Fire-resistant Coatings Research Articles

Research on the properties of brucite-based magnesium phosphate cement fire resistive coating for steel structures

Magnesium Phosphate Cement (MPC) exhibits high strength, exceptional high-temperature resistance, and outstanding adhesion properties at the steel interface, rendering it an ideal material for fire resistive coatings on steel structures. In this study, natural brucite powder was employed as the magnesium source, while hollow glass microspheres (HGM) were utilized as functional modifiers to formulate brucite-based MPC fire resistive coatings for steel structures. This research explored the influence of the mass ratio of brucite powder to ammonium dihydrogen phosphate (M/P), the brucite particle size, and the addition of HGM on the physical, mechanical, and fire-retardant properties of the coatings. The microstructure of the brucite-based MPC before and after fire testing was examined using SEM, XRD, TG-DTG, and X-CT. The results indicated that with an M/P ratio of 2.5:1 and a brucite particle size of 75–150 μm, the material exhibited optimal overall performance and was suitable as a matrix material for MPC. The incorporation of an appropriate amount of HGM increased the compressive strength of brucite-based MPC by 33.4 %, reduced the dry density by 20.5 %, extended the fire resistance of the structure, and decreased the thermal conductivity by 48.2 %. This can be attributed to: (i) HGM filling the pores in brucite-based MPC, creating a denser microstructure; (ii) HGM forming a closed porous structure with the MPC matrix, reducing thermal conductivity and increasing thermal resistance; (iii) The low thermal diffusivity of HGM/MPC impeded heat transfer, thereby decelerating thermal decomposition and flame propagation.

Evonik expands the TEGO® Therm range with fire-resistant coatings for EV battery housings

Evonik expands the TEGO® Therm range with fire-resistant coatings for EV battery housings

Construction of sustainable and highly efficient fire-protective nanocoatings based on polydopamine and phosphorylated cellulose for flexible polyurethane foam

Layer-by-layer (LBL) self-assembly is an effective strategy for constructing fire-resistant coatings on flexible polyurethane foam (FPUF), while the efficiency of fire-resistant coatings remains limited. Therefore, this study proposes an in situ flame retardancy modification combined with LBL self-assembly technology to enhance the efficiency of flame retardant coatings for FPUF. Initially, polydopamine (PDA) and polyethyleneimine (PEI) were employed to modify the FPUF skeleton, thereby augmenting the adhesion on the surface of the skeleton network. Then, the self-assembly of MXene and phosphorylated cellulose nanofibers (PCNFs) via the LBL technique on the foam skeleton network formed a novel, sustainable, and efficient flame retardant system. The final fire-protective coatings comprising PDA/PEI and MXenes/PCNF effectively prevented the collapse of the foam structure and suppressed the melt dripping of the FPUF during combustion. The peak heat release rate, the peak CO production rate and peak CO2 production rate were reduced by 68.6 %, 61.1 %, and 68.4 % only by applying a 10-bilayer coating. In addition, the smoke release rate and total smoke production were reduced by 83.3 % and 57.7 %, respectively. This work offers a surface modification approach for constructing highly efficient flame retardant coatings for flammable polymeric materials.

Silicophosphate fireproof coatings for building materials

The composition of silicophosphate fire-resistant coatings for wooden building structures was developed and their properties were investigated. Fireproof compositions were obtained by mixing aqueous solutions of liquid glass and acetic acid. As a phosphate-containing additive, phosphate buffer solutions were used, which were added to the silicic acid sol in different amounts and with different ratios of the components of the buffer pair. Adjusting the ratio of the components of the buffer solution led to a change in the pH of the buffer solutions, but adding them to the sol did not change its acidity, which was in the pH range of 5.5–6. The effect of the content and ratio of the components of the buffer pair on the change in the optical density of the obtained sols over time was studied. The highest durability of the flame retardant composition was recorded when using a buffer solution with a pH of 7 at a content of 20%. The embedding of phosphate ions into the siloxane framework of experimental gels has been chemically proven, which increases their fire resistance. It is shown that the amount of free phosphate anion in the intermicellar liquid of the experimental gels is less than 5%. The mechanism of the strengthening effect of the acetate buffer solution, which is formed during the mixing of the liquid glass solution with acetic acid, on the phosphate buffer solution is proposed. Fire-retardant compositions were applied to wood samples by the bath method and dried at temperatures of 80–100 ˚С in a drying cabinet. The fire protection effect of coatings was determined during fire tests in a ceramic pipe. The effect of the content of phosphate buffer solution on the fire-retardant properties of experimental coatings was studied. It is shown that increasing the content of the phosphate buffer solution reduces mass loss during fire tests, allows to increase the fire resistance of wood and transfer it to the group of "highly flammable".

