In this study, multilayer lamination welding was employed to prepare graphene/copper (Gr/Cu) composite billets from graphene-coated copper foils, followed by multi-pass cold drawing to produce Φ 1 mm Gr/Cu composite wires. Microstructure and property analyses in both the cold-drawn and annealed states show that the incorporation of graphene significantly improves the ductility and electrical conductivity of the copper wire. After annealing at 350 °C for 30 minutes, the composite wire demonstrates a tensile strength of 270 MPa and an electrical conductivity of 102.74% IACS, both superior to those of pure copper wire under identical conditions. At 150 °C, the electrical conductivity of the annealed composite wire reaches 72.60% IACS, notably higher than the 68.19% IACS of pure copper. The results suggest that graphene is uniformly distributed within the composite wire, with minimal impact on conductivity, while effectively refining the copper grain structure to enhance ductility. Moreover, graphene suppresses copper lattice vibrations at elevated temperatures, reducing the rate of conductivity degradation.

We prepared Co_xPt_100−x (x = 40, 45, 50, 55, 60) nanoparticles by the sol-gel method. The phase composition and crystal structure, morphology and microstructure, and magnetic properties of the samples were characterized and tested using X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM), respectively. The results demonstrate that the coercivity of CoPt nanoparticles can be effectively controlled by adjusting the atomic ratio of Co and Pt in the samples. Among the compositions studied, the Co₄₅Pt₅₅ sample synthesized by the sol-gel method exhibits smaller grain size and a coercivity as high as 6.65×10⁵ A/m is achieved. The morphology and microstructure of the nanoparticles were analyzed by TEM images, indicating that a slight excess of Pt can effectively enhance the coercivity of CoPt nanoparticles.

Ceramic thin plates were prepared using kaolin, potassium sodium feldspar and quartz powder as the main raw materials and kaolin, α-Al₂O₃, MoO₃ and AlF₃·3H₂O as additives. The experiment examined the effects of different additives on mullite formation, as well as the microstructure and properties of the ceramic thin plates. Additionally, the study explored the toughening and strengthening mechanisms induced by the additives, providing a theoretical foundation for further optimizing the toughness of ceramic thin plates. The results showed that the D4 sample fired at 1 220 °C (with an addition of 20 wt% α-Al₂O₃) exhibited the best performance, with a water absorption rate of 0.07%, apparent porosity of 0.18%, bulk density of 2.75 g· cm⁻³, firing shrinkage of 12.76%, bending strength reaching 101.93 MPa, and fracture toughness of 2.51 MPa·m^1/2. As the amount of α-Al₂O₃ additive increased, the ceramic thin plates exhibited a greater abundance of short rod-like mullite and corundum grains, which were tightly packed together, forming a framework for the ceramic thin plates. This microstructure enhanced pathways for crack propagation, dispersed internal stresses, and increased fracture surface energy, resulting in significant improvements in both strength and fracture toughness of the ceramic thin plates.

The development of Pt-free catalysts for the oxygen reduction reaction (ORR) is a great issue for meeting the cost challenges of proton exchange membrane fuel cells (PEMFCs) in commercial applications. In this work, a series of RuCo/C catalysts were synthesized by NaBH4 reduction method under the premise that the total metal mass percentage was 20%. X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM) confirmed the formation of single-phase nanoparticles with an average size of 33 nm. Cyclic voltammograms (CV) and linear sweep voltammograms (LSV) tests indicated that RuCo (2:1)/C catalyst had the optimal ORR properties. Additionally, the RuCo (2:1)/C catalyst remarkably sustained 98.1% of its activity even after 3 000 cycles, surpassing the performance of Pt/C (84.8%). Analysis of the elemental state of the catalyst surface after cycling using X-ray photoelectron spectroscopy (XPS) revealed that the Ru⁰ percentage of RuCo (2: 1)/C decreased by 2.2% (from 66.3% to 64.1%), while the Pt⁰ percentage of Pt/C decreased by 7.1% (from 53.3% to 46.2%). It is suggested that the synergy between Ru and Co holds the potential to pave the way for future low-cost and highly stable ORR catalysts, offering significant promise in the context of PEMFCs.

