https://www.um.edu.mt/library/oar/handle/123456789/118868 Sun, 07 Jun 2026 22:28:40 GMT 2026-06-07T22:28:40Z https://www.um.edu.mt/library/oar/handle/123456789/121710 Title: Assessment of the structural health monitoring of a reinforced concrete water tower Abstract: The Reinforced Concrete Water Tower at the Abattoir in Marsa was in a deteriorated state before an extensive restoration intervention was carried out. The restoration process included restoring the deteriorated water tank and support columns, using ultra high-performance concrete and textile reinforced concrete. A structural health, durability and environmental monitoring system was set up at the Water Tower. Throughout the restoration process, numerous sensors were included in different parts of the water tower, including the columns and in different parts of the tank. The sensors are intended to monitor different durability and structural health characteristics of the restored water tower. These include sensors that would analyse the structural integrity of the water tower and also the performance of the concrete: resistivity, galvanic and electrode durability sensors to analyse the durability of the water tower under various conditions in use. Environmental monitoring was also set up with a weather station which captures data on weather conditions including solar radiation, temperature and precipitation and their effect on the water tower. The aim of this dissertation is to analyse the data obtained from the structural health and durability sensors to understand the way the restored water tower reacts to various conditions, and to see how the condition of the water tower develops with time while in use. This was done by obtaining the data from the extensive sensor system (150 sensors), analysing it and interpreting using different techniques to understand the performance of the structure. The water tower was primarily analysed during the filling in and emptying of the water tank with 400 cubic m of water, which took place during September 2021 before starting this dissertation, as it was crucial to understand how the structure reacts during these critical processes. The performance of the structure during a seismic event was also assessed with reference to the sensor system. In addition, the performance of different sensors in different parts of the structure during different scenarios was analysed. Overall, the results obtained when analysing the structural health monitoring system (strain gauges, accelerometers) and durability sensors on the water tower indicated that the systems are capable of assessing the performance as anticipated at design stage of the monitoring system. In addition, the system indicated that the structure was performing as per design considerations, when considering behaviour at different stages of use of the structure, including before filing in, full of water and on emptying the tank. Observing the water tower’s performance over time through the durability sensor system permits an understanding of the effectiveness of the restoration and the durability of the restoration and strengthening methods employed themselves, which will help to contribute to the development of restoration processes for other reinforced concrete structures in deteriorated states similar to the water tower. Description: M.Eng.(Melit.) Sun, 01 Jan 2023 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/121710 2023-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/121699 Title: Potential organic binders to replace the cement content in reconstituted limestone production Abstract: At the University of Malta, an innovative approach is being developed to produce engineered masonry stones using limestone waste, Ordinary Portland Cement, and water. This process employs a circular process where construction materials are reused within the industry, recycling limestone whilst creating a more sustainable stone. However, the cement content gives these reconstituted limestone elements an undesired high carbon footprint, contributing to carbon emissions and environmental harm associated with cement production. The primary objective of this study is to find a suitable organic binder to replace the cement content in the reconstituted limestone production. The binder was selected for this research is Cascamite, a cold setting organic, resin-based adhesive. This binder was selected following comprehensive research on its ability to replace the cement in the mix, whilst drastically reducing the carbon footprint of the resultant product. This makes the produced reconstituted limestone much more sustainable and environmentally friendly. The results obtained were analysed regarding workability, compressive strength, and durability. These were compared to previous research to understand if the binder can be used as a substitute for Ordinary Portland Cement in the production of reconstituted limestone. Results revealed that the binder chosen can produce strong reconstituted stone, with load bearing compressive strengths. However, the resultant durability was not satisfactory. Description: M.Eng.