Materials

36 pages, 6431 KB

Open AccessArticle

Comparative Thermal Performance of Ultra-High-Performance Concrete and Geopolymer Concrete: Influence of Steel Fibre Geometry on Residual Mechanical and Chemical Properties

by Yusra Muhammed, Jawdat Tashan, Nadia Saiyouri, Youssef Sleiman and Bland Lateef

Materials 2026, 19(16), 3562; https://doi.org/10.3390/ma19163562 - 21 Aug 2026

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Abstract

To investigate the elevated-temperature performance of Ultra-High-Performance Concrete (UHPC) and Ultra-High-Performance Geopolymer Concrete (UHPGC), a systematic comparative study was conducted at 800 °C. This study examined the effects of the steel fibre geometry (micro and hooked-end) and dosage (1.5% and 2.0%) on mass [...] Read more.

To investigate the elevated-temperature performance of Ultra-High-Performance Concrete (UHPC) and Ultra-High-Performance Geopolymer Concrete (UHPGC), a systematic comparative study was conducted at 800 °C. This study examined the effects of the steel fibre geometry (micro and hooked-end) and dosage (1.5% and 2.0%) on mass loss, crack propagation, residual compressive, flexural, and tensile strengths, and chemical evolution following a 24 h pre-drying protocol to mitigate explosive spalling. The results demonstrate that UHPGC exhibits superior thermal stability and residual mechanical performance compared with UHPC after high-temperature exposure. Among all mixtures, the UHPGC mixture reinforced with 2% micro steel fibres (UHPGC-M2) achieved the highest residual compressive strength (30 ± 0.4 MPa, corresponding to 25% strength retention compared with 21% for the equivalent UHPC mixture), the lowest post-exposure crack width (0.08 mm), and the highest tensile strength retention (17.9%). Micro steel fibres were more effective in controlling crack propagation and preserving peak load capacity, whereas hooked-end fibres contributed more significantly to post-peak ductility. Chemical analysis revealed substantial chemical changes in both systems after exposure to 800 °C. However, UHPGC exhibited lower mass loss (4.8%) and greater residual performance. These findings establish micro steel fibre-reinforced UHPGC as a sustainable and high-performance material for fire-resistant structural applications. Full article

(This article belongs to the Special Issue Reinforced Concrete: Mechanical Properties and Materials Design)

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24 pages, 4947 KB

Open AccessArticle

Microstructural Evolution of the NC-UHPC Near-Interface Composite Region Under Sequential Carbonation and Seawater Exposure

by Yan Zeng, Yubin Zheng, Zhu Wei, Foo Wei Lee, Sujie He, Yang Yang and Xiaoli Xie

Materials 2026, 19(16), 3561; https://doi.org/10.3390/ma19163561 - 21 Aug 2026

Viewed by 346

Abstract

The long-term durability of repair systems combining normal concrete (NC) and ultra-high-performance concrete (UHPC) in marine environments depends on the response of the near-interface composite region to sequential carbonation and seawater exposure. However, the effects of seawater immersion following pre-carbonation remain insufficiently understood. [...] Read more.

The long-term durability of repair systems combining normal concrete (NC) and ultra-high-performance concrete (UHPC) in marine environments depends on the response of the near-interface composite region to sequential carbonation and seawater exposure. However, the effects of seawater immersion following pre-carbonation remain insufficiently understood. This study compared an unexposed reference (REF), specimens carbonated for 28 d (C28), and specimens carbonated for 28 d and then immersed in simplified artificial seawater for 60 d (C28-SW60) using X-ray diffraction, thermogravimetry, backscattered electron imaging with energy-dispersive X-ray spectroscopy, and mercury intrusion porosimetry. Pre-carbonation promoted portlandite consumption, carbonate formation, and pore refinement. Subsequent seawater immersion further enhanced calcite-related diffraction and carbonate decomposition signals, while no typical crystalline salt-attack product was detected as dominant. The initial Ca-rich-to-Si-rich gradient from the NC side through the overlay transition zone to the UHPC side was accompanied by marked Cl accumulation and further S and Mg enrichment and redistribution. After seawater immersion, the measured total intrusion volume increased from 0.026 to 0.043 mL/g, the volume-based median pore-entry diameter increased from 27.49 to 58.42 nm, and the >1000 nm pore-volume fraction reached 39.82%, a change consistent with a shift toward coarser mercury-accessible pore entries. Together, the results link the initial heterogeneity of the NC–Overlay transition zone (OTZ)–UHPC region to a sequence-dependent response in which carbonate enrichment coexisted with multi-ion redistribution and transport-relevant defects, distinguishing carbonate accumulation from sustained near-interface refinement. Full article

(This article belongs to the Section Construction and Building Materials)

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13 pages, 713 KB

Open AccessArticle

Patient-Clustered Analysis of Recorded Insertion Torque in 101 MultiNeO Titanium Dental Implant Placements: An Exploratory Retrospective Cohort Study

by Katarzyna Wieczorek, Adrian Wasilewski, Bartłomiej Szwed, Weronika Nicpoń, Natalia Szymkowiak, Grzegorz Hajduk, Mansur Rahnama-Hezavah and Michał Łobacz

Materials 2026, 19(16), 3560; https://doi.org/10.3390/ma19163560 - 21 Aug 2026

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Abstract

Primary implant stability arises from mechanical engagement at placement, and insertion torque is not a direct measure of osseointegration. This retrospective single-centre study included 101 MultiNeO titanium implant placements in 55 adults treated between April 2023 and January 2026. Four experienced operators placed [...] Read more.

Primary implant stability arises from mechanical engagement at placement, and insertion torque is not a direct measure of osseointegration. This retrospective single-centre study included 101 MultiNeO titanium implant placements in 55 adults treated between April 2023 and January 2026. Four experienced operators placed implants subcrestally using a W&H Implantmed SI-1023, a bone-resistance-adapted drilling protocol, and a programmed target of 35 N·cm. Associations with recorded torque were assessed using a patient-clustered Gaussian generalized estimating equation adjusted for sex, age, anatomical sector, implant length and diameter, hard-tissue augmentation, and placement timing. The mean torque was 31.63 ± 5.57 N·cm; the median was 35 N·cm (Q1–Q3, 30–35). Recorded torque was 3.25 N·cm higher for implants placed in women than for those placed in men (95% CI 1.20–5.31; p = 0.002). Relative to maxillary anterior/premolar sites, mandibular molar sites showed higher torque (β = 4.02; p = 0.001), whereas mandibular anterior/premolar sites showed lower torque (β = −5.41; p = 0.013). Implant length had a modest adjusted association (β = 0.93 N·cm/mm; p = 0.022); age, diameter, augmentation, and placement timing did not. The concentration of recorded values at 35 N·cm reflects a clinical target rather than the device limit. These exploratory associations do not establish an intrinsic sex effect or predict osseointegration, and residual confounding due to unmeasured bone characteristics remains possible. Full article

(This article belongs to the Section Biomaterials)

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52 pages, 4719 KB

Open AccessReview

Amazonian Bioactives in Biopolymer-Based Systems for Biomedical Applications: Current Advances and Future Perspectives

by Márcia Raquel Felix da Costa, Yuliana Padron-Antonio, Sara Caroline Pacheco de Oliveira, Lucas de Souza Falcão, Patrícia Melchionna Albuquerque and Mariana Agostini de Moraes

Materials 2026, 19(16), 3559; https://doi.org/10.3390/ma19163559 - 21 Aug 2026

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Abstract

The Amazon region harbors one of the richest biodiversities on the planet, representing a vast reservoir of bioactive compounds with high therapeutic potential. Although several Amazonian bioactives have already been incorporated into biopolymeric matrices, the effects of their incorporation on the mechanical, barrier, [...] Read more.

