Sustainable fiber-reinforced concrete: assessing pineapple leaf fiber as a green reinforcement material

An estimation of main constituents of pineapple leaf fiber (PALF) by conventional method was attempted and the values of 74.44% α-cellulose, 13.39% hemicellulose, 7.12% lignin, 2.89% pectic matter, and 0.58% aqueous extract were obtained. So, the main constituents of PALF are α-cellulose, hemicelluloses, and lignin. The molecular weight of raw, bleached PALF and α-cellulose of PALF were 1.517 × 105, 1.303 × 105, and 1.225 × 105, respectively. Bleached PALF was dyed with two dyes, Direct Green 27 and Acid Orange 52. Maximum dye exhaustion was found to be 98.97% for Direct Green 27 under the conditions of 3% dye concentration, 5% electrolyte concentration, and 70°C temperature, and 93.27% dye exhaustion was found for Acid Orange 52, where dyeing conditions were 4% dye concentration, 6% electrolyte concentration, and 80°C temperature. Dyeing time was fixed for 60 min for both dyes. The color fastness of PALF on exposure to sunlight has also been studied. It was observed that color fastness of raw fiber is higher than bleached fiber. The degradation of PALF under sunlight was studied by tensile strength and molecular weight measurements. Bleached fiber exhibited lesser loss of tensile strength and molecular weight than raw fiber. Infrared spectra (IR) of PALF were measured for different exposure times under sunlight. The PALF containing higher α-cellulose has good characteristics, similar to materials of higher molecular weight. For this, it gives high tensile strength, more dyeability, and better color fastness properties.

In this paper, the Pineapple Leaf fibre (PALF) have been previously treated with various Sodium Hydroxide (NaOH) concentration percentages in the range between 0% to 10% at 1hour Sodium Hydroxide (NaOH) solution immersion time and dried in oven at 80°C for 24 hours. The influence of Sodium Hydroxide (NaOH) treatment on Pineapple Leaf fibre (PALF) tensile properties was studied. The result of tensile test on PALF treated showed an improvement in tensile strength with highest value of 43.13MPa of treated Pineapple Leaf fibre (PALF), particularly the treated PALF with 7% Sodium Hydroxide (NaOH) concentration. The 7% treated Pineapple Leaf fibre (PALF) was then selected to use as raw materials for hybrid composites with glass reinforced epoxy matrix. The hybrid composites were subjected to distilled water immersion to study moisture absorption behavior on hybrid composites with four different layer sequences named 4P, PGGP, GPPG and PGPG. The pure Pineapple Leaf fibre (PALF) (4P) have recorded highest percentage for both moisture uptake as well as thickness swelling as compared to the other hybrid composites with value of 12.16% and 51.30% respectively. Hybrid composites are the candidate to be used a pressure vessel especially in oil gas and marine industry that deal with wet and dry environment.

This study examined the influence of Snake Plant fibers and Pineapple Leaf Fibers (PALF) on the compressive strength and infiltration rate of pervious concrete, with emphasis on sustainability and alignment with the United Nations Sustainable Development Goals (SDGs). Compressive strength was tested at 7-, 14-, and 28-days following ASTM C39, while infiltration rate was assessed in accordance with ASTM C1701. Results showed that Snake Plant fibers provided modest strength improvement, with the 0.3% mix achieving 8.93 MPa at 28 days, slightly higher than the control. The most notable effect was on permeability, where the 0.2% mix attained the highest infiltration rate of 0.0203 m/s, highlighting its suitability for drainage-critical applications. In contrast, PALF demonstrated a stronger influence on strength development, with the 1.0% PALF mix reaching 21.02 MPa at 28 days, outperforming the control at 16.24 MPa. Although PALF slightly reduced infiltration compared to the control, its values remained within the standard range for pervious concrete. Statistical analysis (p > 0.05) indicated no significant differences between control and fiber-reinforced mixes, though consistent performance trends were observed. Overall, the findings suggest that PALF is more effective for enhancing compressive strength, while Snake Plant fibers are more effective for improving infiltration. The use of these natural fibers not only improves pervious concrete performance but also promotes sustainability by utilizing agricultural waste. This aligns with SDG 9 (Industry, Innovation, and Infrastructure), SDG 11 (Sustainable Cities and Communities), and SDG 12 (Responsible Consumption and Production), contributing to eco-friendly construction materials and resilient urban infrastructure.

