https://hdl.handle.net/10259/6171 2026-06-17T16:19:26Z 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%. 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. 2026-05-01T00:00:00Z https://hdl.handle.net/10259/11529 Low‐Carbon Composite Cement Mortar Incorporating Local Raw Materials as SCMs: Performance and Life Cycle Analysis Adediran, Adeolu; Asaam, Nana; Manso Morato, Javier; Perumal, Priyadharshini Performance and life cycle analysis of composite cement mortars developed using local conventional (blast furnace slag and fly ash) and novel non-conventional (stone wool, glass wool, calcined Finnish clay, volcanic pozzolan Iceland, and ladle slag) raw materials as supplementary cementitious materials (SCMs) was investigated. The SCMs and the prepared mortars were characterized using x-ray diffraction, FTIR, TG-DTG, SEM-EDS, flowability, compressive strength, ultrasonic pulse velocity (UPV), water absorption, permeable porosity, and life cycle analysis (LCA). Experimental results showed a difference in the physical, chemical, and mineralogical composition of the SCMs, which in turn influenced the properties of the composite cement mortars developed. Ladle slag (30 wt.%) as SCM performed better, resulting in mortars with comparable mechanical, UPV, water absorption, permeable porosity, and microstructural properties but lower flowability values compared with reference mortars. In contrast, the use of other SCMs resulted in mortars with slightly lower mechanical properties, increased workability, and higher water absorption and permeable porosity than the reference mortars. The better performance of ladle slag may be attributed to the increased amount of precipitated hydration phases and formation of supplemental pore-filling hydration products, such as C3AH6 and Al (OH)3, attributed to the dissolution and participation of alumina from the SCM in gel formation. LCA results revealed a reduction in the environmental impact of the composite cement mortars (except those containing Finnish clay as SCM) when compared to PC-based mortars. 2026-04-01T00:00:00Z https://hdl.handle.net/10259/11484 Effectiveness of Temporal Survey-Based Programs for Teaching Critical Thinking Skills in Engineering Courses: Analysis of Final Assessments Revilla Cuesta, Víctor; Hernando Revenga, Manuel; Martín Para, Ismael; Skaf Revenga, Marta; Ortega López, Vanesa Peer- and self-critical skills are key to properly performing engineering work, as they allow engineering students to develop critical thinking regarding the quality standards required in this professional field. This research aimed to determine whether educational experiences based on temporal survey-based programs enabled the successful development of these skills in students enrolled in six courses in the final years of their engineering degrees. To this end, an educational experience of such a nature was implemented throughout a complete academic year, aimed at fostering peer- and self-critical skills through continuous formative assessment. The experience involved six student presentations evaluated by both teachers and peers using a Likert-scale survey encompassing four dimensions: explanatory ability, file quality, attitude, and overall assessment. Subsequently, these assessments were provided to students to encourage reflection on the scores assigned and their own work. The results revealed strong alignment between teacher and peer evaluations, with average deviations below 7%, demonstrating effective development of peer-critical competences. These results were also verified by means of analyses of variance. The greatest consistency was found in “explanatory ability” and “overall assessment,” while “file quality” and “attitude” showed wider variability, experience playing a key role in their precise evaluation. Peer evaluations tended to be more uniform than teachers’, reflecting students’ limited experience in discerning subtle performance differences. Additionally, 30% of students expressed willingness to repeat their final presentation to achieve a higher grade, evidencing substantial self-critical reflection. Qualitative analysis conducted through deductive cross-coding indicated that this motivation stemmed from both intrinsic self-improvement and peer-related responsibility. Overall, the results confirm that sustained peer- and self-assessment activities can effectively cultivate critical thinking skills among engineering students, although continuous practice is required to consolidate these competences. Future research could explore the more adequate course types, and students’ ages to perform such kind of educational experiences. 2026-02-01T00:00:00Z