Search Results (98)

To address the challenge of balancing flame retardancy and dust suppression in conventional coal mine treatment materials, a multi-component synergistic flame-retardant dust-suppressant gel was fabricated using carboxymethyl cellulose (CMC) as the matrix, compounded with ammonium polyphosphate (APP), zinc borate (ZB), and polycarbodiimide (PCDI) as a cross-linking agent. The optimal formulation was determined via orthogonal experimental design combined with performance characterization, yielding a composition of 1 wt% CMC, 8 wt% APP, 2 wt% ZB, and 0.5 wt% PCDI. Systematic evaluations—including wettability tests, thermogravimetric analysis, and fire-extinguishing trials—demonstrated that the resultant CMC-based composite gel exhibits excellent structural stability and environmental tolerance. Specifically, the contact angle on the coal surface decreased sharply from 72.8° to 17.2°, and the mass loss rate after 30 min of wind erosion was merely 4.16%. Treatment with the gel elevated the critical temperature of the coal–oxygen reaction from 70 °C to 80 °C and reduced CO emissions by 40% at 170 °C. Furthermore, the temperatures corresponding to the maximum weight loss rate, ignition, and burnout increased by 12.9 °C, 16.8 °C, and 28.9 °C, respectively. Fire suppression tests revealed that the gel rapidly cools high-temperature coal seams and effectively prevents reignition. Mechanistic investigations indicate that the CMC-PCDI cross-linked network synergizes with the APP-ZB phosphorus–boron flame-retardant system: the three-dimensional gel architecture provides physical encapsulation and water retention, while the intumescent char layer formed by APP-ZB offers efficient oxygen barrier protection. This study provides a reliable gel-based technical solution for the integrated prevention and control of coal dust pollution and spontaneous combustion disasters in underground mines. Full article

Potassium silicate is used as an inorganic fire-retardant treatment for wood, but its effect on the short-term thermal response of different species under combined temperature–moisture conditions remains insufficiently described. This study investigated spruce (Picea abies (L.) H. Karst) and beech (Fagus sylvatica L.) wood impregnated with potassium silicate and exposed to temperatures representing drying, mild thermal loading and the onset of thermal degradation. The evaluation included impregnation uptake, moisture content, mass changes, heat-transfer behavior, differential scanning calorimetry (DSC), chemical composition, Fourier-transform infrared spectroscopy (FTIR) of isolated cellulose and color measurements. Spruce showed higher uptake than beech, with an average weight percentage gain (WPG) of 10.5% compared with 3.6%. The treatment increased equilibrium moisture content by 2.6 percentage points in spruce and 1.1 percentage points in beech. Heat-transfer measurements showed that temperature and moisture governed heating: higher target temperatures were reached faster, whereas air-conditioned samples heated more slowly due to water evaporation. At lower temperatures, the direct effect of impregnation on heating time was limited, whereas at higher temperatures the treatment more clearly affected the subsequent degradation response. DSC revealed lower thermal resistance of beech and increased endothermic heat absorption in impregnated samples, particularly spruce. Higher-temperature exposure caused mass loss, hemicellulose degradation, moderate cellulose structure modification and visible color changes, with ΔE* exceeding 52 in impregnated spruce after 210 °C. The elevated-temperature response was governed by wood species, uptake, moisture content and thermal exposure level. Full article

This study evaluates the short-term effects of nine commercially available fire retardants (FRs) on water quality under controlled laboratory conditions. FRs were diluted to a 1:10 FR:water stock solution to approximate readily water-extractable fractions, and ion solubility was quantified together with key physicochemical parameters, including pH, electrical conductivity (EC), and dissolved oxygen (DO). Results revealed substantial heterogeneity among formulations in the concentrations of solubilized ions. Notably, FR4 (NP+) exhibited exceptionally high concentrations of NH₄⁺, NO₃⁻, NO₂⁻, PO₄³⁻, and Br⁻, as well as elevated Ca²⁺ and Na⁺. Other formulations also released considerable loads of common nutrients, particularly NO₃⁻ and PO₄³⁻, although at lower magnitudes. Despite the pronounced ionic enrichment, pH and DO remained relatively stable across most treatments. However, DO decreased in several cases at higher FR concentrations, suggesting increased oxygen demand associated with dissolved constituents. EC displayed strong, concentration-dependent increases across treatments, reflecting the rapid dissolution of ionic components in water. Cluster analysis identified three distinct groups of FRs based on their water-quality responses. The PCA biplot further revealed two main gradients structuring the formulations: mineralization and compositional diversity (PC1), and physicochemical solution conditions (PC2), which together distinguish the chemical and physicochemical signatures of the tested products. Overall, the results highlight substantial formulation-specific differences in nutrient and metal release, with potential short-term implications for aquatic chemistry and ecosystem functioning. Although derived from controlled laboratory conditions, these findings provide a first-order assessment of FR impacts on water quality and underscore the importance of considering formulation composition in watershed risk assessments and post-fire water quality management strategies. Full article