The substitution of TiO₂ for SiO₂ in Y₂O₃-Li₂O-Al₂O₃-SiO₂ (YLAS) glass-ceramics significantly altered their crystallization behavior and properties. Introducing TiO₂ reduced the glass transition temperature while increasing the crystallization peak temperature and lowering activation energy, which facilitated crystallization. The crystal growth shifted from three-dimensional to two-dimensional, and the primary phases transitioned from Al_9.83Zr_0.17 and Y₂Si₂O₇ to Y_4.67(SiO₄)₃O, though crystal morphology remained unchanged. Grain size increased with higher crystallization temperatures. Mechanically, Vickers hardness slightly decreased (from 796 to 784 Hv), while bending strength improved (from 141 to 146 MPa), suggesting that TiO₂ enhanced toughness without compromising structural integrity. The strength of the glass can be further improved through two-step ion exchange, but excessive crystallization can lead to cracks on the glass surface due to excessive surface compressive stress, resulting in a decrease in bending strength. These findings provide critical insights for optimizing YLAS glass-ceramics for advanced applications.

Alkali-free SiO₂-Al₂O₃-CaO-MgO with different SiO₂/Al₂O₃ mass ratios was prepared by conventional melt quenching method. The glass network structure, thermodynamic properties and elastic modulus changes with SiO₂ and Al₂O₃ ratios were investigated using various techniques. It is found that when SiO₂ is replaced by Al₂O₃, the Q⁴ to Q³ transition of silicon-oxygen network decreases while the aluminum-oxygen network increases, which result in the transformation of Si-O-Si bonds to Si-O-Al bonds and an increase in glass network connectivity even though the intermolecular bond strength decreases. The glass transition temperature (T_g) increases continuously, while the thermal expansion coefficient increases and high-temperature viscosity first decreases and then increases. Meanwhile, the elastic modulus values increase from 93 to 102 GPa. This indicates that the elastic modulus is mainly affected by packing factor and dissociation energy, and elements with higher packing factors and dissociation energies supplant those with lower values, resulting in increased rigidity within the glass.

Waste glass fibers were used as the main raw materials to prepare foamed glass-ceramics with 0–14 wt% H₃BO₃ as a flux agent. The effects of H₃BO₃ on the crystallization process, foaming behavior, and physical properties of CaO-MgO-Al₂O₃-SiO₂ foamed glass-ceramics were investigated. The results showed that the main crystalline phase of the foamed glass-ceramics was anorthite with diopside as a minor crystalline phase, which exhibited a typical surface crystallization process. The addition of H₃BO₃ modified the surface of glass powders and inhibited crystal precipitation obviously. The low melting point of H₃BO₃ and the decrease of crystallinity jointly promoted the growth of pores, resulting in a reduction of bulk density and an increase in porosity. The compressive strength and thermal conductivity of the samples were linearly related to the bulk density. In particular, the sample added with 10 wt% H₃BO₃ exhibited excellent properties, possessing a low coefficient of thermal conductivity 0.081 W/(m·K) and relatively high compressive strength 3.36 MPa.

Four groups of nano barium titanate powders were prepared using the hydrothermal method. Their phase structure, microscopic morphology and electrical properties were investigated, and the impacts of raw materials on the barium titanate powders as well as the reaction mechanisms were explored. XRD and FTIR indicate the presence of hydroxyl groups and a small amount of carboxyl groups on the powder surface, and the choice of raw materials significantly affects phase purity, with H₂TiO₃ as raw materials being prone to introducing impurity phases. SEM shows that different precursors lead to morphological differences: soluble raw materials form uniform nanoparticles through a “dissolution-precipitation” mechanism while using TiO₂ as the titanium source generates hollow bowl-like structures through an “in-situ transformation” mechanism, attributed to the synergistic effects of Ostwald ripening and Kirkendall diffusion. The dielectric properties tests indicate that the dielectric constant at room temperature (1 500–3 000) and Curie temperature (2 000–5 000) of the ceramics are both lower than those of ceramics produced by solid-state methods (4 000–6 000 and >10 000), and the phase transition temperature range is widened, which is attributed to factors such as grain refinement, reduced tetragonality, grain boundary effects, and increased defects.

