Fire Resistance Performance Research Articles

Structural response of reinforced LECA aggregate concrete slabs subjected to high temperatures

This work reports tests conducted on nine one-way reinforced concrete slabs using lightweight expanded clay aggregate (LECA) as a slab weight reduction technique. Every slab had the same dimensions, steel reinforcement, and the same composition of concrete. The slabs were heated from their bottom faces through a fire chamber and subjected to a sustained line load. The specimens’ fire resistance performance and mechanical characteristics were evaluated after they had undergone the same testing conditions. The study parameters were the replacement of coarse aggregate with different percentages of LECA (20%, 40%), and different temperatures (400 ℃ and 700 ℃). Compared to the reinforced normal-weight concrete slab, the reinforced LECA aggregate concrete slabs’ fire resistance and flexural strength decreased by LECA. The slabs’ deflection rose as the LECA increased. The largest increase in slab deflection was 37.2%, while the most notable decrease in ultimate load capacity was roughly 35.1%. The stiffness depreciation was substantial, though, at roughly 50%. The results for LECA-reinforced aggregate slabs not exposed to high temperatures support this conclusion. Reinforced LECA aggregate slabs maintained structural integrity after fire testing.

Formulation and improved properties of three-dimensional superhydrophobic ultra-lightweight fly ash cement foams with C-S-H nanoparticles-stabilized waterproof emulsion

Ultra-lightweight foamed cement (ULFC) is characterized by the super low-density (≤200 kg/m3), excellent thermal-insulation and fire-resistant performance, however, it can inevitably absorb huge amount of water from the surroundings. In this work, a novel three-dimensional superhydrophobic ULFC with apparent density lower than 160 kg/m3 was innovatively achieved by using the bio-inspired design method and C-S-H-nanoparticles-stabilized waterproof emulsion. The results revealed that the water contact angle of ULFC samples can reach up to 154.6°, and the corresponding 24 h volumetric water absorption can be reduced from 8.7 % to 4.1 %. The low-energy organic group of waterproof agents grafted with the surface of hierarchical rough structure in hardened ULFC, which enhanced the hydrophobicity of cement foams.

Correction to “Fire resistance performance of composite coating with geopolymer‐based bio‐fillers for lightweight panel application—Research article”

Correction to “Fire resistance performance of composite coating with geopolymer‐based bio‐fillers for lightweight panel application—Research article”

An Analysis of the Performance and Comfort Properties of Fire-Protective Material by Using Inherently Fire-Retardant Fibers and Knitting Structures

This paper investigates the development of fabric materials using several blends of inherently fire-resistant (FR) fibers and various knitted structures. The samples are evaluated with respect to their performance and comfort-related properties. Inherently fire-resistant fibers, e.g., Nomex, Protex, carbon and FR viscose, were used to develop different structures of knitted fabrics. Cross-miss, cross-relief, and vertical tubular structures were knitted by using optimum fiber blend proportions and combinations of stitches. Several important aspects of the fabric samples were investigated, e.g., their physical, mechanical and serviceability performance. Thermo-physiological and tactile/touch-related comfort properties were evaluated in addition to flame resistance performance. An analysis of mechanical performance indicated that the knitted structure has a significant influence on the tensile strength, bursting strength and pilling resistance. The cross-relief structure proved to be the strongest followed by the cross-miss and vertical tubular structures. The FR station suits made from 70:30 Protex/Nomex exhibited the best combination of tensile and bursting strength; therefore, this material is recommended for making a stable and durable station suit. Interestingly, it was also concluded from the experimental study that knitted samples with a cross-relief structure exhibit the best fire-resistance performance. Fiber blends of 70:30 Protex/Nomex and 70:30 Nomex/carbon were found to be optimum in terms of overall performance. The best flame resistance was achieved with Nomex:carbon fiber blends. These results were confirmed with vertical flammability tests, TGA, DTGA and cone calorimetry analysis. The optimization of blend composition as well as knitting structure/architecture is a crucial finding toward designing the best FR station suit in terms of mechanical, dimensional, thermal, thermo-physiological and flame resistance performance.