This study investigates the reaction of charred wood cladding systems to fire, focusing on the influence of wood species, charred surface treatment, flame retardant treatment, surface coating and board orientation. Nine different configurations of larch and spruce cladding samples with 20 mm thickness were investigated, which were installed into the system according to standard requirements. The samples differed by wood type, charred surface treatment, board orientation, covering with flame retardant agents and additional surface coverings. Two commercial flame retardant treatments and three commercial surface coatings were included in the experimental matrix. Fire behaviour was evaluated according to the EN 13823 Single Burning Item (SBI) method, analysing the ignition time, fire growth rate index, total heat release from the specimen in the first 600 s of exposure to the main burner flames, smoke growth rate index and total smoke production from the specimen in the first 600 s of exposure to the main burner flames as indicators. Although it was determined that the ignition time fluctuated in a relatively narrow range (from 5 min 12 s to 5 min 36 s), analyses of the additional SBI indicators revealed much clearer differences between the systems. The best results were obtained for the charred notched spruce system treated with the phosphate-, urea- and biocide-based flame retardant, which had the longest ignition time and lowest values for the investigated indicators. Meanwhile, the least favourable behaviour was observed in the notched untreated spruce system and in the horizontally oriented system, marked by higher fire spreading and smoke formation values. The obtained results show that the reaction of a wood cladding system to fire is not determined only by the type or application rate of flame retardant, but also the whole system’s structure, including the wood type, surface processing, covering combination and installation configuration. Full article

Flame-retardant coatings and films are widely used to delay flame spread on interior finishing and wood-based materials; however, their fire effluent toxicity has not been sufficiently characterized, and direct comparisons between these product types remain scarce. This study evaluated three commercial flame-retardant coatings and three flame-retardant films using the KS F 2271 gas toxicity test, NES 713 toxicity index test, and Py-GC/MS and HS-GC/MS analyses. Representative coating and film products were also applied to medium-density fiberboard (MDF) to assess average incapacitation time, total smoke release (TSR), and total heat release (THR). All tested specimens, including the 1 coat/layer, increased-loading, and MDF-applied conditions, satisfied the Korean gas toxicity criterion of 9 min. However, increased loading affected the two product groups differently; the intumescent coating showed a marked reduction in average incapacitation time, whereas the films remained relatively stable. The coatings produced higher toxicity indices and more diverse detected gases and pyrolysis products than the films. In MDF-based specimens, flame-retardant treatment increased average incapacitation time and reduced TSR and THR. These findings show that fire effluent toxicity differs between coatings and films and should be considered together with flame-retardant performance. Full article

The growing application of nanotechnology in wood modification has led to significant improvements in the durability, fire resistance, and biological stability of wood-based building materials, such as glued laminated timber (GLT), as well as related chemical products, including fire retardants and anticorrosion preservatives. While numerous review papers have focused on material performance and functionalisation strategies, a comprehensive analysis of the research methodologies employed in this field remains limited. This review addresses this gap by systematically examining the experimental and analytical methods used in studies on nanomaterial-modified wood surface treatments. Scientific articles published and indexed in the Web of Science and Scopus databases within the last ten years were selected using keywords related to wood, nanotechnology, and surface applications simulating industrial timber treatment processes applied in factories and construction sites. Publications were screened according to predefined inclusion and exclusion criteria. The study selection process was conducted according to the PRISMA methodology, and 74 studies meeting the inclusion criteria were selected for the final analysis. Extracted methodological features were coded and analysed using frequency-based descriptive statistics. Considerable methodological heterogeneity was observed among the analysed studies. Softwood species, TiO₂- and ZnO-based nanomaterials, and brushing or immersion treatments represented the most frequently investigated research configurations. Scanning electron microscopy (SEM), often combined with EDS and XRD analyses, occupied a central role within the analytical framework of nanomodified wood research. In contrast, long-term durability assessments, biological resistance testing, and fire-performance evaluations were comparatively underrepresented. The review also revealed substantial variability in the use of testing standards and statistical methods. By linking research methodologies to normative requirements for construction materials, this work provides a methodological framework supporting future research, standardisation, certification, and commercial implementation of nanomaterial-based wood protection systems. Full article

