română ZHI LI, PING JIANG
Abstract
To address the performance limitations of single silica (SiO2) encapsulated phase change materials, a novel shape-stable composite microencapsulated phase change material (CA/CS/SiO2 MEPCM) was prepared using the sol-gel method. Capric acid (CA) was used as the phase change material (PCM), while chitosan/silica (CS/SiO2) served as the composite encapsulation material. Fourier transform near infrared spectroscopy (FT-NIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were employed to characterize the chemical structure, crystalline phase, and microstructure of the CA/CS/SiO2 MEPCM. The thermal storage properties and thermal stability of the MEPCM were analyzed using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). SEM results indicated that CA was effectively encapsulated within the CS/SiO2 shell, and the reticulated structure of the shell contributed to the high shape stability of the MEPCM. The results demonstrate that CA is effectively encapsulated within the CS/SiO2 shell, and the network structure of the shell significantly enhances the shape stability of the MEPCM. The encapsulation process preserves the chemical integrity of CA, as no structural changes were observed. The synthesized MEPCM exhibits excellent sealing performance at 102 °C, and the thermal stability of the CS/SiO2 composite shell surpasses that of conventional single-shell structures. Furthermore, the material displays a moderate phase transition temperature and a maximum latent heat of 69.38 J/g, meeting the requirements for variable thermal regulation. In conclusion, the CA/CS/SiO2 MEPCM developed in this study is a green, non-toxic, and structurally stable phase change material with a tunable phase transition temperature, offering promising potential for sustainable thermal energy storage applications.
Keywords
capric acid, chitosan, silicon dioxide, microencapsulated phase change materials
SALEM MERABTI, KACI MEZIANE, SLIM ROUABAH
Abstract
This study proposes a robust modeling approach for predicting the drying shrinkage of cementitious composites incorporating expanded cork waste, using a multilayer perceptron (MLP) artificial neural network. An original database consisting of 54 experimental samples and 2430 shrinkage measurements representing nine different material formulations with varying cork, sand, and ground granulated blast furnace slag (GGBFS) contents was used for model development. Five key variables describing material composition, curing conditions, and mass loss served as model inputs. After data normalization and rigorous cross-validation, the MLP significantly outperformed a classical second-degree polynomial regression, as evidenced by a coefficient of determination of R² = 0.999 and a mean absolute percentage error below 1%. Sensitivity analysis identified curing age and mass loss as the most influential factors governing shrinkage evolution, ahead of the cement-to-cork ratio, sand, and GGBFS content. These findings underline the suitability of neural network models for capturing the complex, nonlinear behaviors of bio-based cementitious materials and provide valuable insights for optimizing the design of durable, sustainable composites.
Keywords
Waste expanded cork, river sand, Ground granulated blast furnace slag (GGBFS), composite, shrinkage, Artificial neural networks (ANNs)
VISWANATH KRISHNAN, MOHAN EKAMBARAM, VINOTHKUMAR RAVI, SHEEBA RANI SOUNDARAPANDIAN
Abstract
In this study, powdered magnesium and aluminum particles were combined with a smaller quantity of silicon carbide (SiC) particles, and the sintering process was used to form the metal matrix composite (MMC). The specimens were made at three distinct temperatures such as 4500C, 5000C, and 5400C. The addition of silicon carbide to the magnesium and aluminium leads to increase the hardness. Based on the scanning electron microscopy (SEM), a large number of holes were commensurate with the sintered specimen produced at the minimal sintering temperature. The development of pore was significantly reduced at high temperature, and strong metallurgical bonding was also attained. The hardness of the sintered specimen was also raised at high sintering temperatures. When compared to other traditional machining methods, the reason for using spark erosion machining or electric discharge machining (EDM) is to maintain the optimal surface roughness (SR) and increase material removal rate (MRR). An atomic force microscopy (AFM) and SEM examination was carried out specifically to evaluate the surface parameters of the magnalium MMC. The pit and valley surface was observed in the machining surface. Current and voltage played a crucial role in metal removal and surface roughness.