Environmentally safe installation for determining the fire resistance of coatings and fire resistance tests of small fragments building structures

Actuality. Taking into account fire statistics, the task of preventing the occurrence and spread of fires is urgent. It is obvious that the fire resistance of building structures, which must be taken into account at the design stage, is of the greatest importance and influence on the development and spread of fires in buildings and structures. Conducting fire experiments makes it possible to obtain the most complete information about the behavior of building structures under fire effects, however, the scale of field tests, labor-intensiveness, energy consumption and damage to the environment prompts the search and development of alternative methods that would ensure the environmental friendliness of the tests, compliance with the conditions of the experiment ( standard fire temperature regime), and at the same time would make it possible to estimate the limit of fire resistance of a building structure in reduced dimensions or to experimentally determine the fire-resistant ability (efficiency) of fire-resistant coatings. Purpose. The main goal of the article is rationale use of an installation for determining the fire-resistant capacity (efficiency) of fire-resistant coatings and fire resistance tests of small-sized fragments of building structures, taking into account the reduction of the harmful load on the environment. Main results. Research has been carried out and the design features of the installation have been substantiated, the principle of which is to heat the inner space of the chamber with the help of electric heating elements, which, unlike liquid fuel (diesel fuel, fuel oil, gas), do not harm the environment. A control unit-module of variable voltage regulation designed to regulate the heating temperature of the radiation panel in the test chamber has been developed. The design of the created test setup makes it possible to increase or decrease the temperature on the heating surface of the test sample, not only with the help of the heating temperature regulator, but also in manual mode, by moving the test sample closer or further away from the radiation panel along the guides. Conclusions. According to the results of experimental tests, it was established that the chamber of the installation warms up uniformly and according to the standardized temperature-time dependence Ts = 345lg (8t+1)+20). At the same time, the temperature regulation process using BP-10 with triac output ensures stable operation of electric heating elements up to temperatures of 1000 °C. A feature of the created installation is the possibility of additional lowering or raising of the temperature on the heating surface of the experimental sample, in case of its deviation during the experiment, by means of approaching or moving away from the sample to the heating panel. The conducted studies confirm the necessary reproducibility of experimental results.

Highly Transparent Fire-resistant Coatings with Intumescent Three-source Integration

Highly Transparent Fire-resistant Coatings with Intumescent Three-source Integration

Progress in Achieving Fire-Retarding Cellulose-Derived Nano/Micromaterial-Based Thin Films/Coatings and Aerogels: A Review

The enormous potential of renewable bioresources is expected to play a key role in the development of the EU’s sustainable circular economy. In this context, inexhaustible, biodegradable, non-toxic, and carbon-neutral forest-origin resources are very attractive for the development of novel sustainable products. The main structural component of wood is cellulose, which, in turn, is the feedstock of nanocellulose, one of the most explored nanomaterials. Different applications of nanocellulose have been proposed, including packaging, functional coatings, insulating materials, nanocomposites and nanohybrids manufacturing, among others. However, the intrinsic flammability of nanocellulose restricts its use in some areas where fire risk is a concern. This paper overviews the most recent studies of the fire resistance of nanocellulose-based materials, focusing on thin films, coatings, and aerogels. Along with effectiveness, increased attention to sustainable approaches is considered in developing novel fire-resistant coatings. The great potential of bio-based fire-resistant materials, combined with conventional non-halogenated fire retardants (FRs), has been established. The formulation methods, types of FRs and their action modes, and methods used for analysing fireproof are discussed in the frame of this overview.

