https://www.um.edu.mt/library/oar/handle/123456789/70123 2026-04-04T19:10:32Z 2026-04-04T19:10:32Z https://www.um.edu.mt/library/oar/handle/123456789/145266 2026-03-30T12:31:49Z 2026-01-01T00:00:00Z

Title: Carbon dioxide sequestration in cement-based materials : carbonation treatment of recycled concrete powder Abstract: Urbanisation growth has brought about (i) an increased use of concrete and consequently an increase in Cem I production which is a major contributor to carbon dioxide (CO2) emissions and (ii) an increase of construction and demolition waste (C&DW). The objective of this study is to explore ways of how to provide a partial Cem I replacement whilst mitigating the problems mentioned above, namely by (i) reducing CO2 emissions by using CO2 captured during cement production in a process to produce supplementary cementitious material and (ii) using recycled concrete from construction and demolition waste in the afore-mentioned process to produce supplementary cementitious material (SCM). This dissertation focuses on the production of recycled concrete powder (RCP) and its activation via different treatment methods, to identify the process which yields the best supplementary cementitious material. Treatment processes researched in this dissertation included calcination, dry carbonation, aqueous carbonation, calcination followed by dry carbonation, calcination followed by aqueous carbonation and limewater soaking followed by dry carbonation. Initially, characteristic testing was done on the various treated powders to determine their physical and chemical properties. This was followed by the assessment of these treated powders when introduced as a 20% cement replacement within the mix design of paste and mortar samples, to determine their fresh, mechanical and durability properties. Calcination treatment achieved a material with the highest pozzolanic activity, as XRD results showed it to have the highest percentages of portlandite, tobermorite, gismondine, and belite at 17.4%, 12%, 2.1% and 17.2% respectively, when compared to the other treated samples. Through XRD, compressive strength and durability testing, it was determined that both dry and aqueous carbonation treatments also yielded materials with potential to be suitable supplementary cementitious material. The combined calcination and carbonation treatments yielded the best chemical and mechanical results due to the formation of both calcite and hydrated phases, creating materials of increased reactivity and strength. The dry carbonation in the calcination and dry carbonation process contributed to produce a material with better properties than that produced in the calcination and aqueous carbonation treatment. In fact, calcination followed by dry carbonation achieved the highest compressive strength of 114.90 MPa at 21 days, surpassing that of the cement control. Description: M.Eng.(Melit.)

2026-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/145265 2026-03-30T12:30:02Z 2026-01-01T00:00:00Z

Title: Exploring the use of recycled rubber aggregate in seismically resilient concrete structures Abstract: This dissertation investigates the structural performance of rubberised concrete with a focus on its behaviour under static and cyclic loading. Building upon previous research conducted at the Faculty for the Built Environment at the University of Malta, an experimental programme was undertaken to compare a conventional control concrete mix with a rubberised concrete mix incorporating 25% crumb rubber replacement of fine aggregate (CR25). The experimental investigation comprised concrete cube compressive strength tests, static and cyclic reinforced concrete short column compressive strength tests, and static and cyclic reinforced concrete beam flexural tests. The experimental results confirmed that the inclusion of crumb rubber as partial fine aggregate replacement in reinforced concrete structural members leads to 56.39% and 16.16% reductions in compressive and flexural strength respectively when compared to conventional reinforced concrete structural members. However, under cyclic loading, rubberised reinforced concrete specimens exhibited enhanced deformation capacity, improved crack closure during unloading, and more ductile modes of failure. In contrast, conventional reinforced concrete specimens exhibited stiffer responses at the cost of brittle failure with reduced energy dissipation. Cyclic testing highlighted that rubberised concrete experiences accelerated stiffness degradation at higher stress levels relative to lower and moderate stress levels, where they retain superior shape recovery and damage tolerance. Overall, the experimental results obtained indicate that rubberised concrete may not be suitable for strength-critical structural elements, rather excelling in applications where characteristics such as ductility, energy dissipation, and seismic resilience are preferred. This research study demonstrates that rubberised concrete has potential as a specialised structural material in tailored cyclic and seismic environments, provided its use is appropriately supported by further research work. Description: M.Eng.(Melit.)

2026-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/145263 2026-03-30T12:24:27Z 2026-01-01T00:00:00Z

Title: Tensile behaviour of glue-laminated timber : a comparative analysis between solid and finger-jointed specimens Abstract: This dissertation investigates the structural performance of finger-jointed glue-laminated timber elements, focusing on their behaviour under tensile, creep and cyclic loading scenarios, while also providing comparative analysis of the results with their solid counterparts. The main aim of this study is to evaluate the impact of finger-joints on the ultimate tensile strength and long-term behaviour of glue-laminated timber, as used in structural applications. To accomplish this, dogbone specimens were prepared from a local, commercially purchased glue-laminated beam, in order to have a consistency in the material properties like grade and moisture content. The results demonstrated that the finger-jointed timber specimens, generally exhibited reduced tensile strength when compared to the solid counterparts. Having said this, the finger-jointed specimens showcased satisfactory results under uniaxialtensile conditions, making them suitable for structural applications. Overall, the results of this study show that as long as the structural constraints are appropriately accounted for, the use of finger-jointing technique in timber is still a feasible methodology for sustainable and economical structural applications, since it enables efficient use of material and minimises wastage. Description: M.Eng.(Melit.)

2026-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/145239 2026-03-27T14:55:07Z 2025-01-01T00:00:00Z

Title: The impact of emotional intelligence on project success in the construction industry in the case of Malta Abstract: This research investigates the influence of emotional intelligence on project success within the local construction industry. It provides valuable insights into the correlation between emotional intelligence and project performance in the local construction industry, while also revealing several avenues for further investigation. As construction projects become increasingly complex, emotional intelligence has surfaced as a significant factor in achieving effective project outcomes. Quantitative research approach was used, whereby a survey questionnaire was distributed to professionals working in the Maltese construction industry. Emotional intelligence was measured using Goleman’s framework, which consists of four competencies including selfawareness, self-management, social awareness, and relationship management. Simultaneously, project success was measured using key criteria, which included cost, schedule, quality, and stakeholder satisfaction parameters. Data was analysed using exploratory factor analysis (EFA) and regression modelling. The findings indicated that although professionals within the local construction industry possess a high level of emotional intelligence, there is no significant relationship to project success. The findings indicate that although emotional intelligence may not influence project success, it still significantly contributes to enhancing effective communication, fostering team cohesion, and resolving conflicts, elements that indirectly aid in the successful execution of projects. These results add to the expanding collection of literature that relates emotional intelligence to project success and indicate that construction firms may gain advantages by employing emotional intelligence. Description: M.Eng.(Melit.)

2025-01-01T00:00:00Z