Keywords
Magnalium composite, sintering, powder metallurgy, hardness, spark erosion machining
QIAN HONG, XIAOFENG CHEN, WEIQING YU, XIAOXIAO MA, YANBING WANG, CHONGQING WANG, CHAO LIU
Abstract
Faced with the defects of engineering disturbed slope soil, such as easy erosion and evaporation of water, this paper uses polyvinyl alcohol (PVA) hydrogel as a soil conditioner to improve the water erosion resistance and water retention performance of engineering disturbed slope soil, and studies the vegetation performance and microstructure of modified soil. The results showed that PVA hydrogel changed the soil structure by using its excellent cementation and water holding capacity. PVA hydrogel completely wrapped the soil particles to form the overall structure of network gel, which significantly improved the soil erosion resistance, water stability and water retention capacity of the soil. With the increase of PVA concentration, the soil erosion resistance, water stability and water retention performance are significantly improved. In addition, the effect of increasing PVA concentration on soil vegetation performance shows a trend of first strengthening and then weakening, with the best soil vegetation performance observed when PVA concentration was 3%. The results show that PVA hydrogel has important application value for reducing soil and water loss of engineering disturbed slope and promoting vegetation restoration.
Keywords
disturbed slope, ecological restoration, erosion resistance, water retention performance, vegetation performance
ANGELA GABRIELA PĂUN, ROBERTA-GEANINA MIFTODE, MIHAELA VASILICA MÎNDROIU
Abstract
This paper presents the main findings of our study on the preparation and characterization of polyvinyl alcohol (PVA)-based conductive bio-membranes intended for use as solid polymer electrolytes (SPEs) in smart window applications. The novelty of this research lies in the development of PVA bio-membranes with enhanced ionic and electronic conductivity through the incorporation of lithium perchlorate (LiClO₄) as a lithium-ion (Li⁺) source, as well as functionalization with deoxyribonucleic acid (DNA) and poly(3,4-ethylenedioxythiophene) (PEDOT), the latter introducing electronically conductive pathways. The bio-membranes were characterized by Fourier transform infrared (FTIR) and UV-Vis spectroscopy, along with electrochemical impedance spectroscopy (EIS) to determine their ionic conductivity. The PVA-based bio-membrane exhibiting the highest conductivity was further employed in the assembly of a smart window device, which was evaluated through chronoamperometry, charge density measurements, and UV-Vis spectroscopy. Results demonstrated that the synergistic combination of PEDOT, LiClO₄ and DNA (facilitating ion transport and polymer matrix interaction) led to the formation of mixed ion–electron conductive pathways that support dual charge transport. The electrochromic smart window incorporating the optimized PVA-based bio-membrane exhibited an optical modulation (ΔT) of 22%, with fast switching times of 11 seconds for coloration and 13 seconds for bleaching.
Keywords
Bio-membranes, Electrochromic smart windows, Polyvinyl alcohol, Deoxyribonucleic acid, Ionic conductivity
CHENKANG LIU, SONGLIN YUE
Abstract
Steel fiber reinforced reactive powder concrete (RPC), as a critical material for engineering construction, has garnered significant research interest regarding its mechanical properties. This study investigates the reinforcement mechanism of steel fibers and the dynamic mechanical behavior of RPC. Composite material theory was employed to analyze the steel fiber strengthening and toughening mechanisms. The distribution of steel fibers and the microstructure of the cement matrix were characterized using X-ray computed tomography (CT) scanning and microstructural analysis. Furthermore, dynamic compression experiments were conducted to evaluate the mechanical response of RPC under high-strain-rate conditions. Results indicate that the interfacial bonding properties between steel fibers and the cement matrix substantially influence the mechanical performance of RPC. A uniform, disordered distribution of steel fibers was found to enhance both the isotropy and compressive strength of the composite. The dynamic strength demonstrates a pronounced strain-rate dependency, wherein the dynamic compressive strength and damage severity increase with escalating strain rates. Notably, damage evolution laws during dynamic compression were quantitatively characterized through high-speed camera imaging. These findings provide valuable insights into the reinforcement mechanisms of steel fibers in RPC composites.