In current research, Li₂O-Al₂O₃-SiO₂ glass-ceramics were prepared by conventional melt-quenching and subsequent heat treatment method. The effect of Al₂O₃ content on microstructures, thermal properties, crystallization behaviours and mechanical properties were investigated. FTIR, Raman spectroscopy and nuclear magnetic resonance spectroscopy microstructure analysis showed that the silico-oxygen network was damaged, while the increase of [AlO₄] content repaired the glass network, and finally made the glass network have better connectivity, with the decrease of SiO₂. The thermal analysis confirmed the increasing glass transition and crystallization temperatures from growing Al₂O₃ content. In addition, different crystal phases can be precipitated in the glass matrix, such as LiAlSi₄O₁₀, Li₂Si₂O₅ in glass with low Al₂O₃ content, the combination of Li_xAl_xSi_1−xO₂, LiAlSi₃O₈, Li₂SiO₃ in glass with intermediate Al₂O₃ content, and the combination of LiAlSi₂O₆, SiO₂ in glass with high Al₂O₃ content. The hardness of as-prepared glass gradually increases with the increase of the Al₂O₃ content. The Vickers hardness of the glass-ceramics is highly dependent on the Al₂O₃ content in the glass and the heat treatment temperatures, reaching a maximum of 10.11 GPa. Scanning electron microscope images show that the crystals change from spherical to massive and finally to sheet. The change of glass structure, crystal phase and morphology is the main reason for the different mechanical properties.

To address the issues of short setting time and high bleeding rate of A component, which easily cause pipe plugging and poor grouting performance when a two-component grout is injected synchronously behind the Segmental Lining, the inorganic retarder sodium pyrophosphate (TSPP) and three organic retarders were added to the A component: sodium citrate (SC), sodium tartrate (ST) and glycerol (GLY). The effect law and microscopic mechanism of viscosity, bleeding rate, setting time, gelling time, compressive strength, and stone rate were investigated. The results revealed that the addition of retarders could enhance the stability and setting time of the A component and increase the gelling time, stone rate, and compressive strength of two-component grout. Among them, the performance of the grout with an SC dosage of 0.1% was superior. The bleeding rate of this grout was reduced to 3.5%, the stone rate of the two-component grout was more than 99%, and the early compressive strength and late compressive strength of this grout were increased by approximately 35% and 7%, respectively. The initial and final setting time of the A component with a TSPP dosage of 0.3% was the longest, which was prolonged to 17 and 26 h, respectively. Microscopic analysis revealed that the four retarders hindered the hydration process of cement through complexation and adsorption, and inhibited the hydration of C₃S and the crystallisation of CH. Moreover, they reduced the defects caused by the rapid reaction of water glass and CH on the solid phase structure, enabled the microstructure of the stone body to be denser, and subsequently, enhanced the compressive strength.