The Amazon region harbors one of the richest biodiversities on the planet, representing a vast reservoir of bioactive compounds with high therapeutic potential. Although several Amazonian bioactives have already been incorporated into biopolymeric matrices, the effects of their incorporation on the mechanical, barrier, and biological properties of these materials remain insufficiently systematized. This review addresses this knowledge gap by critically analyzing reported Amazonian bioactive–biopolymer systems, with emphasis on how bioactive incorporation influences matrix properties, release behavior, and biological performance, particularly in biomedical applications. Emphasis is placed on the role of polymer–bioactive interactions in modulating physicochemical, mechanical, and transport properties, as well as in controlling release kinetics and biological performance. Different incorporation strategies, such as encapsulation and matrix embedding, are critically discussed in terms of their impact on stability and functionality. Overall, the reported studies demonstrate that Amazonian bioactives can substantially modulate the physicochemical, mechanical, barrier, and biological performance of biopolymeric systems, depending on the bioactive, polymeric matrix, and incorporation strategy. However, challenges related to variability in raw materials, lack of standardization, and limited reproducibility remain key barriers to translation and large-scale application. Full article

(This article belongs to the Special Issue Natural Products and Bioactive Compounds in Functional Biomaterials)

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20 pages, 1992 KB

Open AccessArticle

Internal Degradation of 2.5D C/SiC Composites Under Continuous-Wave Laser Irradiation: Experiments and Phase-Selective Modelling

by Chuntong Liu, Renke Wang, Yuwei Lv and Yubin Shi

Materials 2026, 19(16), 3558; https://doi.org/10.3390/ma19163558 - 21 Aug 2026

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Abstract

Surface recession can underestimate laser-induced damage in 2.5D C/SiC composites because thermochemical degradation extends beneath the visible pit. Infrared thermography and micro-CT data from six laser conditions (400–1600 W·cm⁻², 3–12 s), together with SEM/EDS observations, were reanalysed using a layered phase-selective [...] Read more.

Surface recession can underestimate laser-induced damage in 2.5D C/SiC composites because thermochemical degradation extends beneath the visible pit. Infrared thermography and micro-CT data from six laser conditions (400–1600 W·cm⁻², 3–12 s), together with SEM/EDS observations, were reanalysed using a layered phase-selective model tracking C, SiC and SiO₂ evolution. For the four conditions with resolvable damage, the internal degradation front lay 0.84–1.07 mm below the recession surface. At 800 W·cm⁻², the 0.02 mm difference between the 6 and 12 s front depths was below the 25 μm voxel size and within specimen uncertainty. The calibrated model matched rear-centre peak temperatures with a mean absolute percentage error of 4.37%, although larger transient discrepancies remained. Temperatures sampled at the measured front coordinates ranged from 2890 to 3080 K. Relative to 800 W·cm⁻² for 12 s, the 1600 W·cm⁻², 6 s condition caused greater near-surface SiC consumption and solid-mass loss, while the maximum retained SiO₂ density decreased from approximately 360 to 180 kg·m⁻³. These results distinguish geometric recession from internal degradation and support experimental-front mapping and mechanistic interpretation. The mapped states are condition-specific and do not constitute an independently predicted front criterion. Full article

(This article belongs to the Section Advanced Composites)

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21 pages, 6799 KB

Open AccessArticle

Effect of Superplasticizer Dosage on Mechanical and Durability Properties of Low-Volume Steel Microfiber Reinforced Self-Compacting Concrete

by Jinchi Wu, Conteh Santigie Morlor, Donghua Yu, Linbin Wang, Gengying Li and Jingjing Huang

Materials 2026, 19(16), 3557; https://doi.org/10.3390/ma19163557 - 21 Aug 2026

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Abstract

This study investigates the effects of low-volume steel microfibers (0–0.4 vol.%) and superplasticizer (SP) dosage (0.8 wt.% and 1.5 wt.%) on the mechanical and durability properties of self-compacting concrete (SCC) for railing structures, with a constant water-binder ratio of 0.28. Fresh (slump flow), [...] Read more.

This study investigates the effects of low-volume steel microfibers (0–0.4 vol.%) and superplasticizer (SP) dosage (0.8 wt.% and 1.5 wt.%) on the mechanical and durability properties of self-compacting concrete (SCC) for railing structures, with a constant water-binder ratio of 0.28. Fresh (slump flow), mechanical (compressive strength up to 90 days, 28-day flexural strength), durability (drying shrinkage, freeze–thaw resistance after 200 cycles), and microstructural (mercury intrusion porosimetry) properties were evaluated. SP enhances flowability while steel fibers reduce it. All mixtures except that with 0.8% SP and 0.4% fibers meet the workability requirements of Chinese standard JGJ/T 283-2012 for SCC. Compressive and flexural strengths generally increase with fiber content but decrease when the SP dosage rises from 0.8% to 1.5%. Steel fibers effectively reduce drying shrinkage and improve freeze–thaw resistance, as indicated by higher relative dynamic elastic moduli and lower mass loss after 200 cycles. Microstructural analysis reveals that the higher SP dosage (1.5 wt.%) significantly increases porosity, which explains the observed higher shrinkage and lower strength. Considering mechanical properties, durability, and castability, the SCC mixture with 0.3 vol.% steel fibers and 0.8 wt.% SP is recommended for railing structure applications. Full article

(This article belongs to the Section Construction and Building Materials)

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19 pages, 13775 KB

Open AccessArticle

Preparation and Performance Optimization of an Expansive Backfill Material for Active Roof Contact in End-Wall Mining

by Jinxing Lyu, Zhimeng Song, Bao Song, Yiquan Lin and Wen Ma

Materials 2026, 19(16), 3556; https://doi.org/10.3390/ma19163556 - 21 Aug 2026

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Abstract

Conventional cemented backfill used in narrow end-wall mining entries commonly suffers from shrinkage and insufficient roof contact, reducing its support effectiveness. In this study, a solid-waste-based expansive backfill was prepared from mine overburden, ordinary Portland cement, fly ash and hydrogen peroxide. Orthogonal tests [...] Read more.

Conventional cemented backfill used in narrow end-wall mining entries commonly suffers from shrinkage and insufficient roof contact, reducing its support effectiveness. In this study, a solid-waste-based expansive backfill was prepared from mine overburden, ordinary Portland cement, fly ash and hydrogen peroxide. Orthogonal tests were performed to evaluate the effects of fly ash dosage, aggregate-to-binder ratio and hydrogen peroxide dosage on slurry flowability, expansion ratio and compressive strength. The slurry exhibited a flowability of 17.9–24.7 cm and an expansion ratio of 11.23–46.52%, confirming the gas-generating expansion effect of hydrogen peroxide. The aggregate-to-binder ratio was the dominant factor influencing flowability, expansion and 28 d strength. Multi-index optimization identified an optimal mix of 40% fly ash, an aggregate-to-binder ratio of 4:1 and 10% hydrogen peroxide. The optimized backfill showed age-dependent increases in uniaxial compressive strength (UCS) and elastic modulus, with failure evolving from inclined shear to tensile and tensile–shear composite modes. Its shear behavior followed the Mohr–Coulomb criterion, with cohesion of 1.61 MPa and internal friction angle of 30.13°. SEM observations indicated that aggregate skeleton support, cementitious bonding and gas-generating expansion jointly controlled the material performance. Full article

(This article belongs to the Section Construction and Building Materials)

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13 pages, 1767 KB

Open AccessArticle

Deodorizing Performance of Modified Polyester-Fiber Seamless Knitted Fabrics

by Yani Cai, Jiaying Liu, Miao Su and Zimin Jin

Materials 2026, 19(16), 3555; https://doi.org/10.3390/ma19163555 - 21 Aug 2026

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Abstract

Bacterial decomposition of sweat produces odors affecting close-fitting garment comfort. This study selected five polyester filament types: coffee carbon polyester filament (CC-PET), bamboo charcoal polyester filament (BC-PET), oyster shell polyester filament (OS-PET), graphene polyester filament (GR-PET), and conventional polyester filament (C-PET). These four [...] Read more.

