Mechanical behavior of K-geopolymers reinforced with silane-coated basalt fibers

A potassium-based geopolymer (KGP) was produced through the combination of metakaolin and a K-based alkali metasilicate solution (K₂O•Al₂O₃•4SiO₂•11H₂O). Two types of silane-coated chopped basalt fibers, manufactured for cement or epoxy-based applications, were used in order to compare their effects. The fibers had a 12.7 mm (½ inch) length and were incorporated initially in 10 wt % contents, due to the limited fluidity of the matrix. The effect of the addition of Sapetin® superplasticizer in varying weight percentages was examined through consistency tests. 0.5% by weight of the matrix was established to be an adequate amount to improve the geopolymer workability, allowing a greater incorporation of both types of fibers into the matrix (20 wt%). The mechanical properties were analyzed through compression and 4-point flexural tests. Pull-out and direct tensile tests were also performed. Additionally, X-ray diffraction (XRD) was conducted with the KGP material and scanning electron microscopy (SEM) was used to measure the fiber cross sections. Both composites manufactured with 10 wt % of fibers reached similar high flexural strengths (~30 MPa), suggesting a suitable crack propagation at higher stresses due to strong fiber-matrix adhesions. The fibers manufactured for epoxy applications presented a greater compatibility in 20 wt % contents, reaching 37.8 MPa in flexural tests. This was attributed to a better dispersion of such fibers in a fresh mix with reduced friction, such as KGP with the addition of superplasticizer, suggesting an improved use of this reinforcement in such contents.     

Sustainable activation of pumice with partially variable substitutions of metakaolin and/or fumed silica

Sustainable alkali activation of pumice from Turkish origin was studied by a partial replacement of metakaolin and/or fumed silica additives. Following the characterization of as-received pumice by X-ray fluorescence spectroscopy, x-ray diffraction, and nuclear magnetic resonance spectroscopy, a series of powder mixtures were prepared by introducing metakaolin and/or fumed silica (8, 14, and 20 M) into 1 M of the pumice. The mixtures were then dissolved in 11 M NaOH or sodium silicate solutions. The slurries were poured into polyacetal molds to obtain geopolymer samples for mechanical testing and cured in a constant 50°C temperature in a humidity oven for 48 h and then left for 1 week to undergo additional curing at ambient temperature. The microstructural, mechanical, and thermal properties of the final geopolymer samples were determined by XRD, scanning electron microscopy, Weibull analysis of 3-point flexural and compressive tests and thermal conductivity measurements. Results showed that all the Weibull values were best for 14 M of metakaolin and/or fumed silica. The metakaolin-added pumice yielded higher compressive strengths of (53.78 ± 33.30 MPa) than fumed silica (10.87 ± 4.04 MPa) and fumed silica plus metakaolin (41.22 ± 5.16 MPa). Thermal conductivities (0.19–0.46 Wm^–1K^–1) were also comparable to the thermal conductivity of metakaolin-based geopolymers.     

Relative importance of Al(V) and reinforcement to the flexural strength of geopolymer composites

We prepared 1 cm × 1 cm × 10 cm geopolymer bars from sodium silicate and six commercial metakaolins, both unreinforced and reinforced with 20 wt% of 55-μm wollastonite (CaO·SiO₂) needles, to evaluate the relative contributions of five-coordinated aluminum in the metakaolin and the presence of a reinforcing phase to the flexural strength of geopolymers. Two metakaolins, with about 20 at% and lower of five-coordinated aluminum content, did not react sufficiently with our processing method and could not be tested. The flexural strengths of the other four geopolymers were similar at about 11–14 MPa unreinforced and 22–29 MPa reinforced. The effect of reinforcement on flexure strength is more significant than the choice of metakaolin provided that the metakaolin is reactive. The geopolymerization reaction depends on the amount of five-coordinated aluminum present in the metakaolin and is the primary difference between the samples that reacted and those that did not react.     