The Analysis of the Application of Using Nanoceramic Oxides in Fire-resistant Coatings

The increased demand for enhanced fire safety in various industries has spurred interest in the properties and applications of nanoceramic oxide materials. This paper provides a thorough examination of the fundamental attributes of nanoceramic oxides, showcasing their exceptional temperature, corrosion, and wear resistance. The paper discusses synthesis methods like evaporation condensation, high-energy mechanical ball milling, and both vapor and liquid phase chemical techniques. The paper further explicates the underlying mechanisms that enable fire-resistant coatings to retard flames, highlighting thermal insulation, intumescence, and more. Of significance is the potential of nanoceramic oxides to augment the performance of these coatings, evidenced by applications like tunnel fire retardant coatings and steel structure coatings that integrate materials such as Mg (OH)2, nano-SiO2, and TiO2. While challenges in raw material sourcing, eco-friendliness, production, and expertise arise, solutions are proposed. Conclusively, the study underscores the transformative potential of nanoceramic oxides in the realm of fire-resistant coatings, pushing boundaries in fire safety across sectors.

Thermal Insulation Products Based on Modified Polyurethane Foam with Fire-Resistant Coating

As part of the study, thermal insulation products based on rigid polyurethane foam (PPU) with a reduced flammability group were obtained. The effect of modification of polyurethane foam with oxidized thermally expansive graphite (OTG) on physical, mechanical and fire hazard properties was studied. A two-component factory-ready system with a G4 flammability group was used as the initial composition for modification. OTG brand: KR 350-80 was used as a modifier, characterized by a degree of expansion of at least 370 ml/g, a temperature of the onset of expansion of 170°C. Products made from polyurethane foam were modified by the method of dispersing OTG in a reactive composition, as well as by applying a fire-retardant coating during injection molding of masses. Samples were made and tests were carried out to determine the flammability group in accordance with GOST 30244. It was established that an increase in the concentration of OTG in the fire retardant coating and the structure of the material reduces the flammability of products, while modification by the dispersion method makes it possible to obtain a material with a flammability group (G3), but has an effect on the technological properties of the initial composition, leads to an increase in the viscosity of the reactive composition and an increase in the density of the products, while the modification of the fire retardant coating with honey does not affect the technological and physical-mechanical properties of the final product, and makes it possible to obtain a flammability group G1–G2 depending on the concentration of OTG.

Fire-Resistant Coatings, Obtained by Layer-by-Layer Assembly, in the System of Silicic Acid Gel – Diammonium Hydrogen Phosphate – Urea

The paper discusses the influence of flame retardant compositions obtained in the system of silicic acid sol (SiO2 sol) – flame retardants on the fire retardant properties of thin dense cotton fabrics and low density voluminous tapestry fabrics. The need to develop the optimal composition of a fire-retardant composition for a specific fabric, or to unify it for two main groups of fabric: thin and bulky low-density ones, is substantiated. Experimental coatings were obtained by applying SiO2 sol, which was obtained by the reaction between liquid glass and acetic acid, followed by application of flame retardant solutions (diammonium hydrogen phosphate (DAHP) and urea) by spraying or by the bath method. As a result of the optimization, using the central composite uniform rotatable plan of the second order, it was established that the main effect of the flame retardant is exerted by diammonium hydrogen phosphate (DAHP). The content or concentration of urea depends on the concentration of DAHP used: if diluted DAHP solutions (9–10 %) are used, trace amounts of urea (0–0.5 %) must be added. In the case of using a concentrated DAHP solution (18–20 %), the concentration of the urea solution should also be increased to 8–10 %.

