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Innovative digital twins (DTs) that allow engineers to visualise, share information, and monitor the condition during operation is necessary to optimise railway construction and maintenance. Building Information Modelling (BIM) is an approach for creating and managing an inventive 3D model simulating digital information that is useful to project management, monitoring and operation of a specific asset during the whole life cycle assessment (LCA). BIM application can help to provide an efficient cost management and time schedule and reduce the project delivery time throughout the whole life cycle of the project. In this study, an innovative DT has been developed using BIM integration through a life cycle analysis. Minnamurra Railway Bridge (MRB), Australia, has been chosen as a real-world use case to demonstrate the extended application of BIM (i.e., the DT) to enhance the operation, maintenance and asset management to improve the sustainability and resilience of the railway bridge. Moreover, the DT has been exploited to determine GHG emissions and cost consumption through the integration of BIM. This study demonstrates the feasibility of DT technology for railway maintenance and resilience optimisation. It also generates a virtual collaboration for co-simulations and co-creation of values across stakeholders participating in construction, operation and maintenance, and enhancing a reduction in costs and GHG emission.

Calcium aluminate cement (CAC) is one of the alternative cements that is widely used for special applications. However, during the hydration process degradation of CAC microstructure, the so-called hydrate conversion process, hexagonal calcium aluminate hydrate (CAH10) transforms into a cubic (C3AH6) phase, resulting in increased porosity and reduced strengths. It is known that alternative means for stabilizing the CAC conversion are conducted by introducing fly ash (FA) in CAC, where its microstructure is attributed to aluminosilicates. However, no study has yet been conducted on different FA compositions influencing CAC performance. This study aims to evaluate the effects of different compositions of FA on CACs’ fresh and hardened characteristics. Results revealed that the microstructure was denser when CAC was mixed with FA. Regarding reactivity, CAC with calcium-rich FA systems is 13% faster than the silica-rich one. The higher the density and the lower the porosity of calcium-rich FA mixtures were found compared with silica-rich FA in both micro- and macro-structures. As seen in the microscopic structure, this is due to the calcium-rich phase formation.

The effects of electrochemical chloride extraction were evaluated using different electrolytes and binders on cylindrical concrete specimens with a water/binder ratio of 0.4. Two-percent NaCl by weight of binder was added to the water as a chloride source during concrete casting. After the specimens were immersed in water for three months, direct current 0.5 A/m 2 was applied to release approximately 30% initial chloride. The use of intermittent mode during extraction process was more efficient in releasing chloride than a continuous mode. After treatment, although the average remaining-chloride content was higher than threshold value, its content at the interface was only approximately 0.4%. The accumulation of alkaline ions around the embedded steel was noticeable but the distribution of calcium ions showed as different tendency. The migration of ions from the electrolyte was insignificant. This demonstrated the important role of internal ions in transferring the charge during extraction; simultaneously, the decomposition or transformation of hydrated products is inevitable. After the treatment was stopped for four weeks, the half-cell potential of the steel reached to low-corrosion state.

This study experimentally evaluates sustainable self-compacting steel fibre-reinforced rubcrete (SCSFRR), incorporating recycled crumb rubber (up to 20% replacement of fine aggregates) and steel fibres (up to 0.75% by volume). Phase 1 assessed flowability/workability (slump flow, V-funnel, L-box, U-box) and hardened properties (compressive/splitting/flexural strengths, density, elastic modulus, brittleness index, and stress–strain behaviour). Phase 2 evaluated deep-beam performance under static and cyclic loading, focusing on load–deflection, shear ductility, and energy absorption. An exploratory analysis showed strong monotonic trends between compressive strength and density, tensile strength, flexural strength, and elastic modulus (R 2 ≈ 0.90–0.93). However, the limited dataset precludes design-level correlations. A novel shear ductility index is introduced to quantify improvements in deformation capacity due to crumb rubber and steel fibres. Results indicated that crumb rubber significantly enhanced ductility and energy absorption but reduced mechanical strengths, which steel fibres effectively mitigated. An optimal blend comprising 10% crumb rubber and 0.50% steel fibres achieved the best balance, increasing shear ductility by ≈ 22% and nearly doubling energy absorption while maintaining comparable strength to conventional concrete. A cradle-to-gate life-cycle assessment showed that replacing 20% of sand with rubber reduced embodied CO₂ per performance index by up to 42%. These findings indicate that SCSFRR can enable sustainable, resilient structural applications, particularly under seismic, cyclic, and low-rate dynamic loading.

Rice husk ash (RHA) is used as a replacement to cement to produce mortar. The effect of 5, 10, and 15wt% addition to the density and compressive strength of mortar is investigated. It was found that with the increasing addition of RHA causes the decrease of compressive strength and density of mortars. Compressive strength of mortar drops with addition of RHA, from a value of 42 MPa of no RHA addition, to 24 MPa of 15wt% RHA addition. Reduction in compression strength may be due to the decrease in density, which arises from porous RHA. This is more dominant in mortar made from addition of RHA without prior acid treated. Carbon residue and impurity in RHA further reduce the compressive strength of mortar. In addition, this research validate the use of a more environmentally friendly citric acid for partially removal of oxide impurities prior to burning the rice husk.

Concrete structures can be deteriorated in extreme service conditions especially for fire incidents. For the evaluation of the post-fire performance, analytical methods are very powerful and useful. However, widely applicable mechanical models of fire-damaged material have not yet been proposed. To develop such models, the scale of control volume considering strength, stiffness and deformability is one of important factors. This paper presents an experimental study in which visual observations and mechanical properties of oven-dried mortar after exposed to the fire curves of ISO 834 and ASTM E119 for 90 minutes and to be left to cool down in air were conducted. Mortars were made from two different types of fine aggregate and cement. Experimental results indicate that the raw material made mortar is a prominent factor to introduce the different fire damage characteristics. Meanwhile, the mechanical properties of mortar in fire problem are strongly related to temperature that mortars were experienced to.