To investigate the effects of different surface coating treatments on the fire resistance of Qing Dynasty traditional corridor-style timber structures, the Long Corridor of the Beijing Summer Palace was selected as the case study. Two representative timber species, red pine and larch, were examined under three treatment conditions, including no treatment, traditional treatment (“San-dao-hui” and “Yi-ma-wu-hui”), and composite treatment combining traditional treatment with modern flame-retardant coatings. Cone calorimeter (CC) testing and Fire Dynamics Simulator (FDS) simulation were used to systematically investigate their combustion performance and fire spread patterns. Results indicate a clear, gradual improvement in timber reaction to fire: composite treatment coating performed best, followed by plaster layer protection, and untreated wood performed the worst. Among these, the composite treatment of red pine with “Yi-ma-wu-hui” (one hemp layer and five lime plaster layers) combined with modern flame-retardant coating showed the highest overall efficacy. The time to ignition (TTI) reached 76.7 s, a 210.5% increase compared with untreated wood. Meanwhile, peak heat release rate and carbon monoxide production were both significantly reduced. Notably, the selected modern flame-retardant coating cures colorless and transparent, preserving the original appearance of the wood, and the composite treatment maintains the historical texture and color consistency required for heritage restoration. The flame-retardant efficiency of the “Yi-ma-wu-hui” plaster layer was superior to that of the “San-dao-hui” (three lime plaster layers), owing to its denser structure that provides a stronger physical barrier effect. Larch exhibited better inherent reaction to fire than red pine, and surface coating treatments effectively reduced differences between substrates. FDS simulations confirmed that the composite treatment could keep peak heat release rate below 6000 kW under the most adverse meteorological conditions, confining high temperatures and dense smoke near the ignition point and effectively restraining sequential fire spread in traditional corridor-style timber structures. These findings provide a scientific basis and practical guidance for the fire-resistant restoration of Qing Dynasty traditional corridor-style timber structures and similar heritage buildings. Full article

Bamboo, as a rapidly renewable and sustainable material, has gained increasing attention in the construction, furniture, automotive interiors, and packaging industries due to its excellent mechanical properties, light weight, and environmental friendliness. However, the inherent flammability of bamboo, characterized by its porous structure and high hemicellulose content, poses a significant fire hazard that severely limits its wide application. This review systematically synthesizes recent advances in the fire performance and flame-retardant modification of bamboo-based materials. First, the thermal degradation behavior and combustion mechanisms of bamboo are discussed in relation to its primary chemical constituents, including cellulose, hemicellulose, and lignin. Subsequently, various flame-retardant strategies are reviewed, including inorganic flame retardants, phosphorus–nitrogen systems, nanomaterial-based additives, and bio-based flame-retardant approaches. The effectiveness of different modification techniques, such as impregnation treatment, adhesive modification, and surface coating, is also analyzed. Future research directions are proposed, emphasizing the development of environmentally friendly flame-retardant systems, multifunctional modification strategies, and the design of high-performance flame-retardant bamboo-based materials. This review aims to provide a comprehensive framework for advancing the fire safety design and sustainable application of bamboo-based materials. Full article

