Sluggish hydration kinetics of conventional Portland cement-asphalt mortars preclude their application in the strict 4-hour rapid rehabilitation of high-speed railway slab tracks. To overcome this, a novel viscoelastic sulphoaluminate cement-emulsified asphalt (SEA) mortar was developed. Synergistic regulation via borax, calcium formate, and polycarboxylate ether successfully decoupled the inherent conflict between workability retention and early-age strength, achieving a 4-hour compressive strength > 15 MPa. Macroscopically, escalating the asphalt-to-cement (A/C) ratio triggers a fundamental rigid-to-viscoelastic transition. While penalizing late-age strength and dynamic modulus, this shift profoundly enhances deformational compatibility and vibration-damping capacity. Microstructurally, demulsified asphalt forms a hydrophobic film encapsulating cement grains, driving a unique "physical retardation-delayed burst" hydration kinetic and macroscopic pore coarsening. Nevertheless, this flexible membrane mechanically interlocks with inorganic hydrates to construct a robust organic-inorganic interpenetrating network. Crucially, this topology dictates a durability trade-off: the hydrophobic film truncates capillary connectivity, drastically reducing chloride permeability, whereas pore coarsening compromises freeze-thaw resilience. Ultimately, this study establishes critical mix-optimization thresholds for rapid track repair and elucidates the microstructure-property-durability constitutive relationships of organic-inorganic composites.

This paper introduces a hydrophobic modified steel fiber concrete (HMSFC) to enhance the freeze-thaw (F-T) durability of cement-based materials while addressing the strength reduction commonly associated with conventional hydrophobic agents. The effects of hydrophobic agent (MMAP) and steel fibers on the mechanical properties of concrete before and after F-T cycles were systematically evaluated through compressive strength, splitting tensile, and axial compressive tests. Results indicated that although MMAP slightly impaired the base strength, the addition of steel fibers effectively restored its structural performance to that of control concrete, and the F-T environment caused minimal damage to HMSFC, with only a 26.62% reduction in compressive strength and a 21.08% decline in splitting tensile strength after 200 cycles. Furthermore, microstructural analysis revealed that MMAP enhanced the complexity of concrete's pore structure and inhibited moisture penetration, while steel fibers reduced crack initiation and delayed crack propagation, which was the key factor to alleviate F-T damage. Finally, an axial compression constitutive model considering the F-T cycles was developed and showed good agreement with the experimental data. These findings highlight the potential of HMSFC as an innovative cement-based material for improving concrete durability in severe F-T environment.

The unsatisfactory rheological properties and inherently poor water resistance of building gypsum limit its broader application. Thus, this study systematically investigates the synergistic effects of binary incorporation of bauxite residue (BR) and rice straw ash (RSA) on the rheological properties, hydration kinetics, mechanical strength, and water resistance of gypsum-based composites. The experimental results demonstrate that the binary incorporation of BR and RSA strategically tailors the workability of gypsum paste. Although the absolute strength is marginally reduced compared with pure gypsum, the water resistance is significantly enhanced. These improvements are linked to their particle characteristics, a balanced and thorough hydration process, and microstructural transformation, including the in situ generation of ettringite and the formation of a homogeneous and dense (C, N)-A-S-H/C-(A)-S-H gel phase, which create a compact and less permeable microstructure. These results not only provide a novel technological pathway for the modification of building gypsum but also offer experimental validation for the large-scale valorization of BR and RSA, thereby extending the applicability of gypsum-based materials to humid environments.

It is an urgent concern to recycle the valuable sulfur from municipal sewage sludge during the incineration. Three metal oxides (CeO2, CuO and Co3O4) were prepared and their feasibility in promoting the conversion of organic sulfur to high-value-added sulfones and sulfoxides at low temperatures (160 degrees C) was explored. Experimental results revealed that these three metal oxides considerably improved the conversion to different degrees. CeO2 exhibited the best effect with 5% addition and increased the conversion of low-valent organic sulfides from 3.3% in the control group to 50.3%. As their amounts increased from 5% to 15%, their promotional effects declined and finally approached an almost constant level. Their excellent promotion effects were mainly attributed to their rich oxygen vacancies and good redox properties. Besides, their porous structural characteristics played an important role in facilitating the oxidation reaction. This study provides novel insights into the reduction of sulfur pollution and high-value recovery before sludge combustion.

