Band 65, Heft 1

The growing demand for lightweight, durable, and sustainable materials in the aerospace sector motivates the development of high value biocomposites. This work experimentally investigates the potential of pure bast flax fiber reinforced with zirconium dioxide (ZrO 2 ) nanoparticles at varying concentrations (1, 2, and 3 wt%) for light weight helicopter structures. Laminates were fabricated using a hand lay-up compression molding technique and characterized for low-velocity impact resistance, flexural strength, and interlaminar shear strength (ILSS). Further, scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA) were used to characterize the thermo-mechanical performance and failure mechanisms. The key finding is that the 3 wt% ZrO 2 nanocomposite significantly enhanced all critical properties, it demonstrated a 63 % higher maximum impact force (740 N), a 86 % increase in flexural strength, reaching 134 MPa, compared to the 72 MPa pure flax, increased ILSS by 38.2 %, reaching 4.7 MPa, and a 91 % enhancement in the DMA storage modulus (8.46 GPa). These findings demonstrate the strong potential of these nanocomposites for use in demanding, weight-sensitive applications, such as lighter helicopter structures.

In this study, both individual and hybrid effects of industrial wastes (silica fume, fly ash), fibers (glass and basalt) and nanoparticles (nano SiO 2 , nanoclay) mixed with clay at different ratios were investigated in detail at macro and micro levels at different water contents and curing times. The efficiency of stabilization in clay soils was determined using Gray Correlation Analysis (GCA). A predictive model for the stress-strain relationship of stabilized soils with hybrid material was proposed. Results showed negligible changes in dry density and optimum moisture content with silica fume and fly ash, while nano SiO 2 and nanoclay induced significant variations. The unconfined compressive strength (UCS) tests showed a significant increase in soil strength with the addition of nanomaterials, especially after long curing times. The presence of nano SiO 2 and nanoclay in the composite specimens increased the UCS by 87.15 % and 63.83 % before curing, respectively, while it increased to 317.50 % and 219.74 % after the maximum curing time. GCA identified curing time as the most influential factor, followed by silica fume, glass fiber, and nanoclay, due to progressive bonding development. Nanoclay demonstrated superior UCS enhancement compared to nano SiO 2 , underscoring its effectiveness in soil stabilization. The study contributes to the literature to realize the full benefits of these additives to improve soil stability and the UCS performance, and to address waste recycling, increase the strength of subgrade soils under different environmental conditions, and reduce the costs associated with the use of waste.

The inherent brittleness and high-temperature recrystallization tendency of tungsten heavy alloys (WHAs) make balancing high strength and ductility under harsh conditions a major challenge. This study introduces V, Ta, and Re as strengthening elements into W-Ni-Fe-Co alloys by powder metallurgy, producing five alloy compositions (in weight fraction): the baseline sample S1 (W-2.46Ni-1.05Fe-0.7Co), single-doped samples S2 (1V), S3 (2Re), S4 (4Ta), and multi-doped sample S5 (1V-2Re-4Ta). The results show that S1 has the highest density of 98.6 ± 0.61 %; S3 has a peak hardness of 443.27 ± 13.33 HV; and S5 exhibits the best tensile strength and elongation, at 816.35 MPa and 8.92 %, respectively. These performance improvements are attributed to specific strengthening mechanisms: V enhances hardness and ductility through solid solution strengthening in the tungsten lattice and induces lattice distortion; Re promotes grain refinement and the formation of ReW phases, mainly enhancing hardness through grain boundary pinning; and Ta contributes to strength improvement by enriching and achieving second phase strengthening. In S5, the synergistic effect of multi-element doping effectively balances the heterogeneity of grain size and the distribution of the binder phase network, minimizing micropores and optimizing interface bonding, thereby achieving an excellent synergy between strength and ductility and expanding the alloy’s application potential.