Mechanical properties of 2100 MPa parallel wire strands under and after elevated temperature

In this study, steady-state tensile tests were conducted at elevated temperatures and after cooling from elevated temperatures on 2100 MPa galvanized parallel wire strands (19 × 5.4 mm) used in long-span suspension bridges. Data collection was done using a charge-coupled device camera (CCDC) system. The results from tests at elevated temperatures indicate that the mechanical properties of parallel wire strands deteriorated gradually with increasing temperature. This degradation trend was well described by logistic curves. The results show that the mechanical properties after elevated temperature decreased significantly when the temperature exceeded 350 °C. By comparing with existing research, it was found that the higher the strength grade, the more severe the strength degradation after elevated temperature. During heating and cooling stages, moderate tension led to beneficial effects on residual strength of the specimens. This applies to temperatures below 400 °C. A linear-exponential-linear (L-E-L) stress-strain model was proposed to establish stress-strain equations for parallel wire strands at and after elevated temperatures. Degradation equations were also obtained for elastic modulus, yield strength, ultimate strength and proportional limit. These findings can be utilized to analyze fire resistance performance of cable systems in large-span bridges and assess post-fire damage.

Study on Fire-Resistance Performance and Heat-Discharge Characteristics Based on the Thickness of Plant Concrete Barriers

Fire-resistant barriers are usually installed in industrial plants to reduce the risk in fire. These barriers are installed in accordance with the guidelines stipulated in various standards applicable to the plant, but the standards for fire-resistance performance and barrier thickness are unclear. In this study, fire-resistance tests were conducted on concrete barriers installed in plants to assess their fire-resistance performance and heat-discharge characteristics. The test results were then analyzed to ensure that the fire performance specified in the relevant standards is satisfied, and the risk in fire was investigated.

Simplified constitutive model of austenitic stainless steel at high temperatures

Based on completed experimental data and constitutive models, we proposed the simplified constitutive model of austenitic S30408 (AISI304) stainless steel at high temperatures. According to continuous trial calculation and analysis fined that the simplified constitutive model can be divided into two segments. In the first segment, the Ramberg-Osgood model (R–O model) was adopted, while the second segment was represented using a straight-line expression. Next, simplified constitutive model was obtained by nonlinear fitting using Matlab. Based on this, FEA models were created, incorporating the simplified constitutive model, refined constitutive model, and constitutive model fitted based on experimental data from other literature. Using the sequential therm-mechanical coupling analysis method, the FEA of the fire-resistant performance of three specimens including simply supported stainless steel rectangular beam, restrained rectangular stainless steel column and restrained stainless steel H-section columns, was carried out and compared. The conclusions drawn were as follows: For members at low temperatures, when the strain value is small, the deformation and force calculated using simplified constitutive model is not much different from that using the constitutive model fitted based on experimental results. For members at high temperatures, when the strain value is large, the deformation and force calculated using simplified constitutive model deviates from that using the constitutive model fitted based on experimental results, but deviation is within an acceptable range. Therefore, the simplified constitutive model demonstrates both feasibility and accuracy, making it suitable for calculating the fire resistance of specimens.

Preparation of calcium silicate board from tobermorite-rich residue for energy conservation in buildings

The tobermorite-rich residue was derived from coal fly ash after alumina extraction via a hydrothermal process, which was used to prepare calcium silicate board for energy conservation in buildings. By employing a formulation comprising 94 wt% tobermorite-rich residue and 6 wt% pulp, the resultant calcium silicate board exhibited notable characteristics when subjected to a compression pressure of 20 MPa, including a bending strength of 6.75 MPa, a bulk density of 0.63 g/cm3, and a thermal conductivity of 0.14 W/(m·K). Tobermorite within the residue predominantly exhibited a fibrous morphology and formed porous aggregations, which proved advantageous in preparing calcium silicate board of high bending strength and good thermal insulation performance. Furthermore, the tobermorite retained its fibrous morphology even at elevated temperatures exceeding 650 °C, this thermal stability conferred excellent fire resistance performance upon the resulting calcium silicate board. Conclusively, the calcium silicate board prepared from tobermorite-rich residue demonstrated superior performances like good thermal insulation, exceptional fire resistance, light weight and high strength, etc., which would show great potential for use in buildings.

