Fire Attack Research Articles

Fire-safe and multifunctional epoxy/layered double hydroxide composites via an interfacial catalysis

Aiming to impart epoxy with a phosphorous-free super-efficient fire safety and multifunctions via a facile interface-manipulation protocol, we innovatively proposed a proof of concept of a two-in-one catalytic function via covalently inducing an interfacial supramolecular assembly of Salen-Fe complex on organic layered double hydroxide (LDH-DBS). Various characterizations confirmed the target LDH-DBS@Salen-Fe with a surface-located uniform and ultrathin deposition of Salen-Fe complex, which was conducive to a better nanodispersion in epoxy matrix. An exceptionally low loading of 2 wt% LDH-DBS@Salen-Fe (i.e., 0.6 % Salen-Fe) endowed epoxy with a UL-94 V-0 level and intensive fire protection with a suppressed peak heat release rate by 45.0 %. An insightful mechanism investigation demonstrated that the interface-located Salen-Fe rapidly catalyzed a charring reaction with an ultrafast formation of protective fire chars to resist an early-stage fire attack. Additionally, relative to EP/2LDH-DBS, a mere 0.6 % Salen-Fe increased the tensile, flexural and impact strength by 39.6 %, 31.5 % and 37.0 %, respectively based on the optimized interface compatibilization. Interestingly, an ultralow loading of Salen-Fe significantly contributed to a degradation recycling of epoxy under a mild condition with mass loss after 7 h treatment 392.8 % higher than its counterpart via catalytically promoting the generation of CHCOO∙ and HO∙ at the interface. In perspective, an interfacial supramolecular assembly of two-in-one catalysts exploits a novel route towards a phosphorous-free fire-safe and multifunctionally reinforced polymers.

Self-ignition behaviour of corn cob, wheat bran and rice husk residues in ambient air from biomass gasification

The possibility of different agrowastes to self-ignite under ambient condition, due to exothermic reactions between their surface molecules and air or other oxidizing agents which are conveyed into the void volume between the particles, exists. It is imperative to investigate the self-ignition ability of these harzadous waste products causing environmental pollution after the milling process to avoid sudden fire outbreaks. In this study, the self-ignition attributes of corn cob, wheat bran and rice husk residues in ambient air from biomass gasification was investigated by evaluating their self-ignition temperatures using DIN EN 15188:2021 standard and Frank-Kamenetzkii's theory of thermal explosion at varying basket volume. The results revealed decrease in the ignition temperature of dust samples as ignition time and dust basket volume were increased. Sample C (rice husk dust residue) was considered to be the most hazardous with respect to its propensity to self-heating possessing the lowest self-ignition temperature of 173 °C at 800 mL cubic mesh. Its moisture content and activation energy of 1.41 % and 46.52 kJ/mol respectively were the lowest. Its thermal conductivity, carbon content, heating value and bulk density of 0.07 W/mK, 78.98 wt%, 26,895 kJ/kg and 255.4 kg/m3 respectively were the highest. Correlation coefficient from the Arrhenius plot showing the self-ignition behaviour of dust samples using the model of Frank-Kamenetzkii were 0.9976, 0.9910 and 0.9962 for corn cob, wheat bran and rice husk residues respectively. In conclusion, the data presented are effective in predicting the self-ignition ability of corn cob, wheat bran and rice husk residues in ambient air from biomass gasification in order to prevent sudden fire attack that may arise based on storage of their dust particles in food processing industries.

Phosphorylated and carbamylated Kraft lignin for improving fire- and biological-resistance of Scots pine wood

In this study, Kraft lignin was modified by ammonium dihydrogen phosphate (ADP) and urea for achieving phosphorylation and carbamylation, aiming to protect wood against biological and fire attack. Scots pine (Pinus sylvestris L.) sapwood was impregnated with a water solution containing Kraft lignin, ADP, and urea, followed by heat treatment at 150 °C, resulting in changes in the properties of the Kraft lignin as well as the wood matrix. Infrared spectroscopy, 13C cross-polarisation magic-angle-spinning (MAS) nuclear magnetic resonance (NMR), and direct excitation single-pulse 31P MAS NMR analyses suggested the grafting reaction of phosphate and carbamylate groups onto the hydroxyl groups of Kraft lignin. Scanning electron microscopy with energy dispersive X-ray spectroscopy indicated that the condensed Kraft lignin filled the lumen as well as partially penetrating the wood cell wall. The modified Kraft lignin imparted fire-retardancy and increased char residue to the wood at elevated temperature, as confirmed by limiting oxygen index, microscale combustion calorimetry, and thermogravimetric analysis. The modified wood exhibited superior resistance against mold and decay fungi attack under laboratory conditions. The modified wood had a similar modulus of elasticity to the unmodified wood, while experiencing a reduction in the modulus of rupture.