This study investigates the compression behavior of circular concrete columns confined with basalt fiber-reinforced polymer (BFRP) stirrups, comparing their performance with traditional steel-reinforced columns. The objective of the study is to assess the impact of the BFRP transverse reinforcements and concrete mix design (CMD) codes on the compressive strength (CS), energy accumulation (G Acc ), fracture energy (G F ), and ductility of RC cylinders. A total of 81 reinforced concrete (RC) cylinders were prepared using three distinct CMD codes and tested under axial compression. The specimens were confined with 6 mm and 8 mm BFRP and steel spirals/ties at varying rib spacings (45 mm, 60 mm, and 90 mm). The experimental results revealed that closer BFRP spiral/tie spacings (45 mm) significantly enhanced the CS by 7–15 % and G Acc by up to 59 % of the columns due to improved confinement effect, compared to those with larger spacings (60 mm and 90 mm). BFRP ties demonstrated superior performance in terms of CS, G Acc , and G F compared to BFRP spirals, particularly at moderate and larger spacings. Finite element model (FEM) simulations validated the experimental results with less than 8 % deviation and demonstrate a high degree of correlation between predicted and observed failure behaviors. The study suggests that BFRP spirals/ties reinforcements with optimal spacing can effectively replace steel in structural applications, offering comparable performance in strength, ductility, and energy absorption. These findings encourage the use of BFRP-based reinforcements in durable, lightweight, and eco-friendly concrete constructions.

The purpose of this research was to synthesize and characterize calcium (Ca) substituted barium titanate (Ba 1-x Ca x TiO 3 ) ceramics. Compositions with calcium substitution levels of x  = 0.0, 0.01, 0.03, 0.05 and 0.07 were prepared using a solid-state reaction method. All compositions were confirmed by X-ray diffraction (XRD) and Rietveld analysis to have a single-phase cubic crystal structure with slight lattice distortions. The optimal grain structure was determined by morphological analysis based on scanning electron microscopy (SEM). The lowest dielectric loss and highest dielectric constant were observed for the composition with x  = 0.03. P-E loop analysis demonstrated a reduction in remanent polarization with increasing Ca content. The highest recoverable energy ( W rec ) and efficiency were obtained for x  = 0.03. These results indicate that the material is suitable for energy storage devices, capacitors and high frequency optoelectronic applications. Through these insights, a pathway to design advanced functional materials for next generation electronic and energy devices is established.

The insufficient skeletal stability of porous asphalt mixtures (PAM) stems critically from the poorly understood dynamic evolution of aggregate gradation during compaction. The differential impacts of distinct compaction methods remain inadequately characterized. This study systematically investigates the effects of Marshall Compaction (MC) and Superpave Gyratory Compaction (SGC) on gradation variation in PAM-13 and PAM-16, incorporating key parameters such as asphalt addition states and compaction energy levels. Specimens were prepared under both with asphalt and without asphalt conditions, subjected to multi-level compaction energy, and subsequently analyzed through sieve analysis. Key findings reveal that MC induces more pronounced coarse aggregate breakage (up to −15.06 %) and fine aggregate generation (up to 101.64 %); SGC better preserves fine aggregate integrity; asphalt provides protective effects predominantly for fine aggregates; and increasing compaction energy continuously exacerbates fine aggregate fragmentation. The findings elucidate the gradation variation patterns induced by different compaction methods, thereby providing a critical theoretical foundation for optimizing the design and construction control of PAM.

The need for energy efficiency and sustainable building materials is increasing today. In this context, new material integrations that aim to improve the thermal and mechanical performance of building elements are being investigated. This study experimentally investigated the effects of two phase change materials (PCM-1(CACI 2 .6H 2 O), PCM-2(NEXTEK24D)) and a thermal insulation material (polyurethane) on the thermal conductivity and compressive strength of hollow bricks. The internal voids of the bricks were filled with polyurethane and two different PCMs to evaluate the contributions of these additives to the mechanical and thermal behavior of the building elements. The findings indicate that adding PCM increases the bricks’ thermal resistance values and reduces internal temperature fluctuations. Bricks filled with polyurethane and FDM showed increased compressive strength, up to 28 % vertically and 74 % horizontally, compared to reference specimens. This emonstrates that filling bricks with such materials improves their compressive strength and thermal insulation. In conclusion, bricks with PCM and polyurethane additives offer significant potential for energy-efficient building solutions, particularly in terms of thermal comfort and insulation. However, given the impact of these additions on mechanical performance, further research is needed to optimize material ratios and enhance applicability without compromising structural safety.