Enhanced mechanical, thermal and fire resistance performance of expanded polystyrene-based fiber-reinforced mortar made with limestone-calcined clay cement (LC3)

Enhanced mechanical, thermal and fire resistance performance of expanded polystyrene-based fiber-reinforced mortar made with limestone-calcined clay cement (LC3)

On the 3D printing and flame retardancy of expandable graphite-coated polylactic acid

In this study, we made a flame-retardant coating layer composed of expandable graphite (ExG) (carbon source), ammonium polyphosphate/boric acid (acid source), melamine (blowing agent), and epoxy/amine resin/hardener system (binding agent). At varying ExG amount, the coating was deposited onto the surface of 3D printed polylactic acid (PLA) by dip coating method. The fire resistance performance of 3D printed PLA was measured in terms of burning rate and burning duration. Surface morphology and thermal stability of the coated samples were investigated by scanning electron microscopy (SEM) and thermogravimetric (TGA) analysis. Residual char after burning was also analyzed by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis. Addition of 9.8 % w/w ExG in the coating formulation showed good adhesion and increased fire resistance of PLA. The coated specimens exhibited high thermal stability, increased residual weight and enhanced surface structure by TGA and SEM analysis. Lastly, FTIR and XRD results revealed the presence of graphite and boron phosphate in the residual char.

Enhancement of fire resistance and mechanical performance of polypropylene composites containing cellulose fibres and extracellular biopolymers from wastewater sludge

In the present research, a bio-based flame retardant (FR) was prepared using a biopolymer derived from wastewater sludge to improve the fire performance of polypropylene (PP). Extracellular polymeric substances (EPS), which were extracted from wastewater aerobic granular sludge, were absorbed into cellulose-based fibres, such as flax and toilet papers. Thermogravimetric analysis results indicated that the EPS-cellulose fibres played a significant role in enhancing the char formation of PP composite. Furthermore, the incorporation of the bio-based FR into PP restricted its vertical burning characteristics, and at the same time enhanced the tensile moduli of the composites. The reaction between phosphoric acids from EPS and hydroxyl groups of cellulose fibres improved dehydration and char formation of the composites to enhance the overall fire reaction properties. This study opens up new possibilities for the wastewater-derived biopolymer “EPS” to prepare the bio-inspired FRs for cellulose-based fibres and composites, and enhance sustainability of wastewater sludge treatment.

The role of a novel coating of SFRCR-ECC in enhancing the fire performance of CFST columns: Development, characteristic and ISO-834 standard fire test

The conventional spray-applied fire-resistive material meets the basic fire resistance requirements. However, it has limited strength and ductility, and poor bonding with the substrate, consequently, it will not deform with the main structure and reduces the fire resistance performance. A multifunctional spray-applied, fire-resistive and corrosion-resistive Engineered Cementitious Composites (SFRCR-ECC) has been developed to overcome these defects. Material properties of SFRCR-ECC coating were initially investigated, as well as the ISO-834 standard fire test of CFST columns sprayed with SFRCR-ECC coating were carried out. The effects of SFRCR-ECC coating thickness and the load ratio of the columns to the fire resistance limit were preliminarily explored, while the damage of the specimens after the open fire test, the temperature distribution and the axial deformation of CFST columns were obtained. The open fire test results also proved that SFRCR-ECC has excellent fire resistance performance as a new sprayable fire resistant material.

Effects of density and resin content on the rebonding performance of bamboo scrimber composite

Bamboo scrimber composite (BSC) is an emerging engineering material that offers various advantages of structural design, high water resistance, and excellent fire resistance performance. However, practical application of this material in the construction industry is limited due to the constraints in its size. Many pieces of the BSCs need to be put together one after the other in order to develop large-scale building components such as beams and columns. The rebonding performance of BSCs depends on their surface properties, and the two key parameters that affect surface properties are density and the resin content that is applied to the BSCs. Therefore, this study employed polyurethane to achieve rebonding of BSC, and the effects of density and resin content of BSC on its rebonding performance was explored in detail. The study revealed that as the density and resin content of BSC was increased, it modified its porous structure, as well as reduced its surface roughness and surface wettability, thus increasing its rebonding performance. Ultimately, this study establishes a relationship between the surface properties and the rebonding performance of BSCs, to evaluate its feasibility in a wide range of applications in the construction industry.

