Search Results (778)

Low carbon, low cost and sustainability are important development trends of ultra-high-performance concrete (UHPC). In this study, municipal solid waste incineration bottom ash (MSWIBA) was used to replace 5%, 10%, 20% and 30% of quartz sand (QS), respectively, and the effect of the MSWIBA substitution rate on the workability, wet packing density, mechanical properties, shrinkage, resistance to chloride ion corrosion, and resistance to sulfate corrosion of UHPC was studied. The mechanism analysis was carried out by combining X-ray diffraction (XRD), thermogravimetric analysis (TG), and scanning electron microscopy (SEM) tests, and UHPC heavy metal leaching tests, environmental impact assessment, and economic analysis were conducted. Results show that the active silicon and aluminum components in MSWIBA reacted with cement hydration products to optimize the matrix density. MSWIBA has an internal curing effect, which is beneficial for reducing the shrinkage of UHPC. When the MSWIBA replacement rate is 10%, the 28-day compressive strength of MSWIBA-UHPC is 128.7 MPa, which is equivalent to the benchmark group. The fluidity, corrosion resistance and heavy metal leaching all meet the requirements. The energy consumption, carbon emissions and costs are reduced by 0.22%, 2.30% and 6.67%, respectively. The research results can provide a reference for the development of ecological UHPC with economic, low-carbon and environmental benefits, as well as the harmless disposal and resource utilization of hazardous wastes such as MSWIBA. Full article

Concrete structures are vulnerable to sulfate attacks during their service life, as sulfate ions react with cement hydration products to form expansive phases, generating internal stresses that cause mechanical degradation. In this study, a cementitious capillary crystalline waterproofing material (CCCW) was incorporated into concrete to mitigate sulfate ingress and enhance sulfate resistance. The evolution of compressive strength, ultrasonic pulse velocity, dynamic elastic modulus, and the microstructure of concrete was investigated in sulfate-exposed concretes with varying CCCW dosages and strength grades; the sulfate ion concentration profiles were also analyzed. The results indicate that the enhancement effect of CCCW on sulfate resistance declines progressively with increasing concrete strength. The formation of calcium silicate hydrate and calcium carbonate fills the pores of concrete, hindering the intrusion of sulfate solution. Moreover, the self-healing effect of concrete further inhibits the diffusion of sulfate ions through cracks, improving the sulfate resistance of concrete. These findings provide critical insights and practical guidance for improving concrete resistance to sulfate-induced deterioration. Full article

Medium and heavy rare earths (REEs) are mainly from weathered crust elution-deposited rare earth ores (WREOs), where REEs are adsorbed in ionic form on the surface of clay minerals such as kaolinite, illite, halloysite, etc. REEs in WREOs are extracted through the in situ leaching process with (NH₄)₂SO₄ solution via ion exchange. However, this process often results in the swelling of clay minerals, subsequently destroying the ore body structure and causing landslides. This study investigated the inhibitory effects of humic acid (HA) on the swelling of primary clay minerals. An optimal inhibition on the swelling of clay minerals was demonstrated at 0.2 g/L. HA was mixed with 0.1 mol/L (NH₄)₂SO₄ solution at the solution pH of 6.8 and temperature of 25 °C. The swelling efficiency of kaolinite, illite, and halloysite in presence of HA decreased by 0.29%, 1.19%, and 0.19%, respectively, compared to using (NH₄)₂SO₄ alone. The surface hydration parameter of clay minerals was further calculated through viscosity theory. It was demonstrated that the surface hydration parameter of kaolinite and halloysite decreased nearly threefold, while that of illite decreased fivefold, demonstrating a desirable inhibition on clay swelling with HA. Viscosity theory offers valuable theoretical support for the development of anti-swelling agents. Full article