Bacterial decomposition of sweat produces odors affecting close-fitting garment comfort. This study selected five polyester filament types: coffee carbon polyester filament (CC-PET), bamboo charcoal polyester filament (BC-PET), oyster shell polyester filament (OS-PET), graphene polyester filament (GR-PET), and conventional polyester filament (C-PET). These four yarns exemplify three mainstream deodorizing mechanisms: BC-PET relies on physical adsorption through its porous structure; CC-PET combines adsorption with antibacterial moisture management to suppress odor at the source; GR-PET and OS-PET inhibit bacteria via reactive radicals from oxygen-containing groups and calcium oxide, respectively. Three structures were tested: weft flat knit, 1 × 1 rib, and 1 + 3 false rib. 1 + 1 rib and 1 + 3 false rib differ markedly in elasticity, thickness, and hand. Plain jersey is smooth, soft, and breathable with good extensibility. 1 + 1 rib delivers superior transverse elasticity and dimensional stability. 1 + 3 false rib is loftier and stiffer with enhanced shape retention and thermal insulation. Fifteen specimens were knitted on a seamless circular machine and evaluated using ammonia adsorption rate and acetic acid adsorption rate. Results show that fiber type significantly influences deodorizing performance, with the graphene polyester filament with the 1 + 3 false rib structure achieving the best adsorption for both gases. This provides a theoretical foundation for deodorizing functional fabric development. Full article

(This article belongs to the Section Polymeric Materials)

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20 pages, 15087 KB

Open AccessArticle

Strength Characteristics and Micromechanisms of Mucky Soil Co-Stabilized with Geopolymer and Gold Tailings Sand

by Zhaoxia Hu, Lei Yu, Yue Zhao and Biao Luo

Materials 2026, 19(16), 3554; https://doi.org/10.3390/ma19163554 - 21 Aug 2026

Viewed by 418

Abstract

A carbide-slag-activated slag-fly ash geopolymer (CSF) and waste gold tailings sand were used to co-stabilize mucky soil, aiming to promote the valorization of multiple industrial solid wastes and provide a low-carbon treatment approach for mucky soil in river and lake regions. Unconfined compression, [...] Read more.

A carbide-slag-activated slag-fly ash geopolymer (CSF) and waste gold tailings sand were used to co-stabilize mucky soil, aiming to promote the valorization of multiple industrial solid wastes and provide a low-carbon treatment approach for mucky soil in river and lake regions. Unconfined compression, direct shear, water stability, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), and heavy metal leaching tests were conducted to investigate the effects of CSF and gold tailings sand contents on the mechanical properties, water stability, microstructure, and environmental safety of the stabilized soil. The results showed that the unconfined compressive strength (UCS) and shear strength increased with increasing CSF content, whereas the strength gain became marginal when the CSF content exceeded 15%. With the CSF content fixed at 15%, both the strength and water stability initially increased and then decreased as the gold tailings sand content increased. The CSF15-G30 specimen exhibited favorable overall performance, with 7 d and 28 d UCS values of 0.65 and 1.53 MPa, respectively, representing increases of 25.0% and 12.5% relative to CSF15. Its cohesion and internal friction angle reached 88.21 kPa and 47.13°, corresponding to increases of 44.5% and 8.1%, respectively. The water stability coefficients at 7 d and 28 d were 76.9% and 87.6%, respectively. SEM-EDS observations indicated that the cementitious products generated by CSF, together with the filling and skeletal effects of gold tailings sand, enhanced interparticle bonding and matrix densification. Although the concentrations of leached heavy metals increased with increasing gold tailings sand content, all measured values remained below the relevant leaching-toxicity limits. These results demonstrate that an appropriate amount of gold tailings sand can effectively improve the mechanical properties and water stability of CSF-stabilized mucky soil while maintaining satisfactory environmental compatibility. Full article

(This article belongs to the Section Construction and Building Materials)

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23 pages, 14026 KB

Open AccessArticle

Effect of Polypropylene Fiber Content on the High-Temperature Performance of Steel Slag UHPS

by Jing Wang, Zhiwei Yuan, Yunlong Zhang, Xuesong Qian and Xiaolong Qu

Materials 2026, 19(16), 3553; https://doi.org/10.3390/ma19163553 - 21 Aug 2026

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Abstract

To solve the problems of explosive spalling and sharp deterioration of mechanical properties of ultra-high performance sprayed concrete (UHPS) under high-temperature conditions during tunnel fires, four groups of specimens with different volume contents (0%, 0.2%, 0.3%, 0.4%) of polypropylene fiber (PPF) were designed [...] Read more.

To solve the problems of explosive spalling and sharp deterioration of mechanical properties of ultra-high performance sprayed concrete (UHPS) under high-temperature conditions during tunnel fires, four groups of specimens with different volume contents (0%, 0.2%, 0.3%, 0.4%) of polypropylene fiber (PPF) were designed based on the optimal mix proportion at room temperature. Multi-gradient high-temperature tests at 20 °C, 200 °C, 400 °C, 600 °C and 800 °C were conducted to explore the effects of PPF on the high-temperature damage evolution and spalling resistance of UHPS. The test results show that no obvious spalling occurs in specimens exposed to temperatures of 400 °C and below. Surface peeling appears in the group without PPF addition at 400 °C, and severe explosive spalling happens in the 0% PPF group at 600 °C to 800 °C, while all PPF-incorporated groups maintain structural integrity. The mass loss rate increases with the rise in temperature and PPF content, reaching 15% in the 0.4% PPF group at 800 °C. In terms of mechanical properties, compressive strength, splitting tensile strength, and flexural strength all rise first and then decline with increasing temperature, and the 0.3% PPF group reaches peak values at 400 °C (compressive strength: 135.95 MPa, splitting tensile strength: 23.24 MPa, flexural strength: 27.42 MPa). Flexural toughness decreases continuously as temperature rises, and the 0.2% PPF group exhibits the best toughness retention. This study clarifies the high-temperature modification effect of PPF on UHPS and its optimal content range, providing important theoretical support and an experimental basis for the fire safety protection design of tunnel lining concrete. Full article

(This article belongs to the Section Construction and Building Materials)

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28 pages, 5202 KB

Open AccessArticle

Novel Cellulose Films Obtained by the Combination of High-Pressure and Cellulase Treatments

by Gonçalo Coelho, Renata A. Amaral, Daniela M. Santos and Jorge A. Saraiva

Materials 2026, 19(16), 3552; https://doi.org/10.3390/ma19163552 - 21 Aug 2026

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Abstract

This research study focused on the use of technologies such as high-pressure processing (400 MPa for 15 min, HPP) and enzymatic hydrolysis (with cellulase) to process eucalyptus pulp, subsequently the pulp submitted to carboxymethylation to produce cellulose films and investigate their properties. The [...] Read more.

This research study focused on the use of technologies such as high-pressure processing (400 MPa for 15 min, HPP) and enzymatic hydrolysis (with cellulase) to process eucalyptus pulp, subsequently the pulp submitted to carboxymethylation to produce cellulose films and investigate their properties. The results revealed that the combination of HPP and cellulase resulted in the production of partially transparent and smoother films. As for mechanical properties, this combination resulted in a 2.7-fold increase in the tensile strength (TS) value, a 35.5-fold increase in the elongation at break (EAB) value, and a 1.4-fold increase in the moisture content of the films. The crystallinity index (CrI) was also increased by HPP and enzymes, resulting in a 6.6-fold increase, compared to the control film. On the other hand, the combined use of HPP and enzymatic hydrolysis resulted in similar contact angle (CA) values on both sides of the films, but in the bottom side, when compared to the control film, a 2.1-fold decrease was observed. Furthermore, the water vapor permeability (WVP) of the films increased 1.8-fold. Finally, the thermal resistance of the films was slightly reduced when either HPP, enzymatic or both treatments were used on the cellulose pulp. In general, this work showed a new potential way to produce cellulose films with novel and potentially tailor-made properties. Full article

(This article belongs to the Special Issue Biobased and/or Biodegradable Films, Coatings, and Packaging Materials)

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13 pages, 5034 KB

Open AccessArticle

Effects of Solution Treatment on the Microstructure and Properties of Al_0.4Co_0.5V_0.2FeNi High-Entropy Alloys

by Hongbo Duan, Wei Yang, Zhijun Ma and Yuan Li

Materials 2026, 19(16), 3551; https://doi.org/10.3390/ma19163551 - 21 Aug 2026

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Abstract

This work explores V-alloyed Al_0.4Co_0.5V_0.2FeNi high-entropy alloys that are solution-treated at 1000–1200 °C for five hours and water-quenched. Solidification of this high-entropy alloy follows the sequence face-centered cubic (FCC) → ordered L1₂ → body-centered cubic (BCC) [...] Read more.