Специфика пассивной противопожарной защиты для атомных электрических станций

Passive fire protection systems (elements) are the most preferred for use to ensure nuclear and radiation safety of the nuclear power plants in case of internal and external fires. The main passive fire protection systems (elements) of the nuclear power plants include: fire-resistant structures (walls, ceilings, columns, screens, etc.); fire-resistant sealing of penetrations (technological, electrical, ventilation, etc.); fire-resistant filling of openings in fire barriers (doors, gates, dampers, airlocks, etc.); structural fire protection; fire-resistant coatings; devices for emergency draining and self-extinguishing of flammable liquids. Among them, it is possible to distinguish both systems (elements) that perform the function only of fire protection (for example, fire-resistant coatings, fire dampers for ventilation systems), and the systems (elements) that perform other basic functions that also require fire protection (for example, building structures, sealed doors). Passive systems (elements) may simultaneously be subject to the requirements for protection against fire, other internal and external influences (flooding, flying objects, explosions, etc.), as well as the operational requirements specific to the nuclear power plants (resistance to radiation-ionizing radiation, decontaminating compositions, vibrations, high temperatures, etc.). Due to the complex nature of the requirements, a certain imperfection of the regulatory framework and processes for organizing design and construction in the nuclear industry, there is a certain shortage of products for the implementation of passive fire protection solutions that meet the necessary requirements. To solve the above problems in the field of passive fire protection of the nuclear power plants, it seems appropriate to organize work in the following areas: conducting research based on the Russian and international experience; development of the regulatory framework; improvement of the design and construction processes. The work in these areas could contribute to the early saturation of the Russian market with domestic products of passive fire protection, as a result, increase the level of safety and economic efficiency of the nuclear power plants.

Construction of layered double hydroxide composites derived from tungsten tailing particles for simultaneously enhancing fire protection and anti-ageing properties of intumescent fire-resistant coatings applied in wood surface

Tungsten tailing is a great deal of solid waste produced in the production process of tungsten metal, for which there is no simple and effective treatment method in the world. The success synthesis of layered double hydroxide composites (TTF-LDH) by co-precipitation method from tungsten tailing is a feasible way to solve this problem. The structure and properties of TTF-LDH were confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The obtained TTF-LDH was in combination with intumescent flame retardants (IFR) to achieve a series of intumescent fire resistance coatings. The effects of TTF-LDH on the fire protection, smoke suppression and anti-ageing performances of coatings were evaluated by fire resistance test, smoke density test, cone calorimeter test and accelerated ageing test, while the flame-retardant mechanism of TTF-LDH in coatings was revealed. The results illustrate that an appropriate amount of TTF-LDH can remarkably enhance smoke suppression and fire-resistant abilities of coatings, among which the coating containing 3 wt % TTF-LDH (IFRC-LDH3) exhibits the optimal synergistic effect, revealing a smoke density rating value of 17.3%, a total heat release of 7.0 MJ/m2 and an equilibrium backside temperature of 146.2 °C at 900 s. Meanwhile, the addition of TTF-LDH can strengthen the char formation and thermal stability abilities of the coatings, and the residual weight of IFRC-LDH3 rises to 35.7% at 800 °C, as supported by thermogravimetric (TG) analysis. The results of accelerated ageing test demonstrate that the presence of TTF-LDH can strengthen structural stability of coating, decrease migration and decomposition of IFR, thus giving the coating better integrity and durability of fire-resistant and smoke suppression properties.

Fire Damage Characteristics of Fire-Resistant Coating Materials in Petrochemical Plant Facilities

As industrial facilities, petrochemical plants require prompt investigation, diagnosis, and recovery in the event of fire damage associated with disasters and accidents. Due to the characteristics of petrochemical plants, which are mostly composed of steel structures with fire-resistant coating materials, the coating materials are the first to be damaged. Accordingly, in this study, the fire damage characteristics of fire-resistant coating materials were analyzed experimentally, verifying the possibility of estimating the heating temperatures based on such characteristics. The results show a correlation between the foam expansion ratio and the heating temperature of intumescent fire-resistant coating materials with foam properties. A significant correlation was found between the density and adhesion strength ratio and the heating temperature of spray-applied fire-resistant coatings. The results suggest the possibility of estimating the heating temperatures based solely on the fire damage characteristics of the coating materials, which could provide a platform for simplifying existing methods for investigating and diagnosing fire damage.

