The incorporation of high levels of supplementary cementitious materials (SCMs) is widely recognized as an effective approach to reducing the carbon footprint of concrete; however, it substantially compromises carbonation resistance and thereby increases the risk of reinforcement corrosion. Current reinforced concrete design standards specify cover thickness primarily based on compressive strength, which is inadequate for high SCM concretes. This study investigated the feasibility of incorporating reclaimed water-based paint (RWBP) to reduce the carbonation coefficient of high-SCM concretes containing up to 70% slag and 20% fly ash. The effects of RWBP on fresh and hardened properties, microstructural characteristics, and transport behavior were examined, and the mechanism governing its influence on carbonation coefficient was elucidated. The implications for life-cycle carbon efficiency were also assessed. Results show that RWBP leads to the formation of discontinuous polymer films coating pore walls in the hardened matrix, retarding capillary water loss, and reducing CO2 diffusivity in high-SCM concrete with comparable strength. Due to the discontinuous nature of these films, prolonged exposure progressively increases capillary water loss, consequently increasing the carbonation coefficient with advancing carbonation duration. The extent of carbonation resistance enhancement depends on the type of SCM. Furthermore, the life-cycle carbon efficiency of high SCM concrete can increase by up to 60% with the incorporation of only 10 L/m3 of RWBP. The predicted service life of all high SCM concretes can be more than doubled under natural exposure conditions. In addition, carbon emissions can be further lowered as RWBP significantly reduces the demand for superplasticiser.

3D Concrete Printing (3DCP) has proven its technological readiness for large-scale applications; however, the absence of comprehensive standards enfolding design, construction and quality control significantly hinders its widespread adoption. As a result, current applications remain largely limited to non-structural or quasi-structural elements and extensively rely on hybrid systems incorporating conventional construction. This paper presents a thematic gap analysis to critically synthesise the evidence from completed projects, emerging standards and existing literature, aimed at highlighting current gaps in specifications and outlining potential future research directions. A comparative assessment of seven current standards identifies: (1) the absence of explicit structural design rules, (2) inconsistent treatment of interlayer properties, (3) limited translation of test results into structural capacity calculations, (4) lack of comprehensive quality control protocol and acceptance logic and (5) limited guidance on non-structural performance indicators capturing peculiarities of 3DCP. Based on this comparative analysis, the paper outlines priority components for a model 3DCP standard, subsequently suggests critical mechanical properties required for structural design, reconnaissance viable design and detailing approaches, reframes durability and serviceability requirements as performance targets, and proposes a minimal and testable quality-control protocol that links process control, material characterisation and structural verification. The proposed comparative framework provides a foundation for transitioning 3DCP from project-specific demonstrations to reliable standards-based structural applications.

3D printing of soils is an emerging additive manufacturing technique that is gaining significant attention across various fields, due to its high level of automation and low environmental impact. Interestingly, also geotechnical engineering applications can benefit from this technique in the future, exploiting the fact that 3D-printed soils can exhibit a peculiar fabric with a distinct bi-modal pore network. These double-structural levels can be adjusted within certain limits due to the design flexibility offered by 3D printing. Current applications of 3D-printed soils rely primarily on empirical criteria, and the existing literature remains in its early stages, particularly lacking a geomechanical perspective. Advancing the understanding of the hydro-mechanical behaviour of these materials is essential—not only to predict their performance in future applications but also to refine the early-stage printing processes currently in use. To address this, the present work focuses on investigating the complete hydro-mechanical behaviour of 3D-printed soil with the special attention to its water retention behaviour. Several 3D-printed samples with a clear double-structure fabric were printed and subjected to drying and wetting paths from the as-printed state, to reconstruct the water retention curves. A novel method was employed to monitor volumetric changes in the samples, using a 3D laser scanner to capture volumetric variations at two microstructural scales. Moreover, fabric analyses through different stages of drying/wetting paths were performed using Mercury Intrusion Porosimetry and Scanning Electron Microscopy. Finally, the water retention behaviour of 3D-printed soil samples was modelled, considering their double-structure nature, and key characteristics of this behaviour are discussed in detail.