Evaluation of feasibility and performance of foamed Fire-Resistant coating materials

A preliminary study found high-performance cement mortar, geopolymer mortar, and magnesium phosphate cement mortar (MPCM) have the potential as new fire-resistant materials. In this study, foam was added to these three fire-resistant materials to further improve their rheological, mechanical, and fire-resistant performance and reduce costs. Systematic design and experimental programs were conducted. The results showed the addition of foam enhanced workability, adhesiveness, and fire resistance, allowing the materials to withstand higher temperatures and further delay heat transfer. A mixture of 70% MPCM and 30% foam was identified as the optimum design, which could withstand 1000 °C with low heat transfer rates.

Fire Performance of Steel-Timber Hybrid Beam Section

Slim-floor-type of steel-timber hybrid floor systems which use steel beams contained within the depth of the cross-laminated timber (CLT) floor slab offer many benefits, but there is still very little research available on the fire resistance performance of these systems. In the study presented in this paper two furnace tests and numerical simulations have been conducted to investigate the thermal profiles of the steel member and CLT slabs and to obtain information on the temperature development and charring of the hybrid beam section when it is exposed to standard fire conditions. Also, the effects of intumescent fire protection on temperatures and charring performance were investigated. Numerical 2D thermal simulations for unprotected and protected cases were conducted using SAFIR software, and the agreement between experiments and numerical-analysis predictions were in general very good. The results show that intumescent protection reduces the temperatures of the steel and CLT components as well as charring depth significantly, and the start of charring at CLT slab support may be delayed if intumescent paint protection thicker than that required for the load bearing steel member is used. The result also showed that CLT temperatures exceed 100°C already in the early stages of the fire which decrease the strength and stiffness properties of CLT much before the start of charring. Therefore, the fire design of the CLT slab support should not only consider the char depth and residual cross-section analysis but also the reduction in strength.

Fire resistance of square reinforced concrete column with one-face gypsum layer insulation under axial loading

This study aims at investigating the fire resistance performance of square-reinforced concrete columns exposed to a standard hydrocarbon fire under a time-range axial loading. The gypsum layer is used as a prime fire protection for aggressive fire-flame. The gypsum boards are commonly employed as finishing material in construction. The ASTM C1529 hydrocarbon fire scenario is adopted in this study for all reinforced concrete samples subjected to axial load simultaneously exposed to direct fire flame of (600 and 900)oC. The experimental investigation is carried out on twelve laboratory-scale concrete samples. The outcome discussed the influence of various gypsum layer thicknesses applied to one face of the column sample under axial loading. The results showed different senses of fire resistance between samples. The gypsum protection layer reduces the effect of fire-exposed concrete specimens. For 1 h duration, 600 °C, and 10 mm and 20 mm gypsum layer thicknesses, the strength load evolution drops by 30.7% and 34.96%, respectively compared to the reference sample. Furthermore, for the 1-h duration, 900 °C, and 10 mm and 20 mm gypsum layer thicknesses, the load evolution drops by 29.6% and 34.58%, respectively compared to the reference model. Also, the strength drops by 15%, 19%, 29.4, and 17.9% for the same testing characterization, but a 2-h fire duration. The results show no spalling or delamination of the concrete substrate. Also, the amount of lateral deflection is improved.

