Search Results (23)

In response to the rising demand for sustainable engineering materials and waste valorisation strategies, this study investigates the multi-objective optimisation of eco-friendly hybrid composites reinforced with natural fibres and industrial waste. Sixteen composite specimens were fabricated using compression moulding by varying sisal fibre from 0 to 45 wt.%, banana fibre from 0 to 45 wt.%, NaOH alkali treatment from 0 to 6%, and red mud filler from 1 to 4 wt.%. Mechanical properties were evaluated following ASTM standards D256 for impact strength, D790 for flexural strength, D638 for tensile strength, D5379 for shear strength, and E18 for hardness. The Taguchi method combined with grey relational analysis was employed to identify optimal processing conditions. The best mechanical performance, with an impact strength of 6.57 J, flexural strength of 72.58 MPa, and tensile strength of 65.52 MPa, was achieved with 30 to 45 wt.% sisal fibre, 15 wt.% banana fibre, 6% NaOH, and 3 to 4 wt.% red mud. ANOVA revealed that NaOH treatment had the most significant influence on mechanical properties, with high F values and p values close to 0.05. Grey relational analysis proved more effective for multi-objective optimisation, with the highest grey grade of 0.894 observed in the specimen containing 45 wt.% sisal fibre, 6% NaOH, and 2 wt.% red mud. These findings highlight the critical role of fibre treatment and hybrid reinforcement in enhancing performance. The optimised composites demonstrate strong potential for use in automotive interior panel applications, offering a sustainable alternative with balanced strength and reduced environmental impact. Full article

In this work, aerogel renders were enhanced with fibres for use in new building walls, emphasising a Mediterranean climate. The main novelty of the study relies on an integrated evaluation of the aerogel-based fibre-enhanced thermal renders from environmental, energy and economic approaches. Therefore, optimum insulation thicknesses, life cycle savings, payback periods, abiotic depletion potential from fossil fuels (ADP-ff) and global warming potential (GWP) impacts were quantified as a function of the energy consumption. The cost optimisation of aerogel-based renders enabled a reduction from 2477.4 to 1021.7 EUR∙m⁻³ for the reference formulation, and the sisal-optimised render led to the best-integrated performance. A higher DD* (degree-days equivalent) led to higher optimum thicknesses (the Azores required 0.02 m and 0.01 m and Bragança 0.06 m and 0.03 m for cost-optimised and non-optimised thermal renders with sisal fibre, respectively). The optimum thickness related to the ADP-ff and GWP impacts was higher, 0.04 m for the Azores and 0.09 m for Bragança. A steeper decrease in the annual energy consumption occurred for thermal renders up to 0.02 m in the Azores and 0.04 m in Bragança. Aerogel-based fibre-enhanced thermal renders had benefits, mainly from 600 DD* onwards. Full article

The current climate change context raises the demand for reducing energy and environmental impacts while keeping an economic balance and building users’ comfort. Thermal insulation solutions are potential allies in ensuring the adequacy of existing buildings for challenging sustainability requirements. In this scenario, silica-aerogel-fibre-based thermal renders are innovative solutions for which integrated approaches still lack information, and they should be compared with benchmark multilayer solutions, such as those based on expanded polystyrene (EPS), extruded polystyrene (XPS), mineral wool (MW), and insulated corkboard (ICB), to evidence their prospective economic, environmental, and energy benefits. This paper quantifies the optimum insulation thicknesses, life cycle savings, payback periods, and environmental impacts of innovative thermal renders compared to conventional thermal insulation materials when applied as a retrofit in existing facade walls. The results show that cost-optimised thermal renders with sisal fibres led to the best overall performance. Higher heating needs led to higher optimum render thicknesses and life cycle savings. With a 0.02 m thickness, aerogel-fibre-based thermal renders outperformed other materials in terms of heating-degree days (HDD) from 1000 °C·day onwards; they can save approximately EUR 60∙m⁻², 1000 MJ∙m⁻², and 100 kg CO₂ eq∙m⁻² while presenting a U-value 13% lower throughout their 30-year lifetime when compared with the second-best multilayer solution with XPS. Full article