Electric vehicle (EV) adoption is rapidly increasing in Australia as well as around the world, as it is supporting national decarbonisation goals. Despite this, the battery used in EVs poses a severe fire risk when subjected to physical damage. The garage of the timber-framed house is highly prone to suffering from this unique and severe fire. As the garage's walls were designed based on the deemed-to-satisfy criteria specified by the fire resistance level (FRL), which follows the standard fire curve. However, an EV fire is non-linear and initiated by a violent thermal runaway, making it unpredictable, and these conditions were not accounted for in the traditional fire safety design approaches for timber-framed walls. This study assesses the FRL of timber-framed walls subjected to EV fires through the validated fire dynamic simulation. A timber-framed wall panel and the walls attached to the representative house garage were subjected to twelve different EV fires. Results show that the FRL of the timber-framed wall attached to the garage declines abruptly within 15 min in both structural adequacy and integrity, leading to early structural compromise and increased fire spread, ultimately resulting in both structural and thermal insulation failure under EV fires. These findings indicate that the fire resilience of the current timber-framed house design is inadequate in the event of EV fires, highlighting the need for improvements in design and construction regulations.

3D concrete printing (3DcP) offers a transformative approach to modern construction, providing unique benefits such as faster construction, lower labour costs, and minimal material waste. Despite these advantages, high cement consumption and the challenge of achieving conflicting rheological requirements limit its widespread application. This study addresses these challenges by developing an Ordinary Portland Cement (OPC)-based 3D printable mortar incorporating magnesium oxide (MgO) as a partial cement replacement and using carbonated water (CW) as the mixing water. MgO is an abundant material capable of reacting with CO2 to form stable carbonates, while CW promotes early hydration and carbonation. Unlike previous approaches that require hydration agents to overcome the low dissolution of MgO, this work combines MgO and CW to meet the rheological demands of 3DcP without additional additives. Rheological properties such as static yield stress, buildability, and workability were evaluated alongside compressive strength and microstructural characteristics using XRD, SEM, TGA, and FTIR analyses. Results showed that MgO increased static yield stress due to higher water absorption, while CW further enhanced it through accelerated hydration. The MgO-CW combinations, particularly mixes with 25% (25MCW) and 50% MgO (50MCW), exhibited yield stress increases of 505% and 425%, respectively, after 30 minutes compared to a control mix with pure water (CPW). Among the tested mixes, 25MCW achieves a practical balance of extrudability, buildability and compressive strength, confirming its applicability for 3D printing applications under the tested conditions. Moreover, microstructural analysis confirms enhanced hydration and carbonation reactions in the MgO-CW modified mix, which contribute to the improved performance of the developed sustainable material. This study offers insights for advancing eco-friendly 3D printable materials and sustainable construction.

The integrity of conductors is the most essential aspect of the reliable operation of overhead power distribution networks. The corrosion is one of the prime reasons for failure in overhead conductors due environmental and operational factors, such as moisture, pollutants, temperature cycling, and mechanical strain. The corrosion induced reduction in tensile strength capacity increase the risk of catastrophic failures. Although existing health monitoring devices provide corrosion detection at an early stage, an efficient transfer of this data to maintenance activities continues to be a concern for utility suppliers. The current study presents the development of corrosion model and probabilistic failure prediction models for aluminium conductors with steel reinforcement. An artificial corrosion environment was experimentally developed for steel and aluminium strands to simulate various corrosion effect. The tensile strength test was conducted to measure the strength of the conductor. Based on the experimental results, a model was developed to predict the loss of strength capacity of the conductor and a probabilistic failure model was established to calculate the expected life of corroded conductors. The developed models will allow to estimate the reliability and to prepare the maintenance plan for overhead conductors.