Amorphous self-glazed,chopped basalt fiber reinforced,geopolymer-based composites

Geopolymer composites reinforced with refractory, chopped basalt fibers, and low melting glass were fabricated and heat treated at higher temperatures. K₂O·Al₂O₃·4SiO₂·11H₂O was the stoichiometric composition of the potassium-based geopolymer which was produced from water glass (fumed silica, deionized water, potassium hydroxide), and metakaolin. Addition of low melting glass (T_m ~815°C) increased the flexure strength of the composites to ~5 MPa after heat treatment above 1000°C to 1200°C. A Weibull statistical analysis was performed exhibiting how the amorphous self-healing and self-glazing effect of the glass frit significantly improved the flexure strength of the geopolymer and ceramic composites after exposure for 1 hour to high temperatures. At 950-1000°C, the K-based geopolymer converted to primarily a crystalline leucite ceramic, but the basalt fiber remained intact, and the melted glass frit flowed out of the surface cracks and sealed them. 1150℃ was determined to be the optimum heat treatment temperature, as at ≤1200°C, the basalt fibers melt and the strength of the reinforcement in the composites is significantly reduced. The amorphous self-healing and amorphous self-glazing effects of the glass frit significantly improved the room temperature flexure strength of the heat-treated geopolymer and ceramic composites.     

Amorphous self-healed,chopped basalt fiber-reinforced,geopolymer composites

Geopolymer composites containing refractory, chopped basalt fibers and low-melting glass were made and systematically heat-treated at higher temperatures. Potassium-based geopolymer of stoichiometric composition K₂O·Al₂O₃·4SiO₂·11H₂O was produced by high shear mixing from fumed silica, deionized water, potassium hydroxide, (i.e., water glass) and metakaolin. With the addition of low-melting glass (T_m ~815°C) the flexure strengths of the composites increased to ~6 MPa after heat treatment above 900°C to 1100°C. A Weibull statistical analysis was performed showing how the amorphous self-healing effect of the glass frit significantly improved the flexure strength of the geopolymer and ceramic composites after high-temperature exposure. At temperatures up to 900°C, the geopolymer-basalt composite remained amorphous and the low-melting glass frit flowed into the dehydration cracks in the geopolymer matrix. This type of composite could be described as amorphous self-healed geopolymer (ASH-G). At ~1000°C, the geopolymer converted to primarily a crystalline leucite ceramic, but the basalt fiber remained intact, and the melted glass frit flowed and sealed the cracks developed at that temperature. This type of composite could then be described as amorphous self-healed ceramic (ASH-C). A temperature of 1150°C was determined to be optimum as at 1200°C the basalt fibers melted and the strength of the reinforcement was lost in the composites. The amorphous self-healing effect of the glass frit significantly improved the room temperature flexure strength of the heat-treated geopolymer-based composites.     

Evaluation of alumina reinforced oil fly ash composites prepared by spark plasma sintering

The thermomechanical behavior of micro/nano-alumina (Al₂O₃) ceramics reinforced with 1-5 wt.% of acid-treated oil fly ash (OFA) was investigated. Composites were sintered using spark plasma sintering (SPS) technique at a temperature of 1400°C by applying a constant uniaxial pressure of 50 MPa. It was evaluated that the fracture toughness of micro- and nanosized composites improved in contrast with the monolithic alumina. Highest fracture toughness value of 4.85 MPam^1/2 was measured for the nanosized composite reinforced with 5 wt.% OFA. The thermal conductivity of the composites (nano-/microsized) decreased with the increase in temperature. However, the addition of OFA (1-5 wt.%) in nanosized alumina enhanced the thermal conductivity at an evaluated temperature. Furthermore, a minimum thermal expansion value of 6.17 ppm*K⁻¹ was measured for nanosized Al₂O₃/5 wt.% OFA composite. Microstructural characterization of Al₂O₃-OFA composites was done by x-ray diffraction and Raman spectroscopy. Oil fly ash particles were seen to be well dispersed within the alumina matrix. Moreover, the comparative analysis of the nano-/microsized Al₂O₃/OFA composites shows that the mechanical and thermal properties were improved in nanosized alumina composites.     

Mechanical and microstructural analysis of geopolymer composites based on metakaolin and recycled silica

This paper evaluated mechanical and thermal stability of alkali-activated materials obtained from metakaolin and alternative silica sources, such as rice husk ash (RHA) and silica fume (SF), and were reinforced with recycled ceramic particles (RP) obtained by grinding bricks. Specimens were produced, and after 7 days of curing, they were exposed to temperatures between 300 and 1200°C to determine the influence that different percentages of RP had on the mechanical behavior and microstructure of the produced composites. The results showed a reduction in the linear contraction by 10.22% with 20 wt% RP and that the reinforcing materials improved the mechanical performance of the geopolymers after exposure to high temperatures; the compressive strengths reached 137.7 (±11.4)  MPa after being exposed to 1200°C for the matrix based on RHA and 180.6 (±19.15) MPa after being reinforced with 20 wt% RP. The improvement was mainly due to densification and the formation of crystalline products such as leucite, kalsilite, and mullite.     