With the increasing demand and use of highways, railways and tunnels in China, the phenomena of foundation settlement, uneven deformation and ground cracking caused by the cyclic loading by traffic are becoming increasingly significant. There is now an emphasis on research to prevent or decrease these phenomena by mixing new materials into the soil body. In this study, cyclic loading tests were conducted on lightweight soils modified with expanded polystyrene (EPS) and sisal. A GDS true/dynamic triaxial apparatus was used to study the dynamic elastic modulus and damping ratio of clays with different dosages of EPS and sisal fibre. The modified soil samples were tested, and then, they underwent micro-scale analysis. The results showed that, with the continuous increase in EPS doping and dynamic stress, the trend of the growth of the dynamic strain of the specimens increased. At the same time, with the increase in the dynamic strain, the dynamic elastic modulus decreased, and the trend increased with increasing doping of the soil with EPS particles. A comparison of the improvement effect coefficient of the soil samples showed that the most suitable EPS doping volume was 5%. Different dosages of sisal fibre were added to the most suitable EPS-modified lightweight soil, and the dynamic elastic modulus first increased and then decreased with increasing sisal dosage. In addition, the damping ratio first increased and then decreased. The best dynamic performance of the soil was obtained when the dosage of sisal was 1.2%. Nuclear magnetic resonance and electron microscope scanning tests verified that, when the sisal doping was 1.2%, the soil particles had the largest compactness, the best interparticle bonding and the best improvement effect. Full article

Aerogel-based renders have been the subject of research in the last few years due to their high thermal insulation characteristics and the need for buildings to become more energy-efficient. This study compares the hygrothermal behaviour of an aerogel-based render (reference) with the same base formulation, replacing the powder with three different fibres (aramid 0.5%, sisal 0.1%, and biomass 0.1%, by total volume) that can be used in buildings’ envelopes. The experimental programme allowed us to characterise and compare the thermophysical properties of the different formulations and then simulate the hygrothermal performance of these solutions when applied to walls for different climatic conditions, considering additional parameters such as total water content, drying potential, water content levels, and thermal insulating performance. These thermophysical parameters were then included in hygrothermal numerical simulations. The results allowed us to verify that the incorporation of fibres improved the hygrothermal properties due to lower capillary absorption and higher water vapour permeability. These renderings showed a high potential for application to building envelopes in different climatic conditions, improving their energy efficiency by up to 20% when compared to other conventional solutions. Full article

The exceptional structural strength and low cost of steel-concrete composite columns make them a popular choice for civil engineering structures. Numerous forms of composite columns, including steel tubes filled with concrete, have been produced recently in response to various construction situations. Cold-formed steel tubular columns with concrete filling have higher strength and ductility due to their capacity to withstand inner buckling and postpone outward buckling. The objective of this research is to determine the ductile and strength performance of composite columns containing various forms of fibre-reinforced concrete when subjected to axial compression. Several different kinds of fibre-reinforced concrete (FRC) are employed as additives in hollow steel columns, including steel FRC, carbon FRC, glass FRC, coir FRC, jute FRC, and sisal FRC. Axial compression tests were performed on 24 columns, including three hollow steel columns and 21 composite columns. Three distinct slenderness ratios were developed and used. Axial bearing capacity, compressive stress-strain curves, ductility, peak strain, axial shortening, and toughness were among the topics covered by the axial compression test. Experimental findings demonstrated that all conventional composite columns experienced failure through overall buckling, Local buckling and crushing of concrete infill, which was transformed into more ductile failure using fibre-reinforced concrete infills. The test results revealed that fibre-reinforced concrete-infilled steel columns outperformed conventional composite columns in terms of strength, ductility, and energy absorption capacity. The percentage increase in load-carrying capacity was observed as 203.88%, 193.48% and 190.03% when compared to hollow cold-formed steel tubular columns in medium, short and stub columns, respectively. Under assessment of stub, short, and medium columns, the load-strain plots demonstrated that the steel fibre-reinforced concrete in-filled columns performed well in terms of ductility. Localized buckling and crushing of the concrete infill caused the composite columns with low slenderness ratios to fail. In contrast, concrete-filled steel tube columns with higher slenderness ratios showed column failure through the overall buckling of the composite column. Full article

