Bamboo Fiber-reinforced Composites Research Articles

Flexural failure mechanism of bamboo composite plates with different construction technologies and tectonic patterns

To investigate the failure mechanism of bamboo fiber reinforced composite (BFRC) plates with different construction technologies and tectonic patterns, flexural experiments were performed. The flexural property of the parallel bamboo strand lumbers (PBSL) is better than that of the glued laminated bamboo (GLB), where the cracking load is increased by 141 % at most and the peak load is increased by 57 % at most. The orthogonal structure for the cross-laminated bamboo (CLB) improves the flexural property to a certain extent by inhibiting the initial cracking whether it is PBSL or GLB, and the peak load is increased by 9.83 % and 11.40 %, respectively. The residual bearing capacity of the PBSL is better than that of the CLB, the PBSL can basically maintain half of the ultimate bearing capacity while the damage factor of CLB is as high as 0.84 when the structure is damaged, revealing that the orthogonal layup structure results in weak interlayer interface after explosion. Orthotropic plate theory and composite failure criteria were proposed and consistently predicted the cracking load and the ultimate load. It is found that matrix fracture controls the cracking load, while fiber fracture determines the ultimate load.

Experimental investigation on mechanical properties of aged bamboo fiber-reinforced composites under quasi-static loading

Bamboo fiber-reinforced composites (BFRC) have gradually attracted the interest of researchers due to their excellent mechanical properties. However, the age factor can affect these composites' mechanical properties and weaken them. This study aims to explore the mechanical properties of BFRC subjected different aging tests. First, the BFRC is prepared from raw bamboo through a series of technological processes. Second, the BFRC sheets are processed into tensile and compressive samples with different directions. Third, the samples are treated with a cold-hot test and a UV dry-wet test, respectively. Finally, quasi-static experiments are carried out to study the mechanical properties of aged BFRC. The results reveal that the BFRC has significant anisotropy. The tensile strength of BFRC parallel with the axis of the reinforcing fiber is as high as 148.53 MPa. It is 26.47 times greater than the tensile strength of BFRC perpendicular to the axis of the reinforcing fiber. The mechanical responses and SEM images show that the UV dry-wet test significantly affects on the BFRC compared to the cold-hot test. It dramatically reduces the mechanical properties of the BFRC. The SEM images further indicate that cracks occur on the surface of BFRC samples under the UV dry-wet test. In addition, two aging tests have an interactive effect on BFRC, which can reduce the sensitivity of BFRC to a UV dry-wet environment. These results are expected to deepen the understanding of the mechanical properties of BFRC and provide guidance for its applicable conditions.

Performance of Bamboo Fiber Reinforced Composites: Mechanical Properties

Fiber Reinforced Polymer (FRP) made from synthetic fiber had been widely used for strengthening of reinforced concrete (RC) structures in the past decades. Due to its high cost, detrimental to the environment and human health, natural fiber composites becoming the current alternatives towards a green and environmental friendly material. This paper presents an investigation on the mechanical properties of bamboo fiber reinforced composite (BFRC) with different types of resins. The BFRC specimens were prepared by hand lay-up method using epoxy and vinyl-ester resins. Bamboo fiber volume fractions, 30%, 35%, 40%, 45% and 50% was experimentally investigated by conducting tensile and flexural test, respectively. Results showed that the tensile and flexural strength of bamboo fiber reinforced epoxy composite (BFREC) was 63.2% greater than the bamboo fiber reinforced vinyl-ester composite (BFRVC). It was found that 45% of bamboo fiber volume fraction on BFREC exhibited the highest tensile strength compared to other BFRECs. Meanwhile, 40% bamboo fiber volume fraction of BFRVC showed the highest tensile strength between bamboo fiber volume fractions for BFRC using vinyl-ester resin. Studies showed that epoxy-based BFRC exhibited excellent results compared to the vinyl-ester-based composite. Further studies are required on using BFRC epoxy-based composite in various structural applications and strengthening purposes.