Keywords
reactive powder concrete; microscopic characterization; dynamic mechanical properties; steel fiber reinforcement; damage evolution
PREPARATION METHOD OF DIATOM-BASED EARTH AND ZINC OXIDE COMPOSITE HIGH-DENSITY POLYETHYLENE MATERIAL
KUN LU, HAN KONG, YAOWEN ZHANG, JIAXING ZHU, YUANYUAN DING, XIYU HUANG, CHAO ZHANG
Abstract
In order to cope with the increasingly severe environmental nanotechnology problems and energy shortage, the development of green new materials has become an inevitable trend in today society. In this paper, a preparation method and application of diatom-based earth and zinc oxide composite high-density polyethylene material are provided, which belong to the solid adsorbent composition material. Firstly, high-density polyethylene composites were prepared according to a certain proportion of diatom-based earth and zinc oxide and polyethylene. Then, to improve its performance and UV resistance, Tinuvin 770 is added and mixed with a composite polyethylene material in a gear mixer. Subsequently, the twin-screw extruding machine is set to a certain temperature and speed, extruded, and the extrusion is cut into composite pellets using a tray machine. Finally, these composite pellets are injected into the injection molding machine, where the target mold is selected and molded. At the same time, it can be used as a food packaging bag material, which can inhibit the growth of Staphylococcus aureus and E. bacillus, so that it has the minimum UV stabilizer content, which is a cost-effective and high-performance choice, and its ability to block ultraviolet rays is strong, and it can well protect the quality of packaged food.
Keywords
diatom-based, Zinc Oxide, High-Density polyethylene, Tinuvin 770
BALÁZS CSABA-FÜLÖP, DRAGOȘ UNGUREANU, GAVRIL KÖLLÖ, NICOLAE ȚĂRANU, GAVRIL HODA, TUDOR-CRISTIAN PETRESCU
Abstract
This paper investigates the structural performance and durability of in-situ stabilized soils used as foundation layers in low- and medium-traffic roads. Two field case studies from Romania (Mureș and Cluj counties) involved the stabilization of weak clayey subgrades with hydraulic binders, aiming to enhance bearing capacity and long-term behavior. Laboratory and in situ evaluations were performed, including compressive strength tests (RC₇, RC₂₈), Benkelman beam deflections, and freeze–thaw resistance assessments, in accordance with Romanian standards (STAS 10473-1-87, STAS 1709, PD 177, CD 31). Results indicate that properly stabilized soils can reach compressive strengths and stiffness moduli comparable to conventional granular materials. Benkelman deflection values and variability remained within permissible limits for foundation layers, while frost–thaw testing confirmed the materials durability. Structural dimensioning based on PD 177 showed that the stabilized layers can accommodate projected traffic demands (Nc = 0.5 million standard axles) with substantial fatigue margins. The study supports the controlled use of stabilized soils in road construction, enabling the reuse of marginal local materials, reducing reliance on quarry aggregates, and promoting sustainable engineering practices aligned with circular economy principles.
Keywords
soil stabilization, road foundation layers, Benkelman beam deflection, hydraulic binders, sustainable road construction
JEBA JENKIN JEBAMONY, ANUSHA GURURAJAN, KRISHNA PRAKASH ARUNACHALAM
Abstract
The significant environmental impact of cement production, particularly its contribution to CO₂ emissions, has driven the search for sustainable alternatives in the construction industry. Alccofine, a byproduct of ground granulated blast furnace slag, offers a promising solution as a supplementary cementitious material (SCM). This study evaluates the mechanical and durability properties of concrete incorporating alccofine as a partial replacement for cement, emphasizing its potential to enhance sustainability in construction. Alccofine, with its ultra-fine particles and unique chemical composition, improves hydration kinetics and pozzolanic reactions, resulting in better workability, and decreased permeability in concrete. Experimental investigations reveal that up to 30% replacement of cement with alccofine yields enhanced strength without compromising concrete structural integrity. Microstructural analysis highlights the role of alccofine in refining pore structure and promoting the formation of calcium-silicate-hydrate (C-S-H) gel. By utilizing an industrial waste material, this study demonstrates a sustainable approach to mitigating environmental impacts while maintaining high-performance concrete.