This work explores V-alloyed Al_0.4Co_0.5V_0.2FeNi high-entropy alloys that are solution-treated at 1000–1200 °C for five hours and water-quenched. Solidification of this high-entropy alloy follows the sequence face-centered cubic (FCC) → ordered L1₂ → body-centered cubic (BCC) → ordered B2. All treated alloys maintain dual FCC–BCC-B2 microstructures, with temperature altering only morphological features. At 1000 and 1100 °C, coherent spinodal decomposition takes place in FCC matrices to form rodlike precipitates with 20.3% lattice misfit; meanwhile, Ostwald ripening lengthens the precipitates from 1.41 to 2.11 μm. Spinodal decomposition is inhibited at 1200 °C, which is accompanied by coarsening and granulation of B2-ordered BCC grains. Slow atomic diffusion prevents recrystallization even above 0.4T_m. Solution heat treatment dissolves the B2 phases to generate supersaturated solutions stronger than the as-cast counterparts. Elevated solution temperatures reduce hardness (243–190 MPa) and tensile strength (919–839 MPa) but boost elongation (26–35%). Fractures display mixed dimple-cleavage features. Overall, a five-hour solution treatment at 1100 °C plus water quenching delivers balanced strength (851 MPa) and ductility (33%), serving as the optimal heat treatment for this alloy. Full article

(This article belongs to the Section Metals and Alloys)

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16 pages, 3152 KB

Open AccessArticle

Unlocking Thermal Insulation Performance and Mechanisms in Decoration Waste Aerogel Mortar: A Multi-Factor Study on Paste-to-Aggregate Ratio, Silica Aerogel Content, and Air-Entraining Agent Dosage

by Tianyu Ma, Hui Liu, Yushi Gu, Xiang Guo, Minqi Hua, Zhongmeng Gao, Jun Cui and Zhihao Zhou

Materials 2026, 19(16), 3550; https://doi.org/10.3390/ma19163550 - 21 Aug 2026

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Abstract

To improve the resource utilization of decoration waste and enhance the thermal insulation performance of building mortar, this study designed and prepared decoration waste aerogel mortar (DWAM) using decoration waste recycled fine aggregate (DWRA) combined with silica aerogel. The effects of paste-to-aggregate ratio [...] Read more.

To improve the resource utilization of decoration waste and enhance the thermal insulation performance of building mortar, this study designed and prepared decoration waste aerogel mortar (DWAM) using decoration waste recycled fine aggregate (DWRA) combined with silica aerogel. The effects of paste-to-aggregate ratio (30/70, 35/65, and 40/60), aerogel content (60–100 vol.%), and air-entraining agent (AEA) dosage (0.1–0.5 wt%) on workability, dry density, mechanical strength, and thermal conductivity were systematically investigated. Microstructural evolution and pore characteristics were analyzed using scanning electron microscopy (SEM) and X-ray computed tomography (X-CT). Results showed that increasing the paste-to-aggregate ratio improved workability and mechanical strength, while aerogel and AEA incorporation significantly reduced thermal conductivity at the expense of strength. An optimum mix with a paste-to-aggregate ratio of 40/60, aerogel content of 80 vol.%, and AEA dosage of 0.4 wt% achieved a dry density of 623.8 kg/m³, compressive strength of 1.27 MPa, flexural strength of 0.61 MPa, and thermal conductivity of 0.0784 W/(m·K). X-CT revealed that closed micropores enhanced thermal insulation by disrupting heat transfer. The developed DWAM offers balanced workability, mechanical properties, and thermal insulation, demonstrating strong potential as a sustainable material for building applications. Full article

(This article belongs to the Special Issue Advanced Experimental Technology, Theory and Numerical Methods in Concrete Materials)

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11 pages, 3524 KB

Open AccessArticle

Directional Freezing Fabrication of RSF/PVA/MXene Aerogels: Layered Structure and High-Efficiency Electromagnetic Interference Shielding

by Peiyi Gao, Yanxiang Wang, Yingfan Li, Bohan Ding, Jinghe Guo, Yanru Yuan, Ziyi Xu, Dong Zhang, Lingyu Li, Xueqi Wang, Can Zhang and Chao Teng

Materials 2026, 19(16), 3549; https://doi.org/10.3390/ma19163549 - 21 Aug 2026

Viewed by 306

Abstract

The rapid development of wireless communication technologies and electronic devices has intensified electromagnetic interference (EMI) pollution, creating an urgent demand for lightweight and efficient shielding materials. In this work, RSF/PVA/MXene composite aerogels with ordered lamellar structures were fabricated by directional freeze-drying. Directional freeze-drying [...] Read more.

The rapid development of wireless communication technologies and electronic devices has intensified electromagnetic interference (EMI) pollution, creating an urgent demand for lightweight and efficient shielding materials. In this work, RSF/PVA/MXene composite aerogels with ordered lamellar structures were fabricated by directional freeze-drying. Directional freeze-drying generated an ordered lamellar architecture, while RSF and PVA facilitated the homogeneous distribution of MXene nanosheets within the aerogel framework. Among the investigated samples, RPM-60 exhibited the maximum shielding effectiveness at 12.4 GHz, corresponding to a shielding efficiency of 99.45%, demonstrating the favorable MXene content for efficient EMI shielding at this frequency. The enhanced shielding performance was mainly attributed to the ordered lamellar structure, which promoted multiple internal reflections, together with conductive loss and interfacial/dipole polarization induced by MXene. These results demonstrate the potential of RSF/PVA/MXene composite aerogels as lightweight bio-based EMI shielding materials. Full article

(This article belongs to the Special Issue MXene-Based Electromagnetic Functional Devices)

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24 pages, 5616 KB

Open AccessArticle

Absorption-Driven Near-Field EMI Shielding of Si-CNT Composite for LED Displays: A Solution for the Transition from Reflective Inefficiency to Absorptive Suppression

by Young-Soon Kim, Sun-Ho Choi, Sumin Jung, Jaeun Jin, Minjin Oh, Suk-Dae Lim and Hong-Gun Kim

Materials 2026, 19(16), 3548; https://doi.org/10.3390/ma19163548 - 21 Aug 2026

Viewed by 322

Abstract

The issue of near-field electromagnetic interference (EMI) is being made worse by the widespread use of highly integrated electronic devices, including commercial LED displays. Although highly conductive pristine carbon networks, like recycled carbon fiber nonwovens (rCFNWs), have excellent far-field shielding effects (~43 dB) [...] Read more.