We used solidification/stabilization methods to remediate highly concentrated Zn²⁺-contaminated soil. An industrial waste mixture of red mud, carbide slag, and phosphogypsum is combined with cement as the curing agent. The mixing ratios of the four materials are determined by comparing the strength, permeability coefficient, pH, and Zn²⁺-leaching concentration of the solidified soil. Microscopic characteristics of the solidified uncontaminated soil and solidified Zn²⁺-contaminated soil were observed using scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. Furthermore, the heavy metals speciation in both pure cement and mixed-material solidified soil was examined, demonstrating the beneficial role of the mixed-type curing agent in stabilizing heavy metals. The research results indicate that Zn²⁺ degrade the strength of the solidified soil by up to 90%. The permeability coefficient, pH, and Zn²⁺-leaching concentration of the solidified soil easily meet standard, especially with Zn²⁺ leaching concentration well below the environmental protection limit. Furthermore, most Zn²⁺ exists in forms with lower biological and chemical reactivity. Both the solidified Zn²⁺-contaminated soil and uncontaminated soil resulted in the formation of hydrated products containing elements such as silicon, aluminum, calcium, and sulfur. Additionally, the solidified Zn²⁺-contaminated soil produced zinc-containing compounds and a large amount of rod-shaped ettringite.

The utilization of discarded coral debris in cementitious material is a prominent research area for island construction projects. The aim of this study is to explore the use of environment-friendly cement and waste coral sand in the preparation of coral mortar, while investigating its performance when exposed to a chloride environment. Three types of low-carbon cements were employed, such as rapid hardening sulphoaluminate (RCSA) cement, high belite sulphoaluminate (HBCSA) cement, and slag sulphoaluminate cement (SSC). The coulomb electric flux, mechanical properties, free chloride content, and mass change of the cement mortar under exposed to 3.5 wt% NaCl solution were examined at various time intervals. X-ray diffraction analysis was conducted to identify the mineral phases present in the mortar samples. The results demonstrate that the flex-ural and compressive strength of the mortar consistently increase throughout the 360 days chloride exposure period. Incorporating coral sand into SSC-based mortars enhances their compressive strength from day 28 up until day 360. However, it adversely affects the strength of HBCSA-based mortars. The behavior of mortars exposed to a chloride-rich environment is closely associated with the amount of C-S-H gel present within them. SSC generates a significant quantity of C-S-H gel which possesses a large specific surface area capable of absorbing more chloride ions thereby reducing their concentration within the mortar matrix as well as increasing its mass and improving resistance against chloride ion penetration.

Dynamic thermal mechanical analysis was used to evaluate the viscoelasticity of asphalt. The parameters included the energy storage modulus (E), the loss modulus (E′), and the loss tangent (tanδ). The impact of three kinds of particles containing CaCO₃ with different size and structure on the mechanical properties was also measured. The addition of limestone increases the glass transition temperature, while nano-CaCO₃@SiO₂ decreases the glass transition temperature. Nano-CaCO₃ has a negligible effect on the glass transition temperature. The particle size of the limestone is 0.075 mm, which is a material at the micrometer level. During the heating process, it hinders the molecular movement and makes the material harder. Thus the glass transition temperature is relatively high.

To investigate the influence of coarse aggregate parent rock properties on the elastic modulus of concrete, the mineralogical properties and stress-strain curves of granite and dolomite parent rocks, as well as the strength and elastic modulus of mortar and concrete prepared with mechanism aggregates of the corresponding lithology, and the stress-strain curves of concrete were investigated. In this paper, a coarse aggregate and mortar matrix bonding assumption is proposed, and a prediction model for the elastic modulus of mortar is established by considering the lithology of the mechanism sand and the slurry components. An equivalent coarse aggregate elastic modulus model was established by considering factors such as coarse aggregate particle size, volume fraction, and mortar thickness between coarse aggregates. Based on the elastic modulus of the equivalent coarse aggregate and the remaining mortar, a prediction model for the elastic modulus of the two and three components of concrete in series and then in parallel was established, and the predicted values differed from the measured values within 10%. It is proposed that the coarse aggregate elastic modulus in high-strength concrete is the most critical factor affecting the elastic modulus of concrete, and as the coarse aggregate elastic modulus increases by 27.7%, the concrete elastic modulus increases by 19.5%.

