Search Results (248)

This study investigates a wallboard integrating encapsulated phase change materials (PCMs) within aluminum honeycomb cells to reduce building energy consumption. The thermal performance of a concrete wall enhanced with this PCM-honeycomb composite was evaluated under varying weather conditions through a two-dimensional heat transfer model. The thermal improvement of PCM is revealed in a comparative analysis of three distinct building envelope materials, i.e., concrete, concrete covered by the honeycomb wallboard, and concrete covered by the honeycomb wallboard containing PCMs. The results demonstrated that the PCM-honeycomb wallboard effectively delays and reduces peak cooling loads. The proposed system lowered building energy consumption by 28.46% and 32.12% in energy consumption over the entire summer season (and 5.76% and 6.27% over one year), respectively, compared to these reference cases. Among the tested PCMs, RT25 was identified as the most effective. The results confirm that incorporating PCM-infused honeycomb wallboards into building envelopes is a viable strategy for passive, year-round temperature regulation. Full article

Concrete materials undergo a series of physical and chemical changes under high temperature, leading to the degradation of mechanical properties. This study investigates basalt fiber-reinforced concrete (BFRC) through high-temperature testing using the split Hopkinson pressure bar (SHPB) apparatus. Impact compression tests were conducted on specimens after exposure to elevated temperatures to analyze the effects of varying fiber content, temperature levels, and impact rates on the mechanical behaviors of BFRC. Based on fractional calculus theory, a dynamic constitutive equation was established to characterize the viscoelastic properties and high-temperature damage of BFRC. The results indicate that the dynamic compressive strength of BFRC decreases significantly with increasing temperature but increases gradually with higher impact rates, demonstrating fiber-toughening effects, thermal degradation effects, and strain rate strengthening effects. The proposed constitutive model aligns well with the experimental data, effectively capturing the dynamic mechanical behaviors of BFRC after high-temperature exposure, including its transitional mechanical characteristics across elastic, viscoelastic, and viscous states. The viscoelastic behaviors of BFRC are fundamentally attributed to the synergistic response of its multi-phase composite system across different scales. Basalt fibers enhance the material’s elastic properties by improving the stress transfer mechanism, while high-temperature exposure amplifies its viscous characteristics through microstructural deterioration, chemical transformations, and associated thermal damage. Full article

Coral reefs are very important ecosystems for the planet, offering ecological and socio-economic benefits. However, they are under threat due to anthropogenic factors and environmental changes. This study assesses the feasibility of weathered Portland cement concrete as a material for marine artificial reefs by comparing its physicochemical and mechanical properties with those of natural coral skeletons from the coast of Paraíba, Brazil. Analyses included microstructural and physical characterization, compressive strength and ultrasonic pulse velocity tests, as well as pH monitoring. The results indicated that weathered concrete exhibits mineralogical similarity to corals, with the presence of carbonate phases and portlandite absent due to advanced carbonation. The compressive strength of the concrete (27.6 MPa) was significantly higher than that of the coral samples (1–6 MPa), while the porosity of the corals (34–41%) exceeded that of the concrete (14%). The alkaline nature of the concrete (pH 9.7) remained stable. Although differences in physical and mechanical properties are evident, the values are within the ranges reported for cementitious materials in marine applications. Mineralogical similarities between coral skeletons and concrete support its potential as a functional analog in artificial reefs, while adjustments in geometry and porosity are suggested to enhance ecological compatibility. Full article

Incorporating phase change materials into asphalt concrete and utilizing phase change heat transfer to control the temperature of asphalt pavement can effectively reduce the impact of high temperatures on the durability of asphalt pavement. In this study, microencapsulated composite phase change materials were prepared using calcium alginate and polyethylene glycol (PEG) 1500 and mixed into SMA-13 Marshall specimens for indoor high-temperature tests. The test results show that the temperature of the specimen was reduced by about 1.5 °C when the doping amount of the composite phase change material was 2.4% and the oven temperature was 60 °C. In order to further investigate the application of phase change energy storage materials in asphalt pavement structure, this study used Comsol finite element software to simulate the summer temperature field of the asphalt surface layer. A three-layer asphalt pavement model consisting of 4 cm SMA-13, 6 cm AC-20, and 8 cm AC-25 was established to study the effect of phase change materials on the temperature change in the pavement. The results of this study show that adding 2.4% of the composite phase change material to each of the top and middle surface layers kept the temperature of all pavement layers outside of the temperature range in which the asphalt’s dynamic stability plunges. Full article