Polymer cement-based coatings (PCC) have great potential in protecting underground structures, while their flame -retardancy is limited by the flammability of the polymer components. Developing multifunctional inorganic fillers that can enhance both mechanical properties and flame retardancy is crucial for improving the safety and durability of the coatings. In this study, an ettringite (AFt) modified by amphiphilic group and aluminum hydroxide (AH) was subjected to surface functionalization treatment and then incorporated into the PCC to enhance the overall performance of the material. The tensile strength and bond strength of the coatings modified by amphiphilic group with AFt were increased by 27.7% and 22.4%, respectively. Meanwhile, the flame burn time, flameless burn time, and carbonization length were reduced by 89.1%, 80.6%, and 90.2%, respectively, and the limiting oxygen index (LOI) increased by 28.9%. The amphiphilic groups act as molecular bridges that couple the inorganic modified AFt with the organic VAE phase, thereby strengthening the organic–inorganic interface and promoting a more integrated polymer–cement network. Meanwhile, the well-dispersed inorganic phases provide endothermic dehydration and a protective residue during heating, jointly improving the mechanical reliability and fire safety of the PCC. Full article

Glued-laminated timber (GLT) and cross-laminated timber (CLT) panels are increasingly used as exposed structural elements in representative buildings. These structures are often part of public-use areas, which require the application of restrictive fire-safety measures without significantly affecting the color of exposed wooden surfaces during the service life of these building elements. The effect of fire-retardant treatments on the color of Scots pine (Pinus sylvestris L.) wood was evaluated using five impregnation agents with different active substances. Changes in gloss and color characteristics—lightness (L*), green-red coordinate (a*), and blue-and-yellow coordinate (b*)—were measured sequentially directly after impregnation, after exposure to variable humidity conditions and after exposure to UV radiation. The total color difference (ΔE*) ranged from 2.82 to 17.76 after impregnation and increased to 6.31–20.71 after aging, indicating a risk of aesthetic deterioration of fire-retardant-treated wood surfaces under typical service conditions for timber structures in representative buildings. The most pronounced color changes were observed for the fire retardant containing potassium and copper compounds (FR4) and the combination of 2-aminoethanol with boric acid (FR5). Full article

To effectively prevent and control coal spontaneous combustion, a novel heat-sensitive hydrogel for mine fire prevention and extinguishment was developed using hydroxypropyl methylcellulose (HPMC) and the organic flame-retardant, sodium alginate (SA). The hydrogel was prepared through single-factor variable control and material compounding. First, the optimal formulation of the hydrogel was determined using analytical instruments and techniques, including a viscometer, vacuum drying oven, and the inverted test tube method. Subsequently, its microstructural characteristics were examined using scanning electron microscopy (SEM) and infrared spectroscopy (FTIR). Finally, a fire suppression test platform was established to perform comparative experiments, verifying the hydrogel’s fire prevention, extinguishing, and cooling performance. Experimental results demonstrated that the optimal hydrogel formulation consists of 2.5 wt% HPMC and 0.3 wt% SA. At this ratio, the hydrogel exhibits excellent fluidity and water retention, ensuring prolonged coverage and wetting of coal surfaces. The gel undergoes a sol–gel phase transition at 58 °C, enabling it to fill voids, bind and reinforce coal particles, and reduce exposed surface area. After drying, the hydrogel forms a uniformly smooth surface capable of both coating the coal body and encapsulating individual coal particles. Following the hydrogel treatment, the coal sample retains its original functional groups, indicating that no chemical reactions occur during mixing. Compared with traditional inhibitors, the hydrogel demonstrates superior fire suppression performance, more effectively covering and encapsulating burning coal. It rapidly reduces the temperature to 28 °C by the cooling effect of water evaporation from the hydrogel, and it maintains thermal stability, achieving outstanding fire-extinguishing efficiency. Full article

Polyester/cotton blended fabrics—valued for comfort and durability—face significant fire hazards due to a synergistic “scaffold effect” during combustion. Conventional treatments with high temperature or some acidic phosphorus flame retardants during preparation often compromise the mechanical strength. Inspired by mussel adhesion chemistry, a mechanically enhanced polyester/cotton fabric was developed by using a novel bio-inspired phosphorus/nitrogen (P/N) synergistic coating. A uniform polydopamine-polyethylenimine (PDA-PEI) layer is rapidly deposited via co-deposition, suppressing dopamine self-polymerization. Subsequent covalent bonding with 2,2-dimethyl-1,3-propanediyl bis (phosphoryl chloride) (DPPC) establishes a robust P/N network. The fabricated PDA-PEI/DPPC coating reduces peak heat release rate (pHRR) and total heat release (THR) by 57.7% and 32.6%, respectively, in cone calorimetry, achieving self-extinguishment and a high limiting oxygen index (LOI) of 24.6%. Remarkably, the coating simultaneously increases the weft-direction breaking strength by 55% and elongation at break by 27.2%; these changes overcome the typical mechanical degradation associated with acidic phosphorus flame retardants. A comprehensive analysis reveals a synergistic mechanism: phosphoric acids catalyze cellulose dehydration and char layer formation in the condensed phase (90% stable C–C bonds), while radical scavengers (PO·, HPO·, and PDA) and non-flammable gases suppressed gas-phase combustion. This work presents a facile and effective strategy for fabricating high-performance and mechanically robust flame retardant polyester/cotton textiles, demonstrating the significant potential for improving fire safety in practical applications. Full article