Waste management poses escalating threats to environmental sustainability, particularly with municipal solid waste (MSW) growth. Incineration, a widely adopted method for reducing waste volume, produces millions of tons of municipal solid waste incineration fly ash (MSWIFA) each year. Despite its high toxicity and classification as a hazardous solid waste, its ultrafine particle size and pozzolanic activity offer potential for its use in construction materials. In this study, MSWIFA was used to replace 6%, 12%, 18% and 24% of cementitious materials, and the effect of MSWIFA substitution rate on the workability, mechanical properties, microstructure, and durability of UHPC was studied. Furthermore, the study assessed the solidification capacity of the UHPC for heavy metal ions and quantitatively analyzed its eco-economic benefits. The results show that, under standard curing conditions, substituting 12% of cementitious materials with MSWIFA significantly modified UHPC hydration, shortened setting time, reduced fluidity, and increased wet packing density. The 28-day compressive strength reached 134.63 MPa, comparable to the control group. Concurrently, fluidity, durability, and heavy metal leaching all met the required standards, with energy consumption reduced by 14.86%, carbon emissions lowered by 12.76%, and economic costs decreased by 6.41%. This study provides a feasible solution for recycling MSWIFA into non-hazardous concrete, facilitating sustainable hazardous waste management and mitigating heavy metal-related environmental pollution. Full article

The durability of cement-based materials can be reduced by the invasion of water and ions from external environments. This can be alleviated by reducing the surface wettability. To evaluate the anti-wetting performances of different graphene-based materials, a molecular dynamics simulation was performed to investigate the wetting behaviors of water and NaCl droplets on a tobermorite surface coated with graphene and functionalized graphene (G-NH₂ and G-CH₃). The results demonstrate that functionalized graphene displays weak surface binding with water and ions, significantly weakening droplet wettability. Moreover, functionalized graphene surfaces exhibit reduced ion immobilization capacity compared with a pristine tobermorite surface. It obviously increases the number of free ionic hydration shells, thus amplifying the influence of ionic cage restriction. Specifically for the G-CH₃ surface, the contact angle of the NaCl droplet reaches 94.8°, indicating significant hydrophobicity. Furthermore, the adhesion between functionalized graphene and tobermorite is attributed to the interlocking characteristics of these materials. Hopefully, this study can provide nanoscale insights for the design of functionalized graphene coatings to improve the durability of cement-based materials under harsh environments. Full article

Polymer-based superplasticizers represent an emerging class of additives in cement and concrete production with demonstrated effects on zeta potential, ion exchange, turbidity and rheological behavior during hydration. This study examines the influence of polymer-based grinding aids focusing on the dosage of A2 on the grinding performance of Portland cement. Among the tested additives, A2 exhibited superior dispersing ability and agglomeration-preventing activity, yielding a zeta potential of −8.98 mV. Correspondingly, the release of the ion concentration of Ca²⁺ decreased to 190 mg/L, while SO₄²⁻ increased to 400 mg/L, indicating enhanced ionic interaction at the optimal A2 dosage of 2.5 g. The turbidity tests further revealed that cement samples ground with 2.5 g of A2 remained homogeneously suspended for longer periods compared to other additives. Overall, the analysis of cement surface properties confirmed that polymer-based grinding aids, particularly A2, significantly improve the dispersion stability of cement particles during grinding. Full article

Wet–dry cycles are a key factor aggravating the durability degradation of foam concrete. To address this issue, this study prepared bentonite slurry–steel slag foam concrete (with steel slag and cement as main raw materials, and bentonite slurry as admixture) using the physical foaming method. Based on 7-day unconfined compressive strength tests with different mix proportions, the optimal mix proportion was determined as follows: mass ratio of bentonite to water 1:15, steel slag content 10%, and mass fraction of bentonite slurry 5%. Based on this optimal mix proportion, dry–wet cycle tests were carried out in both water and salt solution environments to systematically analyze the improvement effect of steel slag and bentonite slurry on the durability of foam concrete. The results show the following: steel slag can act as fine aggregate to play a skeleton role; after fully mixing with cement paste, it wraps the outer wall of foam, which not only reduces foam breakage but also inhibits the formation of large pores inside the specimen; bentonite slurry can densify the interface transition zone, improve the toughness of foam concrete, and inhibit the initiation and propagation of matrix cracks during the dry–wet cycle process; the composite addition of the two can significantly enhance the water erosion resistance and salt solution erosion resistance of foam concrete. The dry–wet cycle in the salt solution environment causes more severe erosion damage to foam concrete. The main reason is that, after chloride ions invade the cement matrix, they erode hydration products and generate expansive substances, thereby aggravating the matrix damage. Scanning Electron Microscopy (SEM) analysis shows that, whether in water environment or salt solution environment, the fractal dimension of foam concrete decreased slightly with an increasing number of wet–dry cycle times. Based on fractal theory, this study established a compressive strength–porosity prediction model and a dense concrete compressive strength–dry–wet cycle times prediction model, and both models were validated against experimental data from other researchers. The research results can provide technical support for the development of durable foam concrete in harsh environments and the high-value utilization of steel slag solid waste, and are applicable to civil engineering lightweight porous material application scenarios requiring resistance to dry–wet cycle erosion, such as wall bodies and subgrade filling. Full article