Moisture intrusion is facilitated by the hydrophilic and porous characteristics of cement-based materials, while current hydrophobic modifications often compromise mechanical strength. In this study, a high-temperature melt-blending process was employed to uniformly coat stearic acid onto the surfaces of metakaolin, zeolite powder, and mica powder, yielding novel hydrophobic mineral admixtures. The effects of these modified admixtures on the hydrophobicity, water absorption, mechanical properties, and microstructure of cement-based materials were systematically investigated. Among the tested materials, stearic acid-modified mica powder (SMMP) exhibited the most promising results, achieving a water contact angle of 136.45 degrees, reducing capillary water absorption by 55.39 %, and limiting compressive strength loss to only 2.83 %. Microstructural observations revealed that SMMP effectively inhibited crack development and maintained the pore structure, while only slightly suppressing early hydration (maximum cumulative heat reduction of 4.55 %). XRD showed SMMP reduced calcium hydroxide (CH) but promoted C-S-H formation, aiding strength retention. The integration of SMMP demonstrated a unique ability to refine the pore structure, as evidenced by MIP results showing an initial rise followed by a decline in total porosity and a shift toward finer pores. This pore-structure refinement is key to concurrently enhancing hydrophobicity and preserving mechanical strength, enabling the development of durable materials for severe service conditions.

Developing sustainable and efficient delivery systems for hydrophobic bioactive compounds remains challenging. Here, fish scale gelatin (FSG), a sustainable alternative to mammalian gelatin, was hydrolyzed under acid (FSG-A) or alkali (FSG-B) conditions to construct hydrogels for curcumin delivery. Curcumin-loaded FSG-A hydrogel (CL-FSG-A-gel) showed markedly higher curcumin solubility (46.93 μg/mL), 3.7- and 3.0-fold above native FSG and FSG-B. Multiscale analyses revealed that acid hydrolysis generated short, flexible peptides that promoted β-sheet/random coil formation, ordered alignment, and dense network assembly (Rg = 3.817 nm; D = 1.95). These structural features enhanced rheological performance, giving CL-FSG-A-gel the highest storage modulus, gelation temperature (23.6 °C), viscosity, and rapid gelation. During simulated digestion, it achieved the highest gastric retention (73.75%) and controlled intestinal release (62.72% retained at 6 h). This study identifies acid hydrolysis as a food-safe strategy to engineer effective hydrophobic nutrient delivery systems while valorizing fish-processing by-products.

Modulating ternesite hydration has become an urgent concern to improve cement performance. Herein, the ternesite was synthesized in laboratory and 5

Polymer-based hard carbon is a potential anode material for sodium-ion batteries (SIBs) due to their structural controllability and electrochemical characteristics. Despite these advantages, its high cost hinders widespread adoption. This study synthesized a polymer-derived hard carbon material from industrial polymer waste through a facile method. The results show that the interlayer spacing of the prepared material (similar to 0.37 nm) is significantly larger than graphite, which facilitates sodium-ion intercalation/deintercalation during the charge/discharge cycles. Furthermore, the material's design, distinguished by a well-developed surface area (i.e., 5.014 m2 g-1), facilitates better electrolyte diffusion and improved ion accessibility, hence enhancing electrochemical performance. The influence of the temperature (900-1500 degrees C) on the microstructure is examined, revealing that elevated heat treatment temperatures result in enhanced graphitization and superior cycle stability. Among various temperatures, hard carbon synthesized at 1300 degrees C has superior electrochemical performance as anode material for SIB, with a maximum stable reversible specific capacity of 350 mAh g-1 at 0.1C (1C = 300 mA g-1). This material has an initial Coulombic efficiency (ICE) of around 80% and maintains a high-capacity retention of 98% after 100 cycles at a rate of 0.1C. The findings underscore the viability of polymer-derived hard carbon as an advantageous anode material for SIBs, offering a sustainable and high-performance alternative for extensive energy storage applications.

Four typical admixtures,polycarboxylate superplasticiser （PCE）,tartaric acid （TA）,sorbitol and polyacrylamide （PAM）,were selected to systematically investigate their regulatory mechanisms on the formation of ettringite through Fourier transform infrared spectroscopy,X-ray diffraction,particle size analysis and nucleation kinetic model.The experimental results indicate that the admixtures alter the formation of ettringite through physical adsorption,complexation and solution viscosity modulation without changing its chemical structure.Low concentrations of PCE inhibit size growth by forming an adsorption layer on the surface of ettringite,whereas high concentrations of PCE alter the size change of ettringite by modulating the distribution of ionic concentrations.TA significantly reduces the size of ettringite by complexing Ca 2+ .Sorbitol and PAM promote the local growth of ettringite at low concentrations,leading to larger sizes.But at high concentrations,the size growth of ettringite is inhibited due to the increase in viscosity or the enhancement of complexation.Matlab nucleation kinetic modelling further shows that the addition of admixtures enhances the initial nucleation during ettringite synthesis,with values ranging from 14.45% to 114.25%.However,the subsequent nucleation rate of ettringite is significantly affected,decreasing by 12.79% to 71.74%.The results provide a theoretical basis for the design of ettringite materials and the optimisation of the application of admixtures.

