Fire and Materials最新文献

Given the seriousness of fire safety issues in high-altitude traffic tunnels, it is essential to investigate the spatial temperature characteristics under the coupling of multiple factors and their correlation with fire safety elements. This study systematically conducted full-scale simulation analyses of highway tunnels to reveal the distribution of transverse and longitudinal spatial temperature as well as the longitudinal smoke diffusion patterns. Based on the simulation data, an integrated approach utilizing orthogonal test analysis, deviation analysis, and sensitivity analysis was employed to explore the impacts of various factors, including altitude, the transverse position of the fire source, fire scale, and wind speed, on tunnel fire safety. The results indicate that the influence of altitude on the longitudinal temperature along the arch and the position of spatial cross-section characteristic points varies. Longitudinal ventilation speed is a relatively key factor affecting tunnel fire safety, particularly in terms of arch temperature and smoke backflow length, where its impact is significant. Additionally, fire scale has a notable impact on evacuation safety, with its overall influence ranking just below that of wind speed. In contrast, altitude and fire source position have relatively minor effects on tunnel fire safety. Inadequate longitudinal ventilation hinders the escape of personnel during tunnel fires, indicating that the design and operation of ventilation systems should be prioritized in fire prevention and control strategies. The findings of this study have significant practical implications for optimizing fire prevention and response capabilities in high-altitude tunnels.

To optimize the performance of inorganic solidified foam and apply it effectively in forest fire fighting, three different ionic surfactants were combined with four viscosity-increasing foam stabilizers. Then, the ratio of inorganic solidified foam was changed to investigate the effects of four factors, namely, water–binder ratio, quick-setting agent dosing, fly ash dosing, and foam dosing, on the foaming multiple and stability of the inorganic solidified foam. Finally, the fluidity and adhesion ability of the inorganic solidified foam were tested with different quick-setting agent dosages and foam dosages, and the optimal working condition range of the inorganic solidified foam was determined based on the test results. The results showed that when SDS:APG = 7:1, the foaming multiples of the foam were higher and it could reach 52.5 times when the surfactant content in the solution was 1.2 wt%; among the four viscosity-increasing stabilizers, the stabilizing effect of xanthan gum was the best. The inorganic solidified foam exhibits an extended foaming time when utilizing a water–binder ratio of 0.45 and a fly ash dosage of 0.5. To ensure optimal mobility and a specific adhesion thickness, it is recommended to maintain a foam dosage of 6 V or higher, with mobility falling within the 11–13 range. The preferred ratio for creating inorganic solidified foam involves a water–binder ratio of 0.45, a 0.6 wt% dosage of accelerating agent, a 0.5 fly ash content, and a foam mixing of 7 V.

As wildfire risks increase, it is essential to retrofit the existing housing stock in wildfire-prone areas to reduce community wildfire risk. Yet there are significant questions regarding the costs and most effective strategies to retrofit homes for improved wildfire resistance. This article identifies the costs for retrofitting homes to meet the requirements specified by Chapter 7A (Materials and Construction Methods for Exterior Wildfire Exposure) in the California Building Code. Guidance from recent research related to ignition-resistant construction was also utilized. Construction costs were calculated as a per-unit value and were explicit to the exterior components of the home. Detailed estimates are offered for upgrading a home's exterior walls, roof, deck, windows and doors, under-eave areas, gutters, and near-home landscaping. Analysis demonstrates that some of the most effective strategies to reduce structure vulnerability to wildfire can be done affordably. This analysis suggested that for a typical 2000-square-foot home in California, retrofitting costs can be as low as $2000 for minimal retrofits to $100,000 for the highest level of protection.