Interfacial Shear Behavior of Composite Concrete Substrate to High-Performance Concrete Overly After Exposure to Elevated Temperature

Basically, the interface shear strength between two concrete layers of varying ages must be sufficient to withstand the applied actions on the structure, specifically fire attack, which may cause the complete collapse of the composite structure. Thus, interfacial shear behavior was investigated and analyzed in this paper under the influence of a set of parameters, including temperature (25, 200, 400, and 600 °C), time exposure (30, 60, 90, 120, and 180 min), concrete type, and fibers type (polypropylene fiber (PPF), steel fiber (SF), and hybrid fiber) by employing a Z-shape push-off test. The test consists of two parts with different ages: normal strength concrete (NCS) and high-performance concrete (HPC). HPC includes high-strength concrete (HSC) and fly ash concrete (FAC). Initially, twenty-five Z-shaped push-off tests were made, four of which were cast as one unit (NSC/or concrete with hybrid (FSP)), and the rest were composite specimens. Furthermore, a 3D finite element model of a composite push-off specimen was developed to simulate and analyze the impact of various time and temperature exposures on the interfacial shear strength of composite specimen N-FSP. The results indicated that temperature degree and exposure time adversely affected the interfacial shear strength. Also, interfacial shear strength is significantly influenced by fiber types. Including combined fiber (SF + PPF) improved the interfacial shear strength by 114% compared to the composite specimen NSC-NSC after exposure to a temperature of 600 °C. In contrast, using PPF negatively affected the interfacial shear strength, recording only 84% of the composite specimen NSC-NSC. In addition, the inclusion of supplementary cementitious material enhanced the interfacial shear strength by 60.5% in the NSC-FAC composite specimen with 30% FA, compared to the NSC-NSC specimen. Finally, a finite element (FE) model was proposed with a satisfactory level of accuracy (0.95 to 1.03) in predicting the maximum shear strength. Additionally, the difference between the FE and experimental stiffness was between 0.92 and 1.07.

Psychological implications of man-made trauma and efficacy of “Teaching Recovery Techniques” on children and adolescents exposed to trauma

Trauma is a mental state of distress and pain resulting from memories of an unexpected, terrifying experience that threatens the survivor's sense of security, especially in children. The present research aimed to examine the Psychological Implications of man-made trauma and the efficacy of Teaching Recovery Techniques (TRT) to children and adolescents exposed to trauma.The Study comprises two parts. First, it aimed to find out the relationship between Child trauma (ChT) and Post-Traumatic Stress and Depressive Symptoms (PSTD) in children and adolescents who were exposed to fire incidents and terrorist attacks. Non-probability Purposive sampling was used in which 80 participants (45 boys and 35 girls) aged 8—17 years were selected from Joseph Colony and Yohanabad Christian Community of Lahore, and the second aimed to assess the TRT on the children and adolescents exposed to terrorist attacks. The results revealed a significant positive relationship between ChT and PTSD in children and adolescents exposed to fire incidents and terrorist attacks. Significant differences were found between the two groups in PTSD symptoms experienced by the participants. Furthermore, participants exposed to terror attacks experienced more PTSD symptoms than fire attacks. Age and proximity to the traumatic incident were significant predictors of PTSD symptoms. The intervention was given in five sessions at the Sunday school of Christ Church Yohanabad Lahore, and the results were promising. It concludes that significant improvement in post-intervention reduces PTSD symptoms in children and adolescents. The study findings can be applied to other such man-made and natural traumas in the future.