We investigated the effects of fly ash (FA) content on the mechanical properties of recycled aggregate concrete (RAC) and its regeneration potential under freeze and thaw (F-T) cycles. The physical properties of second-generation recycled concrete aggregates (RCA) were used to analyze the regeneration potential of RAC after F-T cycles. Scanning electron microscopy was used to study the interfacial transition zone microstructure of RAC after F-T cycles. Results showed that adding 20% FA to RAC significantly enhanced its mechanical properties and frost resistance. Before the F-T cycles, the compressive strength of RAC with 20% FA reached 48.3 MPa, exceeding research strength target of 40 MPa. A majority of second-generation RCA with FA had been verified to attain class III, which enabled their practical application in non-structural projects such as backfill trenches and road pavement. However, the second-generation RCA with 20% FA can achieve class II, making it ideal for 40 MPa structural concrete.

To study the durability of concrete in harsh environments in Northwest China, concrete was prepared with various durability-improving materials such as concrete anti-erosion inhibitor (SBT-TIA), acrylate polymer (AP), super absorbent resin (SAP). The erosion mode and internal deterioration mechanism under salt freeze-thaw cycle and dry-wet cycle were explored. The results show that the addition of enhancing materials can effectively improve the resistance of concrete to salt freezing and sulfate erosion: the relevant indexes of concrete added with X-AP and T-AP are improved after salt freeze-thaw cycles; concrete added with SBT-TIA shows optimal sulfate corrosion resistance; and concrete added with AP displays the best resistance to salt freezing. Microanalysis shows that the increase in the number of cycles decreases the generation of internal hydration products and defects in concrete mixed with enhancing materials and improves the related indexes. Based on the Wiener model analysis, the reliability of concrete with different lithologies and enhancing materials is improved, which may provide a reference for the application of manufactured sand concrete and enhancing materials in Northwest China, especially for the study of the improvement effects and mechanism of enhancing materials on the performance of concrete.

Based on the split hopkinson pressure bar (SHPB) tests results, the cubic specimens have been numerically modeled in this paper to investigate the impact of key factors, such as the rise time, duration, and incident pulse shape, on achieving stress uniformity. After analysis, the paper provides actionable methods aimed at optimizing the conditions for stress uniformity within the cubic specimen. Finally, the lateral inertia effect of cubic specimen has been scrutinized to address the existing gap in this academic area.

In order to realize the comprehensive utilization of industrial solid waste rice husk ash and heavy metal cadmium contaminated soil, rice husk ash-based geopolymer prepared by alkaline activator was used to modify cadmium contaminated soil. The main physical and chemical properties of rice husk ash were clarified by SEM, XRF and X-ray diffraction. The unconfined compressive strength test and toxicity leaching test were carried out on the modified soil. Combined with FTIR and TG micro-level, the solidification mechanism of rice husk ash-based geopolymer solidified cadmium contaminated soil was discussed. The results show that the strength of geopolymer modified soil is significantly higher than that of plain soil, and the unconfined compressive strength at 7 d age is 4.2 times that of plain soil. The strength of modified soil with different dosage of geopolymer at 28 d age is about 36% to 40% higher than that of modified soil at 7 d age. Geopolymer has a significant effect on the leaching of heavy metals in contaminated soil. When the cadmium content is 100 mg/kg, it meets the standard limit. In the process of complex depolymerization-condensation reaction, on the one hand, geopolymers are cemented and agglomerated to form a complex spatial structure, which affects the macro and micro characteristics of soil. On the other hand, it has significant adsorption, precipitation and replacement effects on heavy metal ions in soil, showing good strength and low heavy metal leaching toxicity.