Sustainable construction has evolved into a global priority to mitigate the impacts of climate change, as the construction industry significantly contributes to environmental degradation and the overexploitation of resources. This study considers the effects on sustainability, particularly the inadequate management of resources, the ecological impact, and the anticipated degradation of the structures, all of which are due to the omission of the structural analysis during the design phase of the reinforced concrete (RC) structure. A methodical survey was conducted in three major cities among 258 professionals in the construction sector in Burundi, a developing country that has suffered socio-political and infrastructural challenges. The study examines the impact of these challenges on construction results. Quantitative analysis was carried out using SPSS v.30 and Amos 26 Software. For this research, reliability analysis, Kaiser-Meyer-Olkin test (KMO), Bartlett test, Exploratory Factor Analysis (EFA), Principal Component Analysis (PCA), and the Relative Importance Index (RII) were used to ensure the reliability and accuracy of the data. The results indicate that many projects are taking place in the absence of proper structural analysis due to financial constraints, poor quality materials, lack of qualified personnel, poor enforcement of regulations, and insufficient monitoring. These parameters have led to structural deficiencies compromising sustainability. The study recommends that government agencies, professional construction workers, and building owners improve regulation, teaching effectiveness, and professional responsibility to ensure that fundamental practices, such as structural analysis and the use of right sustainable materials, are logically applied to improve public safety and environmental resilience. Full article

This study investigates rapid-setting, phosphate-based, chemically bonded phosphate ceramic (CBPC) composites for emergency pothole repair through a two-phase experimental approach. Phase I involved fundamental mix design experiments that systematically examined the effects of water-to-binder ratio (20–40%), filler content (10–50%), and phosphate powder fineness (570–3640 cm²/g) on setting and mechanical performance. Based on Phase I results, Phase II evaluated field-applicable mixes optimized for concrete and asphalt pavement conditions in terms of rapid strength development: compressive strength exceeding 24 MPa within 30 min, flexural strength surpassing 3.4 MPa within 1 h, and adhesive strength reaching up to 1.62 MPa (concrete) and 0.68 MPa (asphalt) within 4 h. Additional performance evaluations included Marshall stability (49,848 N), water-immersion residual stability (100% under the test protocol), length change (small magnitude over 28 days), and self-filling behavior (complete filling in 17 s in the specified setup). These rapid early-age results met or surpassed relevant domestic specifications used for emergency repair materials. Based on these data, mix designs for field application are proposed, and practical implications and limitations for early-age performance are discussed. Full article

Concrete used in high-risk infrastructures must withstand elevated temperatures and thermal shocks. This study investigated the thermal transfer behavior of explosion-proof concrete exposed to 100–400 °C through a combined experimental and numerical approach. X-ray diffraction (XRD) revealed that the dominant crystalline phases remained identifiable across this range, but peak broadening and intensity reduction indicated partial decomposition of hydration products and microstructural disorder. Thermal conductivity reached its maximum of 1.48 W/(m·K) at 100 °C and decreased at higher temperatures due to porosity growth and microcracking, reflecting detrimental alterations in heat conduction pathways. In contrast, the specific heat capacity increased from 963.89 J/(kg·K) at 100 °C to 1122.22 J/(kg·K) at 400 °C, enhancing the material’s heat absorption. Density initially decreased with temperature but showed a temporary rebound at 300 °C due to secondary hydration, before dropping sharply to 1830 kg/m³ at 400 °C. Numerical simulations confirmed that high temperatures reduce surface–core temperature gradients, leading to more uniform but structurally weakened heat transfer. These findings highlight that explosion-proof concrete retains acceptable thermal stability below 200 °C, while significant degradation occurs beyond 300 °C. The novelty of this work lies in integrating experimental thermophysical tests with finite element simulations to link microstructural changes with macroscopic thermal behavior. Practically, the results provide guidance for optimizing concrete formulations and protective strategies in fire- and explosion-prone facilities such as LNG storage units and petrochemical infrastructures. Full article

Chloride-based deicing salt solutions have been contacted with concrete pastes containing slag cement at different conditions, such as slag replacement (20–80%), type (CaCl₂, MgCl₂, NaCl), and concentration (1 M–5 M) of the deicing salt, as well as temperature (ambient & −18 °C), and the extent of their reactions have been studied using XRD and ICP-OES. Also, solubility of Friedel salt (FS) has been measured in different types and concentrations of deicing salt solutions. It has been observed that the chemical deterioration arising from the formation and then dissolution of FS is more significant than the damage caused by the formation and expansion of oxychlorides in the pastes containing slag. While calcium oxychloride in its dried form can linger inside the paste for a long time, FS undergoes incongruent dissolution in CaCl₂ and MgCl₂ solutions and leaves the system. Presence of higher levels of AFm phases in pastes containing slag will further underscore this phenomenon. The extent of this chemical deterioration is relatively lower in NaCl solutions. Also, it was found that the nature of the chemical interaction changes with the concentration of the salt, as some disappeared phases might reappear and then disappear again. Using XRD and ICP-OES, this study provides a mechanistic understanding of salt-induced chemical deterioration in slag cement pastes by identifying phase-specific vulnerabilities and tracking the formation, transformation, and dissolution of key phases, such as Friedel’s salt and calcium oxychloride; additionally, the influence of various parameters have been studied, and chemical mechanisms have been proposed. Full article