Generation of Architectural and Other Safety Measures Against Crises and Killings at Residential Environments in Plateau State of Nigeria

Over the years there have been series of crisis in Plateau State of Nigeria and they have led to massive killings and destruction of valuable properties; this is a very serious problem. Hence, it became necessary to conduct a research work with the aim of overviewing the cases of crises and killings at residential environments in Plateau State, in order to generate architectural and other safety measures to reduce their future occurrences in Nigeria. The research focused on desktop study as the instrument for data collection; reviewed different newspapers in Nigeria with available crisis and killing cases in Plateau State, in order to get relevant information to the research. Thus, table was used for the presentation and analysis of the research data, so as to generate results and the results were checked by using contents analysis technique, in order to validate them. Among the architectural research findings is: 1,290 houses were burnt during December, 2023 crisis in Bokkos Local Government Area of Plateau State and some other research findings are: the security agencies knew that an attack was coming before the 2023 Christmas eve massacre; the security forces know the attackers, and they even know their hideouts for two decades. Among the recommended architectural safety measures to reduce future crises and killings is: the design of the members of roof, door, window, ceiling and any other part of building that can easily burn with the use of wood should be fire retardant type, in order to reduce death, massive destruction of houses and valuable properties in times of fire attack from the terrorists. Some other recommended safety measures are: there should be advanced training of security agencies on immediate defensive responses against the terrorists been rumored of their coming to the state; urgent investigations must be made on the security forces that knew the attackers and their hideouts for two decades without revealing the information, so that the defaulted members of those security forces can receive a very severe/appropriate punishment, in order to stop this kind of bad service in Nigeria.

Finite element investigation on the post-fire behavior of reinforced composite NSC-HPC slabs

Purpose Even though it is widely used, reinforced concrete (RC) is susceptible to damage from various environmental factors. The hazard of a fire attack is particularly severe because it may cause the whole structure to collapse. Furthermore, repairing and strengthening existing structures with high-performance concrete (HPC) has become essential from both technical and financial points of view. In particular, studying the postfire behavior of HPC with normal strength concrete substrate requires experimental and numerical investigations. Accordingly, this study aims to numerically investigate the post-fire behavior of reinforced composite RC slabs. Design/methodology/approach Consequently, in this study, a numerical analysis was carried out to ascertain the flexural behavior of simply supported RC slabs strengthened with HPC and exposed to a particularly high temperature of 600°C for 2 h. This behavior was investigated and analyzed in the presence of a number of parameters, such as HPC types (fiber-reinforced, 0.5% steel, polypropylene fibers [PPF], hybrid fibers), strengthening side (tension or compression), strengthening layer thickness, slab thickness, boundary conditions, reinforcement ratio and yield strength of reinforcement. Findings The results showed that traction-separation and full-bond models can achieve accuracy compared with experimental results. Also, the fiber type significantly affects the postfire performance of RC slab strengthened with HPC, where the inclusion of hybrid fiber recorded the highest ultimate load. While adding PPF to HPC showed a rapid decrease in the load-deflection curve after reaching the ultimate load. Originality/value The proposed model accurately predicted the thermomechanical behavior of RC slabs strengthened with HPC after being exposed to the fire regarding load-deflection response, crack pattern and failure mode. Moreover, the considered independent parametric variables significantly affect the composite slabs’ behavior.

A machine learning based interaction model to predict robustness of concrete-filled double skin steel tubular columns under fire condition

Concrete-filled double skin steel tubular (CFDST) column is a hollow composite structure component, which shows better performance than traditional reinforced concrete and steel columns due to the favorable composite action between steel and concrete. In the current study, a machine learning based interaction model combine with the extended Rankine method is developed to predict fire resistance of eccentrically loaded CFDST cylinder columns. The prediction of the reliable shear bond parameter was conducted by back propagation artificial neural network (BP-ANN) and Extreme Gradient Boosting Tree (XGBoost). To perform a reliable production, the architecture and the parametric setting of both models were constructed. Furthermore, the results of the prediction were verified by experimental results and finite element analysis. The results show that the proposed method can predict the behavior of the eccentrically load CFDST columns under fire attack with reasonable accuracy.

