Search Results (76)

The growing need for sustainable materials in architecture has sparked significant interest in natural-fiber-based composites. Among these, coconut coir, a by-product of the coconut industry, has emerged as a promising raw material owing to its abundance, renewability, and excellent mechanical properties. The promise of coir-based composites in architecture is highlighted in this review, which also looks at their problems, advantages for the environment, manufacturing processes, and mechanical, thermal, and acoustic performances. The fibrous shape of the coir provides efficient thermal and acoustic insulation, while its high lignin concentration guarantees stiffness, biological resistance, and dimensional stability. Fiber-matrix adhesion and durability have improved owing to advancements in treatment and environmentally friendly binders, opening up the use of cement, polymers, and hybrid composites. In terms of the environment, coir composites promote a biophilic design, reduce embodied carbon, and decrease landfill waste. Moisture sensitivity, inconsistent fiber quality, and production scaling are obstacles; however, advancements in hybridization, grading, and nanotechnology hold promise. This review provides comprehensive, architecture-focused review that integrates material science, fabrication techniques, and real-world architectural applications of coir-based composites. Coir-based composites have the potential to be long-lasting, sustainable substitutes for conventional materials in climate-resilient architectural design if they are further investigated and included in green certification programs and the circular economy. Full article

This study investigates the use of untreated coconut coir fibers as a sustainable reinforcement in cement mortars, with emphasis on the combined effects of fiber content (0.5–2.0% by volume) and length (10–25 mm) on mechanical performance and water absorption. Sixteen mortar mixes were tested for water absorption, flexural and compressive strength, and microstructural characteristics. Results showed that moderate fiber addition significantly improved both strength and durability. The optimal mix (1.0% fiber, 15 mm length) achieved 8.36 MPa in flexural and 29.28 MPa in compressive strength, representing 61% and 131% improvements over the control, respectively. It also recorded the lowest water absorption (8.38%), attributed to improved fiber–matrix bonding and densification of the interfacial transition zone, as confirmed by Scanning Electron Microscopy. In contrast, excessive fiber dosages led to agglomeration, reduced workability, and diminished performance. A third-degree polynomial regression model was developed to predict mechanical properties based on fiber parameters. The findings demonstrate the feasibility of using untreated coconut waste fibers to enhance mortar performance while contributing to sustainable construction practices aligned with circular economy principles and SDGs. This work provides practical insights into fiber optimization and supports broader adoption of bio-based materials in cementitious systems. Full article

Studies underscore the significance of coir fibers as a sustainable building material. Based on these insights, this research aims to evaluate coir fiber composite panels of various thicknesses as eco-friendly sound absorbing alternatives to synthetic construction materials like rockwool and fiberglass, aligning its use with the United Nations Sustainable Development Goals. Acoustic absorption was quantified with an impedance tube, and subsequent simulations compared the performance of coir composite panels with that of conventional materials, which constitutes an underexplored evaluation. Using 10 receiver points, the simulations reproduced the acoustic conditions of a multipurpose auditorium before and after the coir covering of parts of the rear and posterior walls. The results indicate that when coir coverings account for approximately 10% of the auditorium surface, reverberation times at 250, 500, 2000, and 4000 Hz are reduced by roughly 1 s. Furthermore, the outcomes reveal that early reflections occur more rapidly in the coir-enhanced model, while the values of the early decay time parameter decrease across all receiver points. Although the original configuration had poor speech clarity, the modified model achieved optimal values at all the measurement locations. These findings underscore the potential of coir fiber panels in enhancing acoustic performance while fostering sustainable construction practices. Full article

(1) Background: Soil stability is essential for hydroseeding applications, particularly in erosion-prone areas. This study examines the effects of coir fiber reinforcement on soil properties and optimizes fiber length and content for improved performance. (2) Methods: Triaxial tests, soil physical measurements, and cracking experiments were conducted on sandy and silty soils using five fiber lengths (1–5 cm) and three fiber contents (0.2–0.6%). Principal component analysis (PCA) and Response Surface Methodology (RSM) were applied for optimization. (3) Results: The results show that coir fiber increases soil cohesion, shear strength, porosity, and permeability while reducing bulk density. The best reinforcement occurred at a 3–4 cm fiber length and 0.4–0.6% content, enhancing both the shear strength and crack resistance. Correlation analysis indicated a positive relationship between porosity and shear strength and a negative correlation between crack ratio and shear strength, confirming fiber reinforcement benefits. RSM analysis identified 3.051 cm + 4.07% as optimal for sandy soil and 3.376 cm + 0.456% for silty soil. (4) Conclusions: The optimal coir fiber combination significantly improves soil stability, providing theoretical support for optimizing spray substrates. Full article