Polystyrene (PS) and its nanocomposites have shown considerable potential as selective barriers for gas permeation, yet the influence of molecular weight (MW) on their gas transport behavior remains insufficiently understood. In this study, three PS samples with ascending MWs (PS1–PS3) and their reduced graphene oxide (rGO) nanocomposites (PS1-G–PS3-G) were prepared via hot pressing. Notably, the water vapor transmission rate (WVTR) exhibited a non-monotonic dependence on MW, increasing from 1.50 g/m 2 ·day (PS1) to 1.59 g/m 2 ·day (PS2), then decreasing to 1.27 g/m 2 ·day (PS3). A similar trend was observed in the nanocomposites, which displayed lower WVTR values (0.54, 0.61, and 0.48 g/m 2 ·day, respectively). In contrast, the oxygen transmission rate (OTR) rose sharply with MW – from 509.41 g/m 2 ·day (PS1) to 1,119.8 g/m 2 ·day (PS2) and further to 4,586.11 g/m 2 ·day (PS3) – while rGO incorporation substantially suppressed oxygen permeability (40.72, 58.09, and 138.32 g/m 2 ·day, respectively). Hydrogen transmission rates (HTR) varied only slightly among the PS samples (830, 842, and 907 cm 2 /(m 2 ·day·0.1 MPa), and the addition of rGO induced minimal changes. Among all samples, PS1 and PS1-G exhibited the most favorable barrier selectivity, combining strong water and oxygen resistance with retained hydrogen permeability. These results demonstrate that MW plays a decisive role in governing gas barrier selectivity and provide design insights for optimizing polymer nanocomposites in advanced barrier applications.

This research explores the synthesis of zinc oxide nanomaterials (ZnO NMs) through the utilization of neem leaf extract, presenting an environmentally conscious and sustainable methodology. The biosynthesized ZnO NMs exhibit dual functionality, showing remarkable efficacy in the photocatalytic degradation of natural organic matter (NOM) as well as antimicrobial activity against drug-resistant microorganisms. Under low-energy UV light, ZnO effectively degraded 92 % of NOM within a span of 180 min, concurrently exhibiting substantial antimicrobial effects against Escherichia coli and Candida albicans , characterized by significant inhibition zones. The research further highlights the application of low-energy UV light to improve the photocatalytic efficiency of ZnO NMs, thereby promoting sustainability and reducing the toxicity of by-products. The characterization of ZnO NMs was conducted employing various techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV–vis), and scanning electron microscopy (SEM). At a concentration of 3 g/l, ZnO accomplished a 92 % reduction in NOM over a period of 180 min, accompanied by a 59 % reduction in organic carbon deposition (OCD). The low levels presence of OCD on the surface after the reaction further confirmed the effectiveness of the process. The findings highlight the promise of neem-extract ZnO NMs as an eco-friendly and adaptable substance for environmental cleanup and antimicrobial uses, demonstrating significant antibacterial efficacy at concentrations of 0.05 mg/ml and 0.1 mg/ml.

Granite powder (GP) has gained attention as a sustainable alternative material in concrete production due to its potential to improve the durability and sustainability. The previous researchers focused on the mechanical properties of concrete and limited studies provided a detailed review on the effects of durability and microstructural characteristics of concrete. Therefore, this review critically examines the influence of GP on the concrete durability and microstructural properties. The findings indicate that GP improves concrete density, reduces water absorption, enhances impermeability, and increases resistance to acid and sulphate attacks. It also lowers the heat of hydration which making it suitable for mass concrete applications. In addition, GP improves the pore structure by reducing capillary porosity and improving packing density. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses indicate that GP promotes calcium silicate hydrate (CSH) gel formation. However, higher percentages of GP restrict CSH gel development, which leads to a looser mix, increased micro-cracking, and higher porosity. The optimal percentage of GP varies depending on factors such as the source of materials, mix design, water-cement ratio, curing time, and environmental conditions, which led to variation in research findings. Finally, the review identifies a research gap and recommends future studies.