Theoretical and conceptual features of the implementation of state policy in the sphere of ensuring the rights and freedoms of persons with disabilities by the Cabinet of Ministers of Ukraine under martial law

The article is devoted to the administrative and legal analysis of the implementation of state policy by the key subject of public administration in the field of social protection of persons with disabilities under martial law.
 It should be stressed (emphasized) that state policy is based on a complex approach of functional direction aimed at solving interrelated political and socio-economic problems with timely response to changes and innovations to overcome these problems in the state and society.
 The task of the Government, assigned to the sphere of social protection of persons with disabilities, is revealed, and the main normative legal acts of the Cabinet of Ministers of Ukraine on ensuring compliance with human rights and freedoms, creating favorable conditions for the free and comprehensive development of the individual without barriers are analyzed. The peculiarities of the complex of measures guaranteed by the state and aimed at providing life support for persons with disabilities and groups with limited mobility have been clarified. Attention was drawn to the peculiarities of the implementation of this complex in the conditions of the state of war in which Ukraine is.
 It is specially noted, in the conditions of martial law and for the implementation of civil security measures, guaranteeing the provision of life-saving measures to all citizens of the country, persons with reduced mobility and persons with disabilities need additional assistance.
 The procedure for organizing notifications about the threat of occurrence or occurrence of emergency situations and organizing communication in the field of civil protection of persons with disabilities and mobile groups was analyzed; carrying out the evacuation of persons with disabilities and mobile groups in the event of the threat of occurrence or the occurrence of emergency situations.
 It has been established that in the conditions of martial law and the constant threat to life and health due to constant massive rocket attacks, and in some areas, the rapid fire attacks of residential communities, where civilians among them and those who are physically unable to take care of themselves die every day, are persons with various physical disabilities, low-mobility population groups, persons with disabilities.
 In this regard, there is an urgent need for the adoption of a special normative legal act defining the detection, notification and evacuation of persons with disabilities and other less mobile population groups during the period of emergency and military operations, with the definition of the subject of the implementation of these measures.

Fabrication and Analysis of Thermal Insulation Ceiling Panel from Corn Husk Fiber

Every year, the Philippines experiences hot and rainy weather. For those who choose to remain at home, summer feels like torture. So, Filipinos have no choice but to turn on their air-conditioning system, which can cause their electricity bill to skyrocket. Corn husk fibers, being a waste product, have great potential to be applied in home textiles, home furnishing, carpet, rugs, and packaging of food grains and crops. The researchers thought of making thermal insulation ceiling panels made of corn husk fibers. The study yielded a result of 0.119 W/m.K for thermal conductivity using a calibrated hot box, below the 0.25 W/m.K maximum threshold for thermal conductivity value. Furthermore, its fire resistance characteristic made it less susceptible to small fire attacks. It was also found that the insulator has 2.19% and 8.42% water absorption values for short and long-term soaking, which is less than the 40% range value for water absorption. Hence, it can be said that it is an excellent thermal insulator.

Behavior of magnesium phosphate cement with addition of sulphoaluminate cement at elevated temperatures

Magnesium phosphate cement (MPC) as repair materials of the structures or package materials for wastes may be exposed to elevated temperatures during fire attack. When MPC paste was exposed to about 1300 °C, a sharp increase in compressive strength was observed due to sintering. However, MPC exposed to elevated temperature, especially below 1000 °C showed a sharp decrease in compressive strength. Ye'elimite mineral in sulphoaluminate cement (CSA) has been proven to take part in the hydration of MPC and form some amorphous phases. The introduction of CSA in MPC could provide reactive Al and Si, which may be beneficial to improving the high temperature resistance of MPC. The present study aims to introduce CSA into MPC to improve its thermal properties at elevated temperatures. MPC pastes with pure dead burned MgO and various contents of CSA were prepared and exposed at elevated temperatures from 200 to 1100 °C. The compressive strengths, strength retention, dimensional changes, weight loss, phase changes, microstructures and open porosities of MPC pastes with CSA at elevated temperatures were studied. The proper addition of CSA in MPC pastes could form some new amorphous phases, reduce the open porosities, promote the sintering progress and enhance the strengths at elevated temperatures. To promote the properties of the MPC pastes at elevated temperatures, 10% and 30% CSA were recommended to replace dead burned MgO in MPC pastes at exposure temperatures above 1000 °C and below 400 °C, respectively.