Targeting the engineering properties of poor strength and susceptibility to damage in roadbeds and slopes within clay regions, xanthan gum is employed as a soil enhancer, concurrently addressing the issue of the low utilization rate of plant coir fiber. The unconfined compressive strength test (UCS) is used to analyze the influence of different maintenance methods, maintenance duration, xanthan gum dosage, and coconut fiber dosage on the mechanical properties of the enhanced soil. Furthermore, based on scanning electron microscope (SEM) tests, the underlying mechanisms governing the mechanical properties of fiber-reinforced xanthan gum-improved soil are uncovered. The results indicated that the compressive strength of amended soil is significantly enhanced by the incorporation of xanthan gum and coir fiber. After 28 days of conditioning, the compressive strength of the amended soil under dry conditions (conditioned in air) was significantly higher (3 MPa) than that under moist conditions (conditioned in plastic wrap) (0.57 MPa). Xanthan gum influenced both the compressive strength of the specimens and the degree of strength enhancement, whereas coir fibers not only augmented the strength of the specimens but also converted them from brittle to ductile, thereby imparting residual strength post-destruction. Microscopic analysis indicates that the incorporation of xanthan gum and coconut shell fiber significantly diminishes the number of pores and cracks within the soil matrix, while enhancing the internal inter-particle cementation. This synergistic effect contributes to soil improvement, providing theoretical and technical guidance for roadbed enhancement and slope repair. Full article

Renewable polyurethane (PU) composites were developed using castor oil and long coir (LCF), ground coir (GCF) or cellulose fiber (CF) at PU/fiber ratios of 50/50, 60/40 and 70/30 wt/wt%, respectively. The aim was to study the influence of natural fibers on composite flexibility via thermogravimetry, differential scanning calorimetry, scanning electron microscopy and water absorption, density, tensile strength, flexural and flammability tests. The set of properties was evaluated (1) subjectively by assigning importance values to the different properties and (2) via multicriteria decision analysis (MCDA). In general, the PU composites with cellulose fiber (PU/CF) exhibited higher thermal degradation temperatures, greater tensile moduli and toughness and less flammability. The composites with the best results for both analysis methods (property set analysis) were PU/CF:60/40 wt/wt% and 70/30 wt/wt%, obtained with cellulose fiber (low lignin content) and the highest PU percentage; these were the most suitable for applications that require flexibility, such as in interior design. When comparing the different coir fiber sizes, the composites containing more long coir fiber (PU/LCF 60/40 wt/wt% and 70/30 wt/wt%) presented the best results. The results of subjective property set analysis were validated using multicriteria analysis, resulting in a simple analysis for application. Full article

This study investigates the effects of different pH environments on the durability of coir fiber-reinforced epoxy resin composites (CFRERCs). The CFRERCs were prepared by combining alkali-treated coir fibers with epoxy resin and exposing them to acidic, alkaline, pure water, and seawater environments for a 12-month corrosion test. The results show that an alkaline environment has the most significant impact on the tensile strength of CFRERCs, with a 55.06% reduction after 12 months. The acidic environment causes a 44.87% decrease in strength. In contrast, tensile strength decreases by 32.98% and 30.03% in pure water and seawater environments, respectively. The greatest reduction in tensile strain occurs in the alkaline environment, with a decrease of 36.45%. In the acidic environment, tensile strain decreases by about 25.56%, while in pure water and seawater, the reductions are 18.78% and 22.65%, respectively. In terms of stiffness, the alkaline environment results in a 49.51% reduction, while the acidic environment causes a 54.56% decrease. Stiffness decreases by 43.39% in pure water and 36.72% in seawater. Field emission scanning electron microscope (FE-SEM) analysis shows that corrosive agents in different pH environments cause varying degrees of damage to the microstructure of CFRERCs. In the acidic environment, corrosive agents erode the fiber–resin interface, leading to delamination and fiber breakage. In the alkaline environment, corrosive agents penetrate the fiber interior, increasing surface roughness and porosity. While pure water and seawater also cause some damage, their effects are relatively mild. Full article