Production of nepheline/quartz ceramics from geopolymer mortars

This research has investigated the mechanical properties and microstructure of metakaolin derived geopolymer mortars containing 50% by weight of silica sand, after exposure to temperatures up to 1200 °C. The compressive strength, porosity and microstructure of the geopolymer mortar samples were not significantly affected by temperatures up to 800 °C. Nepheline (NaAlSiO₄) and carnegieite (NaAlSiO₄) form at 900 °C in the geopolymer phase and after exposure to 1000 °C the mortar samples were transformed into polycrystalline nepheline/quartz ceramics with relatively high compressive strength (～275 MPa) and high Vickers hardness (～350 HV). Between 1000 and 1200 °C the samples soften with gas evolution causing the formation of closed porosity that reduced sample density and limited the mechanical properties.     

Consolidation of mine tailings through geopolymerization at ambient temperature

Mine tailings-based geopolymers were prepared at ambient temperature. The evolution of their microstructure and the immobilization of lead were studied. Characterizations include measurements in compressive strength, scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and toxicity characteristic leaching procedure (TCLP) tests. With increasing the ratio of metakaolin from 0% to 50%, geopolymer gel in the mine tailings-based geopolymers increased from 33.92% to 79.45%, leading to the compressive strength that increased from 2 to 15.5 MPa. With addition of Pb(NO₃)₂, a three-stepped changes in the compressive strength and microstructure of the geopolymers were observed. As increasing Pb(NO₃)₂ dosage from 0% to 6%, geopolymer gel was kept constant, while lead silicate glass increased from 0% to 10.51%, and Si sites in calcium silicate hydrate (CSH) gel decreased from 20.55% to 11.3%. Pb²⁺ was effectively immobilized in the geopolymers. This study first presents the evolution of geopolymer gel, belite, lead silicate glass, and CSH gel in mine tailings-based geopolymers as the functions of metakaolin and Pb(NO₃)₂ additions.     

Synthesis of SiAlON-type compounds by carbothermal reduction and nitridation of nanoparticulate geopolymers

Various types of SiAlON compounds were synthesized by heating of carbon-mixed, geopolymer compositions of M₂O•Al₂O₃•4.5SiO₂•12H₂O + 9C. A fixed molar ratio of carbon to silica of 2 and charge-balancing cations Na⁺, K⁺, or Cs⁺ were used to prepare the geopolymer-carbon precursor resins. After curing, the precursors were ground to powders and then fired at 1400 to 1600°C for 2 h under flowing nitrogen. In contrast to previous studies, powdered forms of the precursors and moderate carbon ratios were used in these syntheses. X-ray diffraction results indicated that phase-pure β- or O-SiAlON powders were synthesized, in the case of potassium at 1400 or 1500°C (for β-SiAlON) and sodium cations at 1400°C (for O-SiAlON), respectively. In the cases of cesium, high purity β-SiAlON with some corundum and pollucite were synthesized. Furthermore, depending on the cation type and temperatures, tailored compositions of SiAlON or other compounds (mainly Al₂O₃) were formed by other reactions between precursors in this systematic study.     

Geopolymer reinforced with E‐glass leno weaves

This study explores the viability of fiberglass‐geopolymer composites as an intermediate temperature structural ceramic composite. E‐glass fibers are cheap, readily available, resistant to heat, electricity and chemical attack. Geopolymers are refractory and can be processed at room temperature. However, pure geopolymers have low tensile strength and fracture toughness, as is typical of ceramics. In this work, tensile and flexure properties of metakaolin‐based sodium and potassium geopolymers reinforced with E‐glass leno weaves were measured and the data was analyzed by Weibull statistics. The average tensile and flexural strengths for sodium geopolymer reinforced with E‐glass leno weaves were 39.3 ± 7.2 MPa and 25.6 ± 4.8 MPa, respectively. For potassium geopolymer reinforced with E‐glass leno weaves, the average tensile and flexural strengths were 40.7 ± 9.9 MPa and 15.9 ± 4.0 MPa, respectively. The composites were heat treated for one hour at two temperatures, 300°C and 550°C and their flexure properties were studied at room temperatures. The average flexural strengths for sodium geopolymer reinforced with E‐glass leno weaves were reduced to 6.6 ± 1.0 MPa after heat treatment at 300°C, and 1.2 ± 0.3 MPa after heat treatment at 550°C, respectively. For potassium geopolymer reinforced with E‐glass leno weaves, the average flexural strengths were 6.1 ± 1.5 MPa and 1.3 ± 0.3 MPa after heat treatment at 300°C and 550°C, respectively. SEM and EDS were performed to observe the fiber‐matrix interface. XRD was done to check if the geopolymer was amorphous as expected.     