Incorporating recycled materials into concrete paves the way for sustainable construction while reducing landfill waste. The application of foam concrete in construction has demonstrated its potential to improve thermal insulation capacity and lower the dead load on structures, thereby enhancing sustainability. However, it has high embodied carbon and low thermal insulation when used for structural applications. Therefore, this study used waste clay bricks and recycled polypropylene fibres from face mask waste to develop an eco-friendly geopolymer foam concrete to improve the thermal and sustainability performance. Initially, the foam content of the geopolymer foam concrete mix was optimised based on the flowability, wet density and stability using different foam contents of 5 %, 10 % and 15 % by weight. Additionally, the effect of varying fibre dosages (0.5 %, 1 % and 1.5 % by volume) on the mechanical properties (compressive and flexural strength), mix homogeneity and thermal insulation characteristics were evaluated. The results showed that increased foam content resulted in a highly flowable mix, whereas reduced mix stability was attributed to a higher air content and the faster collapse of the air bubbles. However, adding fibres up to 1 % dosage improved the fresh properties and enhanced the stability of the mix. Furthermore, this also increases the flexural capacity by approximately 84 % when a 1.5 % fibre dosage is added. Based on the fresh properties and foam stability observations, a 10 % foam content was deemed optimal and adopted to develop fibre-reinforced geopolymer foam concrete. Furthermore, the compressive strength reduction for this foam content with the addition of fibre is insignificant (i.e. <= 10 %). Nevertheless, the fibre-reinforced geopolymer foam concrete exhibited low thermal conductivity (i.e. ranging from 0.245 to 0.331 W/mK) and diffusivity. This indicates that recycled fibres from face mask waste and waste clay bricks can be used to enhance the sustainability of foam concrete.

Rapid advancements in four-dimensional (4D) printing have introduced time-dependent functionality into additive manufacturing. Research trends indicate that biomedical, aerospace, and materials science disciplines primarily drive 4D printing. However, its applications in civil engineering remain underexplored, while some developed applications remain in the laboratory stage. This paper systematically examines the current progress, applications, and emerging potential of 4D printing with a focus on its relevance to civil and construction engineering. A bibliometric mapping and critical analysis were conducted. Results show that, within civil engineering, about 35 research articles were published focusing on modular self-assembling components, climate-adaptive façades, deployable bridges, and regolith-based lunar construction. However, large-scale adoption is constrained by limited materials and printing equipment, as well as the absence of performance-based standards. To transition 4D printing from experimental studies to practical applications, future research should focus on developing AI-driven predictive modelling and a formalised standardisation framework.

Soil-based 3D printing has emerged as a potential solution for sustainable construction, due to growing concerns over the environmental impact of cement-based materials. However, the limited understanding of soil printability, material behaviour, and performance under real-world conditions remains a significant barrier to its application. This review provides an in-depth evaluation of material performance and technological challenges of soil 3D printing with a special focus on the extrusion-based printing method. Furthermore, this study explores the fresh and hardened state properties of soil-based mixtures, highlighting the importance of rheology in achieving extrudability and buildability during the printing process. Notably, the incorporation of certain additives has been shown to reduce shrinkage by up to 50% and increase compressive strength by 10-30%, although results remain highly dependent on soil type. The environmental assessments indicate that soil 3D printing can reduce the carbon footprint by up to 20% compared to traditional construction methods, especially when local or excavated soils are used. Despite these advancements, challenges persist in standardising mix designs, managing variability in soil composition, and ensuring long-term durability under environmental exposure. To advance soilbased 3D printing in sustainable construction, it is important to integrate soil mechanics principles, standardise testing protocols, and validate results at the field scale.

The bolted connections are important components in overhead power distribution network systems, fixing the insulator to the cross-arm. This connection is subjected to various loads, such as the self-weight of the conductor, wind, and thermal, which induce cyclic stresses that can lead to fatigue failure. The presence of separation gaps, resulting from non-compliances with dimensional tolerances in insulator connections, increases stress concentrations at the thread roots and promotes the initiation of cracks. Therefore, the role of gap size in the fatigue performance of the insulator connection is investigated in this study. The fatigue performance of a commonly used bolted connection (i.e., M24x3.0p stud) in a distribution power network having controlled gap sizes was experimentally tested under reverse cyclic flexural load using a test rig specifically developed for this purpose. The experimental results were used to develop a probabilistic fatigue life model for bolted connections with gaps. Furthermore, the probability of failure was estimated considering the effect of both gap size and load level of the connection. Also, the Miner's linear cumulative damage theory was employed, together with Monte Carlo simulation, to enable the inclusion of wind load variation to describe variable in-service loading and used for life expectancy estimation of the in-service connection. It was observed that fatigue life is reduced by approximately 80% as the gap distance increases from 1 mm to 3 mm. Finally, probabilistic life expectancy curves were developed to provide a quantitative assessment tool to assist the asset owners, in performing risk-based asset management.