Urban leaf litter represents an underutilized biomass resource with potential applications in sustainable building materials. This study investigates the suitability of dried, comminuted leaves collected from municipal green areas as a loose-fill thermal insulation material. The material was characterized in terms of thermal conductivity, settlement behavior, fire reaction, resistance to mold growth, water vapor diffusion, hygroscopic sorption, and short-term water absorption. Tests were conducted following relevant DIN and ISO standards, with both untreated and flame-retardant-treated samples examined. Results indicate that the thermal conductivity of leaf-based insulation (λ = 0.041–0.046 W/m·K) is comparable to other bio-based loose-fill materials such as cellulose and wood fiber. Optimal performance was achieved for particles sized 2–16 mm, showing settlement below 1%. All variants, including untreated material, fulfilled the fire resistance requirements of class E, while selected treatments further improved fire resistance. The material exhibited moderate vapor permeability (μ ≈ 4–5), low water absorption, and moisture buffering behavior similar to that of other bio-based insulation materials. Resistance to mold growth was satisfactory under standardized conditions. Overall, the results demonstrate that leaf litter can serve as an effective and environmentally favorable loose-fill insulation material, offering an innovative recycling pathway for urban green waste. Full article

Lignocellulosic bio-based materials, such as wood, biocomposites, and natural fibers, exhibit desirable structural properties. This comprehensive review emphasizes the foundational and latest advancements in bioinspired improvement strategies, such as direct mineralization, biomineralization, lignocellulosic nanomaterials, protein-based treatments, and metal-chelating processes. Significant focus was placed on biomimetics, emulating natural protective mechanisms, with discussions on relevant topics including hierarchical mineral deposition, free-radical formation and quenching, and selective metal ion binding, and relating them to lignocellulosic bio-based material property improvements, particularly against fire and fungi. This review evaluates the effectiveness of different bioinspired processes: mineralized and biomineralized composites improve thermal stability, nanocellulose and lignin nanoparticles provide physical, thermal, and chemical barriers, proteins offer biochemical inhibition and mineral templating, and chelators interfere with fungal oxidative pathways while simultaneously improving fire retardancy through selective binding with metal ions. Synergistic approaches integrating various mechanisms could potentially lead to long-lasting and multifunctional protection. This review also highlights the research gaps, challenges, and potential for future applications. Full article

Calcium magnesium phosphate cements (CMPCs) were obtained starting from dolomite (alone or mixed with fly ash) thermally treated at two different temperatures. Dolomite calcination at 750 °C for 3 h determined the formation of a mixture of MgO and CaCO₃. The mixing of dolomite with fly ash and the increase in the calcination temperature at 1200 °C determined the formation of new compounds (calcium aluminum silicate and calcium magnesium silicates), which are present along with MgO and small amounts of CaO in the thermally treated material. These two precursors were mixed with KH₂PO₄ solution and borax (as a retardant admixture) to obtain the CMPCs. The setting time and compressive strengths of these CMPCs were assessed and the XRD analyses provided insights into their mineralogical composition after hardening and thermal treatment. The cements, as so or mixed with perlite, were applied on steel plates, to assess their behavior when put in direct contact with a flame. The compatibility of these materials with the steel substrate was evaluated by scanning electron microscopy (SEM). The direct contact with the flame up to 60 min provided information regarding the CMPCs’ ability to prevent the rapid increase in the substrate (steel plate) temperature. The findings indicate that CMPC pastes and composites containing perlite can offer a degree of protection for steel structures in the event of a fire. Full article