The issue of near-field electromagnetic interference (EMI) is being made worse by the widespread use of highly integrated electronic devices, including commercial LED displays. Although highly conductive pristine carbon networks, like recycled carbon fiber nonwovens (rCFNWs), have excellent far-field shielding effects (~43 dB) in theory, their purely reflection-oriented mechanisms cause severe secondary signal interference in practical near-field applications due to reflective inefficiency. This study suggests employing a custom-formulated silicone-carbon nanotube (Si-CNT) composite to switch to an absorption-based shielding mechanism in order to get around these restrictions. This study used FE-SEM, Raman spectroscopy, XPS, ICP-AES, FTIR, and TGA-DTG to systematically investigate the morphological, chemical, and thermal properties of the rCFNW, Si-CNT composite, and a Cu-integrated variant (Si-CNT-Cu). Surface reflection was greatly reduced by adding CNTs to the silicone matrix, converting the materials into absorption-oriented localized shielding composite materials (~16 dB). Both the designed Si-CNT membrane and the Cu-integrated Si-CNT-Cu product totally eliminated the 850 MHz switching noise peak (>40 dBuV) in real near-field tests of commercial LED modules running under worst-case conditions (5.36 A). Additionally, the bare Si-CNT membrane showed a lower coefficient of thermal expansion (CTE) in the thermomechanical analysis (TMA) than the Si-CNT-Cu product. On the other hand, the macroscopic integration of Cu wires in the Si-CNT-Cu composite provided remarkable thermomechanical stability, preventing thermal softening by preserving an exceptionally high storage modulus of 97.54 MPa at 198 °C, according to dynamic mechanical analysis (DMA). These findings show that using absorptive suppression to overcome near-field inefficiency is a very successful method for creating dependable EMI shielding composite materials in high-power electronic systems. Full article

(This article belongs to the Section Advanced Composites)

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24 pages, 4578 KB

Open AccessArticle

A Comparative Multi-Scale Study on the Regeneration Mechanisms of a Bio-Based and a Petroleum-Based Asphalt Rejuvenator

by Xiying Yang, Wencai Zhang, Xiaogang Guo and Mingqian Zhai

Materials 2026, 19(16), 3547; https://doi.org/10.3390/ma19163547 - 21 Aug 2026

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Abstract

Growing demand for pavement maintenance promotes reclaimed asphalt pavement (RAP) recycling, yet multi-scale comparative research on rejuvenators remains limited. This study compared a commercial bio-based Rejuvenator A and a petroleum-based Rejuvenator B to reveal how chemical compositions control asphalt regeneration. Following JTG 3410-2025 [...] Read more.

Growing demand for pavement maintenance promotes reclaimed asphalt pavement (RAP) recycling, yet multi-scale comparative research on rejuvenators remains limited. This study compared a commercial bio-based Rejuvenator A and a petroleum-based Rejuvenator B to reveal how chemical compositions control asphalt regeneration. Following JTG 3410-2025 standards, asphalt binders underwent extended RTFOT aging (75, 112.5, and 150 min) and were externally blended with rejuvenators at 5%, 7.5%, and 10% by binder mass. A multi-scale framework combining macro tests, interfacial characterization, SARA fraction analysis, ATR-FTIR, and molecular dynamics (MD) simulations was established. Results indicated that the two rejuvenators acted via different mechanisms. Rejuvenator B contained 31.64% saturates and restored aged asphalt mainly through physical dilution and softening. This rejuvenator formed 0–80 hydrogen bonds dominated by weak C–H···O interactions, and the corresponding rejuvenated asphalt yielded a CII of 0.293. It was effective for 75 min-aged binders yet produced more oxidation products after re-aging. Conversely, Rejuvenator A, characterized by 68.10% aromatics and 20.17% resins, exhibited a 3–5° lower equilibrium contact angle, and a roughly 13% shorter relative penetration time than Rejuvenator B. Its network of 150–250 hydrogen bonds effectively disrupted asphaltene aggregates, reducing the CII to 0.180. Consequently, Rejuvenator A successfully restored 112.5 min- and 150 min-aged asphalt with significantly lower secondary oxidation. These performance differences were governed by aromatic and polar fractions rather than feedstock origins. While quantitative findings are sample-specific, the established framework provides theoretical references for engineering rejuvenator selection and high-performance regenerant design. Full article

(This article belongs to the Special Issue Road and Rail Construction Materials: Development and Prospects)

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26 pages, 14676 KB

Open AccessArticle

Effect of Calcination Temperature on the Reactivity of Lithium Slag Powder as a Supplementary Cementitious Material

by Yoo Jung Hwang and Young-Cheol Choi

Materials 2026, 19(16), 3546; https://doi.org/10.3390/ma19163546 - 21 Aug 2026

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Abstract

Lithium slag powder (LSP), a by-product of lithium extraction, has attracted increasing interest as a supplementary cementitious material (SCM) due to its aluminosilicate-rich composition and growing availability. However, its limited intrinsic reactivity constrains direct use in cementitious systems. This study systematically investigates the [...] Read more.

Lithium slag powder (LSP), a by-product of lithium extraction, has attracted increasing interest as a supplementary cementitious material (SCM) due to its aluminosilicate-rich composition and growing availability. However, its limited intrinsic reactivity constrains direct use in cementitious systems. This study systematically investigates the effect of calcination temperature on the physicochemical properties, pozzolanic reactivity, and cement hydration performance of LSP. LSP was thermally treated at 300–900 °C, and structural and morphological changes were characterized using X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy. The reactivity of calcined LSP was quantitatively assessed through isothermal calorimetry (R3 test), thermogravimetric and derivative thermogravimetric analysis. Chapelle testing, leaching tests, and compressive strength measurements of cement mortars. Controlled calcination was found to enhance the intrinsic reactivity and pozzolanic activity of LSP, resulting in improved long-term mechanical performance. The findings provide mechanistic insights and practical guidance for the sustainable use of lithium slag as an SCM in cement-based materials. Full article

(This article belongs to the Special Issue Advanced Green Building Materials: Synthesis, Characterization and Sustainable Development Technologies)

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11 pages, 4443 KB

Open AccessArticle

Microstructure and Properties of Ag-SnO₂ Electrical Contact Composites with Different SnO₂ Volume Fractions

by Zhijie Lin, Bin Liu and Xudong Sun

Materials 2026, 19(16), 3545; https://doi.org/10.3390/ma19163545 - 21 Aug 2026

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Abstract

Ag-SnO₂ composites are widely adopted as electrical contact materials in low-voltage apparatuses. Ongoing upgrades of electrical devices impose higher standards for their mechanical strength, machinability, and electrical conductivity, among which the SnO₂ volume fraction is a dominant factor regulating material performance. [...] Read more.

Ag-SnO₂ composites are widely adopted as electrical contact materials in low-voltage apparatuses. Ongoing upgrades of electrical devices impose higher standards for their mechanical strength, machinability, and electrical conductivity, among which the SnO₂ volume fraction is a dominant factor regulating material performance. In this work, Ag-SnO₂ electrical contact composites are reinforced with 15 μm SnO₂ particles at various volume fractions. Increasing SnO₂ volume fractions can improve the hardness. The ultimate tensile strength reaches a maximum value of 219.1 MPa at the SnO₂ volume fraction of 18.3 vol%. Excessively high SnO₂ content (26.5 vol%) leads to the brittle fracture of the composite and a sharp decline in tensile strength. Indirect strengthening dominates the overall mechanical performance, among which grain refinement serves as the primary strengthening mechanism, followed by dislocation multiplication strengthening, while the Orowan looping effect is negligible for coarse 15 μm SnO₂ particles. This work clarifies the microstructure–performance correlation and strengthening mechanism of particle-reinforced Ag-SnO₂ composites, providing a theoretical and experimental basis for the optimal design and performance optimization of high-performance electrical contact materials. Full article

(This article belongs to the Special Issue Mechanical Behavior of Composite Materials (4th Edition))

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13 pages, 433 KB

Open AccessArticle

Thermoelastic State of a Magnetocaloric Ferromagnetic Plate Under Constant-Rate Ambient Temperature Rise

by Roman Musii, Myroslava Klapchuk, Uliana Zhydyk, Nelya Pabyrivska, Zenoviy Kohut, Dariusz Całus, Piotr Gębara and Karolina Kutynia

Materials 2026, 19(16), 3544; https://doi.org/10.3390/ma19163544 - 21 Aug 2026

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Abstract

A simply supported rectangular isotropic ferromagnetic plate with magnetocaloric properties subjected to convective heating on its upper surface is considered. The governing equations comprise a system of two-dimensional transient equations for the thickness-averaged temperature characteristics of the plate and the two-dimensional bending equations [...] Read more.

