A Review on Natural Fibre-Reinforced Biopolymer Composites: Properties and Applications

In ongoing decades, material researchers and scientists are giving more consideration towards the improvement of biobased polymer composites as various employments of items arranged by natural fibres and petrochemical polymers prompt natural awkwardness. The goal of this review paper is to provide an intensive review and applications of the foremost appropriate commonly used biodegradable polymer composites. It is imperative to build up the completely/incompletely biodegradable polymer composites without bargaining the mechanical, physical, and thermal properties which are required for the end-use applications. This reality roused to create biocomposite with better execution alongside the least natural effect. The utilization of natural fibre-reinforced polymer composites is concerned with the mechanical properties that are highly dependent on the morphology, hydrophilic tendency, aspect ratio, and dimensional stability of the natural fibre. With this in-depth consideration of eco-friendly biocomposites, structural application materials in the infrastructure, automotive industry, and consumer applications of the following decade are attainable within the near future.

Enhanced Thermal Stability, Mechanical Properties and Structural Integrity of MWCNT Filled Bamboo/Kenaf Hybrid Polymer Nanocomposites

Recently, there has been an inclination towards natural fibre reinforced polymer composites owing to their merits such as environmental friendliness, light weight and excellent strength. In the present study, six laminates were fabricated consisting of natural fibres such as Kenaf fibre (Hibiscus cannabinus L.) and Bamboo fibre, together with multi-walled carbon nanotubes (MWCNTs) as reinforcing fillers in the epoxy matrix. Mechanical testing revealed that hybridization of natural fibres was capable of yielding composites with enhanced tensile properties. Additionally, impact testing showed a maximum improvement of ≈80.6% with the inclusion of MWCNTs as nanofiller in the composites with very high energy absorption characteristics, which were attributed to the high specific energy absorption of carbon nanotubes. The viscoelastic behaviour of hybridised composites reinforced with MWCNTs also showed promising results with a significant improvement in the glass transition temperature (Tg) and 41% improvement in storage modulus. It is worth noting that treatment of the fibres in NaOH solution prior to composite fabrication was effective in improving the interfacial bonding with the epoxy matrix, which, in turn, resulted in improved mechanical properties.

Natural Fibre Insulation Materials: Use of Textile and Agri-food Waste in a Circular Economy Perspective

Fibrous materials are among those most used for the thermal and acoustic insulation of building envelopes and are also suitable for a wide range of applications. In building construction, the demand for products with low environmental impact — in line with the Green Deal challenge of the European Community — is growing, but the building market is still mostly oriented towards traditional products, missing the many opportunities for using waste materials from existing industrial production. The paper presents the experimental results of new thermal and acoustic insulation products for building construction and interior design, based on previous experiences of the research group. They are produced entirely using waste sheep’s wool as a “matrix” and other waste fibres as “fillers”. The materials proposed originate from textile and agri-industrial chains in the Piedmont region and have no uses other than waste-to-heat biomass. The panels have characteristics of rigidity, workability, and thermal conductivity that make them suitable for building envelope insulation.

Effect of Mix Proportions on Fresh and Rheological Properties of Cementitious Mixture Containing Natural Fibre: Modelling Using Factorial Design

This paper aims to discuss the influence of mix composition of cement mortar on fresh and rheological properties of cement mortar. Two different natural fibres, basalt (BA) and sisal (SL) are selected based on fresh and rheological behaviour for its usability in a cementitious mixture. The workability and rheological behaviour are evaluated by flow table test, cone penetrometer and slump test of the mixture. A full factorial design method was used to investigate the effects of four mix components: dosage of cement content (B), percentage of fly-ash (FA) by mass of cement, dosage of basalt fibre (BA) and dosage of superplasticizer (SP) along with a water/binder ratio of 0.41. A mathematical model which predicts the main effect and interactions of these components for each of the measured properties are derived using the factorial design. The proposed mixtures consist of two levels of binder content as 550 kg/m3 and 650 kg/m3, FA as 5% and 20% by mass of cement, BA as 1 kg/m3 to 3 kg/m3 and SP as 2 kg/m3 to 4 kg/m3. By reducing the number of test batches needed, the mathematical models produced with this method can expedite optimizing the mixture proportions of cement mortar to achieve desired fresh and rheological properties.

Mechanical Properties and Fracture Energy of Concrete Beams Reinforced with Basalt Fibres

Fibre-reinforced concrete (FRC) is widely employed in the construction industry, with assorted fibre types being used for different applications. Typically, steel fibres give additional tensile strength to the mixture, while flexible fibres may be used in large sections, such as floor slabs, to control crack width and to improve the handling ability of precast sections. For many reasons, including durability concerns, environmental impact, thermal performance, etc, alternatives to the currently available fibres are being sought. This study examines the potential of using basalt fibres, a mineral and natural material, as reinforcement of concrete sections in comparison to steel fibres and plain concrete mix. Mixes were tested containing 0.5% and 1.0% of basalt fibres measuring 25mm length, 0.5% of the same material with 48mm length and steel fibres measuring 50mm by 0.05%, 0.1%, 0.15% and 0.2% of the concrete volume. For the mechanical performance analysis, the 3-point bending test was led and the fracture energy, Young’s modulus and tensile strength in different moments of the tests were calculated. When compared to the control mixtures and the steel-fibre-reinforced concrete, the mixes containing basalt had a reduction in their elastic modulus, representing a decrease in the concrete brittleness. At the same time, the fracture energy of the mixtures was significantly increased with the basalt fibres in both lengths. Finally, the flexural strength was also higher for the natural fibre reinforced concrete than for the plain concrete and comparable to the results obtained with the addition of steel fibres by 0.15%.