Nuclear waste management has become a critical issue due to growing concerns about the long-term safety and sustainability of radioactive waste disposal and its impact on infrastructure. Insufficient knowledge and regulations surrounding nuclear waste management are significant challenges to sustainable development. This review provides an in-depth categorisation of nuclear waste, with particular emphasis on high-level waste (HLW), which requires extensive pre-disposal treatments, and explores its impact on infrastructure and structures. Recent innovations, such as thermal treatment, partitioning and transmutation, are highlighted for their effectiveness in reducing HLW volume and radiotoxicity. The review also examines the detrimental effects of radiation on containment materials, especially concrete and steel. Notably, containment infrastructure is vulnerable to degradation, with studies showing a loss of up to 50% in compressive strength in concrete exposed to extreme neutron irradiation and reductions of up to 70% in Young’s modulus. Advanced materials, such as fibre-reinforced concrete and oxide-dispersion-strengthened steels, offer promising solutions by mitigating these effects and improving durability by 10–30%. Furthermore, the review identifies significant strides in international collaboration on nuclear waste management, which have led to advancements in minimising hazards and improving waste processing. These efforts are further supported by the integration of digital tools and material innovations, ensuring continued progress in managing nuclear waste safely and sustainably.

The use of supplementary cementitious materials (SCMs) and carbon capture, utilization, and storage (CCUS) technologies has become important for reducing CO2 emissions. This study explores the feasibility of using cement kiln dust (CKD) as a partial replacement for cement and CO2 mixing as an in situ carbon sequestration strategy in 3D concrete printing (3DcP) applications. The synergistic effects of CKD and CO2 mixing on the fresh and hardened properties of 3D printable mixes were investigated, including workability, yield stress, plastic viscosity, compressive strength, microstructural properties, and pH. Results showed that the static yield stress increased by more than 100% in the mixes with CKD and CO2 compared to the control. While CKD reduced compressive strength, CO2 injection mitigated this loss through early carbonation. The scanning electron microscopy images revealed increased ettringite formation in CKD samples, and thermogravimetric analysis confirmed up to 2.2% of CO2 uptake upon CO2 integration with CKD.

Beyond ensuring the structural integrity of the foundation system, its sustainability is equally important, as enhancing the environmental performance of foundations plays a key role in advancing sustainable construction. There are different types of foundation systems, and their applicability varies on the type of the building and the soil conditions. The main objective of this research is to evaluate the sustainability of screw piles (SP) and bored piers (BP) through a life cycle analysis (LCA) from the perspectives of carbon emission and energy consumption. A cradle-to-grave LCA is performed for the pile systems, starting from the manufacturing to the end-of-life, to quantify the associated global warming potential (GWP) and energy consumption (EC) of both BP and SP. This study follows a process-based approach, where individual processes associated with each life cycle stage are considered separately in the analysis. For an average job with 50, 3-m piles under normal circumstances (i.e. standard material and machinery use, normal weather), screw piles showed a 56% reduction in GWP and a 34% reduction in EC compared to an equivalent bored pier system. However, based on the pile length and the diameter impacts can vary and at higher length, SP have significant low environmental impacts compared to BP.

Incorporating postconsumer reclaimed water-based paint (RWBP) into concrete provides a sustainable alternative to landfill disposal. However, the application of RWBP-incorporating concrete has remained limited mostly to sidewalks, because critical parameters for practical use remain unclear, such as air-entrained stability, slump loss, and drying shrinkage of formed concrete over time. Additionally, the effect of RWBP on the carbonation resistance of concrete has not been explored, which is critical for concrete containing supplementary cementitious materials. This study systematically investigated these aspects in concrete with fly ash. Due to its liquid phase and fine particles, RWBP partially replaced fine sand and water at different dosages. The air bubble stability and slump loss of fresh concrete were tested, along with compressive strength at 3, 7, and 28 days. Moreover, the carbonation resistance of RWBP-incorporating concrete was evaluated by measuring the pH value of the pore solution. Finally, the sorptivity and drying shrinkage of concrete were tested. The results show that incorporating RWBP adds significant value, particularly by slowing alkalinity loss in carbonated areas and improving carbonation resistance. The presence of RWBP increased air bubbles in concrete, leading to reduced strength. However, sorptivity and drying shrinkage improved with increasing RWBP dosage. Notably, these air bubbles were unstable, which accelerated slump loss and increased drying shrinkage.