A simply supported rectangular isotropic ferromagnetic plate with magnetocaloric properties subjected to convective heating on its upper surface is considered. The governing equations comprise a system of two-dimensional transient equations for the thickness-averaged temperature characteristics of the plate and the two-dimensional bending equations for isotropic plates expressed in terms of generalized displacements within the framework of first-order shear deformation theory. Closed-form solutions to the governing equations are obtained by expanding all thermal and mechanical field quantities in double Fourier sine series satisfying the prescribed boundary conditions, combined with the Laplace transform in time applied to the thermal quantities. A comparative numerical analysis is carried out for the magnetocaloric ferromagnetic plate and a carbon steel plate under ambient temperature rising at a finite rate to a prescribed value. The dependences of all quantities under investigation on the ambient temperature rise rate, time, convective heat transfer coefficient, thermal conductivity of the ferromagnetic material, and geometric parameters of the plate are analyzed and presented graphically. The results obtained provide a quantitative basis for assessing the thermoelastic state and for optimizing the geometry and operating conditions of active magnetic regenerator plate stacks with a view to enhancing their structural reliability. Full article

(This article belongs to the Special Issue Advanced Material for Magnetocaloric Effect)

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21 pages, 13665 KB

Open AccessArticle

Rheological Restoration and Multi-Criteria Dosage Optimization of Aged SBS-Modified Asphalt Using an Epoxy-Based Reactive Rejuvenator

by Wenwen Jiang, Chunpeng Yan, Jiahao Ji, Ning Li and Jiandong Huang

Materials 2026, 19(16), 3543; https://doi.org/10.3390/ma19163543 - 21 Aug 2026

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Abstract

High reclaimed asphalt pavement (RAP) contents are often limited by insufficient restoration of field-aged SBS-modified asphalt and the lack of a comprehensive method for rejuvenator dosage selection. This study aimed to develop a multi-performance-based approach for determining the dosage of an epoxy-based reactive [...] Read more.

High reclaimed asphalt pavement (RAP) contents are often limited by insufficient restoration of field-aged SBS-modified asphalt and the lack of a comprehensive method for rejuvenator dosage selection. This study aimed to develop a multi-performance-based approach for determining the dosage of an epoxy-based reactive rejuvenator under high-RAP conditions. Rejuvenated binders with different dosages were evaluated using conventional tests, DSR, MSCR, BBR, and LAS tests. Continuous low-temperature grading temperature, dissipated energy ratio, and entropy-weight TOPSIS were used for comprehensive evaluation, while GPC was employed to characterize molecular-weight distribution. The rejuvenator improved low-temperature relaxation, fatigue resistance, energy dissipation, and workability, whereas excessive dosages reduced rutting resistance and elastic recovery. Entropy-weight TOPSIS ranked RA-6 highest, with a relative closeness coefficient of 0.66504, and this ranking was consistent with the overall trends obtained from individual performance tests, supporting the feasibility of the proposed evaluation method. GPC results showed systematic changes in molecular-weight distribution after rejuvenation. For the investigated material system, 6% is recommended among the tested dosages. The proposed framework provides a practical basis for dosage determination when material characteristics and performance requirements vary. Full article

(This article belongs to the Special Issue Sustainability in Asphalt, Concrete and Pavement Materials: Design, Performance, and Characterization (Second Edition))

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29 pages, 13655 KB

Open AccessArticle

Strength of Wooden Truss Connections with Nail Plates Under Cyclic Humidity Changes

by Marek Wieruszewski, Adam Czerwiński, Agnieszka Katarzyna Wdowiak-Postulak, Maciej Jarzębski and Adrian Trociński

Materials 2026, 19(16), 3542; https://doi.org/10.3390/ma19163542 - 21 Aug 2026

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Abstract

Metal-plate-connected (MPC) joints govern the stiffness and load-bearing performance of many prefabricated timber roof trusses, yet their response to repeated moisture changes remains critical for serviceability and durability. This study evaluated five continuous C24 Norway spruce reference specimens and fifteen specimens joined with [...] Read more.

Metal-plate-connected (MPC) joints govern the stiffness and load-bearing performance of many prefabricated timber roof trusses, yet their response to repeated moisture changes remains critical for serviceability and durability. This study evaluated five continuous C24 Norway spruce reference specimens and fifteen specimens joined with GNA20-MIT nail plates using sequential four-point-bending stiffness measurements and wetting–drying conditioning. Test I was used as the initial stiffness stage, whereas Tests II and III followed successive 24 h water-immersion and 6-day natural-drying intervals; the specimens were subsequently tested to failure. The mean apparent modulus of elasticity of the MPC specimens decreased from 1.39 to 1.22 GPa (approximately 12%), but a Friedman repeated-measures test did not show a statistically significant stage effect (χ²(2) = 4.13, p = 0.127). Because the same specimens were repeatedly loaded, and no unexposed MPC control group was included, this change cannot be attributed exclusively to moisture cycling. In the primary analysis retaining all 15 MPC specimens, the mean apparent bending strength of the connected elements was 16.92 MPa, compared with 34.14 MPa for the structurally different continuous reference specimens; excluding M7 yielded 17.87 MPa only as a sensitivity analysis. Failure of the connected specimens was progressive and dominated by plate slip and partial spike withdrawal, whereas solid specimens failed more abruptly in bending. The results therefore support attention to connection flexibility and serviceability under variable environmental and loading histories, while further controlled testing is required to isolate the specific contribution of moisture cycling. Full article

(This article belongs to the Special Issue Recent Advances in Wood and Wood-Based Materials)

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14 pages, 299 KB

Open AccessReview

Catalytic Hydrogenation of CO₂ to Alternative Fuels: A Review of Methanation and Related Pathways

by Kornelia Nejranowska, Agnieszka Szymaszek-Wawryca and Monika Motak

Materials 2026, 19(16), 3541; https://doi.org/10.3390/ma19163541 - 21 Aug 2026

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Abstract

The imperative to mitigate climate change has accelerated the development of Carbon Capture, Utilization, and Storage (CCUS) technologies, particularly CO₂ hydrogenation into high-value chemicals and alternative fuels. This work evaluates the fundamental thermodynamic limitations and the primary directions of CO₂ conversion, [...] Read more.

The imperative to mitigate climate change has accelerated the development of Carbon Capture, Utilization, and Storage (CCUS) technologies, particularly CO₂ hydrogenation into high-value chemicals and alternative fuels. This work evaluates the fundamental thermodynamic limitations and the primary directions of CO₂ conversion, with a primary focus on methanation, alongside related pathways such as methanol synthesis and the reverse water-gas shift (RWGS) reaction. To overcome the high kinetic barriers of CO₂ activation, various catalytic systems are analyzed. While noble metal catalysts exhibit high catalytic performance, nickel-based catalysts serve as a viable and cost-effective alternative. To overcome nickel’s susceptibility to thermal sintering and coking, advanced bimetallic and multimetallic formulations are being developed to enhance structural stability and selectivity. These advancements are crucial for producing Synthetic Natural Gas (SNG) and sustainable aviation fuels (SAF). Ultimately, the objective of this comprehensive review is to systematically summarize recent advancements in catalyst design, critically analyze the advantages and fundamental bottlenecks of distinct catalytic systems, and outline prospective paths for the efficient industrial-scale production of sustainable alternative fuels. Full article

(This article belongs to the Special Issue Advances in Waste Materials’ Valorization (2nd Edition))

34 pages, 5599 KB

Open AccessArticle

Linking ISO Dynamic Stiffness and Acoustic Modal Identification for FEM-Oriented Modelling of Elasticized Expanded Polystyrene

by Krzysztof Nering, Konrad Nering and Ewa Kozak-Jagieła

Materials 2026, 19(16), 3540; https://doi.org/10.3390/ma19163540 - 20 Aug 2026

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Abstract

Elasticized expanded polystyrene (EPS-T) is widely used as a resilient layer in floating floors, where dynamic stiffness is the key input for impact-sound prediction, while FEM modelling additionally requires elastic parameters and damping descriptions consistent with the adopted test or modelling configuration. This [...] Read more.