MoB2/MoB ceramic particulate reinforced W-1 wt % Ni matrix composites as potential plasma facing materials

This study reports on the synthesis and characterization of MoB₂/MoB ceramic particulate reinforced W-1 wt % Ni matrix (W1Ni) composites for their potential usage as plasma facing materials. A powder metallurgical route consisting of mechanical alloying (MA), cold pressing (CP), cold isostatic pressing (CIP) and pressureless sintering (PS) was applied for the production of MoB₂/MoB particulate reinforced W1Ni composites. Different percentages of MoB₂/MoB (x = 1, 2, 5 and 10 wt %) were incorporated into W1Ni pre-alloy. MA was performed in a planetary ball mill for different times as 24, 48 and 72 h. After compaction using CP and CIP, green bodies were pressureless sintered at 1400 °C for 1 h under Ar/H₂ gas flow. According to the results of XRD characterization, and lattice strain, crystallite size and particle size analyses performed on the powders, MA time was determined as 72 h with an average lattice strain of 2.37% and crystallite size of 7.40 nm. Sintered samples characterized in terms of compositional, microstructural, wear, density and microhardness properties exhibited that W1Ni-10 wt % MoB₂/MoB composite has the highest hardness value of ∼6.74 GPa and the lowest wear volume loss of 2.08 × 10^-4 mm³, as compared to those of other samples. Sintered samples exposed to 20 eV He⁺ ion irradiation with a flux of 1.102 × 10²¹ ions/(m²s), irradiation fluence of 1.32 × 10²⁴ ions/m² for 20 min had a degraded wave-shaped structure (wavy erosion layers) on their surfaces. However, W1Ni-2 wt % MoB₂/MoB composite showed relatively more resistant to ion irradiation attributed to its higher densification rate.     

Fully reacted high strength geopolymer made with diatomite as a fumed silica alternative

Geopolymers are formed by mixing of aluminosilicate sources with alkaline meta-silicate solution at room temperature. In the current study, diatomite of Turkish origin was fully utilized as a fumed silica alternative for the preparation of geopolymer, having a typical formula of K₂O•Al₂O₃•4SiO₂•11H₂O. From XRD of this sample, a broad peak centered at 28° 2θ indicated the well-known formation of amorphous geopolymer, as well as a fully reacted microstructure of geopolymer as seen by scanning electron microscopy. Additionally, geopolymer having the same formula was made by using fumed silica, in order to compare with geopolymers prepared from diatomite. The Weibull modulus was calculated from four-point bending and compressive strength testing of both geopolymer composites. The use of diatomite as a fumed silica substitute in geopolymer production resulted in a very close flexure strength 9.2 (± 4.2 MPa) when compared to geopolymer made from fumed silica 10.2 (± 3.3 MPa). There was a significantly higher compressive strength 71 (± 13.9 MPa) and Weibull modulus (5.4), than comparable properties of geopolymer made from fumed silica, which had a compressive strength 54 (± 25.8 MPa) and Weibull modulus of 2.0. The discrepancy was attributed to some self-reinforcement of the geopolymer matrix due to unreacted diatomite.     