The utilization of sugarcane molasses (SCM), a byproduct of sugar refining, offers a promising bio-based alternative to conventional chemical admixtures in cementitious systems. This study investigates the effects of SCM at five dosage levels, 0.25%, 0.50%, 0.75%, 1.00%, and 1.25% by weight of cement, on cement mortar performance across fresh, mechanical, thermal, durability, and density criteria. A comprehensive experimental methodology was employed, including flow table testing, compressive strength (7, 14, and 28 days) and flexural strength measurements, embedded thermal sensors for real-time hydration monitoring, water absorption and chloride ion penetration tests, as well as 28-day density determination. Results revealed clear dose-dependent behavior, with SCM enhancing mortar flowability proportional to dosage, raising the spread diameter from 11.5 cm (control) to 20 cm at 1.25%. At 0.25% SCM, compressive strength (47.5 MPa at 28 days) and flexural strength (~2.9 MPa) were higher than those of the remaining SCM dosages, supported by sustained heat release and positive temperature differentials. However, dosages ≥ 0.5% drastically suppressed hydration kinetics and mechanical performance, with compressive strength falling below 10 MPa. Furthermore, high SCM content led to increased water absorption (up to 10.6%) and chloride permeability (CIP above 5100 C), while bulk density declined from 2250 kg/m³ to 2080 kg/m³ at 1.25% SCM. Statistical validation using one-way ANOVA confirmed that these differences across dosage levels were significant (p < 0.05), underscoring the importance of dosage optimization. This investigation confirms that low-dosage SCM (≤0.25%) can be an effective bio-additive, providing improved workability with negligible compromise in strength and durability. In contrast, higher dosages undermine matrix integrity and performance. Future work is recommended to assess long-term microstructural evolution, field exposure durability, and adaptability across diverse cementitious systems. Full article

The inherent hydrophobicity of poly(vinylidene fluoride) (PVDF) ultrafiltration membranes leads to severe membrane fouling when processing proteinaceous solutions and organic contaminants, significantly limiting their practical applications. This study presents a novel metal-ion mediated co-deposition strategy for fabricating high-performance antifouling poly(vinylidene fluoride) (PVDF) hollow fiber ultrafiltration membranes. Through Zn²⁺ coordination-driven self-assembly, a uniform and stable composite coating of dopamine (DA), tannic acid (TA), and ZIF-8 nanoparticles was successfully constructed on the membrane surface under mild conditions. The modified membrane exhibited significantly enhanced hydrophilicity, with a water contact angle of 21° and zeta potential of −29.68 mV, facilitating the formation of a dense hydration layer that effectively prevented protein adhesion. The membrane demonstrated exceptional separation performance, achieving a pure water permeability of 771 L/(m²∙h∙bar) and bovine serum albumin (BSA) rejection of 97.7%. Furthermore, it showed outstanding antifouling capability with flux recovery rates exceeding 83.6%, 74.7%, and 71.5% after fouling by BSA, lysozyme, and ovalbumin, respectively. xDLVO analysis revealed substantially increased interfacial free energy and stronger repulsive interactions between the modified surface and protein foulants. The antifouling mechanism was attributed to the synergistic effects of hydration layer formation, optimized pore structure, additional water transport pathways from ZIF-8 incorporation, and electrostatic repulsion from negatively charged surface groups. This work provides valuable insights into the rational design of high-performance antifouling membranes for sustainable water treatment and protein separation applications. Full article