In 3D concrete printing (3DCP), achieving rapid development of high static yield stress after extrusion is critical to ensure buildability for preventing collapse of freshly printed concrete. Commonly, this is achieved by incorporating buildability enhancing additives during the initial mixing stage. However, high dosage of such additives often increases flow resistance within the pipeline, which leads to pumping challenges (i.e., blockage and high energy consumption). To address this limitation, this study explores the feasibility of applying active rheology control approach using mechanical vibration to improve the pumpability of 3D printable concrete. A laboratory scale pumping setup was developed to monitor pumping pressure, and rheological properties of both concrete and lubrication layer were examined under applied vibration and different resting times. The results reveal that vibration could reduce the pumping pressure up to 22

The rapid growth of electric vehicles (EVs) has introduced new fire safety challenges for the built environment, particularly within reinforced concrete structures. Fires involving lithium-ion batteries are substantially different from conventional hydrocarbon-fuelled fires due to their rapid heat escalation, extended burning duration, and potential for re-ignition caused by thermal runaway. This study assesses the adequacy of existing fire design standards in addressing these emerging hazards, emphasising the spalling behaviour of concrete under EV induced fire exposure. The study found that concrete structures are highly vulnerable to spalling when exposed to EV fires, as the typical temperatures initiating concrete spalling are significantly lower than the extreme temperatures and re-ignition produced during an EV battery fire. Moreover, the evidence suggests that EV fires can sustain peak temperatures exceeding 1000 °C in a short period, which exceeds the assumptions underlying standard fire curves, such as ISO 834. A comparative assessment of the National Construction Code (NCC 2022) and standards (i.e., AS 1530.4, EN 1992-1-2) reveals that current design methodologies and fire-resistance ratings underestimate the severity and duration of EV fire conditions. This study also proposes code-aligned improvements and a performance-based evaluation framework that integrates empirical EV fire curves. The findings highlight a pressing need to re-examine fire design provisions and update thermal exposure assumptions to ensure that reinforced concrete infrastructure remains structurally safe and reliable as EV adoption increases.

3D printing of soils is an emerging additive manufacturing technology with significant potential for various geotechnical applications. These include automating the construction of earth-based houses using locally available soil to reduce the carbon footprint of the building process, as well as constructing infrastructure such as embankments for roads or dams, clay liners for landfills, and engineered barriers. Moreover, due to its flexibility in designing varying printing geometries, 3D printing in geotechnics offers the unique ability to produce soils with a distinct double-structured fabric, enabling the customization of geotechnical properties. Despite its potential, this technology remains in its early stages, with current applications largely developed through empirical approaches. Additionally, existing literature lacks studies adopting a geomechanical perspective. A robust understanding of the hydro-mechanical behaviour of 3D- printed soils is crucial for predicting their performance in geotechnical applications and advancing this emerging technology. To address this gap, this study investigates the drying behaviour of a double- structured 3D-printed soil from its as-printed state, with a particular focus on fabric evolution at both the micro and macro scales. The results provide initial insights that will contribute to the future development of a comprehensive hydro-mechanical model for 3D-printed double-structured soils.