This article presents a comprehensive study of the insulation materials used for lithium-ion battery fire blanket coatings. First, a novel testing method is introduced to quantify the impact of insulating agents on the softness and wraparound capabilities of the blanket. Second, to guarantee the explosion resistance as well as other functions of the blanket, insulation materials are introduced, and the insulation effectiveness of various insulating agents is assessed using a 1200°C flame, with findings indicating that a 10% addition of 20 nm silica aerogel yields the best insulation effect. Further analysis of the influence of insulating agents on the release of pyrolysis particles and smoke reveals that both concentrations are elevated compared to the bare silicon dioxide cloth, thereby enabling fire detectors to trigger alarms at the earliest possible stage. Finally, low-temperature tests are conducted to verify the enhanced insulation properties of the coating in non-fire scenarios. The outcomes confirm that a 10% addition of 20 nm silica aerogel provides the best insulation. The research results demonstrate that this innovative coating exhibits outstanding insulation performance across a broad temperature range and offers significant fire detection and protection functionalities.

In February 2024, a total of 221 recorded excess wildfires occurred throughout Guizhou Province. The atypical weather conditions attributed to climate change, seasonal drought during the non-monsoon period, and human activities associated with the Spring Festival are identified as the primary factors contributing to this period of extensive wildfires. To facilitate a comprehensive assessment of the local ecosystem, analyses were conducted on precipitation, temperature, air quality index records, and water quality monitoring of downstream lakes and rivers. The early onset of the rainy season in April exacerbated soil erosion in Guizhou Province, where 81% of the terrain is mountainous. The repercussions of the excess wildfires on the downstream surface water ecosystem may persist for several months. The findings revealed significant differences in biomass accumulation and response times between rivers and lakes. A more thorough understanding of the impacts of wildfires on water and soil is essential for the formulation of effective recovery policies aimed at safeguarding downstream water resources.

Two organizations in the United States have developed codes to protect against the hazards associated with wildfires: the International Code Council (ICC; a private not-for-profit organization) and the state of California. Both codes contain strict requirements that, when put into effect, do significantly improve fire safety. The ICC code (IWUIC) has been adopted (either as issued or with amendments) by several states in the USA while the California code (CA Chapter 7A) applies only in that state. There are many similarities between both sets of codes but there are also some clear differences. The most important difference is that CA Chapter 7A allows wood that has not been treated with fire retardants (untreated wood) to be used on decks and walls, while the IWUIC requires the use of materials with improved fire performance for those applications. On the other hand, there are also requirements in CA Chapter 7A that are more conducive to fire safety than the equivalent ones in the IWUIC. One example is the fact that CA Chapter 7A does not permit the use of coated wood materials, in view of the act that all wildland applications involve exterior use and that coatings on wood materials have been shown to be susceptible to suffer fire performance degradation when exposed to weather; IWUIC is silent on that issue, meaning that the use of coated wood materials is not prohibited. The two codes (in the USA only) will be compared and contrasted in this work with respect to delivering improved fire safety.

Poly (lactic acid) (PLA) is a promising thermoplastic aliphatic polyester to replace petroleum-based polymers in many fields. However, its flammability has limited its application in areas where fire safety is crucial. Chitosan (CS) is a type of natural alkaline polysaccharide with abundant content and good biocompatibility. In this study, a bio-based flame-retardant phosphating chitosan (PCS) was prepared and the effects of PCS on the flammability, mechanical and thermal properties of PLA were evaluated. The limiting oxygen index (LOI) of PLA/PCS blend containing 9 wt% PCS reached 28.9% which was relatively higher than LOI of pure PLA of 20% and passed UL-94 V-0 rating. PCS accelerated the carbonization of PLA matrix, and increased the char residue at 800°C. The combustion process was further investigated by cone calorimeter test, and the peak heat release rate and total heat release were significantly decreased. X-ray photoelectron spectrometer and thermogravimetric-infrared analysis were used to analyze the composition of char residue and pyrolysis products, which further confirmed that the flame-retardant mechanism of PCS was the combination of condensed phase and gas phase. However, the mechanical properties of PLA/PCS blend inevitably decreased with increasing of PCS content.