This paper presents the mechanical behaviour of pineapple leaf fibre (PALF) in oil palm shell (OPS) lightweight concrete (LWC). Various fibre volume fractions were considered which include 0.5%, 1.0%, 1.5% and 2.0% of PALF. In this study, the PALF was extracted and treated with sodium hydroxide solution with a 10% concentration. The length of the PALF was made constant as 40 mm based on the optimum fibre length obtained from previous work. The experimental testing in this work includes slump test, compressive strength test, splitting tensile test and four-point bending test. Results showed that the compressive strength decreased at all ages with an increase in PALF volume fraction, whereas improvement in strength was observed in both splitting tensile strength and flexural strength. The inclusion of PALF increases the tensile and flexural strength up to 3.28 MPa and 6.55 MPa respectively. The findings revealed that 1.0% PALF is the optimum fibre volume ratio for tensile and flexural strength. The oven-dry density and demoulded density of all OPS concrete mixes fall within the range of 1526–1731 kg/m3 and 1787–1853 kg/m which are in the range of structural lightweight concrete. The splitting tensile strength of OPS and PALF reinforced OPS-LWC in this study falls in the range to that of conventional concretes. Flexural strength to compressive strength ratio showed that all PALF reinforced OPS concretes had ratios ranging 12–22% which were greater than the usual range for lightweight aggregate concrete. Hence, this indicates that PALF fibre can improve significantly the flexural strength of OPS lightweight concrete.KeywordsFibreLightweight concretePineapple leafReinforcement

The poor compatibility of natural fibers with hydrophobic matrices due to their hydrophilic nature has led researchers to improve their properties to enable better compatibility. Pineapple leaf fiber is one of the abundantly available natural fibers obtained from pineapple leaf. It has good chemical properties and strong admirable mechanical properties and can be used as a replacement for synthetic fibers despite the same deficiencies as other natural fibers. In this study, Pineapple leaf fiber was treated with Alkali at varying concentrations, temperatures, and times. Treated pineapple leaf fiber was reinforced with tapioca-based bio resin (cassava starch). This fiber was subjected to tensile testing and Fourier transform infrared (FTIR) spectroscopy. The results of FTIR indicated the various peaks in the absorbance versus wave number relation. The FTIR analysis of untreated pineapple leaf fiber indicated the presence of O-H stretch, N-H stretch, C ≡ stretch, C=O stretch, and H-C-H bond. The modification of fibers achieved by disruption of hydrogen bonding in the network structure was possible due to its treatment with alkali. Mechanical testing (tensile test) and FTIR were also used to know the effects of chemical treatment on the fibers. Alkali treatment improved the fiber properties as the concentration, temperature, and treatment time increased.


 The utilization of pineapple leaves (Ananas comosus) has gained significant momentum as a source of value-added products, owing to the myriad benefits offered by Pineapple Leaf Fibres (PALF). PALF presents a range of advantages, including its contribution to a greener environment and sustainability. PALF production plays a pivotal role in reducing environmental pollution and minimizing waste. Moreover, PALF stands out due to its availability, remarkable thermal and acoustic insulation properties, cost-effectiveness, and exceptional tensile strength. Further, the extraction of PALF can be accomplished manually or mechanically, and various methods have been explored to enhance its compatibility with textile applications. In this context, extensive research has been carried out to modify PALF for its application in the textile industry. Researchers have primarily focused on surface modifications. These modifications encompass chemical treatments, physicochemical treatments, physical treatments, and thermal treatments. All of these contribute to improved interfacial adhesion and enhanced physical, mechanical, and thermal properties of PALF. Additionally, investigations into bleaching and dyeing of PALF have led to achieving superior whiteness and the ability to impart various colours to the fibres. PALF fibres exhibit remarkable qualities, including excellent sweat absorption, breathability, durability, and notable air and water permeability. These attributes make PALF a sought-after material for creating blended fabrics in conjunction with other polymers, such as polyester and wool, enhancing the performance of resulting textiles. The versatility of PALF enable its integration into an extensive range of textile products, underscoring its significance in the industry. This review also explores innovative approaches, such as blending PALF with jute, resulting in the creation of home textiles and carpets, while simultaneously improving the quality of blended yarns. Furthermore, within the textile industry, PALF fibres find diverse applications in the production of an array of products. This involves the crafting of wedding dresses, casual attire, and formal garments. It also includes the manufacturing of table linens, mats, bags, shoes, belts, cords, transmission cloths, airbag tying cords, and carpets. This comprehensive review delves into the wealth of research conducted on PALF modifications, shedding light on the potential of PALF as a sustainable and high- performance material in the textile industry, contributing to further eco-friendly and innovative future.
 