This study looks at how incorporating nanofiller into sisal/flax-fibre-reinforced epoxy-based hybrid composites affects their mechanical and water absorption properties. The green Al₂O₃ NPs are generated from neem leaves in a proportion of leaf extract to an acceptable aluminium nitrate combination. Both natural fibres were treated with different proportions of NaOH to eliminate moisture absorption. The following parameters were chosen as essential to achieving the objectives mentioned above: (i) 0, 5, 10, and 15% natural fibre concentrations; (ii) 0, 2, 4, and 6% aluminium powder concentrations; and (iii) 0, 1, 3, and 5% NaOH concentrations. Compression moulding was used to create the hybrid nanocomposites and ASTM standards were used for mechanical testing such as tension, bending, and impact. The findings reveal that combining sisal/flax fibre composites with nanofiller improved the mechanical features of the nanocomposite. The sisal and flax fibre hybridised successfully, with 10% fibres and 4% aluminium filler. The water absorption of the hybrids rose as the fibre weight % increased, and during the next 60 h, all of the specimens achieved equilibrium. The failed samples were examined using scanning electron Microscopic (SEM) images better to understand the composite’s failure in the mechanical experimentations. Al₂O₃ NPs were confirmed through XRD, UV spectroscope and HPLC analysis. According to the HPLC results, the leaf’s overall concentrations of flavonoids (gallocatechin, carnosic acid, and camellia) are determined to be 0.250 mg/g, 0.264 mg/g, and 0.552 mg/g, respectively. The catechin concentration is higher than the phenolic and caffeic acid levels, which could have resulted in a faster rate of reduction among many of the varying configurations, 4 wt.% nano Al₂O₃ particle, 10 wt.% flax and sisal fibres, as well as 4 h of NaOH with a 5 wt.% concentration, producing the maximum mechanical properties (59.94 MPa tension, 149.52 Mpa bending, and 37.9 KJ/m² impact resistance). According to the results, it can be concluded that botanical nutrients may be used effectively in the manufacturing of nanomaterials, which might be used in various therapeutic and nanoscale applications. Full article

In the reported study, two composites, namely sisal-wool hybrid composite (SWHC) and pineapple leaf fibre(PALF)-wool hybrid composite (PWHC) were prepared by mixing natural rubber with equal quantities of wool with sisal/PALF in a two-roll mixing mill. The mixture was subjected to curing at 150 °C inside a 2 mm thick mold, according to the curing time provided by the MDR. The physico-mechanical properties of the composite viz., the tensile strength, elongation, modulus, areal density, relative density, and hardness were determined and compared in addition to the solvent diffusion and thermal degradation properties. The hybrid composite samples were subjected to accelerated aging, owing to temperature, UV radiation, and soil burial tests. The cross-sectional images of the composites were compared with a scanning electron microscopic analysis at different magnifications. A Fourier transform infrared spectroscopic analysis was conducted on the hybrid composite to determine the possible chemical interaction of the fibres with the natural rubber matrix. Full article

In recent years, there has been an increasing demand for engineering materials that possess good mechanical and thermal properties and are cheap an d environmentally friendly. From an industrial and academic point of view, there is a need to study the heat conductivity of newly developed polymer composites and the influence of porosity on the insulation performance of polymer composites. Experimental and theoretical studies were conducted on mainly sisal/glass fibre gypsum composites with different fibre volumes (0, 20, 25, 30, and 35 wt.%). The outcomes from the theoretical model in ANSYS have shown that there is a high possibility to simulate the experimental work and high accuracy for reflecting the experimental findings. Moreover, the results show that natural fibre polymer composites with a high-volume fraction of natural fibres have higher insulation performance than synthetic polymer composites with the same volume fraction of synthetic fibres. Furthermore, the results suggest and support that the improved performance of natural fibre-based composites was due at least in part to the internal porosity of the fibres. Full article

