https://www.um.edu.mt/library/oar/handle/123456789/16068 Sat, 25 Apr 2026 17:04:39 GMT 2026-04-25T17:04:39Z https://www.um.edu.mt/library/oar/handle/123456789/145406 Title: Waste tire rubber recycling for developing a high viscosity-elasticity composite modified asphalt Authors: Zhang, Derun; Tang, Jinbiao; Luan, Dongxing; Xu, Xiong; Borg, Ruben Paul; Lewis, Odette Abstract: Non-biodegradable waste tire rubber poses serious environmental and public health risks. Thus, waste tires recycling has become a critical global issue. In this study, crumb rubber (CR) derived from waste tires was recycled to synthesize a new type of high viscosity-elasticity composite modified asphalt (RSTMA) with styrene-butadiene block copolymer (SBS), and terpene resin (T105). Three major indicators, dynamic viscosity, elastic recovery rate, and softening point difference after segregation were used to determine the optimal formula of RSTMA. Dynamic shear rheometer (DSR) tests were employed to systematically evaluate the rheological properties of RSTMA. The individual contributions of the three modifiers to RSTMA performance improvement were quantified via the Entropy Weight Method (EWM). Experimental results show that compared with base asphalt, the elastic recovery rate of RSTMA with the optimal formulation increases by 71%, while the non-recoverable creep compliance decreases by 98.56%. The segregation index (SI) of this optimal RSTMA reaches 0.87, and its fatigue life at a 35% damage degree exceeds 8000 loading cycles. It was also found that CR significantly increases the viscosity upper limit of RSTMA, CR and T105 jointly elevate its elasticity upper limit, while SBS improves both viscosity and elasticity. Overall, under the synergistic modification of CR-SBS-T105, the performance of RSTMA is significantly enhanced, with CR content reaching up to 15% (by asphalt mass). This study provides a pathway for the high-value, low-carbon recycling of crumb rubber, promoting sustainable development in the solid waste management. Thu, 01 Jan 2026 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/145406 2026-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/145252 Title: Hydration and marine durability of high-ferrite Portland cement-fly ash blends under varied curing temperature Authors: Yang, Huamei; Xu, Kaiqin; Zhang, Shuming; Liao, Yishun; Cui, Jinyang; Tang, Shengwen; Li, Wenwei; Wang, Lei; Barbara, Klemcazk; Bakhtiyarovich Atabaevh, Farrukh; Borg, Ruben Paul Abstract: To meet the demanding conditions of marine environment, cementitious materials of concrete must exhibit low hydration heat, high strength, and superior erosion resistance. This study investigates the hydration and marine durability of high-ferrite Portland cement (HFPC)-fly ash blends under varied curing temperature. Its mineral composition, rich in C4AF and C2S, results in significantly slower and lower early-age heat release – only 86.7% of ordinary Portland cement at 3 days (20°C). Fly ash slightly delays early hydration and reduces heat release of HFPC, but accelerates it after an initial inhibition period (~12 h at 20 °C, ~6 h at 60 °C) through providing hydration product nucleation sites and dilution effects. Incorporating fly ash (40% being optimal) markedly refines pore structure and enhances chloride penetration resistance. HFPC-fly ash blends demonstrate excellent early durability in NaCl and Na2SO4 solutions, offering promising marine applications. Thu, 01 Jan 2026 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/145252 2026-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/144728 Title: Mapping circularity strategies in building sustainability assessment methods Authors: Giarma, Christina; Askar, Rand; Trubina, Nika; Salles, Adriana; Lombardi, Patrizia; Karaca, Ferhat; Mateus, Ricardo; Feizollahbeigi, Bahar; Karanafti, Aikaterina; Moghadam, Sara Torabi; Pineda-Martos, Rocío; Santana Tovar, Daniela; Borg, Ruben Paul; Bragança, Luís Abstract: The widespread adoption of circularity principles in the building sector fuels the need for robust and comprehensive evaluation systems, which could benefit from the approaches and indicators employed in widely accepted building sustainability assessment (BSA) methods. Simultaneously, the effective consideration of circular economy (CE) principles into BSA methods becomes increasingly urgent. An important step towards achieving these targets is the investigation of whether, and to which degree, the existing BSA methods encompass and express circularity principles; this study focuses on this relatively underexplored theme. Specifically, this study investigates the degree of association between five widely used BSA methods and the circularity strategies included in the 10R Framework. The methods examined are BREEAM, DGNB, LEED, Level(s) and SBTool (versions and criteria for new buildings). The examination was conducted at the lowest self-contained and score-attributing level of each method and was undertaken by five expert groups—each assigned one method. A quantitative scale from 0 to 5 was used to assess the strength of the association. The results are analysed in terms of (i) the criteria/thematic areas within each method receiving high/low scores, and (ii) the circularity strategies deduced to be strongly/weakly represented in and across the BSA methods. Common trends and milder differences across these axes are observed. Generally, the associations appear stronger in thematic areas relevant to, among others, resources and lifecycle performance, and weaker regarding parameters linked to user comfort. The R-strategies Reduce, Reuse, Recycle and Rethink emerge as more intensely represented in the examined methods. The study’s results indicate areas for further research and potential methodological enhancement. Thu, 01 Jan 2026 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/144728 2026-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/144567 Title: Carbon capture and performance enhancement of lime putty finishes with organic additives : implications for sustainable construction and heritage conservation Authors: Malladi, Ravi Chandra; Czerwinski, Jacek; Patyna, Krystian; Borg, Ruben Paul; Selvaraj, Thirumalini Abstract: This study investigated the potential of lime putty finishes incorporated with traditional additives, i.e. kadukkai (Terminalia chebula) and jaggery, to enhance their carbon capture and utilization (CCU) and to produce carbon neutral material in sustainable construction and heritage conservation. Mechanical and microstructural performances of modified lime putties were analyzed with reference to compressive strength, x-ray diffraction, infrared analysis, thermogravimetric analysis, and gas adsorption techniques. These findings confirmed that organic lime putty finishes improved performance predominantly in the mechanical strength, carbon sequestration, and microstructural development. Results demonstrated that jaggery mixed putty exhibited a 39.7 % higher carbonation rate with 36 % higher mechanical performance, 2.5 % higher CCU capacity, and better calcite crystallization than the reference, driven by enhanced porosity and accelerated CO2 diffusion by fermentation derived alcohols. Kadukkai modified lime showed moderate carbonation and denser microstructure with enhanced formation of hydration products with high amorphous content (44.8 %) in the form of amorphous calcium carbonate (ACC). Microstructural studies revealed that jaggery promotes calcite formation, while kadukkai improves ACC formations. Lime with both additives achieved balanced strength (33 % high) and CCU efficiency (2.5 % high), highlighting the synergistic effects of combined organics in promoting uniform carbonation with both amorphous and crystalline carbonates with controlled porosity. This investigation emphasizes the lime putty finishes pertinence as sustainable building materials, providing a practical resolution for use in heritage restoration and potentially in non-load bearing sustainable construction applications. Thu, 01 Jan 2026 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/144567 2026-01-01T00:00:00Z