Waste tyre rubber (TR) from end-of-life tyres poses a major environmental challenge. Therefore, recycling this waste into useful applications contributes to sustainable waste management strategies and supports a circular economy. Rubber possesses properties that can enhance the flexibility and ductility of pavements, making it a feasible material for use in road infrastructure. This study investigates the mechanical and fatigue performance of recycled concrete aggregates (RCA) mixed with waste TR. RCA was partially replaced at three different levels: 5%, 10% and 15% by weight. To mitigate the loss in mechanical strength associated with rubber inclusion, the TR + RCA mixes were stabilised through geopolymerisation using slag as a precursor. The unconfined compressive strength (UCS) increased with higher binder content. For instance, the mix containing 15% TR and stabilised with 5% slag geopolymer achieved a UCS of only 0.7 MPa, whereas increasing the binder content to 15% raised the UCS to 2.2 MPa. Similarly, resilient modulus improved with increasing slag content. Results from the four-point bending fatigue test showed that replacing RCA with rubber particles enhanced the fatigue performance of the mixes. The initial fatigue modulus of 100% RCA mix stabilised with 15% binder was 13,690 MPa, which reduced to 9740 MPa when 10% TR was introduced. In contrast, the number of cycles to reach half the initial modulus increased by four times when the TR content was raised from 0% to 15%. Microstructural observations of the slag-stabilised TR + RCA mixes showed improved microstructure due to geopolymerisation. Only insignificant traces of arsenic (<0.0008 mg/L) and barium (<0.000208 mg/L) were present in the TR + RCA mixes, while all other concerning heavy metals, including mercury and lead, were not detected in the leaching test. This indicates that there is no potential risk of soil or groundwater contamination, confirming the environmental safety of using slag geopolymer-stabilised TR + RCA mixes in subbase applications.

Rigid pavements are typically constructed with concrete and the pavement structure consists of a concrete base and lean-mixed concrete (LMC) subbase. Compared to the base layer, the LMC subbase has low strength requirements. According to the Australian pavement design standards LMC with a strength in the range 6 MPa to 17 MPa is used for subbase. Although the current construction practice is to use ordinary Portland cement (OPC) as the binder material in LMC, OPC has severe negative environmental impacts due to the high greenhouse gas (GHG) emissions and energy consumption associated with its manufacturing process. This study focuses on developing LMC by fully replacing OPC with eco-friendly binders to achieve the required performance criteria while improving the sustainability of pavement industry. Fly ash, slag and waste clay bricks (WCB) sourced from construction and demolition waste combined with solid sodium silicate were used to prepare the alternative binders. LMC mixes with these WCB-based binders were first optimized considering the compressive strength to select a suitable aggregate gradation and water-to-binder ratio. The workability and consistency of LMC were improved by optimizing the aggregate grading by eliminating coarse sand. Due to the low binder content in LMC (i.e., 200 kg/m3), higher water-to-binder ratios (i.e., 0.65 to 0.70) and use of ambient curing (i.e., 25 °C ± 3 °C) resulted in longer setting times. Conventional accelerators used for OPC concrete were found to be inefficient for the WCB-based binders. The addition of hydrated lime as an accelerator reduces the setting time from around 36 h down to 8 h. An increase of hydrated lime content reduces the setting time as well as the strength. A hydrated lime content of 5

Ensuring the fire safety of timber structures is important in promoting timber and timber-based construction materials. Among the engineering timber used in the construction, Glue laminated timber (GLT) is a commonly used timber type. Considering timber's anisotropic and heterogeneous nature, it is essential to understand the behaviour of the timber under extreme loading conditions. Developing a numerical model to predict timber behaviour is of importance to designers, considering the cost and time for experimental tests. This study developed and validated a detailed numerical model using Abaqus software with the VUMAT user subroutine. Two models were used for the validation. Charring rates of a non-load-bearing model were studied, while the deflection of a load-bearing beam during fire was analysed. The validated model was then used to predict the residual stiffness of the GLT beam of a 5.2 m span with different numbers of plies. Further, a reliability framework was developed to assess the reliability of timber beams in the event of a fire, and 54 beam samples were numerically analysed. Results show that the number of plies in the GLT beam significantly affects the flexural stiffness when subjected to fire. It was also observed that stiffness reduction with the fire exposure is higher with lesser depths where the GLT beam with 14, 12, 9, 7 and 5 plies have flexural stiffness reduction by 25%, 28%, 29%, 32% and 53%, respectively at the end of the 120 min fire exposure. Moreover, the residual stiffness reduction of the beams of 14 plies with Young's modulus in the 9-13 GPa range is up to 81-76 % during the considered time. Using the reliability framework, a 40 % - 60% reduction in the reliability index of beams was observed due to a nearly 62% increase in span from 3.2 m to 5.2 m for normal conditions and during fire events.