Numerous studies have been conducted recently on fibre reinforced concrete (FRC), a material that is frequently utilized in the building sector. The utilization of FRC has grown in relevance recently due to its enhanced mechanical qualities over normal concrete. Due to increased environmental degradation in recent years, natural fibres were developed and research is underway with the goal of implementing them in the construction industry. In this work, several natural and artificial fibres, including glass, carbon, steel, jute, coir, and sisal fibres are used to experimentally investigate the mechanical and durability properties of fibre-reinforced concrete. The fibres were added to the M40 concrete mix with a volumetric ratio of 0%, 0.5%, 1.0%, 1.5%, 2.0% and 2.5%. The compressive strength of the conventional concrete and fibre reinforced concrete with the addition of 1.5% steel, 1.5% carbon, 1.0% glass, 2.0% coir, 1.5% jute and 1.5% sisal fibres were 4.2 N/mm², 45.7 N/mm², 41.5 N/mm², 45.7 N/mm², 46.6 N/mm², 45.7 N/mm² and 45.9 N/mm², respectively. Comparing steel fibre reinforced concrete to regular concrete results in a 13.69% improvement in compressive strength. Similarly, the compressive strengths were increased by 3.24%, 13.69%, 15.92%, 13.68% and 14.18% for carbon, glass, coir, jute, and sisal fibre reinforced concrete respectively when equated with plain concrete. With the optimum fraction of fibre reinforced concrete, mechanical and durability qualities were experimentally investigated. A variety of durability conditions, including the Rapid Chloride Permeability Test, water absorption, porosity, sorptivity, acid attack, alkali attack, and sulphate attack, were used to study the behaviour of fiber reinforced concrete. When compared to conventional concrete, natural fibre reinforced concrete was found to have higher water absorption and sorptivity. The rate of acid and chloride attacks on concrete reinforced with natural fibres was significantly high. The artificial fibre reinforced concrete was found to be more efficient than the natural fibre reinforced concrete. The load bearing capacity, anchorage and the ductility of the concrete improved with the addition of fibres. According to the experimental findings, artificial fibre reinforced concrete can be employed to increase the structure’s strength and longevity as well as to postpone the propagation of cracks. A microstructural analysis of concrete was conducted to ascertain its morphological characteristics. Full article

This article presents an integrated analytical method to investigate the polychrome clay sculptures of the Qinglian Temple in Jincheng City, Shanxi Province, China. Digital microscopy, SEM-EDS, XRD, Herzberg stain, Micro-Raman spectroscopy and FT-IR were selected to identify the raw materials and techniques used to produce the ground clay layer, the white powder layer and the mineral pigment of the polychrome clay sculptures. The investigation shows that the clay used to make the coarse and fine clay layer is consistent. However, different kinds of fibres were found mixed in the coarse and fine clay layers: wheat straw was the main fibre used in coarse clay layer, while the bast fibres, including ramie, kenaf and sisal hemp, were used as the fibre supports in the fine clay layers due to their useful properties. The white powder layer was made of a mixture of kaolinite and gypsum. For the mineral pigments, it principally contained red (hematite, minium or a mixture of minium and cinnabar), green (atacamite and atacamite), blue (azurite), yellow (yellow ochre), black (amorphous carbon) and white (the mixture of kaolinite and gypsum). Additionally, a gilding technique and multiple paint layers also typified many pigment areas. This work has furthered understanding of the materials and techniques used in making the sculptures of the Qinglian Temple and has clear implications for the restoration and conservation treatments on these kinds of ancient painted clay sculptures. Full article