Elasticized expanded polystyrene (EPS-T) is widely used as a resilient layer in floating floors, where dynamic stiffness is the key input for impact-sound prediction, while FEM modelling additionally requires elastic parameters and damping descriptions consistent with the adopted test or modelling configuration. This study investigates whether ISO-type dynamic stiffness testing and acoustic-response modal identification can provide consistent vibroacoustic parameters for EPS-T. Rectangular specimens of different thicknesses were tested for dynamic stiffness and damping using an ISO 9052-1-type setup. Additional cylindrical compression tests were used to examine apparent Young’s modulus and Poisson’s ratio, while impulse-excited acoustic responses of clamped specimens were combined with inverse FEM identification. The ISO-type dynamic stiffness decreased from approximately 53.3 MN/m³ for nominal 17 mm specimens to 27.0 MN/m³ for nominal 53 mm specimens. This trend was described by a compliance model with an effective Young’s modulus of 2.04 MPa and an equivalent contact/support stiffness of 101.2 MN/m³. Acoustic-response inverse FEM gave consistent Young’s modulus values, ranging from 1.77 MPa to 2.16 MPa, with a mean close to 2.05 MPa. Direct use of s′ = E/h overestimated stiffness and underestimated predicted ΔL_w by approximately 2–5 dB. The two routes provided consistent estimates of the effective modulus, but this consistency applies only to modulus identification and not to direct stiffness conversion or damping transfer. Full article

(This article belongs to the Special Issue Research on Properties of Polymers and Their Engineering Applications—2nd Edition)

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23 pages, 11310 KB

Open AccessArticle

Performance Enhancement of the Passive Heat Exchanger in the MNTZV-159 Metal Hydride Storage System Using Triply Periodic Minimal Surface (TPMS) Structures

by Šimon Hudák, Marián Lázár, Gabriela Ižaríková, Tomáš Brestovič, Natália Jasminská, Peter Čurma, Romana Dobáková and Peter Milenovský

Materials 2026, 19(16), 3539; https://doi.org/10.3390/ma19163539 - 20 Aug 2026

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Abstract

Low thermal conductivity of metal hydride beds significantly limits the hydrogen absorption kinetics and performance of metal hydride storage systems. This study presents a new design of a passive internal heat exchanger for a certified MNTZV-159 low-pressure hydrogen storage tank using the Triply [...] Read more.

Low thermal conductivity of metal hydride beds significantly limits the hydrogen absorption kinetics and performance of metal hydride storage systems. This study presents a new design of a passive internal heat exchanger for a certified MNTZV-159 low-pressure hydrogen storage tank using the Triply Periodic Minimal Surface (TPMS) structures. The parametric improvement in the design of a cylindrical Diamond TPMS-based geometry was performed by applying various cell dimensions, arc counts, and wall thicknesses while maintaining the original volume of the heat exchanger. The analysed configuration was subsequently evaluated through three-dimensional numerical heat-transfer simulations conducted in ANSYS CFX. Compared with the original finned heat exchanger, the TPMS-based design reduced the average metal hydride temperature from 107.7 °C to 86.2 °C and the maximum temperature from 130.9 °C to 114.0 °C. The improved temperature uniformity enhanced the heat removal from the hydride bed and created more favourable conditions for hydrogen absorption. The results demonstrated that TPMS structures constitute a promising solution for improving passive thermal management in metal hydride hydrogen storage systems while maintaining the storage capacity of the vessel. Full article

(This article belongs to the Special Issue Hydrides for Energy Storage: Materials, Technologies and Applications)

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18 pages, 12213 KB

Open AccessArticle

Molecular-Scale Regulation of Cement Hydration and Microstructure via Synergistic Aluminum Sulfate–Amide Interactions

by Chuanjiu Zhang, Jie Chen, Hu Chen, Peng Li, Kaiwen Shi, Fei Gao, Xuanliang Li, Qiangqiang Hu and Meng Li

Materials 2026, 19(16), 3538; https://doi.org/10.3390/ma19163538 - 20 Aug 2026

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Abstract

High-performance alkali-free accelerators require a mechanistic understanding of interactions between inorganic accelerants and organic modifiers. Although aluminum sulfate (AS) promotes rapid ettringite (AFt) formation, uncontrolled crystallization leads to coarse microstructures and instability from AFt-to-AFm conversion. Here, a molecular-scale synergistic mechanism is identified in [...] Read more.

High-performance alkali-free accelerators require a mechanistic understanding of interactions between inorganic accelerants and organic modifiers. Although aluminum sulfate (AS) promotes rapid ettringite (AFt) formation, uncontrolled crystallization leads to coarse microstructures and instability from AFt-to-AFm conversion. Here, a molecular-scale synergistic mechanism is identified in which an amide regulates AS-driven hydration. The amide controls nucleation and growth of AFt and C–S–H via chemisorption on C₃A/C₃S and complexation with Ca²⁺. Within the tested mixing proportions, the high-aluminum-sulfate and moderate-amide combination achieves the highest early strength (17.05 MPa at 1 day) via constructing an interlocked AFt/C–S–H skeleton, whereas excessive amide suppresses crystallization and low AS accelerates AFt-to-AFm conversion, reducing long-term performance. In-situ XRD, thermal analysis, and microscopy confirm a denser, more stable microstructure (27.37 MPa at 10 days) with minimal 28-day strength loss (17.38 MPa). Density functional theory shows an adsorption hierarchy of amide > AS species > H₂O, explaining its dominant surface-modifying role. This study provides a framework for designing cement accelerators with balanced early strength and durability. Full article

(This article belongs to the Section Construction and Building Materials)

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18 pages, 1444 KB

Open AccessPerspective

The Forgotten Allotrope: γ-Sulfur Stabilization in Carbon Matrices for Energy Storage Applications

by Marlena Bytniewska, Dimitrios A. Giannakoudakis and Mariusz Barczak

Materials 2026, 19(16), 3537; https://doi.org/10.3390/ma19163537 - 20 Aug 2026

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Abstract

Lithium–sulfur (Li-S) batteries are widely regarded as one of the most promising candidates for next-generation electrochemical energy storage, owing to their very high theoretical energy density and reliance on abundant, low-cost elements. However, the practical deployment of Li-S technology remains severely constrained by [...] Read more.

Lithium–sulfur (Li-S) batteries are widely regarded as one of the most promising candidates for next-generation electrochemical energy storage, owing to their very high theoretical energy density and reliance on abundant, low-cost elements. However, the practical deployment of Li-S technology remains severely constrained by the polysulfide shuttle effect, originating from the dissolution, migration and parasitic redox cycling of lithium polysulfide intermediates, which leads to rapid capacity fading, low coulombic efficiency and incompatibility with industrial carbonate-based electrolytes. Recent reports on the formation and stabilization of γ-sulfur, a rare monoclinic allotrope, within porous carbon matrices have identified a prospective direction in sulfur electrochemistry, theoretically enabling polysulfide-free cycling and improved stability, also in conventional carbonate electrolytes. These findings challenge the long-held assumption that polysulfide formation is unavoidable in sulfur cathodes and suggest that control over sulfur allotropy and nanoconfinement, as well as carbon–sulfur chemistry, may unlock previously inaccessible performance and integration windows for metal–sulfur batteries, including most technologically advanced Li-S batteries. Based on recent studies, this Perspective article critically evaluates the evidence for γ-sulfur stabilization in carbon hosts, discusses the interplay between pore geometry, carbon surface chemistry and sulfur speciation, and finally identifies key knowledge gaps. Full article

(This article belongs to the Section Energy Materials)

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18 pages, 4470 KB

Open AccessArticle

Optimization of Microwave-Assisted Fracture Energy Recovery in Early-Damaged Asphalt Mixtures: Damage-State Regulation by Basalt Fiber Reinforcement

by Bo Li, Jian Hu, Yu Wang, Aihong Kang and Zhengguang Wu

Materials 2026, 19(16), 3536; https://doi.org/10.3390/ma19163536 - 20 Aug 2026

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Abstract

Microwave-assisted recovery provides a potential approach for restoring fracture damage in asphalt mixtures, but previous studies have mainly focused on heating and curing conditions, while the role of the pre-heating fracture state remains less understood. This study investigated microwave-assisted fracture energy recovery from [...] Read more.