In this study, pectin was extracted from potato with the hydrolysis of cellulose, as well as its acid‐induced and Ca 2+ ‐induced gelation behavior was investigated, too. The gelation process of unhydrolyzed pectin might be used as a model for studying the gelation behavior and characteristic of pectin within the cell wall. The results showed that potato pectin solution (3%) could form a gel state at a minimal concentration of 0.25% CaCl 2 or a maximum pH value of 4.60. Furthermore, acetic acid‐induced and CaCl 2 ‐induced gels were both concentration‐independent. Specifically, the gel strength increased with decreasing levels of pH and increasing concentrations of CaCl 2 . Moreover, CaCl 2 ‐induced gels exhibited superior gelation characteristics with a higher storage modulus (7.2 Pa), larger fractal dimension (2.58), smaller porosity (12.11%), shorter relaxation time T 2 , and a denser gel network structure. This disparity stemmed from different mechanism: acetic acid provided H + to combine with free carboxyl groups on the pectin chains, reducing the repulsion between pectin molecules, narrowing chain spacing, and fostering hydrogen bond formation; whereas CaCl 2 promoted gelation primarily via the information of the “egg box” structure involving non‐covalent bonded calcium bridges. This research could provide a theoretical basis for acid‐induced and Ca 2+ ‐induced gelation of unhydrolyzed pectin extracted from the cell wall.

In view of the problems caused by impurities to the comprehensive utilization of phosphogypsum, this study employed a combination of calcination and lime neutralization processes to harmless treatment of impurities in phosphogypsum. The phosphogypsum was pretreated by wet neutralization and dry neutralization respectively, followed by calcination at medium temperature to obtain II-anhydrite. XRD, XRF, SEM, FTIR, and other techniques were applied for analysis of the impact of these two pretreatments on impurity removal as well as their effects on the properties of calcined II-anhydrite. Then, the calcination process was optimized to reduce calcination energy consumption. The results show that the reaction between phosphorus and lime is superior to fluorine in the process of neutralizing. When the lime content reaches 1.4

Curcumin-loaded alkali-induced fish scale gelatin (AFSG) was fabricated to evaluate its efficacy as a potential carrier for hydrophobic nutrients. In this study, the effect of the alkali hydrolysis period on the AFSG hydrolysate structure and corresponding curcumin loading efficiency have been elucidated. Results showed that alkali-induced degradation of gelatin yields different polymers with molecular weights (Mw) from 19319 to 3881 Da. Moderate alkali hydrolysis of fish scale gelatin exposes hydrophobic amino acids, enhancing hydrophobic interactions and increasing the proportion of these amino acids. This process also promotes a structural shift, favoring β-sheet formation while reducing α-helix content. Moreover, the curcumin loading efficiency of AFSG (2 h) (10.06 ± 0.27 μg/mL) was significantly higher than that of untreated gelatin (2.16 ± 0.39 μg/mL), while its excessive hydrolysis weakens hydrophobic interactions among hydrophobic amino acids, limiting their binding sites for curcumin. Fluorescence spectroscopy indicated that curcumin-induced fluorescence quenching in AFSG follows a static mechanism. Thus, the above results demonstrated AFSG’s potential as an effective carrier for lipophilic nutrients with high encapsulation efficiency.

Steam-cured concrete prefabricated components are widely used in infrastructure construction such as highspeed railway, but its long-term performance is severely constrained by the heat damage induced by hightemperature curing, particularly in cold regions. This study aims to explore the regulatory effects and mechanisms of trace phase change materials (PCMs) on the performance of steam-cured concrete, offering a novel technology for damage mitigation. Four types of PCMs, paraffin wax (P46), stearic acid (SA), lauric acid (LA), and polyethylene glycol (PEG), were selected and incorporated into equivalent mortar specimens at 1 % by cement mass. The evolution of mechanical properties under standard curing and a four-stage steam-curing regime was compared. Techniques such as hydration heat analysis, XRD, TG-DTG, SEM, and MIP were employed to investigate the hydration process and microstructural characteristics. The results revealed that although PCMs led to early-age strength loss, stearic acid and polyethylene glycol facilitated strength recovery at mid-to-late ages by optimizing the hydration process. Paraffin wax accelerated early-age hydration reaction, whereas polyethylene glycol inhibited the hydration rate. The PCMs refined the pore structure by reducing the proportion of harmful pores, with stearic acid exhibiting the best overall performance under steam-curing conditions. This study demonstrates that trace PCMs alleviate steam-curing-induced heat damage through hydration regulation and microstructural optimization, providing a feasible solution for enhancing the long-term performance of steam-cured precast components.