Lightweight Flame-retardant Material Reinforced with Hevea Brasiliensis Ash Intumescent Agent

Flame retardant materials play an important role in many building construction components. The ability of building components to resist fire is crucial to the safety and well-being of the occupants. This research examines a lightweight flame-retardant material-Vermiculite (V) reinforced with a renewable Hevea Brasiliensis Biomass Ash Intumescent Agent (HBAIA) in different compositions. Four specimens of vermiculite reinforced with HBAIA (V/HBAIA) with standard size 200 mm x 200 mm x 10 mm (W x Lx H) were fabricated for investigations. All V/HBAIA specimens were assessed in terms of their density, fire-resistant, fire endurance and smoke, char surface morphology, and flexural toughness. Data disclosed V/HBAIA-2 with the composition of 90% vermiculite reinforced with 10% HBAIA obtained the most prominent outcomes in overall. V/HBAIA-2 attained the lightest density of 37.5 kg/m3 and weight of 0.20 kg, with lowest end temperature of 122 °C after exposure to one-hour of 1000 °C fire. This indicated the best fire-resistant performance in V/HBAIA-2. No structural deformation and only mild smoke and odor were observed in V/HBAIA-2 during the fire endurance examination. V/HBAIA-2 was able to resist the maximum loading force of 67.4 N before and 52.5 N after the fire resistant, with the higher flexural toughness value of 1.47 MPa. Scanning electron microscopy revealed a more uniform, denser, closely connected air cavities char cell quality in V/HBAIA-2 explained its superior outcomes in fire-resistant and flexural toughness as compared to the rest of specimens.

Fire Resistance Characteristics of Firewall Structure Associated with Impact Damage Induced by Explosion

When a fire accident accompanied by an explosion occurs, the surrounding firewalls are affected by impact and thermal loads. Damaged firewalls due to accidental loads may not fully perform their essential function. Therefore, this paper proposes an advanced methodology for evaluating the fire resistance performance of firewalls damaged by explosions. The fragments were assumed to be scattered, and fire occurred as a vehicle exploded in a large compartment of a roll-on/roll-off (RO-RO) vessel. The impact velocity of the fragments was calculated based on the TNT equivalent mass corresponding to the explosion pressure. Damage and thermal-structural response analyses of the firewall were performed using Ansys LS-DYNA code. The fire resistance reduction was analyzed in terms of the temperature difference between fire-exposed and unexposed surfaces, temperature increase rate, and reference temperature arrival time. The degree of damage and the fire resistance performance of the firewalls varied significantly depending on impact loads. When naval ships and RO-RO vessels that carry various explosive substances are designed, it is reasonable to predict that the fire resistance performance will be degraded according to the explosion characteristics of the cargo.

공동주택의 방화문 방･내화성능 기준 및 유지관리 개선연구

공동주택의 방화문 방･내화성능 기준 및 유지관리 개선연구

Aluminium Bridges under Fire Conditions: Structural Behaviour

Due to a number of advantages, aluminium is used in the attachment units of mullion and transom systems for decorative panels and translucent fillings, as well as for bridge structures. Despite its advantages, aluminium has a low melting point and does not have fire resistance performances required by regulatory documents under fire conditions. Therefore, this article is aimed at studying the behaviour of aluminium structures under high temperatures. To achieve this objective, we have analysed the aluminium structures most commonly used in construction—the attachment units of mullion and transom systems, with different protections against fire, columns and orthotropic decks used in bridge construction. In order to assess the behaviour of selected structures under fire conditions, we have developed methods for studying temperature distributions in structures in detail. Using the developed methods, tests have been carried out. Based on the received experimental data, we analysed the behaviour of aluminium structures in fire conditions and developed measures to increase the fire resistance of aluminium structures. Such measures include using hollow profiles to ensure air exchange with the cold sections of the structure, applying dedicated cooling agents to cool the structure and removing heat to the atmosphere and thermal barriers so as to protect aluminium structures. We found that fire resistance measures enhance the fire resistance of aluminium attachment units of mullion and transom systems by 1.5 times. The use of hollow air-permeable profiles and cooling agents in orthotropic decks increases fire resistance by 3 times by removing heat from the structures. The fire resistance rating of hollow profile aluminium columns is 1.5 times higher than that of structures without air-permeable profiles. The obtained results can be used as the most effective basis for the design of aluminium structures. The principles of increasing fire resistance given in this article are applicable to other types of structures, and can also be used with other methods of fire protection. Increasing the fire resistance of aluminium structures enables the expansion of the scope of their applications.