Functional assignment of technological accessories for woodworking

Forming a heat and sound insulation board from wood using non-combustible binders can increase the fire protection of the material by forming a protective layer of coke. This will make it possible to develop a new type of fireproof roofing products for building structures. It is not always advisable to treat the surface of a heat and sound insulation board with fireproof coatings, since after prolonged thermal exposure, the combustion stage can be transferred to the interior of the material by smoldering. Therefore, the manufacture of fire-resistant heat- and sound-insulating wood materials, the study of fire protection and the impact of their components on this process is an unresolved component of ensuring the fire resistance of building structures. And, accordingly, they determine the need for such research.
 The paper presents the results of research into the process of protecting wood wool boards with binders based on fire-resistant coatings. Tests on model samples of a wooden board showed that the material based on wood wool and an inorganic binder is characterized by heat absorption and inhibition of oxidation in the gas and condensed phase and the formation of a thermally protective ceramic layer on the surface of the wood. Experimental studies have confirmed that a material based on wood wool and an inorganic binder at a ratio of 1:1 refers to combustible materials, since its smoldering was recorded during exposure to temperature. So, by thermal action for 90 s, the material ignited and the flame spread over the first three zones for 41 s. On the other hand, an increase in the amount of an inorganic-based binder and the use of an organic-mineral binder does not lead to a material fire. In this case, the maximum temperature of the flue gases was about 120 °C, and the flammability index was 0 due to the decomposition of fire retardants under the influence of temperature with the release of incombustible gases, which inhibit the oxidation of the material and significantly increase the formation of a heat-protective layer of coke on the surface of the material. This leads to inhibition of heat transfer of the high-temperature flame to the material. Due to this, it became possible to determine the conditions of fire resistance of the material by forming a barrier for thermal conductivity. The obtained results indicate the possibility of targeted regulation of high temperature transfer processes to organic material by using special binders for wood products.

Comparative response of tiled finishes and bonded fire resistive coatings for normal weight concrete tunnel liners under high-intensity one-sided heating

Experimental tests were performed to examine the relative fire resistance provided by several bonded coatings for normal weight concrete (NWC) panels that emulate a tunnel liner: ceramic tiling on mortar, spray-applied fire resistive material (SFRM), and intumescent paint (IP). Sixteen panel specimens (150-mm [6-in.] thick, 457-mm [18-in.] wide, and 610-mm [24-in.] tall) were subjected to one-sided heating using a gas-fired radiant panel, which can apply heat flux at intensities similar to hydrocarbon fuel fire. All specimens were cast from a single batch of NWC (approx. 40 MPa compressive strength) with a single curtain of steel reinforcing bars at 38-mm (1.5-in.) cover to the heated face. All specimens were vertically loaded to a service level of compressive uniaxial stress (approx. 14% of ambient specified compressive strength), which remained relatively constant during each test. Four bare concrete panel specimens were tested as a control group, and a ceramic tile finish was installed on six specimens in accordance with a current state department of transportation specification. The other six specimens were coated with fire resistive material (three each with SFRM and IP) at thicknesses corresponding to a 1-hr fire resistance rating per manufacturer specifications. Thermally-induced explosive concrete spalling was observed in 3 of 4 control specimens, 4 of 6 tiled specimens, and none of the 6 SFRM/IP coated specimens. The tiled finishes delaminated and eventually became fully detached from the concrete surface, thus providing negligible fire resistance compared to that provided by the SFRM or IP. Temperature time histories recorded within the outer 25-mm (1.0-in.) thickness of the heated concrete were used to evaluate the relative thermal resistance of each surface finish, as well as to validate a simplified thermal numerical model used for a brief parametric study. Post-fire removal of the surface finishes is also demonstrated.