Gellan gum (GG) is a promising biomaterial due to its biocompatibility, tunable gelation, and modifiability. This study investigates the influence of triple crosslinking mechanisms—thermal gelation, UV-induced covalent crosslinking, and ionic crosslinking—on the mechanical and physicochemical properties of GG-based hydrogels, designed to function as a neuromaterial with hierarchical neuro-architecture as a potential nerve substitute for peripheral nerve injury. Initial thermal gelation forms a physical network via double-helix junctions. Methacrylation introduces vinyl groups enabling UV crosslinking, while post-treatment with Mg²⁺ ions strengthens the network through ionic bridging with carboxylate groups. Plasticizers—glycerol and triethyl citrate—were incorporated to modulate chain mobility, network hydration, swelling behavior, and mechanical flexibility. Seven-day erosion studies showed that glycerol-containing hydrogels eroded 50–60% faster than those with triethyl citrate and up to 70% more than hydrogels without plasticizers, indicating increased hydrophilicity and matrix loosening. In contrast, triethyl citrate reduced erosion, likely due to tighter polymer chain interactions and reduced network porosity. Mechanical testing of 1% v/v methacrylated GG hydrogels revealed that 1.5% v/v triethyl citrate combined with UV curing (30–45 min) produced tensile strengths of 8.76–10.84 MPa. These findings underscore the synergistic effect of sequential crosslinking and plasticizer choice in tuning hydrogel mechanical properties for neuro application. The resulting hydrogels offer potential as a neuromaterial in peripheral nerve injury where gradient mechanical properties with hydration-responsive behavior are required. Full article

Basic magnesium sulfate cement (BMSC) has attracted increasing attention as a low-carbon alternative to traditional Portland cement. Therefore, this study investigates the feasibility of using carbonated boron mud (CBM), an industrial solid waste, as a partial substitute for magnesium oxide (MgO) in BMSC. Prior to its incorporation into the cementitious matrix, boron mud (BM) underwent rapid carbonation treatment to improve its reactivity, microstructure compatibility, and CO₂ sequestration potential. Experimental results from macroscopic and microscopic analyses confirmed the effectiveness of the carbonation process, showing that the carbonate ions carried by the CBM were successfully incorporated into the cementitious system. These carbonate ions reacted with MgO to form stable magnesium carbonate phases, effectively suppressing the formation of magnesium hydroxide (Mg(OH)₂), which typically detracts from strength and stability. Compared to BMSC specimens containing untreated BM, the CBM-modified BMSC exhibited significantly improved mechanical performance and excellent volume stability. Furthermore, the carbonation pre-treatment effectively mitigated volumetric instabilities associated with rapid MgO hydration, thereby promoting a more favorable environment for the formation of the crucial 5·1·7 phase (5Mg(OH)₂·MgSO₄·7H₂O). Overall, this research presents a promising strategy for producing CBM-BMSC, offering a sustainable approach to CO₂ utilization and enhancing the volume stability of magnesium-based cements, providing a new direction for improving the sustainability of the concrete industry and advancing the development of magnesium cements. Full article

Mutations in the CFTR genes causing cystic fibrosis (CF) are associated with the presence of thick, viscous mucus and the formation of biofilms in the gastrointestinal tract (GI) that impair intestinal homeostasis, triggering chronic inflammation, epithelial barrier dysfunction, and changes in the composition and activity of the gut microbiota. CFTR protein modulators represent a promising approach to enhancing lower GI function in patients with CF. The aim of the review is to present the complex relationships between the presence of CFTR gene mutations and the gut microbiota dysbiosis in patients with cystic fibrosis. Mutations in the CFTR gene, the molecular basis of cystic fibrosis (CF), disrupt epithelial ion transport and profoundly alter the gastrointestinal environment. Defective chloride and bicarbonate secretion leads to dehydration of the mucosal layer, increased mucus viscosity, and the formation of biofilms that favour microbial persistence, which together promote gut microbiota dysbiosis. This dysbiotic state contributes to impaired epithelial barrier function, chronic intestinal inflammation, and abnormal immune activation, thereby reinforcing disease progression. The interplay between CFTR dysfunction and microbial imbalance appears to be bidirectional, as dysbiosis may further exacerbate epithelial stress and inflammatory signalling. Therapeutic interventions with CFTR protein modulators offer the potential to partially restore epithelial physiology, improve mucus hydration, and foster a microbial milieu more consistent with intestinal homeostasis. The aim of this review is to elucidate the complex relationships between CFTR gene mutations and gut microbiota dysbiosis in patients with cystic fibrosis, with a particular emphasis on the clinical implications of these interactions and their potential to inform novel therapeutic strategies. Full article