Against the backdrop of intensifying global climate change and advancing the goal of the “dual-carbon” strategy, the built environment is being viewed as a complex socio-technical system in which technological, economic, demographic and institutional subsystems are coupled and evolving at different scales. As a core node in this system, residential buildings not only carry infrastructural functions, but are also deeply embedded in energy flows, material cycles and behavioural structures, which have a significant impact on carbon emissions. Given the high volume of residential buildings in China and the significant differences between urban and rural construction, there is an urgent need to systematically identify and analyse the implicit carbon emissions during the materialisation phase. In this paper, from the perspective of systems engineering, we selected 30 urban and rural residential buildings in provinces and cities from 2005 to 2020 as the research objects, adopted the life cycle assessment (LCA) method to account for the implied carbon emissions in the materialisation stage, and systematically identified the driving factors of carbon emissions based on the Stochastic Impacts by Regression on Population, Affluence and Technology (STIRPAT) model. From this study, we made the following conclusions: (1) the total carbon emissions of residential buildings in urban and rural areas in China continue to rise during the materialisation stage, showing a spatial pattern of “high in the south-east and low in the north-west”, with a significant trend of structural transformation in urban and rural areas and with steel–concrete structures dominating in towns and cities, and bricks and steel being used in rural areas. (2) Resident population and disposable income are generally positive driving factors, while the influence of industrial structure and energy intensity is heterogeneous between urban and rural areas. For overall residential buildings, every 1% increase in resident population and income will lead to a 1.055% and 0.73% increase in carbon emissions, respectively. The study shows that life-cycle-oriented carbon accounting and the identification of multidimensional driving mechanisms are of great policy value in developing urban–rural differentiated emission reduction paths and enhancing the effectiveness of carbon management in the building sector. Full article

Despite Greece’s historical and geographical significance in the Mediterranean, there is currently no national digital repository offering systematic access to Arabic chronicles, diplomatic letters, and travelogues from the eighth to sixteenth centuries. This absence critically impedes rigorous Arabological and Islamological research within Greek academia and restricts the educational landscape to predominantly Eurocentric perspectives. The Hellenic Digital Library of Arabic Historical Sources (HDB-AHS) is proposed as a pre-implementation targeted solution, presenting a trilingual (Greek–English–Arabic) digital platform designed to aggregate, preserve, and openly disseminate these vital sources. The article outlines a six-phase implementation plan combining IIIF, TEI-XML, FAIR for interoperability and reuse and CARE principles where community authority or sensitivity requires it, and open licensing with a robust rights–clearance framework for modern copyrights and sensitive materials. Beyond academic benefits, the project aspires to act as a meeting point of cultures, offering concrete tools for building bridges, combating intolerance, and fostering intercultural understanding. In a world that is rapidly changing, the creation of such an inclusive and responsibly curated digital resource is vital not only for advancing research but also for supporting dialogue and mutual respect across societies. The HDB-AHS provides a blueprint for similar initiatives in underrepresented fields. Full article

Understanding concrete creep aging is essential for ensuring structural safety and long-term durability, while the lack of robust numerical models limits the ability to thoroughly investigate and accurately predict time-dependent deformation and cracking behaviors. This study proposes a numerical framework integrating a discrete model and the microprestress solidification (MPS) theory to describe the aging creep and quasi-static performance of concrete at early-age and beyond. Hydration kinetics were formulated into constitutive equations to consider the time-dependent evolution of elastic modulus, strength, and fracture properties. Derived from the MPS theory, a unified creep model is developed within the equivalent rheological framework based on strain additivity. This formulation accounts for both visco-elastic and purely viscous creep phases while coupling environmental humidity effects with aging through the hydration degree. The proposed model is validated against experimental datasets encompassing diverse curing conditions, loading histories, and environmental exposures. The simulation results demonstrate that extended curing age enhances concrete strength (compression and fracture), while increased curing temperature has minimal impact due to the competing effects of microstructural refinement and thermal microcracking; both drying-induced transient creep and thermally induced microcracking contribute to increased creep deformation, driven by changes in microprestress resulting from variations in the chemical potential of nanopore water. The proposed numerical model can provide an effective tool to design and predict the long-term performance of concrete under various environmental conditions. Full article