This study explored the tensile and impact strength of polylactic acid (PLA) through the incorporation of sisal and coir fibers. Hybrid natural fiber composites were prepared using PLA as the matrix and sisal and coir fibers as the reinforcements. The hybrid composites were prepared with an internal mixer, followed by compression molding. A constrained mixture design was employed to determine the optimal material combinations and their effects on the tensile and impact strength. Confirmatory experiments based on response surface methodology revealed no significant differences in the data means at the 0.05 significance level. PLA reinforced with sisal fibers alone exhibited the highest tensile strength of 75.36 MPa but demonstrated a low impact resistance of 12.94 kJ/m² at a 95.22:4.78 (PLA:sisal by volume) ratio. Conversely, the maximum impact resistance of 36.71 kJ/m² was achieved with PLA and coir at the same ratio. An optimal blend, consisting of 95.22% PLA, 0.78% sisal, and 4.0% coir by volume, resulted in a tensile strength of 51.08 MPa and an impact strength of 26.59 kJ/m², outperforming other mixtures and pure PLA in the mechanical properties. Additionally, water absorption tests showed that reinforcement with sisal and coir fibers increased both water absorption and stability over 60 h. Full article

Natural and bio-based construction materials such as bamboo, cork, or natural fiber composites offer a promising solution for enhancing the environmental sustainability of buildings. In this sense, the paper presents an experimental thermo-acoustic characterization of four common Ecuadorian natural fibers, abaca (Musa textilis), cabuya (Furcraea andina), coir (Cocos nucifera), and totora (Schoenoplectus californicus). Different densities were considered, from 85 kg/m³ (Cabuya) to 244 kg/m³ (totora), to thermo-acoustically characterize the samples built with these fibers, by means of the guarded-hot-plate (GHP) and impedance tube methods in-lab experimental benches. The exhaustive original characterization of the evaluated natural fiber composites showed a promising overall thermo-acoustic behavior. The thermal conductivity of the fibers was around 0.04–0.06 W/m·K and, therefore, comparable to other materials such as polystyrene, polyurethane, or aerogel that are already utilized for similar applications. On the other hand, the sound-absorption properties of the evaluated fibers are also very competitive, but strongly affected by the thickness of the sample, with noise reduction coefficient NRC ranging from 0.12 to 0.53. Consequently, the production and distribution of these materials in the Ecuadorian market for thermal insulation and acoustic conditioning constitute an alternative characterized by good technical performance, which, compared to synthetic composites used in the construction industry for similar duties, is ecological, sustainable, and has low built-in energy consumption. Full article

Perennials are usually pre-cultivated on vegetation mats consisting of coconut fiber (coir), which require weather-dependent irrigation and regular fertilization with fast-acting fertilizer to achieve a saleable condition as quickly as possible. In the pre-cultivation of sheep’s wool–coir–vegetation mats, nitrogen (N) is already sufficiently contained in the vegetation mats due to the natural nitrogen content of the sheep’s wool fibers, so that additional liquid fertilization during pre-cultivation can be dispensed with if necessary. In this study, sheep’s wool–coir–vegetation mats of 4.5 kg/m² were pre-cultivated with 16 perennial plants (8 species) in 2018. Variant 1 (V1) received regular fertilization with mineral liquid fertilizer (total 8.7 g N/m²) during pre-cultivation. Variant 2 (V2) was not fertilized during pre-cultivation. In spring 2019, all pre-cultivated vegetation mats were lifted and laid on an area prepared with topsoil. No additional fertilization was applied after laying. The overall impression, plant height, number of flowering perennials, and plant coverage were examined in the 2018 and 2019 growing seasons, with only minor differences observed between V1 and V2. The number of flowers, biomass, and nitrogen content were determined for the two aster species used. There were differences between V1 and V2 in 2018, but not in 2019. The coverage of perennials of 50%, which is the prerequisite for the saleability of the vegetation mats, was already achieved on both V1 and V2 after 4 months of pre-cultivation. The overall impression of the perennials on both V1 and V2 also did not differ during pre-cultivation nor in the following year. Therefore, liquid fertilization is not necessary during the pre-cultivation of perennials on sheep’s wool–coir–vegetation mats. Full article