Keywords
Alccofine, Ordinary Portland Cement (OPC), cement replacement, compressive strength, fresh properties, CO2 emission
IVANKA DIMITROVA
Abstract
Objective: The heat production and transfer to the dental pulp can result from various dental procedures such as friction during cavity preparation without water cooling, bleaching, applying lasers and exothermic reactions during the setting of calcium silicate cements. Calcium–silicate cements are hydraulic materials. Their setting process is associated with temperature changes in the cement paste. These bioactive materials have a variety of uses in endodontics such as a repair perforation material, retrograde root filling material and pulp preservation material. Calcium–silicate cements such as direct pulp capping agents are in direct contact with exposed vital pulp . Excessive heat production during the setting of these materials could lead to serious irreversible pulpal damage. The aim of this study was to record variations in temperature changes during the setting process of conventional calcium silicate cements. Materials and Methods The subjects of this study are three commercially-available in the dental practice calcium silicate cements: White MTA-Angelus (Angelus, Londrina, Brazil), White ProRoot MTA (Dentsply, Tulsa, Johnson City, TN), BioAggregate (InnovativeBioceramix, Vancouver, Canadа) and one industrial Portland cement..For this study thermovision camera FLIR T620 and the Flir Reporter Professional 2013 software were used.Thermal imaging capture was carried out under the following conditions: Distance from the camera lens to the experimental set -1 meter, Room Temperature – 20 - 22 degrees Celsius.Statistical Analysis The mean values of the data were compared using the Student t test. Results: The maximum average temperatures during the cement hydration process range between 26.20 and 26.80 degrees. The highest rise in temperature peak was observed with Bioagreggate at 3 minutes after starting the setting process and the warming peak after 7 minutes at ProRoot. WMTA Angelus exerts the lowest mean temperature rise. Conclusion: The knowledge of temperature rise during the setting reaction of conventional calcium silicate cements can help the dentist to make the right decision and choice of the type of calcium silicate cements. During the dental cement hydration process a rise in temperature up to 2 degrees was recorded. This difference is considered insignificant in the alteation of dental pulp and hard dental tissue.
Keywords
Calcium-silicate cements, temperature changes, hydration process, direct pulp capping material
TAREK NAADIA, DJAMILA GUECIOUER, YOUCEF GHERNOUTI, MALİKA SABRİA MANSOUR
Abstract
This experimental study focuses on the development of a steel fiber-reinforced self-compacting concrete (SFSCC) incorporating tuff powder as a local mineral addition. Five mixes were evaluated to assess the influence of fiber dosage on both fresh and hardened properties. The incorporation of steel fibers leads to reduced workability and longer flow times but significantly enhances the stability of the mix by minimizing segregation risks. Mechanically, the addition of fibers results in a marked improvement in flexural strength, with gains exceeding 40% at the highest fiber content. Ductility is substantially increased, reflecting a better ability to absorb post-cracking energy. In contrast, compressive strength shows only a moderate increase, around 11%, confirming that the main contribution of fibers lies in flexural behavior and toughness. The porous texture and pozzolanic activity of the tuff promote strong fiber–matrix bonding, contributing to improved cohesion and crack control. Overall, the findings highlight the feasibility of producing a high-performance, ductile, and stable self-compacting concrete using local resources, offering a sustainable and efficient solution for modern construction needs.