ASSESSMENT OF THE FIRE RESISTANCE OF BUILDINGS FROM FIREPROOF REINFORCED CONCRETE BUILDING STRUCTURES

The paper developed a computer model of the thermal and stress-strain state of a three-story car parking building, which consists of fire-resistant structures, taking into account: thermophysical characteristics of fire-resistant coatings, thermophysical and mechanical properties of the materials that make up the structure, nonlinear laws of deformation of the model materials, mechanical properties of materials at high temperature and force. Modeling of non-stationary heating of a reinforced concrete parking column with a square cross-section, dimensions 0.5×0.5×3 m under the conditions of exposure to a standard fire for 150 minutes was carried out. At the same time, it was found that the temperature on the reinforcing rods reaches 853 °C, which is sufficient to ensure the fire resistance of R150 at the given calculated forces in the column, and the mosaic of movements along the Z axis was not significant and amounted to 1.1 mm. The maximum reinforcement area was 5.55 cm2. When ensuring R180 fire resistance at the given calculated forces in the column, the temperature at the corner reinforcing bars reached 914 °С and the program calculated additional reinforcement. This indicates that the existing reinforcement is not enough to ensure the fire resistance of R180 at the given design forces in the column, so the maximum area of the reinforcement as a result of the calculation by the program increased to 58.7 cm2 (10 times more than the initial one). Measures to increase the fire resistance limits of structures, consisting in the use of fire-resistant coatings with scientifically based parameters, are proposed. The thickness of the passive fire-resistant coating, the coefficient of thermal conductivity, the specific heat capacity, which must be ensured when evaluating the fire resistance of a fire-resistant reinforced concrete column and increasing the limits of fire resistance to 180 minutes, are substantiated. Numerical calculations of non-stationary heating of a fire-protected reinforced concrete column of a parking lot (coating thickness 11 mm) under the conditions of exposure to a standard fire for 180 minutes revealed that the temperature on the reinforcing rods reached 213 °C, which is 4 times less than the heating of an unprotected column. Keywords: fire resistance, fire-resistant reinforced concrete structures, fire-resistant coating, thermophysical characteristics.

Fabrication of Intumescent Fire-Retardant Coating for Structural Applications

Applicability of materials limited by the effect of flammability in case of any sudden incident. Worldwide protection of any structure from the fire is covered through intumescent fire resistant coatings since many past years. Purpose of this study is to prepare and to fabricate several intumescent fire retardant coatings (IFRC) using different proportions of materials per unit weight. Also to find most optimistic formulations and analyse the performance of intumescent fire retardant coatings (IFRC). On the basis of background studies 5 different materials were considered to prepare several formulations i-e Titanium dioxide (TiO2), Ammonium polyphosphate (APP), Zinc borate, Epoxy hardener, Kaolinite (Clay), Melamine (MEL) and Expandable Graphite (EG). IFRC formulations were applied on Mild Steel plates after its preparation Each formulation was subjected to a temperature of 700°C for a period of five minutes. The results revealed that the coatings, Out of 5 formulations of IFRC, IFRC-4 exhibited promising performance. It demonstrated excellent stability and adhesion at the elevated temperature, lasting for over five minutes. Additionally, its coating expanded up to four times the initial thickness. Heat Transfer rate was completely reduced.

Reformative Effects of Intumescent Coating on the Structural Characteristics of Cold-Formed Steel.

Intumescent fire-resistive coatings are a more recent type of passive fireproofing thin film that swells many times its initial applied thickness, generating an insulating char that functions as a thermal barrier between the fire and structural steel. It keeps the heat of steel members from reaching critical levels and aids in the structural integrity during a fire. They are architects and designers' favorite choice for passive fire protection of load-bearing steel frame structures because of their aesthetic look, versatility, rapidity of application, and ease of inspection and maintenance. In this study, axial tensile, thermal conductivity, and hardness tests have been performed on S235 cold-formed steel specimens that were exposed to increasing temperature periods. The mechanical behavior of coated and uncoated specimens was investigated over the modulus of elasticity, yield strength/strain, and ultimate strength/strain values for all temperatures. As a result of the research, gradually increasing changes were observed in the mechanical properties of coated and uncoated specimens at increasing temperature levels, compared to each other. However, performance increment on the coated specimens was limited in terms of strength and strain characteristics than expected. Two essential reasons for this conclusion are that the specimens were exposed to heat for a long time after reaching the target temperature and also that the wall thickness of the specimens was thinner with respect to the usual application method of the protective coating. In order to examine the structural properties of the test specimens after elevated temperature effects, thermal conductivity measurement was also performed. Temperature difference between coated and uncoated surfaces provided a benefit in the range of 29-56% due to the coating. Lastly, microstructure imaging techniques demonstrated grain coarsening and no crack development with the increase in temperature.