 Keywords: Pineapple Leaf Fibres (PALF), Textile Industry, Sustainability, Greener environment

In this study, ultra-high performance liquid chromatography-tandem mass spectrometry was used to isolate and identify terpenoids in three types of pineapple fibers (pineapple leaf fiber, pineapple stem fiber, and pineapple root fiber). The research results showed that in the positive and negative ion modes, 9 and 26 terpenoid compounds were identified from the three types of pineapple fibers, totaling 35 species in 12 categories, among which triterpene saponins had the largest number of species. Pineapple root fiber contains the highest total terpenoid content, followed by pineapple stem fiber and leaf fiber. In the OPLS-DA model, the VIP and S-plot methods revealed the differences in terpenoid compounds in three pineapple fibers. The research results showed that there were 9, 8 and 7 significantly different terpenoid compounds in pineapple leaf fiber and pineapple stem fiber, pineapple leaf fiber and pineapple root fiber, and pineapple stem fiber and pineapple root fiber respectively. Functional terpenoids such as ivy saponin, dehydroabietic acid, myrcene and ginsenoside are distributed in different parts of pineapple with varying degrees of enrichment. This study provides a basis for differentiated utilization and value-added use of pineapple leaves, stems and roots. Utilization provides scientific basis.

In tropical regions such as the Philippines, pineapple leaf fiber (PALF) is abundantly available as a low-cost and renewable source for industrial purposes. In this research, PALF was used as a reinforcing material for cement-based composites to open up further possibilities in waste management. Since natural fibers are not fully compatible with the matrix due to their hydrophilic nature, surface treatment is necessary to enhance the fiber-matrix bonding. Fibers were treated using sodium hydroxide (NaOH) with varying concentrations (4%, 8% and 12%) for 6-hr immersion time at room temperature. PALF was then added at varying content (1%, 4% and 7% w/w cement) to the concrete mixture with a design mix ratio of 2:1 (sand: cement) and a constant water-cement ratio of 0.55. The samples were mechanically characterized after 28 curing days following ASTM C209 and ASTM C473. Full factorial experimental design (FFED) was used to investigate the effects of alkali treatment and the fiber content on the mechanical strengths of the composite. Experimental methods, analysis of variance (ANOVA) and normality test were carried out to evaluate, analyze and validate the results. The best results for tensile strength parallel to the surface and flexural strength at 2.028 MPa and 1.495 kN, respectively, were observed at composites with 1% PALF with 4% NaOH. Meanwhile, composites with 1% PALF with 12% NaOH showed the best result for tensile strength perpendicular to the surface at 1.681 MPa. According to ANOVA results, only the model for the tensile strength perpendicular to the surface showed a curvilinear behavior (p-value=0.012). Results revealed that the factor with the most significant effect was the interaction of the fiber content and alkali treatment on the tensile strength parallel to the surface (p-value=0.000), tensile strength perpendicular to the surface (p-value=0.001) and flexural strength (p-value=0.001).

Recently, there is ongoing interest in the use of natural plant fibers as alternatives for conventional reinforcements in cementitious composites. The use of natural plant fibers makes engineering work more sustainable, since they are renewable, biodegradable, energy-efficient, and non-toxic raw materials. In this contribution, a comprehensive experimental program was undertaken to determine the influence of pineapple leaf fiber and ramie fiber on the mechanical properties and mass transport of cement-based composites. The compressive strength, tensile strength, modulus of elasticity, modulus of rupture, fracture energy, flexural toughness, coefficient of capillary water absorption, and chloride diffusion were measured. Natural plant fiber-reinforced cement-based composites (NPFRCCs) containing pineapple leaf fiber and ramie fiber, as compared to the plain control, exhibited a slight reduction in compressive strength and a considerable improvement in tensile strength, modulus of elasticity, modulus of rupture, and flexural toughness; the enhancement was remarkable with a higher fiber content. The coefficient of capillary absorption and chloride diffusion of NPFRCCs were significantly larger than the plain control, and the difference was evident with the increase in fiber content. The present study suggests that the specimen with 2% pineapple leaf fiber content can be used in normal environments due to its superior mechanical properties. However, one should be careful when using the material in marine environments.

Pineapple leaf fiber (PALF) having an average diameter and length of about 4 μm and 6 mm, respectively, was used as reinforcing element for natural rubber (NR) composites. PALF was coated with different amount of stearic acid at 10, 30 and 50 wt% of PALF. PALF-NR composites containing two levels of PALF at 5 and 10 part per hundred rubber (phr) were prepared in a two roll mill. Mastication times of 2, 4 and 8 min were used. Tensile stress-strain curves and fracture surfaces of both untreated PALF and stearic acid coated PALF (SA-PALF) reinforced NR prepared with different mastication times were compared. At low level of PALF where aggregation was not a problem, stearic coating had adverse effect on mechanical properties due to the slippery PALF-rubber interface. At high level of PALF, the coating gave composites with higher tensile strength and strain at break. Moreover, tensile strength and strain at break increased with increasing mastication time. This indicates that stearic acid coating reduces the formation of PALF aggregations and allows PALF to work effectively.