This study introduces superabsorbent polymers (SAP) into recycled concrete and, through freeze-thaw cycle tests, unconfined compressive strength tests, and nuclear magnetic resonance (NMR) analysis, evaluates the freeze-thaw resistance and durability of recycled concrete samples under varying freeze-thaw cycles. The results indicate that an appropriate addition of SAP significantly enhances the freeze-thaw resistance of recycled concrete. After 200 freeze-thaw cycles, the RS0.6 sample retained good surface integrity, demonstrating the best performance. Compared to NAC, its mass loss decreased by 1.16%, the relative dynamic modulus improved by 7.01%, and the compressive strength loss rate decreased by 5.41%. Additionally, T₂ spectrum analysis revealed that adding SAP optimized the pore structure of recycled concrete and mitigated pore development during freeze-thaw cycles. As the number of freeze-thaw cycles increased, the RS0.3 and RS0.6 samples demonstrated superior frost resistance compared to NAC. However, an excessive amount of SAP increased pore expansion during subsequent freeze-thaw cycles, ultimately weakening frost resistance.

A green pregelatinized glutinous rice flour biological admixture was developed in this paper. The cement hydration process, hydration products, pore structure, and strength of mortar with different quantities of glutinous rice flour (GRF), and the macroscopic changes in concrete cracking resistance testing were investigated. Simultaneously, a fast cracking resistance evaluation method based on graphic recognition was proposed. The results indicated that pregelatinized glutinous rice flour (T-GRF) delayed the dissolution rate of anhydrous cement during the induction period, shifting the main exothermic peak of hydration backward. The compressive strength developed slowly in 7–28 d age and returned to normal in 28–56 d. The compressive strength of T-GRF-0.6% modified mortar at 56 d age is less than 10% different from that of control group. The 3.0% T-GRF decreased the total porosity by 3%, and the average pore size decreased from 31.2 to 21.3 nm measured by MIP, indicating that T-GRF could inhibit harmful pores and densify concrete. The crack resistance coefficient of T-GRF modified concrete was obtained by image recognition method, and the GRF could decrease the length, width, and damaged area of cracks in the early age of concrete.

To explore the best preparation process for terminal blend (TB) composite-modified asphalt and to filter its formulation with excellent performance, this study evaluates the performance of TB composite-modified asphalt by physical property index, microscopic morphology, rheological testing, and infrared spectroscopy on multiple scales. The results show that the best preparation process for TB-modified asphalt is stirring at 260 °C for 4 h at 400 rpm, which significantly reduces the modification time of the asphalt. From a physical property viewpoint, the TB composite-modified asphalt sample with 5% styrene–lbutadiene–lstyrene (SBS) + 1% aromatics + 0.1% sulfur exhibits high-comprehensive, high- and low-temperature properties. Moreover, its crosslinked mesh structure comprises black rubber particles uniformly interwoven in the middle, which further enhances the performance of the asphalt and results in an excellent performance formulation. In addition, the sample with 5% SBS content has a higher G* value and smaller δ value than that with 3% SBS content, indicating that its high-temperature resistance is improved. The effect of adding 3% SBS content on the viscoelastic ratio is, to some extent, less than that caused by 20% rubber powder.

Calcium carboaluminate was successfully prepared by a simple and efficient one-step method, and the effects of temperature, time, raw material ratio, carbonate type and heavy CaCO₃ particle size on the products were investigated in detail. The results show that increasing the temperature and extending the reaction time can enhance the yield and crystallisation degree of calcium carboaluminate. The proportion of Ca (OH)₂, Al(OH)₃ and CaCO₃ is a pivotal factor in the synthesis of calcium carboaluminate. When the ratio of Ca (OH)₂, Al(OH)₃ and CaCO₃ is 3:2:1, the diffraction peaks of calcium carboaluminate in the products are relatively sharp and strong. Furthermore, the purity and crystallinity of the synthesized calcium carboaluminate are higher when heavy CaCO₃ with the particle size of 120 mesh is used as the carbonate raw material, in comparison to CO₂, Na₂CO₃ and light CaCO₃. As results, a simple and efficient method for the synthesis of calcium carboaluminate is proposed, which will provide a solid experimental foundation and technical support for the industrial application of calcium carboaluminate in marine concrete.