Phenylboronic acid-decorated ZrP nanosheets for enhancing fire resistance, smoke suppression, and water/acid/alkali tolerance of intumescent coatings

To enhance the integrated properties of intumescent fire-resistant coatings (IFRCs) for structural steel, multifunctional phenylboronic acid-decorated zirconium phosphate (ZrP-M) nanosheets were fabricated in this work. The ZrP-M nanosheets featured superior char-forming capacity, flame-retardant effect and hydrophobicity, which simultaneously enhanced the fire resistance, smoke suppression, thermal stability, and water/acid/alkali tolerance of IFRCs. Compared with the unmodified IFRC, the IFRC with 3 wt% ZrP-M (IFRC-4) showed 74.3%, 74.5% and 41.9% reductions in the peak heat release rate (PHRR), total heat release (THR) and total smoke release (TSR). Meanwhile, the IFRC-4 exhibited significantly improved charring capacity and water tolerance, of which the char yield and water contact angle reached 70.9% and 116.9°. The superior fire retardancy and carbonization ability of IFRC-4 enabled it to outperform previous fire-retardant coatings. The introduction of ZrP-M nanosheets also improved the acid and alkali resistance of IFRC. In a fire, the ZrP-M mainly promoted the formation of highly intumescent and compact chars in the condensed phase, thereby strengthening the fire resistance of IFRC. Thus, this work offers an integrated strategy to prepare fire-resistant, smoke-suppressive, thermally-stable and water/acid/alkali-tolerant coatings via introducing versatile ZrP nanosheets, which are expected to find ubiquitous applications in modern construction.

Influence of fire-resistant coating on the physical characteristics and residual mechanical properties of E350 steel section exposed to elevated temperature

PurposeMost of the industrial buildings which are designed to moderate loads are constructed using light gauge cold-formed steel (CFS) sections. Residual mechanical properties of CFS sections exposed to elevated temperature need to be investigated as it is necessary to predict the deterioration of elements to avoid failure of the structure or its elements. Also, it would be helpful to decide whether the structural elements need to be replaced or reused. The use of fire-resistant coatings in steel structures significantly reduces the cost of repairing structural elements and also the probability of collapse. This study investigates the effect of fire-resistant coating on post-fire residual mechanical properties of E350 steel grade.Design/methodology/approachIn this study, an attempt has been made to evaluate the residual mechanical properties of E350 steel. A tensile coupon test was performed for the extracted specimens from the exposed CFS section to determine the mechanical properties. Four different fire-resistant coatings were selected and the sections were coated and heated as per ISO 834 fire temperature curve in the transient state for time durations of 30 minutes (821°C), 60 minutes (925°C), 90 minutes (986°C), and 120 minutes (1,029°C). After the exposure, all the coupon specimens were cooled by either ambient conditions (natural air) or water spraying before conducting the tension test on these specimens.FindingsAt 30 min exposure, the reduction in yield and ultimate strength of heated specimens was about 20 and 25% for air and water-cooled specimens compared with reference specimens. Specimens coated with vermiculite and perlite exhibited higher residual mechanical property up to 60 minutes than other coated specimens for both cooling conditions. Generally, water-cooled specimens had shown higher strength loss than air-cooled specimens. Specimens coated with vermiculite and perlite showed an excellent performance than other specimens coated with zinc and gypsum for all heating durations.Originality/valueAs CFS structures are widely used in construction practices, it is crucial to study the mechanical properties of CFS under post-fire conditions. This investigation provides detailed information about the physical and mechanical characteristics of E350 steel coated with different types of fire protection materials after exposure to elevated temperatures. An attempt has been made to improve the residual properties of CFS using the appropriate coatings. The outcome of the present study may enable the practicing engineers to select the appropriate coating for protecting and enhancing the service life of CFS structures under extreme fire conditions.