Properties and characterization of alumina platelet reinforced geopolymer composites

Geopolymers are porous, amorphous, alkali-aluminosilicate hydrate materials formed at room temperature via a solution process. Geopolymer based on metakaolin had a relatively homogeneous microstructure that offered consistent behavior but suffered from dehydration cracking and large densification shrinkages when heated. It was found that by reinforcing a metakaolin geopolymer of composition (K₂O·Al₂O₃·4SiO₂·11H₂O) with 50 µm diameter alumina platelets, dehydration cracking could be prevented, and shrinkage could be reduced by an order of magnitude. Samples were reinforced with 30, 50, and 70 wt% of alumina platelets. Although the properties of the 30 and 50 wt% conditions were better than those of unreinforced geopolymer, those samples still showed warping, cracking, and strength losses on heating. The 70 wt% samples did not warp or crack when heated to temperatures of up to 1500°C. The room-temperature 4-point flexural strength of these samples remained at around 20 MPa regardless of heat treatments. The in situ measured flexural strength increased to almost 40 MPa at 600°C, and remained higher than 20 MPa until 1200°C. Samples subjected to propane-torch thermal shock heating and subsequent quenching did not crack or fragment. Dilatometry, X-ray diffraction, and scanning electron microscopy were used for additional characterization. Given these properties, this material showed promise as a castable refractory.     

Synthesis and mechanical properties of novel composites of inorganic polymers (geopolymers) with unidirectional natural flax fibres (phormium tenax)

This study reports the synthesis and mechanical properties of new inorganic polymer (geopolymer) composites unidirectionally reinforced with 4–10 vol.% natural cellulose-based fibres (NZ flax, phormium tenax). The geopolymer matrix was derived from dehydroxylated kaolinite-type clay. The mechanical properties of the fibre-reinforced composites improve with increasing fibre content, achieving ultimate flexural strengths of about 70 MPa at 10 vol.% fibre content. This represents a significant improvement on the flexural strength of the unreinforced geopolymer matrix (about 5.8 MPa), and all the composites show graceful failure, unlike the brittle failure of the matrix. Scanning electron microscopy was used to study the morphology of the fibre-matrix regions and a combination of thermogravimetric analysis (TGA) and thermal shrinkage measurements of these composites suggests that despite the formation of microcracks due to water loss from the geopolymer matrix, the fibres are thermally protected by the matrix up to 400 °C. The flax fibres do not appear to be compromised by the alkaline environment of the matrix, suggesting new possible applications for these low-cost simply prepared construction materials.     

Synthesis and adsorption performance of fly ash/steel slag-based geopolymer for removal of Cu (II) and methylene blue

In order to realize the value-added resource utilization of solid waste, geopolymer particle adsorbents were prepared at low temperatures using silica-aluminum-rich fly ash and steel slag powders as raw materials. In order to investigate the mechanism of their adsorption of dyes and heavy metal ions from wastewater, the effects of steel slag/fly ash ratio, adsorbent dosage, initial concentration of methylene blue (MB) and Cu²⁺ solution, adsorption time and temperature on the adsorption performance of the fly ash/steel slag-based geopolymer adsorbents were investigated, systematically. Results presented that the adsorption capacities of MB and Cu²⁺ were 33.30 and 24.15 mg/g, and the removal efficiencies were 99.90% and 96.59% with the dosages of 3 and 4 g/L geopolymer adsorbents (steel slag/fly ash ratio of 20 wt.%), respectively. The adsorption processes of MB and Cu²⁺ on the adsorbents were in accordance with the proposed pseudo-second-order and Langmuir isotherm models, which mainly included physical and chemical adsorption mechanisms. The adsorption was a spontaneous endothermic process. The fly ash/steel slag-based geopolymer had good removal ability for dyes and heavy metal ions, and it could maintain good adsorption performance after three cycles of regeneration. It had potential application in wastewater treatment.     

Al2O3·2SiO2 powders synthesized via sol–gel as pure raw material in geopolymer preparation

Geopolymers are inorganic aluminosilicates mainly proposed as environmentally friendly building materials, which are obtained by alkali activation of natural minerals, calcined clay (e.g., metakaolin) and other aluminosilicate sources. The wide range of chemical and mineralogical compositions of these raw materials influences several properties of the obtained geopolymers. In the present work, pure Al₂O₃·2SiO₂ powders were synthesized via the sol–gel technique and proposed as pure aluminosilicate sources to prepare alkali activated geopolymers. Samples differing in the ratio between the SiO₂ precursor and the H₂O used in the sol–gel process were prepared, in order to study the effect of water content on the material structure and reactivity. The chemical structure of all the obtained Al₂O₃·2SiO₂ powders were characterized by Fourier transform infrared (FT‐IR) and solid‐state nuclear magnetic resonance (²⁷Al and ²⁹Si MAS NMR) spectroscopies and compared to that of a reference metakaolin. Moreover, material reactivity was evaluated by alkali activation of the samples. After 28 days of ageing, ²⁷Al and ²⁹Si MAS NMR and FT‐IR spectra ascertained the formation of a geopolymeric network in the activated samples. The results showed that lower water content allows obtaining a homogeneous Al‐rich geopolymer similar to that obtained, using metakaolin as raw material.     