Evaluation of real time fire performance of eco-efficient fly ash blended self-consolidating concrete including granite waste

Manufacturing of granite products generates enormous amounts of granite waste (GW) worldwide, which triggers environmental pollution on its dumping. On the other hand, the resistivity of concrete structures and the safety of humans are likely to undergo intense threats when exposed to fire attacks. Therefore, an experimental study was conducted to determine the real-time fire attack performance of eco-efficient fly ash blended self-consolidating concrete (SCC) containing up to 60% GW as a replacement for natural fine aggregate. The change in weight, compressive strength, water absorption, and ultrasonic pulse velocity characteristics of SCC were determined after being exposed to varying elevated temperatures of 200 ± 10 °C, 400 ± 10 °C, 600 ± 10 °C, and 800 ± 10 °C. Advanced Fourier transform infrared test was done to examine chemical changes in fire-exposed specimens. Test results revealed that FA blended SCC containing GW (up to 60%) exhibits better post-fire properties, with optimum mechanical and durability properties at 30%. Besides, sustainability analysis results revealed that the use of GW up to 40% exhibited better sustainable solutions under the given economic and environmental cost factors. This study concluded that up to 40% GW as a replacement to fine aggregate could be positively incorporated in the production of FA blended SCC, where failure due to fire is a problem.

Phosphonitrile decorating expandable graphite as a high-efficient flame retardant for rigid polyurethane foams

Researchers have widely focused on the high flammability and releasing toxic gases of rigid polyurethane foam (RPUF) under fire attack. In this work, the hybrid expandable graphite (EG) intumescent flame retardant is designed and fabricated for the fire safety of RPUF. Hexachlorocyclotriphosphazene (HCCP) is self-assembled on the surface and interlamination of EG (HCCP@EG) via water bath method and incorporated into RPUF matrix to improve the flame retardant efficiency of EG and the interfacial adhesion between EG particles and RPUF matrix. The structural morphological characterization indicates that HCCP@EG is successfully synthesized. HCCP@EG also exhibits good thermal stability and high char residues. Compared with neat RPUF, RPUF composites with 15% HCCP@EG show excellent flame-retardant properties and achieve a UL-94 V-0 level and a limiting index higher than 27.0%, which is due to the construction of a network structure of HCCP in the graphite lamellas and its synergistic and barrier effect. In addition, compared with EG, the presence of HCCP enhances interface compatibility between EG and RPUF, resulting in improving the mechanical property of RPUF composites. In summary, this work provides a facile approach to manufacturing high-performance RPUF products with outstanding fire safety.

Finite element modelling of lattice angle steel structures exposed to wildland fires

Essential civil infrastructure such as transmission line supporting towers and communication base towers that are traditionally formed from lattice angle steel structures are critical global assets, since their development promotes the establishment of electric power supply systems and modern telecommunication networks. Because this infrastructure is commonly located in rural and urban wildland areas, such towers may be prone to wildland fire attack, particularly in the current climate of severe heatwaves and droughts. Accordingly, a comprehensive study of the behaviour and response of lattice angle steel structures under fire loading is needed to assist in structural design to resist fire loading. In this paper, a finite element (FE) model of lattice angle steel structures is constructed using ABAQUS software. Several aspects that include material and geometric non-linearities, load eccentricities on component members, bolted joint slippage, and the use of the explicit dynamic analysis technique for a quasi-static loading procedure, are considered and applied in the FE model. The accuracy and reliability of the FE representation are validated by comparing its predictions with relevant existing experimental results. By incorporating the codified temperature-dependent material properties of structural steel as well as a calibrated load-slip relationship for bolted connections at elevated temperatures, the FE model is extended for performing structural fire analysis. The variations of the steelwork temperatures in wildland fires can be calculated based on representative temperature-time wildland fire curves and is adopted in the fire analysis. By invoking the FE model, an example of lattice angle steel structures is contrived to elucidate the fundamental behaviour of these structures in wildland fires, through both steady and transient state fire analyses. Parametric studies are also undertaken to evaluate the effects of the changes in the wind load direction, bolt pretension and the protection of critical panel sections on the behaviour of lattice structures when exposed to wildland fires.