Experimental Investigation on the Fracture Energy and Mechanical Behaviour of Hemp and Flax Fibre FRC Compared to Polypropylene FRC

Natural fibre reinforced concrete is been studied for many years as a more sustainable option to current reinforced concrete used in industry. The most common fibre materials currently adopted are steel, glass and synthetic fibres. Apart from the high oxidation and cost, their environmental impact is a serious issue as they are petroleum-based materials. This study assesses the feasibility of replacing polypropylene fibre with hemp and flax fibres. According to the inventory of carbon and energy (ICE) the embodied energy of polypropylene (PP) is 95.4MJ/kg and the embodied carbon is 4.98kgCO2/kg during its lifetime. It represents approximately 3 times more than the estimated values for vegetable fibres. For this, Different concrete mixtures reinforced by 0.5% to 1.0% of hemp, flax and polypropylene fibres were tested, and their post-crack flexural tensile strength, elastic’s modulus, compressive strength and fracture energy were evaluated. The mixtures containing hemp fibres presented properties equivalent to those containing polypropylene under the same proportion. Although both compressive and tensile strength were reduced for the mixes containing flax fibres, the Young’s modulus was 49% smaller and could be an interesting approach for applications that require better elasticity from the concrete, such as industrial floors and structures that may be submitted to impact.

Kenaf Fibre Reinforced Cementitious Composites

Increased environmental awareness and the demand for sustainable materials have promoted the use of more renewable and eco-friendly resources like natural fibre as reinforcement in the building industry. Among various types of natural fibres, kenaf has been widely planted in the past few years, however, it hasn’t been extensively used as a construction material. Kenaf bast fibre is a high tensile strength fibre, lightweight and cost-effective, offering a potential alternative for reinforcement in construction applications. To encourage its use, it’s essential to understand how kenaf fibre’s properties affect the performance of cement-based composites. Hence, the effects of KF on the properties of cementitious composites in the fresh and hardened states have been discussed. The current state-of-art of Kenaf Fibre Reinforced Cement Composite (KFRCC) and its different applications are presented for the reader to explore. This review confirmed the improvement of tensile and flexural strengths of cementitious composites with the inclusion of the appropriate content and length of kenaf fibres. However, more studies are necessary to understand the overall impact of kenaf fibres on the compressive strength and durability properties of cementitious composites.

Composite materials based on natural fibres applied for structural reinforcement

Environmental problems and environmental protection triggered a rapid development of natural fibres as sustainable materials for the reinforcement of reinforced concrete structures. Synthetic fibre polymer composite materials have been widely accepted by the construction industries as an effective external reinforcement material to rehabilitate deficiencies in existing structures. These materials have exceptional performance such as high strength to weight ratio, corrosion resistance and lightness. However, the disadvantages include high costs during manufacturing and end-of-life services, less environmentally friendly and causing adverse effects on human health. This article presents an experimental program on the use of natural fibres as reinforcement in composite materials for structural strengthening. Different types of natural fibre fabrics (hemp, flax, mixed hemp and cotton) in terms of their mechanical properties were studied. The fibre and fibre fabric sheets were tested in tension test and compared with carbon and glass fibre fabric sheet as reference. So, this study carries out the effect of natural hemp and flax fibre fabric thickness on ultimate loads of specimens. In addition, the ultimate load and stiffness of strengthened beams were investigated. In fact, the results show that the reinforcement technique allows to increase the load-bearing of strengthened structure by 8% to 35% in bending tests.

Investigation of specific energy absorption of natural fiber honeycomb sandwich structure composite as building construction material application

The usage of incorporating natural fibre in composite material has seen some potential to be used as a future building construction material due to its recyclability, lightweight and high-reliability feature. However, the issue of implementing natural fibre as building construction material in composites material concerns the structural integrity of the material. As the characteristics of the natural fibre honeycomb composite have been discovered more in terms of properties which ranges from its physical and chemical structural composition to the quasi-static impact collapse of the material, the absorption energy of the material in different cell geometry is unknown. Therefore, the purpose of this study involves the testing of the natural fibre honeycomb (NFH) composite made from cement fibre (face sheet) and corn starch (core) with regards to its crushing behaviour when subjected to flatwise compression load according to ASTM D-3410 standard to analyse the performance of energy absorption of NFH composite with different thicknesses of the hexagonal core and cell wall thickness to determine the Specific Energy Absorption of the material. The result obtained shows that the increasing thicknesses of the core and cell wall improves the ability of the composite to absorb more energy and the specific energy absorption is higher when both factors are increased.