Modern heritage (MH) is a key component of our built environment; however, it currently lacks widespread recognition and a clear, universally accepted definition, placing it in an emerging phase. This category of heritage, understood within the context of modernisation processes and the changes characteristic of the late modern period, remains underrepresented and warrants further study. The objective of this article is to fill the identified research gap, thereby fostering awareness of MH, improving its accessibility and enhancing its visibility and appreciation. It offers a diagnostic analysis of the corpus on MH through the design and development of a concrete methodology, which is transferable to the other heritage categories. This study reveals insights into the present understanding of the term ‘Modern Heritage’ and its relevance within an international framework. This understanding prompts a reflection on the terminology used to describe this concept, which serves not only as a significant result in itself but also as a foundation for future research. Despite the close association of modern heritage with the 20th century, this research identifies a cross-cutting nature that needs to be recognised, encompassing a wide range of periods, themes and typologies in this category. Full article

The European Health Technology Assessment (HTA) regulation (HTAR) came into effect in January 2025 and impacts the HTA process in all European Member States. Member States must give due consideration to the joint clinical assessment (JCA) report. This may require adaptations at the national level. This paper describes the anticipated changes to the Dutch national HTA process and how the Dutch National Health Care Institute (Zorginstituut Nederland, ZIN) prepared for this, because sharing experience between Member States can be of general interest for future expansion of the EU HTAR. ZIN’s implementation activities were facilitated by a project-governance structure and by a continuous gap analysis of the current national assessment and appraisal process of medicinal products, resulting in a concrete action plan. The implementation of the HTAR has two major implications for ZIN’s HTA process, namely that the scoping phase starts much earlier and that the JCA report is the starting point for the national assessment. Gaps, challenges and issues were identified in the categories: information and knowledge, IT and template, communication and stakeholder engagement, capacity and resources, and financial aspects. Based on a thorough and well-defined implementation plan, ZIN is ready to implement the HTAR in national HTA processes and to take on (co-)assessor roles for JCA of medicinal products in 2025. Full article

The recent evolution of the space industry, commonly referred to as New Space, has changed the way space missions are conceived, developed, and executed. In contrast to traditional approaches, the current paradigm emphasizes accessibility, commercial competitiveness, and rapid and sustainable innovation. This study proposes a research methodology for selecting relevant literature to identify the key design drivers and associated enablers that characterize the New Space context from an engineering design perspective. These elements are then organized into three categories: the evolution of traditional drivers, emerging manufacturing and integration practices, and sustainability and technology independence. This categorization highlights their role and relevance, providing a baseline for the development of systems for New Space missions. The results are further contextualized within three major application domains, namely Low Earth Orbit (LEO) small satellite constellations, operations and servicing in space, and space exploration, to illustrate their practical role in engineering space systems. By linking high-level industry trends to concrete design choices, this work aims to support the early design phases of New Space innovative systems and promote a more integrated approach between strategic objectives and technical development. Full article

Electrochemical treatment by means of direct current (DC) is usually used as a measure for steel rebar corrosion protection, e.g., cathodic protection (CP), electrochemical chloride extraction (ECE), and re-alkalization (RA). However, the passage of an electrical charge through the pore system of concrete or mortar, coupled with the migration of ions, concentration changes, and resulting phase changes, may alter its chloride penetration resistance and, subsequently, the time until rebar corrosion activation. Porosity changes in hardened Portland cement mortar were studied by means of mercury intrusion porosimetry (MIP) and electrochemical impedance spectroscopy (EIS), and alterations in the mortar surface phase composition were observed by means of X-ray diffraction (XRD). In order to innovatively investigate the impact of DC treatment on the properties of the mortar–electrolyte interface, the cathode-facing mortar surface and the anode-facing mortar surface were analyzed separately. The corrosion of steel coupons embedded in DC-treated hardened mortar was monitored by means of the free corrosion potential (E_oc) and polarization resistance (R_p). The results showed that the DC treatment affected the surface porosity of the hardened Portland cement mortar at the nanoscale. Up to two-thirds of the small pores (0.001–0.01 µm) were replaced by medium-sized pores (0.01–0.06 µm), which may be significant for chloride ingress. Although the porosity and phase composition alterations were confirmed using other techniques (EIS and XRD), corrosion tests revealed that they did not significantly affect the time until the corrosion activation of the steel coupons in the mortar. Full article