Intelligent cyclic fire warning sensor based on hybrid PBO nanofiber and montmorillonite nanocomposite papers decorated with phenyltriethoxysilane

An abundance of early warning graphene-based nano-materials and sensors have been developed to avoid and prevent the critical fire risk of combustible materials. However, there are still some limitations that should be addressed, such as the black color, high-cost and single fire warning response of graphene-based fire warning materials. Herein, we report an unexpected montmorillonite (MMT)-based intelligent fire warning materials that have excellent fire cyclic warning performance and reliable flame retardancy. Combining phenyltriethoxysilane (PTES) molecules, poly(p-phenylene benzobisoxazole) nanofiber (PBONF), and layers of MMT to form a silane crosslinked 3D nanonetwork system, the homologous PTES decorated MMT-PBONF nanocomposites are designed and fabricated via a sol–gel process and low temperature self-assembly method. The optimized nanocomposite paper shows good mechanical flexibility (good recovery after kneading or bending process), high tensile strength of ∼81 MPa and good water resistance. Furthermore, the nanocomposite paper exhibits high-temperature flame resistance (almost unchanged structure and size after 120 s combustion), sensitive flame alarm response (∼0.3 s response once exposure onto a flame), cyclic fire warning performance (>40 cycles), and adaptability to complex fire situations (several fire attack and evacuation scenarios), showing promising applications for monitoring the critical fire risk of combustible materials. Therefore, this work paves a rational way for design and fabrication of MMT-based smart fire warning materials that combine excellent flame shielding and sensitive fire alarm functions.

Production, experimental investigation of SCC using fly ash and granite debris

The proportion of fly ash (30%) was fixed in the second phase, whereas the proportion of granite debris (up to 60%) was changed. Thus, for the second phase, a comprehensive investigation for Fly Ash (FA) blended SCC containing various amounts of Granite Debris (GD) was conducted by performing fresh, mechanical and durability properties of concrete. The microstructure of concrete samples were evaluated using electron scanning microscopy (SEM). Prepared FA mixed SCC compositions was further tested for impact resistance, fire resistance, and economic and environmental properties. The FA blended SCC mixes were compared to those of conventional SCC mixture made using Ordinary Portland cement (OPC). The results of the second phase suggested that adding up to 40% GD to a fly ash blended SCC mixture improved mechanical performance. The replacement of samples with 50% of GD was found to improve the durability properties (such as resistance to chemical ingress and water penetration) and impact resistance. The use of up to 60% GD in a FA blended SCC mixture was found to improve resistance to chloride attack and fire attack. Though fly ash blended SCC mixtures had worse mechanical performance than the OPC-based control SCC mixture at up to 90 days curing, they had superior mechanical performance at 180 days and 365 days curing than the OPC-based control SCC mixture.

Machine learning algorithms in wood ash-cement-Nano TiO2-based mortar subjected to elevated temperatures

Mortar is subjected to high temperatures during fire attacks or when it is near heat-radiating equipment like furnaces and reactors. The physical and microstructure of mortar were considerably altered by high temperatures. In this investigation, the effects of elevated temperatures on the flexural and compressive strengths of wood ash (WA) cement mortar modified with green-synthesised Nano titanium oxide (NT) were examined. In order to produce mortar samples, the cement was replaced with 10% WA, and 1–3% NT by weight of binder were added at constant water-binder ratio. The specimens were heated to 105, 200, 400, 600, and 800 °C with an incremental rate of 10 °C per min in the electric furnace for a sustained period of 2 h to measure their strengths. The machine learning algorithm of artificial neural networks with Levenberg-Marquardt backpropagation training techniques of different network architectures was engaged to predict the compressive strength of WA-cement-NT-based mortar produced. The findings showed that higher temperatures reduced compressive strength after 400 °C and flexural strength after 200 °C. The mortar specimen with a 3% NT addition showed the highest residual compressive strength increase, ranging from 18.75 to 27.38%. Compared to compressive strength, flexural strength is more severely affected by high temperatures. The backpropagation training algorithm revealed that each hidden layer displayed its unique strong prediction. However, Levenberg-Marquardt backpropagation training technique of 7–10-10-1 network structures yielded the best performance metrics for training, validation, and testing compared to 7-10-10-10 and 7-10-1 network architectures.