This study systematically investigated the dissolution equilibrium of lithium carbonate (Li₂CO₃) in mixed Na₂CO₃-NaCl aqueous solutions through isothermal dissolution experiments spanning 283.15–353.15 K. Precise solubility determinations were conducted using a gravimetric analysis under controlled thermodynamic conditions. The obtained solubility data were successfully correlated with the Extended Debye–Hückel (E-DH) model, yielding residual standard deviations below 0.09, which validates the model’s applicability in this ternary system. Both experimental observations and theoretical predictions confirmed that increasing the salt molality enhances the synergistic suppression of the Li₂CO₃ solubility through combined common-ion and salt effects. The thermodynamic analysis revealed the dissolution process to be exothermic (ΔH_d < 0), and entropy change dominates (ξ_S ≈ 78%), with negative entropy changes (ΔS_d < 0) indicating predominant hydration ordering effects. These mechanistic insights establish critical thermodynamic benchmarks for optimizing lithium carbonate precipitation processes in brine lithium extraction operations. Full article

Octacalcium phosphate (OCP) is a calcium phosphate compound with a layered structure in which apatite layers, which have a structure similar to hydroxyapatite, and hydrated layers are stacked alternately. OCP can incorporate various carboxylate ions into its interlayers. OCPs with incorporated carboxylate ions, also known as OCP carboxylates (OCPCs), are organically modified at the molecular level. OCPCs are an attractive research target in a wide range of fields, from basic inorganic chemistry to applied materials chemistry. Therefore, it is expected that a comprehensive overview of recent research on OCPCs will be useful in progressing this field. This review focuses on recent advances in OCPCs, namely their synthesis, the identification of new types of carboxylate ions that can be incorporated into OCP interlayers, the steric structure estimation of the interlayer carboxylate ions, and applications of OCPCs as functional materials. OCPC-based functional materials include fluorescent materials, artificial bones, and adsorbents. Furthermore, based on existing studies, challenges in OCPC research and future research directions are described. Full article

Alkanolamine additives play a critical role in enhancing the early process performance of cement slurries, thereby improving construction efficiency and structural durability. This study systematically evaluates the effects of ethanolamine (EA), diethanolamine (DEA), and triethanolamine (TEA) on cement slurry properties, including the thickening time, rheology, density, shrinkage, and hydration kinetics. Clear structure–activity relationships are established based on the findings. The experimental analysis demonstrated that increasing the hydroxyl group count in the alkanolamines significantly accelerated cement hydration. At a dosage of 1.0%, the thickening time of the cement slurry was significantly shortened to 125 min (EA), 15 min (DEA), and 12 min (TEA), respectively. Concomitantly, a reduction in fluidity was observed, with flow diameters measuring 15.8 cm (EA), 14.6 cm (DEA), and 14.1 cm (TEA). The rheological analysis revealed that the alkanolamine additives significantly increased the consistency coefficient (K) and decreased the flowability index (n) of the slurry, with TEA exhibiting the most pronounced effect. The density measurements confirmed the enhanced settlement stability, as the density differences diminished to 0.1 g/cm³ at the optimal dosages (0.6% TEA and 0.8% DEA). The hydration degree analysis indicated a hydration rate acceleration of up to 32% relative to plain slurry, attributed to the hydroxyl-facilitated promotion of Ca(OH)₂ formation and C₃S dissolution. The XRD analysis confirmed that the alkanolamines modified the reaction kinetics without inducing phase transformation in the hydration products. Crucially, the hydroxyl group count governed the performance: a higher hydroxyl density intensified Ca²⁺/Al³⁺ complexation, thereby reducing ion mobility and accelerating setting. These findings establish a molecular design framework for alkanolamine-based additives that balances early process performance development with practical workability. The study advances sustainable cement technology by enabling targeted optimization of rheological and mechanical properties in high-demand engineering applications. Full article