1H Low-field nuclear magnetic resonance (LF NMR) has emerged as a promising technique for tracking water migration of superabsorbent polymers (SAPs) incorporated cementitious materials. Critical challenges persist in signal identification and pore size estimation, particularly dependent on echo time (TE) selection. This study aimed to establish optimal TE settings for monitoring SAPs water evolution considering various types of SAPs materials. Experimental results revealed that TE variations govern the detectability of water signals and systematically altered the measured transverse relaxation times (T2) of identical water signals, as T2 was inversely proportional to the square of TE. The effect of SAPs' characteristics on water absorption and desorption was determined by its physical structure and chemical composition. An optimized TE protocol was developed through the research purposes and SAPs characteristics. The approach enables quantifying the SAPs absorption and desorption behaviors accurately. This work provides practical guidelines for parameter selection in NMR-based SAPs studies, advancing standardized characterization of water migration and microstructural evolution of SAPs blended concrete.

Complex corrosive marine environments significantly impair the durability of marine structures. Slippery coatings are known to provide effective protection against marine corrosion and biofouling. However, the complex surface topography and molecular structure of concrete restrict the application of these coatings in marine environments. In this study, a silicone-based slippery coating (S-SC) with a reliable bonding strength to concrete and effective marine protective capabilities was designed and fabricated. The coating can be applied to concrete surfaces via a simple brushing process, with lubricating oil spontaneously exuding through intermolecular forces within the coating to form a slippery surface. Moreover, after depletion of the lubricating oil on the S-SC surfaces, the oil continues to exude spontaneously to the coating surface, enabling self-healing of the slippery performance. The presence of the film of lubricating oil on the S-SC surfaces enabled the effective inhibition of seawater penetration, thereby mitigating erosion by the chloride ions in seawater. Bacterial adhesion experiments demonstrated that S-SC effectively inhibited the adhesion of marine bacteria, thereby suppressing biofouling. Protein adhesion experiments demonstrated that S-SC effectively reduced the adhesion of protein molecules to prevent the formation of early-stage biofilms associated with marine biofouling. In summary, a durability-enhancing protective coating was designed and fabricated for marine concrete structures, which offers a new protective strategy to improve the durability of these structures.

This study aimed to investigate the performance evolution characteristics of concrete under permafrost ambient temperatures and to explore methods to mitigate the thermal perturbation by concrete on the permafrost environment. A program was designed to investigate the properties of various concretes at three curing conditions. The compressive strength development pattern of each group was evaluated and the concrete’s performance was characterized by compressive strength damage degree, hydration temperature and SEM analysis in a low temperature environment. The experimental results show that the incorporation of fly ash alone or incombination with other admixtures in concrete under low-temperature curing does not deteriorate its microstructure, and at the same time, it can slow down the hydration rate of cement and significantly reduce the exothermic heat of hydration of concrete. These findings are expected to provide valuable references for the proportioning design of concrete in permafrost environments.

To fully utilize the excellent mechanical properties and durability of ultra-high performance concrete (UHPC) as well as reduce the production cost, a novel UHPC encasing inverted T-steel (PUES) composite beam with hollow section is proposed in this paper. This paper aims to study the flexural behaviors of PUES beams, a bending test program consisted of one solid PUES beam and seven hollow PUES beams is carried out. The test parameters include thickness of inverted T-shape steel flange, tensile reinforcement ratio and stud spacing. The results showed that the PUES beams failed in the typical flexural failure mode and exhibited excellent ductility without obvious drop in load. Compared to composite beam with solid section, the hollow section had negligible influence on the flexural performance of PUES beams, while it saved 26 % UHPC used compared with the one with solid section. The increasing of the thickness of inverted T-shape steel flange and the reinforcement ratio effectively improved the stiffness and the flexural capacity of PUES beams, while the larger diameter of reinforcement incurred an obvious reduction of ductility. An excessively large stud spacing resulted in a poor composite behavior and a reduction of flexural capacity. Based on the analysis of the experimental results, calculating methods considering the shear connection degree between inverted T-steel and peripheral reinforced UHPC were developed to predict the ultimate flexural capacity of the hollow PUES beams. This study provides a reference for further research and practical engineering applications of this innovation composite beam.

The small solid particles and surfactants inclusion have the potential to furnish abundant nucleation sites, yet the concurrent operation mechanisms in cement remain unclear. Thus, calcium-silicate-hydrate-polycarboxylate ether (C-S-H-PCE) nanoparticles and calcium stearate (CaSt2) all were introduced as composites nucleation agents in this work, and then the properties of fresh cement paste, hydration process and microstructure of hardened pastes were especially investigated. Experimental results demonstrated that C-S-H-PCE and CaSt2 enhanced cement hydration by utilizing their ability to provide nucleation sites, but they were less compatible. Therefore, the combination showed the antagonistic effects: a decrease in fluidity and compressive strength. The decrease in fluidity was mainly attributed to the lowered particle dispersion. The decrease in compressive strength was associated with a lower overall density and increased cumulative porosity of the C-S-H gels. This work establish the theoretical foundation for selecting components of green composite nucleation agents.