Microwave-assisted recovery provides a potential approach for restoring fracture damage in asphalt mixtures, but previous studies have mainly focused on heating and curing conditions, while the role of the pre-heating fracture state remains less understood. This study investigated microwave-assisted fracture energy recovery from a damage-state regulation perspective by comparing a control asphalt mixture (CAM) with a basalt fiber-reinforced asphalt mixture (BFAM). Semi-circular bending (SCB) tests were combined with an L9 orthogonal design to evaluate three pre-heating conditions, target surface temperatures of 45–85 °C, and curing times of 6–24 h. Rather than directly enhancing binder recovery, basalt fiber reinforcement increased the initial fracture resistance and altered the relative fracture condition reached under a given external load. The recovery index RI ranged from 20.7% to 55.9% for CAM and from 35.2% to 82.3% for BFAM. Main-effects ANOVA showed that the pre-heating damage condition had the largest main-effect contribution within the adopted L9 framework, reaching 82.3% for CAM and 95.2% for BFAM, substantially exceeding those of target surface temperature and curing time. Under a comparable external load of approximately 2.5 kN, CAM reached the 70% P_max condition, whereas BFAM remained at the 40% P_max condition, with corresponding mean RI values of 42.8% and 76.9%. These results support a proposed conceptual damage-state regulation framework within the investigated material and experimental conditions, in which basalt fiber reinforcement preserves a more favorable pre-heating state and thereby greater recovery potential. The findings highlight the importance of improving fracture resistance and applying microwave-assisted treatment before extensive fracture development occurs, while broader validation is required before generalizing the proposed framework to other materials or field conditions. Full article

(This article belongs to the Special Issue Mechanical Property Research of Advanced Asphalt-Based Materials—Second Edition)

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16 pages, 91273 KB

Open AccessArticle

Influence of La and Ce Additions on the Microstructure and Stress Rupture Property in GH4079 Superalloy

by Ping Yu, Xiangyi Hou, Dong Liu, Yinjun Feng, Qiang Tian and Xintong Lian

Materials 2026, 19(16), 3535; https://doi.org/10.3390/ma19163535 - 20 Aug 2026

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Abstract

GH4079 is a newly developed Ni-based superalloy with a high content of alloying elements and excellent high-temperature mechanical performance. Rare earth (RE) elements are always added to superalloys to improve their stress rupture properties. This study explored how varying additions (0–0.22 wt.%) of [...] Read more.

GH4079 is a newly developed Ni-based superalloy with a high content of alloying elements and excellent high-temperature mechanical performance. Rare earth (RE) elements are always added to superalloys to improve their stress rupture properties. This study explored how varying additions (0–0.22 wt.%) of lanthanum (La) and cerium (Ce) affected the precipitation and stress rupture performance of the GH4079 superalloy and revealed the related strengthening mechanisms. The addition of RE elements restrained the excessive growth of the γ′ phase to keep its particles fine and uniform, while more RE led to a larger quantity and size of RE-rich precipitates and carbides. At 650 °C and 882 MPa, La and Ce notably boosted the alloy’s stress rupture life. The sample with 0.22 wt.% RE showed optimal overall performance, with a stress rupture life of 179.3 h, more than three times that of the RE-free alloy (55.2 h). The improvement in the stress rupture properties by La and Ce was attributed to beneficial intracrystalline and grain boundary effects. RE reinforced the γ′ phase to impede dislocations and purified the grain boundaries by decreasing the segregation of P and S elements. Additionally, small-sized RE-rich precipitates combined with the fine γ′ phase formed zigzag grain boundaries, alleviating stress concentration and retarding intergranular crack propagation. Full article

(This article belongs to the Section Metals and Alloys)

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22 pages, 2502 KB

Open AccessArticle

Transforming Residual Microbial Biomass into High-Value Bicomposite Material for Reactive-Dye Removal: Insights from Batch Investigations to Fluidized-Bed Reactor Applications

by Daniela Suteu, Alexandra Cristina Blaga, Lacramioara Rusu, Adrian Catalin Puitel and Ramona-Elena Tataru-Farmus

Materials 2026, 19(16), 3534; https://doi.org/10.3390/ma19163534 - 20 Aug 2026

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Abstract

The development of sustainable adsorbents from industrial biowaste has become an important strategy for reducing the environmental impact of both solid waste generation and wastewater pollution. In this study, residual Saccharomyces pastorianus biomass recovered from the brewing industry was immobilized in a polymeric [...] Read more.

The development of sustainable adsorbents from industrial biowaste has become an important strategy for reducing the environmental impact of both solid waste generation and wastewater pollution. In this study, residual Saccharomyces pastorianus biomass recovered from the brewing industry was immobilized in a polymeric matrix and evaluated as a bio-composite for the removal of reactive dyes from aqueous media. Orange 16 was selected as the target molecule. Batch biosorption experiments were conducted to identify the optimum operating conditions and to determine the adsorption capacity through Langmuir isotherm analysis. The performance of the biosorbent was subsequently validated under continuous-flow conditions in a fluidized-bed reactor, where the effects of flow rate on column (3.8 and 8.5 mL/min) efficiency were investigated. Experimental breakthrough curves were analyzed using the Clark, Yan, Bohart–Adams, and Yoon–Nelson models, which adequately described the dynamic biosorption process, particularly at the lower flow rate. The best agreement was obtained at a flow rate of 3.8 mL/min, an initial dye concentration of 87 mg/L, and a biosorbent mass of 19.5 g. The developed bio-composite material exhibited efficient dye removal and stable operation, demonstrating that residual brewing biomass can be successfully transformed into a low-cost and sustainable biosorbent suitable for continuous treatment of reactive-dye-containing wastewaters. Full article

(This article belongs to the Special Issue Recent Innovations in Adsorbent Materials for Emerging Water Pollutants)

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13 pages, 9828 KB

Open AccessCommunication

A Novel Re-Entrant Honeycomb with Tunable Auxetic Response and Enhanced In-Plane Mechanical Performance

by Chenxi Li, Siyan Bai, Jueran Yin, Qianqi Cao, Haoxin Tian, Yifei Dong, Han Wang, Jiurui Liu, Guocheng Que and Yiwen Chen

Materials 2026, 19(16), 3533; https://doi.org/10.3390/ma19163533 - 20 Aug 2026

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Abstract

Re-entrant honeycombs with tunable auxetic response have attracted increasing attention for energy absorption, yet their in-plane stiffness and load-bearing capacity are often limited by bending-dominated deformation and local instability. In this study, a re-entrant honeycomb with cosine-curved walls and X-shaped ligaments, denoted as [...] Read more.

Re-entrant honeycombs with tunable auxetic response have attracted increasing attention for energy absorption, yet their in-plane stiffness and load-bearing capacity are often limited by bending-dominated deformation and local instability. In this study, a re-entrant honeycomb with cosine-curved walls and X-shaped ligaments, denoted as X-CRS, was proposed to enhance the in-plane mechanical response and energy absorption performance. Three X-CRS configurations with different X-ligament angles were fabricated by fused deposition modeling using PLA and investigated through quasi-static compression tests and finite element simulations. The results show that the X-CRS-30 achieved the highest load-bearing performance, with approximate increases of 148%, 133%, and 102% in elastic modulus, collapse stress, and plateau stress, respectively, and the highest mean specific energy absorption (SEA) of 1.225 ± 0.015 kJ kg⁻¹. At a nominal compressive strain ε_c = 0.20, the numerical effective Poisson’s ratios ν_eff were −0.676, −0.609, −0.376, and +0.156 for CRS, X-CRS-10, X-CRS-20, and X-CRS-30, respectively. Thus, X-CRS-20 retained auxeticity with more stable progressive collapse, whereas X-CRS-30 prioritized stiffness and energy absorption at the expense of auxetic response. Full article

(This article belongs to the Special Issue Mechanics of Sustainable Engineering Materials: Performance, Degradation and Applications)

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