Keywords
Steel fibers, Tuf powder, ductility, workability, flexural strength, compressive strength
LARISA PURDEA, CARMEN OTILIA RUSĂNESCU, GIGEL PARASCHIV, SORIN ȘTEFAN BIRIȘ, SABRINA-MARIA BĂLĂNESCU
Abstract
In this paper, we highlighted the research results regarding the physical and chemical characteristics of the ash obtained from the incineration of sewage sludge and its potential use in cement composition. Considering the climate targets set for 2030 and 2050, it is essential for the circular economy to be implemented for as many waste categories as possible. To this end, this study analyses the ash, classified under waste code 19 01 14, obtained from the incineration of municipal and stormwater sewage sludge from Bucharest, with the aim of its use in the cement industry. This paper includes statistical data regarding the amount of sewage sludge generated in certain countries, some experimental results concerning the properties of the sewage sludge ash (SSA) and its impact on the mechanical strengths of cement.
Keywords
sewage sludge ash (SSA), sewage sludge, cement, waste.
PENG ZHANG
Abstract
The intensification of climate change has aggravated the fatigue damage mechanisms of asphalt pavement materials, posing severe challenges to the long-term durability of road infrastructures. At the same time, conventional repair methods often generate high environmental loads, limiting their ecological sustainability. To address these issues, this study develops a fatigue performance evolution model of asphalt mixtures under coupled temperature–moisture conditions, grounded in nonlinear viscoelastic continuous damage (NVECD) theory. Microscopic damage variables and energy dissipation parameters are introduced to achieve high-fidelity simulation of performance degradation during the service life of pavements. Based on this model, an integrated eco-restoration strategy is proposed that combines the molecular penetration mechanism of bio-based rejuvenating agents with the viscosity-reducing effect of warm-mix technology. This composite approach enhances bonding strength, delays microcrack propagation, and reduces repair-related emissions. Furthermore, a full-process experimental system encompassing aging–repair–refatigue cycles is established to validate the model and evaluate the long-term durability of the repair method. Results demonstrate that the deviation between predicted and experimental fatigue damage within 5.00×105 loading cycles remains below 0.023, confirming the model’s predictive accuracy. With the composite restoration method, the fatigue life of aged asphalt mixtures increases from 1.15×105 to 4.05×105 cycles, while the average crack width is controlled to 3.04 μm and the surface roughness Ra is reduced to 1.49. These findings provide both theoretical guidance and practical solutions for the development of climate-resilient and environmentally sustainable road materials.
Keywords
asphalt pavement materials, fatigue performance, climate change adaptation, eco-restoration, nonlinear viscoelastic damage
IOANA ION, CIPRIAN MIHAI MITU, EMANUEL VIRGIL MARINESCU, ANDREI CUCOS, ALINA RUXANDRA CARAMITU
Abstract
This study presents an eco-friendly synthesis route for a novel hybrid hydrogel (HHy) designed for wastewater remediation using dual crosslinking method: freezing–thawing (FT) and gamma irradiation (GIrr). Polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) form the polymeric matrix, silver nanoparticles (AgNPs), and AgNPs decorated graphene oxide (AgNPs/GO) are incorporated to enhance adsorption and photocatalytic properties. Methylene blue (MB) dye was employed as a model pollutant to assess improved adsorption performance. The HHy demonstrated significant improvements compared to unmodified Hy for equilibrium adsorption capacity (EAC): 20% increase with HyAgNPs and 130% for HyAgNPs/GO; swelling ratio (SWR) measurement revealed an increase of 6% for HyAgNPs, 109% for HyAgNPs/GO; water content (WCR) had an increase of 1 % for HyAgNPs, 14 % for HyAgNPs/GO compared to unmodified Hy. Thermal analysis revealed that total carbonaceous residue after pyrolysis at 800 ⁰C, reached approximately 20% of the Hy’s mass for HyAg and HyAgNPs/GO. This indicates effective char formation due to the catalytic role of the AgNPs and graphene oxide (GO) as nucleation sites. The study optimizes the design of functional Hy for water treatment, and also proposes a viable end-of-life strategy through controlled pyrolysis. The synergistic effects of CMC, graphene oxide (GO), and AgNPs enhance both the structural and functional performance of the HHy system, positioning this approach as a promising avenue for advanced wastewater treatment technologies.
Keywords
wastewater remediation, hybrid hydrogel, silver nanoparticles, graphene oxide, graphene oxide decorated with silver nanoparticles, methylene blue adsorption