Due to its high strength, the use of ultra-high-performance concrete (UHPC) is particularly suitable for components subjected to compressive loads. Combined with its excellent durability, UHPC can be used to produce highly resource-efficient components that represent a sustainable alternative to conventional load-bearing structures. Since UHPC fails in a brittle manner without the addition of fibers, it is typically used in conjunction with micro steel fibers. The production of these steel fibers is both expensive and energy-intensive. Natural plant fibers, due to their good mechanical properties, cost-effective availability, and inherent CO₂ neutrality, can provide a sustainable alternative to conventional steel fibers. Thanks to the low alkaline environment and dense matrix of UHPC, the use of natural plant fibers in terms of durability and bond is possible in principle. For the application of natural plant fibers in UHPC, however, knowledge of the load-bearing and post-cracking behavior or the performance of UHPC reinforced with natural plant fibers is essential. Currently, there are no tests available on the influence of different types of natural plant fibers on the load-bearing behavior of UHPC. Therefore, five series of compression and bending tensile tests were conducted. Three series were reinforced with natural plant fibers (bamboo, coir, and flax), one series without fibers, and one series with steel fibers as a reference. Under compression loads, the test specimens reinforced with natural plant fibers did not fail abruptly and exhibited a comparable post-failure behavior and damage pattern to the reference specimens reinforced with steel fibers. In contrast, the natural plant fibers did not perform as well as the steel fibers under bending tensile stress but did show a certain post-cracking bending tensile strength. A final life cycle assessment demonstrates the superiority of natural plant fibers and shows their positive impact on the environment. Full article

Concrete is the most commonly used and essential material in the construction industry, and it is also the most widely utilized product globally. The construction industry is a rapidly expanding industry. To improve the efficiency and strength properties of concrete, researchers from all over the world continue to search for supplementary cementitious materials (SCMs) and industrial by-products that can be incorporated as alternative materials. The current study aimed to determine the effects of partially substituting coir pith ash (CPA) for cement in coconut shell concrete, in addition to utilizing steel and coconut fibers. Various percentages of CPA were used to replace cement in the concrete mixes, ranging from 5% to 20% by cement weight. Steel fibers were utilized in this study at volume ratios of 0.25%, 0.5%, 0.75%, and 1.0%, and coconut fibers were utilized at volume ratios of 0.1% to 0.5% with an increment of 0.1% in the concrete to achieve the desired results. Various properties have been examined, such as workability, mechanical, durability, and morphological tests. The addition of coir pith ash to concrete increased its compressive, flexural, and tensile strengths by 10.36%, 8.75%, and 7.7% at 28 days compared to control concrete. The incorporation of coconut fiber and coconut shell in concrete production improves its performance and strength while also preserving natural resources and offering a solution to the problem of disposing of solid waste. Full article

As peat (P) demand increases throughout the horticultural industry, alternative fibers must be evaluated. Sugarcane bagasse (B), wood fiber (W), and coconut coir (C) have received interest as domestically available alternatives to P, with demonstrated success in producing greenhouse crops. However, there is limited research comparing these materials to peat. This research evaluated the substrate properties and productivity of Petunia Supertunia Mini Vista ‘Indigo’ in pine bark substrates amended with C, W, B, or P and fertigated weekly at 100, 200, or 300 parts per million (ppm) nitrogen (N) to account for possible N immobilization. The container capacity was lowest and air-filled porosity was highest in W and B substrates. Substrate pH increased in W and B substrates, and C substrates were fertigated at 100 ppm N. Increasing the N rate increased the growth index in all substrates, especially B and W substrates later in the production period. Higher fertilization increased shoot mass, chlorophyll content, and blooms across all substrates, demonstrating that fertilizer supplementation may offset possible N immobilization. While plant growth and quality parameters were greatest in the P blend, increasing N applications produced similar-quality plants using alternative substrates, demonstrating that modifying fertilizer management practices can make alternative fibers a viable horticultural substrate. Full article