Recycling used engine oil in concrete: Fire performance evaluation

Recycling used engine oil (UEO) into concrete is a viable and clean solution, as UEO has functions similar to chemical additives (i.e. as a water reducer and air entrainer) for concrete production. However, prior to the use of this ecofriendly concrete within the building industry, its fire performance should be thoroughly evaluated to further prove the technical feasibility and promote its safe application. Here, the fire performance of UEO concrete following exposure to elevated temperatures was assessed by measuring its compressive strength and elastic modulus. Experimental outcomes suggest that concrete admixed with 2% UEO by mass of cementitious materials shows enhanced fire performance and that concrete admixed with 5% UEO exhibits comparable mechanical properties to reference concrete. In ascertaining the microstructural origins behind the mechanical performance changes, scanning electron microscopy (SEM) analysis was conducted to analyze the surface morphology of UEO concrete. The analysis demonstrates that concrete with 2% UEO features densely packed fibrous calcium silicate hydrates (C–S–H) at 200 °C that contribute to strength increase. In addition, the surface characteristics of UEO concrete in terms of color changes, cracks, and pore density were analyzed to supplement the fire performance information, with the intention of facilitating structural health assessments following fire attacks. Moreover, the environmental and economic assessments of the proposed UEO disposal approach concerning carbon dioxide emissions, energy consumption, and costs, respectively, are discussed and contrasted with the mainstream disposal options. The discussion suggests that the present recycling strategy can reduce carbon dioxide emissions by 8050–10750 kg, energy consumption by 2.87–4.13 billion MJ, and disposal costs by HK$3250–9450 per tonne of UEO. These findings will contribute to advancing a clean UEO management strategy and to engineering waste-enhanced concrete with desired fire performance for sustainable civil infrastructure.

Nanohybrid of Co3O4 Nanoparticles and Polyphosphazene-Decorated Ultra-Thin Boron Nitride Nanosheets for Simultaneous Enhancement in Fire Safety and Smoke Suppression of Thermoplastic Polyurethane.

Thermoplastic polyurethane (TPU) is widely used in daily life due to its characteristics of light weight, high impact strength, and compression resistance. However, TPU products are extremely flammable and will generate toxic fumes under fire attack, threatening human life and safety. In this article, a nanohybrid flame retardant was designed for the fire safety of TPU. Herein, Co3O4 was anchored on the surface of exfoliated ultra-thin boron nitride nanosheets (BNNO@Co3O4) via coprecipitation and subsequent calcination. Then, a polyphosphazene (PPZ) layer was coated onto BNNO@Co3O4 by high temperature polymerization to generate a nanohybrid flame retardant named BNNO@Co3O4@PPZ. The cone calorimeter results exhibited that the heat release and smoke production during TPU combustion were remarkably restrained after the incorporation of the nanohybrid flame retardant. Compared with pure TPU, the peak heat release rate (PHRR) decreased by 44.1%, the peak smoke production rate (PSPR) decreased by 51.2%, and the peak CO production rate (PCOPR) decreased by 72.5%. Based on the analysis of carbon residues after combustion, the significant improvement in fire resistance of TPU by BNNO@Co3O4@PPZ was attributed to the combination of quenching effect, catalytic carbonization effect, and barrier effect. In addition, the intrinsic mechanical properties of TPU were well maintained due to the existence of the PPZ organic layer.

Fire Effects on Reinforced Concrete

Concrete is a structural material that can be destroyed as a result of varied nature actions. Among them, fire is important: fire is a physical action of great destructive capacity and, at the same time, fire is an accidental action. In general, a fire is a vandalism action or an accidental event, which can affect every structural element. Fire is frequently an aggressor agent for constructions, in general, and for concrete structural elements, in particular. The fire attack is always complex. It acts over material made up of steel and concrete, with different behaviors and reactions to rising temperatures. Thus, it is necessary to study the alterations produced on the mechanical characteristics of the concrete, the alterations produced on the mechanical characteristics of the steel reinforcement and the alterations produced on the adherence between the steel and the concrete, and other phenomena such as the deformations imposed as a consequence. of the prevented expansions or the stresses produced by the temperature distribution gradients. This article aims to analyse the resistant capacity and the safety level of deterioration mechanisms, comparing real mechanisms and standard normative theoretical postulates.