Progress in engineering research has shifted the interest from traditional monolithic materials to modern materials such as fibre reinforced composites (FRC). This paradigm shift can be attributed to the unique mechanical characteristics of FRCs such as high strength to weight ratio, good flexural strength, and fracture toughness. At present, synthetic composites dominate the automotive, aerospace, sporting, and construction industries despite serious drawbacks such as costly raw materials, high manufacturing costs, non-recyclability, toxicity, and non-biodegradability. To address these issues, naturally occurring plant fibres (such as jute, hemp, sisal) are being increasingly researched as potential reinforcements for biodegradable or non-biodegradable polymer matrices to produce environmentally friendly composites. In this study, sisal fibres were selected owing to their low production costs, sustainability, recyclability, and biodegradability. The hydrothermal ageing and mechanical characteristics of sisal fibre-reinforced epoxy (SFRE) composites were determined and compared with glass fibre-reinforced epoxy (GFRE) synthetic composites. Moreover, a first-of-its-kind numerical model have been developed to study the hydrothermal ageing and mechanical characteristics of SFRE, along with GFRE, using ANSYS software. Moreover, microstructural analysis of flexural tested GFRE and SFRE samples were carried out to identify the microstructural properties of the composites. Both experimental and numerical results exhibited an influence of short- or long-term hydrothermal treatment on the flexural properties of glass and sisal fibre-based composites. In the case of GFRE, the moisture uptake and fibre-matrix de-bonding existed, but it is less severe as compared to the SFRE composites. It was found that the dosage of sisal fibres largely determines the ultimate mechanical performance of the composite. Nonetheless, the experimental and numerical flexural strengths of SFRE were comparable to GFRE composites. This exhibited that the SFRE composites possess the potentiality as a sustainable material for advanced applications. Full article

Fibre metal laminates (FMLs) are lightweight structures with high structural performance and are suitable for many industrial applications. This work describes the impact behaviour of novel sisal fibre-reinforced aluminium laminates (SiRAL) and their dependence upon the orientations of the fibres, the composite core used and the surface treatment of the metal skins. A cold-pressing technique is used to produce SiRALs in six configurations. The FMLs here also have treated or untreated aluminium skins (2024 T3) and three different types of core materials (0°/90° fabric, ±45° fabric and random matt). The ±45° core treated SiRAL provides the highest energy absorption and deflection properties. The pre-treatment of aluminium skins using sandpaper, deep cleaning and primer significantly affects the delamination of the panels under bending impact. The findings reveal that the SiRAL concept is a promising multifunctional FML suitable for different applications that require lightweight, bending and impact performance, together with sustainability characteristics. Full article

Filled hybrid composites are widely used in various structural applications where machining is critical. Hence, it is essential to understand the performance of the fibre composites’ machining behaviour. As such, a new hybrid structural composite was fabricated with redmud as filler and sisal fibre as reinforcement in polyester matrix. The composite was then tested for its drilling performance. A comprehensive drilling experiment was conducted using Taguchi L27 orthogonal array. The effect of the drill tool point angle, the cutting speed, the feed rate on thrust force, delamination, and burr formation were analysed for producing quality holes. The significance of each parameter was analysed, and the experimental outcomes revealed some important findings in the context of the drilling behaviour of sisal fibre/polyester composites with redmud as a filler. Spindle speed contributed 39% in affecting the thrust force, while the feed rate had the maximum influence of ca. 38% in affecting delamination. Full article

Biocomposites comprising a combination of natural fibres and bio-based polymers are good alternatives to those produced from synthetic components in terms of sustainability and environmental issues. However, it is well known that water or aqueous chemical solutions affect natural polymers/fibres more than the respective synthetic components. In this study the effects of water, salt water, acidic and alkali solutions ageing on water uptake, mechanical properties and flammability of natural fibre-reinforced polypropylene (PP) and poly(lactic acid) (PLA) composites were compared. Jute, sisal and wool fibre- reinforced PP and PLA composites were prepared using a novel, patented nonwoven technology followed by the hot press method. The prepared composites were aged in water and chemical solutions for up to 3 week periods. Water absorption, flexural properties and the thermal and flammability performances of the composites were investigated before and after ageing each process. The effect of post-ageing drying on the retention of mechanical and flammability properties has also been studied. A linear relationship between irreversible flexural modulus reduction and water adsorption/desorption was observed. The aqueous chemical solutions caused further but minor effects in terms of moisture sorption and flexural modulus changes. PLA composites were affected more than the respective PP composites, because of their hydrolytic sensitivity. From thermal analytical results, these changes in PP composites could be attributed to ageing effects on fibres, whereas in PLA composite changes related to both those of fibres present and of the polymer. Ageing however, had no adverse effect on the flammability of the composites. Full article