Crushing waste coral concrete into recycled aggregates to create recycled coral aggregate concrete (RCAC) contributes to sustainable construction development on offshore islands and reefs. To investigate the impact of recycled coral aggregate on concrete properties, this study performed a comprehensive analysis of the physical properties of recycled coral aggregate and the basic mechanical properties and microstructure of RCAC. The test results indicate that, compared to coral debris, the crushing index of recycled coral aggregate was reduced by 9.4%, while porosity decreased by 33.5%. Furthermore, RCAC retained the early strength characteristics of coral concrete, with compressive strength and flexural strength exhibiting a notable increase as the water-cement ratio decreased. Under identical conditions, the compressive strength and flexural strength of RCAC were 12.7% and 2.5% higher than coral concrete’s, respectively, with porosity correspondingly reduced from 3.13% to 5.11%. This enhancement could be attributed to the new mortar filling the recycled coral aggregate. Scanning electron microscopy (SEM) analysis revealed three distinct interface transition zones within RCAC, with the ‘new mortar-old mortar’ interface identified as the weakest. The above findings provided a reference for the sustainable use of coral concrete in constructing offshore islands.

The effect of antibacterial adhesive on the biological corrosion resistance of mortar in seawater environment was studied by means of scanning electron microscope, thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy, and ultra-depth microscope. The results show that the antibacterial adhesive can effectively inhibit the growth of sulfur-oxidizing bacteria in seawater, hinder their metabolism to produce biological sulfate, and reduce the formation of destructive product gypsum. The mineral composition and thermal analysis showed that the peak value of plaster diffraction peak and the mass loss of plaster dehydration in antibacterial adhesive group were significantly lower than those in blank group (without protective coating group). In addition, the electric flux of chloride ions (> 400 C) in the blank group of mortar samples was higher than that in the antibacterial adhesive group (< 200 C), indicating that the antibacterial adhesive can effectively reduce the permeability of chloride ions in mortar, and thus hinder the Cl⁻ erosion in seawater.

To investigate the pore structure of graphene oxide modified polymer cement mortar (GOPM) under salt-freeze-thaw (SFT) coupling effects and its impact on deterioration, this study modifies polymer cement mortar (EMCM) with graphene oxide (GO). The micro-pore structure of GOPM is characterized using LF-NMR and SEM. Fractal theory is applied to calculate the fractal dimension of pore volume, and the deterioration patterns are analyzed based on the evolution characteristics of capillary pores. The experimental results indicate that, after 25 salt-freeze-thaw cycles (SFTc), SO₄²⁻ ions penetrate the matrix, generating corrosion products that fill existing pores and enhance the compactness of the specimen. As the number of cycles increases, the ongoing formation and expansion of corrosion products within the matrix, combined with persistent freezing forces, and result in the degradation of the pore structure. Therefore, the mass loss rate (MLR) of the specimens shows a trend of first decreasing and then increasing, while the relative dynamic elastic modulus (RDEM) initially increases and then decreases. Compared to the PC group specimens, the G3PM group specimens show a 28.71% reduction in MLR and a 31.42% increase in RDEM after 150 SFTc. The fractal dimensions of the transition pores, capillary pores, and macropores in the G3PM specimens first increase and then decrease as the number of SFTc increases. Among them, the capillary pores show the highest correlation with MLR and RDEM, with correlation coefficients of 0.974 38 and 0.985 55, respectively.