Greenhouse tomato production faces multiple challenges, including the excessive use of nonrenewable substrates that are difficult to dispose of after use. Currently, most growers propagate tomatoes in rockwool, but there is an increasing demand for sustainable media. The objective of this research was to evaluate sustainable and organic alternatives for greenhouse propagation of tomato seedlings intended for high-wire production. Different organic and inorganic substrates were evaluated in three experiments, using a nutrient solution composed of a complete water-soluble fertilizer. Germination and growth parameters, including height, stem diameter, number of leaves, leaf area, foliar chlorophyll levels (SPAD), and shoot fresh and dry weight, were measured. In the first experiment, which employed overhead irrigation, rockwool, coir, wood fiber–coir mix, medium-grade pine bark, pine bark < 0.64 cm, and pine bark < 0.32 cm were evaluated. Tomato germination was faster and achieved higher percentages with pine bark < 0.64 cm compared to other substrates. However, growth performance was similar or better in coir than in rockwool four weeks after transplantation. For the second experiment with sub-irrigation only, rockwool, coir, wood fiber–coir mix, pine bark < 0.32 cm bark, and peat were evaluated at different container heights. Peat resulted in greater growth across all parameters, followed by wood fiber–coir mix in all container heights, while pine bark had the least growth across all measured parameters. In the third experiment with overhead irrigation, rockwool, wood fiber–coir mix, pine bark < 0.32 cm, and a commercial peat-based mixture were evaluated under different fertilizer rates (electrical conductivity of 1.1 and 2.2 mS·cm⁻¹). Wood fiber–coir mix, peat-based mix, and rockwool were the substrates with the highest values for all evaluated parameters. While all the organic substrates showed potential for use in tomato propagation, pine bark < 0.32 cm bark and wood fiber–coir mix provided the best media for germination. Peat and wood fiber–coir mix showed the best media for subsequent seedling growth and demonstrated potential to be used as substitutes for rockwool. Full article

Rainfall-induced soil erosion is a significant environmental issue that can lead to soil degradation and loss of vegetation. The estimated global annual loss increased by 2.5% over 11 years, from 35 billion tons in 2001 to 35.9 billion tons in 2012, mainly due to spatial changes. Indonesia is predicted to be among the largest and most intensively eroded regions among countries with higher soil erosion, regarded as hot-spots higher than 20 Mg yr⁻¹ ha⁻¹. Due to climate change, natural rainfall patterns in the tropical regions have been subject to change, with a lower number of rainy days and increased intensity of precipitation. Such changes trigger more soil erosion due to heavier rainfall kicking up dried soil particles that are exposed in the bare embankments. Unfortunately, there is no prevention available in developing countries due to the lack of availability and high prices of mitigation techniques such as terraces and covering areas with geotextiles or blankets. Erosion control blankets (ECBs) have emerged as a potential solution to mitigate soil erosion. This research article aims to evaluate the effectiveness of sugar-palm-fiber-based ECB in reducing soil erosion caused by natural rainfall. The study investigates the effectiveness of sugar-palm-based ECB in protecting against erosion at the designated embankment. During the three months of typical rainy seasons (February to April 2023), total eroded mass (kg) was collected and measured from two adjacent microplots (10 m² each), one covered with ECB and the other one left as uncovered soil (bare soil). The results indicate that eroded mass is proportional to rainfall, with coefficients of 0.4 and 0.04 for bare soil and ECB-covered embankments, respectively. The total soil loss recorded during the monitoring period was 154.6 kg and 16.7 kg for bare and ECB-covered soil, respectively. The significantly high efficiency of the up to 90% reduction in soil losses was achieved by covering the slope with sugar-palm-fiber-based ECB. The reason for this may be attributed to the intrinsic surface properties of sugar palm fiber ropes and the soil characteristics of the plot area. Sugar palm (Arenga pinnata) fiber has higher lignocellulosic contents that produce a perfect combination of strong mechanical properties (higher tensile strength and young modulus) and a higher resistance to weathering processes. Although the cost of production of handmade sugar-palm-fiber-based ECB is now as high as 4 EUR, further reductions in cost production can be achieved by introducing machinery. Compared to typical ECBs which have smaller openings, sugar-palm-based ECB has larger openings that allow for vegetation to grow and provide it with a lower density. As such, we recommend improvements in the quality of palm-fiber-based ECB via the introduction of further automation in the production process, so that the price can be reduced in line with other commercially available natural fibers such as jute and coir. Full article