manso Morato, Javier; Avci, Erdi; Perumal, Priyadharshini Approximately 300,000 tons of municipal solid waste incineration bottom ash (BA) and 600,000 tons of fayalite slag (FS) are generated annually in Finland from metallurgical and incineration processes, with the majority of them disposed of in landfills or used in low-value applications. This study investigated the potential upcycling of FS and BA as sand replacements in cementbased mortars to avoid landfilling, conserve natural resources, and ensure efficient use of industrial residues. Standard sand (SS) was used as the main fine aggregate. The effect of replacing SS partly or wholly with either FS or BA was investigated through workability, compressive strength, ultrasonic pulse velocity (UPV), scanning electron microscope analysis, capillary water absorption, alkali–silica reaction (ASR), freeze-thaw cycles in water, and combined sodium sulfate and sodium chloride solution exposure. The aggregates’ leaching results were below the values stipulated by Finnish and EU regulations. Partial or full replacement of SS with either FS or BA resulted in lower workability. Full replacement of SS with FS resulted in comparable properties to the reference mix in terms of compressive strength, UPV, and capillary water absorption. Meanwhile, partial replacement of SS with FS resulted in higher compressive strength and UPV but reduced water absorption. In contrast, partial or full replacement of SS with BA resulted in lower compressive strength and UPV, as well as increased water absorption compared with the reference mix. All samples remained stable after exposure to freeze-thaw cycles in water. However, only the reference samples and samples containing 50% replacement of SS with either FS or BA were stable after exposure to freeze-thaw cycles in a combined sulfate and chloride solution, whereas those containing 100% FS or BA were completely degraded. Of all the aggregates, only FS satisfied the 14-day ASR requirements according to the ASTM C1260 standard, achieving a low expansion rate of 0.009%. Fri, 01 May 2026 00:00:00 GMT https://hdl.handle.net/10259/11830 2026-05-01T00:00:00Z https://hdl.handle.net/10259/11825 Technical feasibility of adding 20% wind turbine blade waste to concrete: Fresh, mechanical, deformational, and sustainability assessment Revilla Cuesta, Víctor; Manso Morato, Javier; Espinosa González, Ana Belén; Skaf Revenga, Marta The recycling and valorization of decommissioned wind turbine blades represent a pressing environmental challenge. This study explores a recycling route in which the blades were not selectively crushed, thus yielding Wind Turbine Blade Waste (WTBW) composed of balsa wood, polymers, and fibers and microfibers from Glass Fiber-Reinforced Polymer (GFRP). This by-product was subsequently incorporated as a partial replacement (20% by volume) of natural aggregates in concrete. The fresh, mechanical, deformational, and sustainability performance of the resulting concrete was evaluated. 20% WTBW inclusion slightly reduced workability, though concrete maintained a slump class S2 thank empirical adjustment of water and plasticizer contents, in principle ensuring placement by conventional vibration. Mechanical properties were generally reduced due to the weak particles in WTBW. Nevertheless, flexural strength was preserved (5.59 MPa) owing to the three-dimensional reinforcement of the GFRP fibers. Such fiber network also enhanced post-failure performance, doubling the absorbed energy under bending and promoting more ductile failure modes characterized by reduced crack width and absence of surface spalling. Scanning electron microscopy confirmed a proper orientation and crack stitching of GFRP microfibers, which also contributed to this improvement. A cradle-to-gate life cycle assessment showed reductions of approximately 6% in both abiotic depletion potential for fossil fuels and global warming potential, both in total terms and per unit of strength or absorbed energy under bending. These results, statistically validated by an analysis of variance, indicate that concrete incorporating 20% WTBW could, in theory, be sustainably used in elements with reduced mechanical requirements and predominantly bending stresses. Fri, 01 May 2026 00:00:00 GMT https://hdl.handle.net/10259/11825 2026-05-01T00:00:00Z