The engineering application of low-alkali sulphoaluminate cement (L-SAC) is hindered due to the difficulty in adjusting the setting and hardening time. In this paper, lithium hydroxide and borax are mixed into L-SAC to regulate its setting and hardening process, so as to prepare a sulphoaluminate concrete material with high early strength and high fluidity. The effects of the ratio of lithium hydroxide to borax on the properties of L-SAC concrete were studied by hydration heat, XRD, TG-DTG, SEM and MIP. The experimental results show that the slump increases with the increase of borax content, and the early (3 h) strength increases with the increase of lithium hydroxide content. When 0.05% lithium hydroxide and 0.4% borax are added, the 0.5 h slump reaches 195 mm, and the 3 h compressive strength reaches 15.9 MPa. The increase of lithium hydroxide will promote the formation of early hydration products AFt and AH₃ gel and accelerate the hydration process, while borax will inhibit the dissolution and hydration of cement and delay the setting and hardening process of concrete. The combination of the two ensures that the concrete has the characteristics of high early strength and high fluidity, and the early workability and mechanical properties can be controlled by the mix ratio. For long-term mechanical properties, the special concrete does not produce AFm, which can ensure the continuous development of strength.

Two viologen derivatives containing fluorine substituent (F) with an asymmetric structures, 1, 1′-bis(4-(trifluoromethyl)phenyl)-[4,4′-bipyridine] dihexafluorophosphate (DFPV) and 1-benzyl-1′-(4-(trifluoromethyl)phenyl)-[4,4′-bipyridine]di-hexafluorophosphate (Bn-FPV), were synthesized. These viologen derivatives as active materials were used to assemble both flexible and rigid electrochromic devices (ECDs). ECDs based on DFPV exhibited reversible color change from colorless to deep green and ECDs based on Bn-FPV exhibited reversible color change from colorless to blue-green within applied voltage. It was found that the devices based on DFPV showed cycle stability, which could still maintain more than 90% after 1 000 cycles. In addition, the modulation rate of the device to the solar irradiance is also calculated to characterize its application potential in smart windows. Among them, the rigid device (R-DFPV) based on the DFPV has a large solar irradiance modulation rate of 54.66%, which has the potential to be used as smart windows.

In ultraviolet cured-in-place-pipe (UV-CIPP) pipeline rehabilitation, resin performance critically determines repair effectiveness. Current UV-curable resins exhibit high volatile organic compound (VOC) emissions and inadequate post-cure toughness, which compromise fatigue resistance during service. To address these issues, we synthesized hydroxyl-terminated polyurethane acrylate prepolymers using diphenylmethane diisocyanate (MDI), polypropylene glycol (PPG), and hydroxyethyl methacrylate (HEMA). Fourier transform infrared spectroscopy (FTIR) confirmed successful prepolymer synthesis. We developed UV-curable resins by incorporating various crosslinking monomers and optimized the formulations through mechanical property analysis. Testing revealed that the polyurethane–acrylic UV-cured resin system combines polyurethane’s mechanical excellence with acrylics’ high UV-curing activity. The PPG200/MDI/HEMA formulation achieved superior performance, with a tensile strength of 55.31 MPa, an impact toughness of 22.7 kJ/m², and a heat deflection temperature (HDT) of 132 °C. The optimized system eliminates volatile components while maintaining high reactivity, addressing critical limitations in trenchless pipeline rehabilitation. The improved mechanical properties meet the operational demands of underground pipes, suggesting practical applicability in trenchless pipeline repair.

MPHPB was prepared from melamine, phenylphosphonic acid and boric acid, and its flame retardant effect in PE was investigated. Compared to the intermediate product (melamine phenyl hypophosphite (MPHP)), the residual char increased from 17.9% of MPHP to 41.2% of MPHPB at 800 °C. The limiting oxygen index (LOI) of PE/20% MPHPB is 23.6%, which reaches V-0 rating. After the addition of 20% MPHPB, the total heat release (THR), peak heat release rate (pK–HRR), and average effective thermal combustion rates (av–EHC) of PE decreased. Additionally, characterizations including the pyrolysis gas chromatography-mass spectrometry (Py-GC-MS), scanning electron microscopy (SEM), raman spectroscopy test (LRS) and fourier transform infrared (FT–IR) were taken to investigate the flame retardant mechanism, and the results show that MPHPB plays roles in both gas and condensed phases.