Warm mix asphalt (WMA) is a sustainable innovation in road construction that enables bituminous mixtures to be produced and compacted at lower temperatures than traditional hot mix asphalt (HMA). This reduction in temperature significantly decreases greenhouse gas (GHG) emissions and other pollutants, supporting global climate change mitigation efforts. WMA technology enhances energy efficiency while maintaining the performance and durability of road surfaces, offering an environmentally responsible alternative for the construction industry. Its adoption reflects a commitment to reducing the carbon footprint of infrastructure projects. These innovations are anchored in three primary techniques, chemical additives, organic additives, and foaming processes, each of which contributes uniquely to reducing energy consumption while improving pavement performance. Extensive research has revealed the multifaceted advantages of WMA. Mechanically, WMA demonstrates exceptional properties, including enhanced resistance to stripping, fatigue, thermal cracking, and rutting, which collectively contribute to the longevity and resilience of asphalt pavements. Environmentally, the reduced energy demands of WMA production not only reduce emissions but also provide an opportunity to integrate recycled materials and industrial byproducts, further reinforcing its eco-friendly credentials. Economically, the lower production temperatures translate into operational cost savings, although a detailed analysis of long-term cost implications is essential to fully understand its financial viability. This review highlights the historical development, material innovations, and advanced techniques underpinning WMA, providing a thorough evaluation of its rheological and fractured properties. This research aims to support the widespread implementation of WMA in pavement applications. This study also emphasized the critical role of life cycle assessment (LCA) in quantifying the sustainability benefits of WMA mixtures. Moreover, the study explores the emerging trends and challenges in the widespread adoption of WMA, emphasizing the need for robust evaluations of its economic, environmental, and safety aspects. Ultimately, WMA technologies represent a pivotal innovation, offering an integrative solution to modernize the road construction industry while addressing pressing environmental concerns.

This narrative review explores the role of Artificial Intelligence (AI) in advancing the synthesis, optimization, and clinical translation of dental biomaterials. It critically evaluates how AI-driven approaches address existing challenges related to material performance, biocompatibility, and durability, while identifying current research gaps and outlining future perspectives. A comprehensive literature synthesis was conducted through electronic searches in PubMed, Scopus, Web of Science, and Google Scholar. Selected articles encompassed both experimental and computational studies. Case studies were analyzed to illustrate the application of AI techniques, including machine learning (ML) for predicting mechanical properties, deep learning (DL) for microstructural and imaging analysis, and optimization algorithms ( e.g. , genetic algorithms) for materials discovery and formulation enhancement. The findings indicate that ML models can accurately predict mechanical properties ( e.g. , flexural modulus), DL enables automated detection of material degradation, and optimization algorithms accelerate the discovery of advanced biomaterials such as high-entropy ceramics. AI also facilitates the development of personalized, adaptive materials, including pH-responsive and self-healing resin composites. Nonetheless, barriers remain, including data scarcity, limited generalizability, high computational demands, and lack of standardization. AI is poised to redefine the landscape of dental biomaterials by enabling smarter material design, improved performance prediction, and accelerated clinical translation. This review advances the field by integrating emerging computational approaches with practical needs and identifying unresolved challenges that hinder real-world adoption. Ultimately, leveraging AI alongside technologies such as 3D printing and digital twin systems can drive the development of next-generation biomaterials tailored to patient-specific clinical outcomes.

The use of recycled tire rubber, particularly crumb rubber (CR), as a partial fine aggregate replacement offers a sustainable pathway to reduce environmental waste and conserve natural resources, aligning with SDG 9 and SDG 12. This review synthesizes 84 peer-reviewed studies to evaluate the mechanical performance, durability, microstructural characteristics, and practical applicability of crumb rubber concrete (CRC). While CRC typically shows reductions in compressive, tensile, and flexural strengths, stemming from weak ITZ bonding, low stiffness, and increased porosity. It exhibits improved ductility, freeze–thaw resistance, and chemical durability. Empirical polynomial regression models are introduced to quantify strength degradation as a function of CR content, and benchmarking against major design codes indicates that CR levels up to 20 % can satisfy minimum strength requirements for selected exposure classes. Recent enhancement strategies, including RF-RC systems and matrix modifications using sulfate-resistant cement, silica fume, and fly ash, demonstrate quantifiable gains, such as ∼25 % increases in compressive strength, post-crack residual strength improvements from 0.10 MPa to 1.4–3.1 MPa, and ductility enhancements exceeding 70 %. Environmental assessments further show that CRC and multi-waste composite systems can reduce embodied energy by 153–227 MJ/m 3 and CO 2 emissions by 30–135 kg/m 3 , with LCA studies reporting up to 75 % decreases in total environmental impacts. Field-scale investigations confirm CRC’s feasibility, with composite slabs achieving 10–19 % higher peak loads and 17–33 % higher first-crack loads than conventional concrete. Overall, limiting CR content to 10–20 % and employing performance-based mix optimization are recommended to balance mechanical performance, durability, and sustainability in next-generation low-carbon construction.