(Melit.) Sun, 01 Jan 2023 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/121699 2023-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/120584 Title: Cellular origami sandwich panel cores used for blast energy absorption Abstract: The objective of this dissertation is to explore various types of sandwich panel cores used within structural walls, so as to create optimal blast-resistant structural envelopes in firework factories. This is done by comparing five distinct sandwich panel core types with constant geometrical constraints for each type – such as volume, width, and thickness. These panels include a square honeycomb core, y-core, z-core, and two origami-type cores made from a single-layer Miura Origami core and another from a double-layer Miura Origami core. Such core types are compared to verify the unique qualities of Origami cores in contrast to traditional sandwich panel cores. Structural blast walls must absorb significant, massive and rapid loading in order to remain contained, meaning that the structure making up such walls must offer both strength and ductility so as to minimise the blast’s penetration risk. The two identifiable characteristics, which determine such properties, include the overall displacement of the walls composed of sandwich panels and the core's deformability. The former refers to the ability of the wall to control excessive deflections, which would cause damage to the structural components, such as the foundations and connections with other walls. On the other hand, the latter refers to the ability of the core to absorb energy such that, by following the principle of energy conservation, little-to no-energy is left to be dissipated to the wall boundaries. This research study adopted a research methodology by means of using numerical analysis computational software based upon the Finite Element Method (FEM). A total of 105 FEM numerical models were analysed in order to study these different characteristics, where each core type was tested against varying explosive TNT levels and the elevation aspect ratio of the walls. The walls were assumed to be simply-supported at the bottom and side edges, and free at the top so as to model the lack of restraint offered by frangible roofs. The blast analysis results showed that the best sandwich panel cores for constructing firework factory walls are the doublelayer Origami core and z-core, since, while some core types may produce better flexural stiffness than Origami cores, they prove to be inadequate for energy absorption, and vice versa. Moreover, the square honeycomb core experienced low deflection and, hence, high flexural stiffness, but it was inefficient in energy absorption. On the other hand, the z-core portrayed better overall flexural stiffness. However, this core type showed slightly inferior energy dissipation compared to the Origami cores. Finally, some thoughts on possible future research work are also presented. Description: M.Eng.(Melit.) Sun, 01 Jan 2023 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/120584 2023-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/119679 Title: Investigation on the structural behaviour of precast/prestressed hollow core concrete floor slabs used for overhangs Abstract: This research study aims to test the structural behaviour of precast/prestressed hollow core concrete floor slabs used for overhangs. These precast slabs are commonly used in frame buildings, as they offer ease of constructability, whilst also offering greater load capacity to weight ratio than that of a cast-in situ reinforced concrete slab. These slabs have been used in the local industry over the past 50 years mainly in order to span greater distances, whilst carrying greater imposed loads from the structure above. Using an experimental research methodology, a set of slab specimens were prepared and tested in order to investigate the structural behaviour of these precast/prestressed hollow core concrete floor slabs used for overhangs in the local construction industry. The experimental programme involved preparing a testing-rig set-up within the Civil Engineering laboratory at the University of Malta. The testing programme was conducted upon a number of full-scale precast/prestressed hollow core concrete floor slabs with different configurations of concrete structural topping and steel bar reinforcement. These slabs were set-up in a way to create an overhanging end, while restraining the other end in order to prevent overturning of the slab when the cantilever end was loaded. The vertical load was applied through a load cell situated at the cantilevered end of the slab. Measuring apparatus, such as steel strain gauges, concrete strain gauges and linear variable differential transformers (LVDTs) were set up along the span of the slab. These instruments recorded the strain of the concrete at the compression side (underside), the strain in the main steel tension reinforcement within the concrete topping and the vertical displacement due to the applied load on the slab at the cantilevering end and at the midpoint between the internal supports. In total, five experimental configurations were tested in order to investigate the structural behaviour and benefits of using a reinforced concrete structural topping over the precast/prestressed hollow core concrete floor slabs in order to be able to resist the hogging moments induced within the slab by the applied loading. Quality control checks and safety parameters were used throughout the testing programme. This research study includes a descriptive and comparative analysis of the failure loads and failure modes (flexure or shear) obtained for each slab specimen. The experimental results obtained are presented graphically in order to facilitate the comparison during the loading of the slabs to failure and the corresponding post-ultimate unloading. The experimental results obtained showed that there is a significant improvement in the load-carrying capacity of the slabs with reinforced structural concrete topping compared to the control slab without topping. The experimental results were also found to compare well with analytical predictions of structural strength and failure modes This research study also includes suggestions for further research work, which are relevant to the scope of this field of research. Description: M.Eng.(Melit.) Sun, 01 Jan 2023 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/119679 2023-01-01T00:00:00Z