Pineapple leaf fiber is a waste that is widely found on the island of Sumatra and its potential utilization has not been maximized. Pineapple leaf fiber has potential as a constituent of natural fiber composites. This study aims to determine the effect of volume fraction variation on tensile and bending strength reinforced with pineapple leaf fiber and fiberglass. The composite manufacturing process uses the compression molding method for 24 hours with a pressure of 50 bar and is given a variation of 70% polyester resin, 25% fiberglass, 20%, 15%, 10%, 5%, and 25%, 20%, 15%, 10%, 5% pineapple leaf fiber. After completion of the composite manufacture, density and porosity testing was carried out with ASTM C271 standards, tensile testing was carried out using D3930 standards and bending testing using D790 standards. The lowest density test results and the highest porosity in composites with 70% resin variation, 25% fiberglass, 5% pineapple leaf fiber with a value of 0.87 gr/cm3 - 7.80% and the highest density value and the lowest porosity with 70% resin variation, 5% fiberglass, 25% pineapple leaf fiber with a value of 1.81 gr/cm3 - 1.53%. The highest tensile strength test results in the variation of 5% fiberglass volume fraction 25% pineapple leaf fiber of 237.76 MPa, and the lowest value in the variation of 25% fiberglass volume fraction 5% pineapple leaf fiber of 98.37 MPa. And the highest bending test was obtained in the variation of the volume fraction of 5% fiberglass 25% pineapple leaf fiber at 332.14 MPa, and the lowest value was obtained in the variation of 25% fiberglass 5% pineapple leaf fiber at 194.95 MPa.

Natural fibers derived from plants are gaining attraction for its low-cost production, excellent mechanical properties, eco-friendly nature and availability. They act as an effective replacement of synthetic materials, makes them suitable for industrial applications. In this work, natural fiber derived from the Pineapple leaf fiber (PLF) and powder derived from Prosopis Juliflora (PJP) plant as the filler was utilized as an effective reinforcement for polymer matrix composites. PLF has high cellulose content, makes it suitable for the achievement of high tensile strength, whereas the porous nature of the fiber surface enhances bonding with the polymer matrix. The low cost and wide availability of the fibers make it a suitable alternative for the harmful synthetic fibers. Semi-crystallinity of the fiber allows reduction in water absorption. The PJF belonged to gelatinous or mucilaginous type. PLF was chemically treated with NaOH to remove the wax content on the surface and to improve its mechanical properties. Composites were fabricated by using compression molding machine with 30 weight percentage (wt.%) of untreated PLF and PJP, 30 wt.% of treated PLF and PJP, 40 wt.% of treated PLF and PJP, 50 wt.% of treated PLF and PJP. The remaining wt.% attributes to the epoxy matrix addition. In the fiber wt.%, equal weights of PLF & PJP were taken. The untreated and treated fiber composite samples are tested for their tensile, impact and flexural strength. SEM images of the PLF, PJP and mechanical tested samples were analyzed. Water absorptivity test was carried out to identify the absorption level of fibers in the composite. The test results suggest that the Pineapple leaf fiber and Prosopis Julifora powder reinforced epoxy reinforced composites would be a low-weight, low cost and higher strength material appropriate for industrial applications.

In this work, the effect of cellulose nanofiber (CNF) on the mechanical properties of long pineapple leaf fiber (PALF)-reinforced epoxy composites was investigated. The content of PALF was fixed at 20 wt.% and the CNF content was varied at 1, 3, and 5 wt.% of the epoxy matrix. The composites were prepared by hand lay-up method. Comparison was conducted between CNF-, PALF- and CNF-PALF-reinforced composites. It was found that the introduction of these small amounts of CNF into epoxy resin caused very small effects on flexural modulus and strength of neat epoxy. However, impact strength of epoxy with 1 wt.% CNF increased to about 115% that of neat epoxy, and, as the content of CNF increased to 3 and 5 wt.%, the impact strength decreased to that of neat epoxy. Observation of the fractured surface under electron microscope revealed the change in failure mechanism from a smooth surface to a much rougher surface. For epoxy containing 20 wt.% PALF, both flexural modulus and strength increased significantly to about 300% and 240% that of neat epoxy. The composite impact strength increased to about 700% that of the neat epoxy. For hybrid systems containing both CNF and PALF, there were few changes observed in both flexural modulus and strength compared to the PALF epoxy system. However, much improvement in impact strength was obtained. By using epoxy containing 1 wt.% CNF as the matrix, the impact strength increased to about 220% that of 20 wt.% PALF epoxy or 1520% that of neat epoxy. It thus could be deduced that the spectacular improvement in impact strength was due to the synergistic effect of CNF and PALF. The failure mechanism leading to the improvement in impact strength will be discussed.

Review on mechanical properties evaluation of pineapple leaf fibre (PALF) reinforced polymer composites

Evaluating Tensile Properties of Successive Alkali Treated Continuous Pineapple Leaf Fiber Reinforced Polyester Composites