Characterization and adsorption performance of waste-based porous open-cell geopolymer with one-pot preparation

Porous geopolymer foams are promising lightweight materials combining strong strength and adsorption properties. A waste-based porous open-cell geopolymer (POG) was synthesized by one-pot method and investigated in terms of unconfined compressive strength (UCS), pore distribution and adsorption ability. This paper investigates the effect of preparation conditions (raw materials and stabilizing/foaming agents proportion, modulus, curing temperature) on the performance of POG. Results indicated that POG was successfully prepared by industrial wastes (blast furnace slag, BFS) and municipal wastes (water treatment residue, WTR). The appropriate range of conditions were determined for the preparation of POG (H₂O₂ = 1.50 ~ 2.50 wt%, K12 = 1.50 ~ 2.00 wt%, modulus = 1.25 ~ 2.00, and temperature = 60 ~ 70 °C). Under these conditions, the UCS in the range 1.77 ~ 4.77 MPa, and the total porosity in the range 35.19 ~ 69.97 vol%. The extreme environments resulted in the form of instable structure and discontinuous pore structure. The statistical results demonstrated that the total porosity, mean diameter, and max diameter of POG are significantly negative correlated with UCS, and the relationship of total porosity and UCS can be described by Ryshkevith (R²=0.8459) and Schiller model (R²=0.8689). Compared to the geopolymer bulk, POG showed significant adsorption advantage for heavy metal cations and cationic dyes, and the adsorption removal rates of POG for Cd²⁺, Cu²⁺, Pb²⁺, and MB rising to 92.25%, 119.80%, 110.77%, and 163.98%, respectively. The adsorption mechanisms are mainly based on the negative charge of [AlO₄]^- tetrahedron and cation exchange between heavy cations and Na⁺ or Ca²⁺ in internal matrix. This study indicated that the BFS and WTR are feasible solid wastes for the fabrication of POG, which can be applied in the filtration and adsorption fields for contaminants removal.     

Effect of high temperature on the mechanical properties of hierarchical porous cenosphere/geopolymer composite foams

A hierarchical porous cenosphere/geopolymer composite foam (FHCs/KGP) was fabricated by the simultaneous incorporation of O₂ pore from hydrogen peroxide and cenosphere filler addition. Effects of both H₂O₂ content and high-temperature treatment on the microstructure, porosity and strength of porous FHCs/KGP foams were investigated systematically. The obtained FHCs/KGP foams showed typical amorphous structure and desirable porosity from 65 to 82%. The composites could crystallize in situ to FHCs/leucite foams above 1000℃. Compression strength of the FHCs/leucite foams showed a maximum value of 5 ± 0.3 MPa when treated at 1000°C. The improvement of mechanical properties for the composite foams was attributed to crack deflection, fractured microspheres and the good bond between the FHCs and matrix. This study could open opportunities to employ cellular foams as alternatives in structure and filtration applications.     

Production and thermomechanical characterization of wool–geopolymer composites

Load‐bearing and thermal insulating wool waste/geopolymer composites with fire‐resistant properties were produced and characterized. Two formulations, with different amounts of wool fibers, corresponding in the final composites to about 23 vol% and 31 vol%, were tested. The composites exhibited an average density of 1.0 g/cm³, with a thermal conductivity of 0.2 W/mK, and compressive and flexural strength around 9 and 5 MPa, respectively. The flexural strength and fracture behavior were improved by the presence of the fibers, which promoted the onset of a toughening mechanism in the material. Results showed that a geopolymer matrix loaded with 23 vol% of wool fibers is suitable as flame‐resistant barrier, as reaction to fire is in class A2 (UNI‐EN 13501‐1), and as insulating structural partition in buildings because it ensures a consistent load‐bearing ability coupled with thermal insulating properties, similarly to other man‐made fiber products, with a considerable gain in terms of cost and environmental impact.