Low velocity flexural impact behaviors of bamboo fiber reinforced composite beams

To investigate the anti-impact behavior and loading rate sensitivity of bamboo fiber reinforced composite (BFRC) beams, low-velocity-impact flexural experiments were performed under impact velocity changing from 2 m/s to 10 m/s. Quasi-static flexural tests were carried out under the same conditions to supply a quasi-static reference to the dynamic performance. Velocity-dependent effects of the impact force, the velocity, the impulse, the displacement and the absorbed energy were revealed by the weight-dropping experiments. The impact force, the energy absorption and the impact toughness increase nearly linearly to the impact velocity. These rate sensitivities of the BFRC beam were expressed quantitively by linear fitting equations, providing a basis to design shock and explosion resistant BFRC structures.

External strengthening of reinforced concrete beam with opening by bamboo fiber reinforced composites

This paper presents the structural behaviour of reinforced concrete (RC) beams with and without openings strengthened externally with bamboo fiber reinforced composite (BFRC) plates in shear and flexure, respectively. Mechanical properties include tensile and flexural strength of epoxy, polyester and vinyl-ester based BFRC plates with 0%, 10%, 20%, 30% and 40% fiber volume fractions were evaluated. A total of fourteen beams were cast to evaluate the structural behaviour of RC beams strengthened with BFRC plates. All the beams were tested to failure under four-point bending. The results presented were in terms of load–deflection behaviour, failure mode and crack pattern. A comparison was also made between the performance of epoxy, polyester and vinyl-ester based BFRC plates in shear strengthening of RC beams with openings. Results revealed that the presence of openings in the shear zone reduced the original beam capacity of the control beam to about 52–55%. Shear strengthening of RC beams with openings using epoxy based BFRC plates showed significant improvement in regaining the beam structural capacity to approximately 32–36% higher than the un-strengthened beams. Meanwhile, strengthening of RC beams in flexure with epoxy based BFRC plates managed to regain the beam original capacity up to 98% of the control beam. Bamboo fiber composite reinforced with epoxy, polyester and vinyl-ester resins of 40% fiber volume fraction managed to regain the beam original capacity up to 82%. It was found that BFRC plates could divert and mitigate the formation of cracks away from the strengthened region as well as improved the beam ductility.

Thermal and mechanical properties of bamboo fiber reinforced composites

This paper presents the thermal and mechanical properties of bamboo fiber reinforced composite (BFRC) derived from Gigantochloa scortechinii. The bamboo fibers were prepared through chemical treatment by sodium hydroxide (NaOH) followed by physical milling method. The thermal characteristics of the bamboo fiber and its polymer composite were analysed using a thermogravimetric analysis and differential scanning calorimetric. The functional groups and crystallinity of the fiber were analysed with Fourier transform infrared and x-ray diffraction spectroscopy. Meanwhile, the fiber morphology was examined using a scanning electron microscope. The BFRCs with fiber volume fractions ranging from 0 % to 40 % embedded in three thermoset resins (epoxy, polyester, vinyl ester) were subjected to tensile and flexural tests and the fracture pattern was examined. The NaOH concentration of 10 % with soaking duration of 48 h was found to produce a bamboo fiber with the highest ultimate tensile and modulus strength. The tensile and flexural properties of all the BFRCs were found to be directly proportional to the fiber volume fractions. It was found that the bamboo fiber reinforced epoxy composite (BFREC) with 40 % fiber volume fraction exhibited the highest tensile and flexural strength compared to polyester and vinyl ester composites. The method of bamboo fiber composite preparation in this work may serve as a useful guide to produce a strong BFRC for external strengthening of buildings and structures.

Effects of internal structure and chemical compositions on the hygroscopic property of bamboo fiber reinforced composites

Abstract As a kind of bioresource material, the hygroscopic property of the Bamboo Fiber Reinforced Composite (BFRC) plays the key role in their physical, mechanical and adhesive interface properties which further seriously influence both the indoor and outdoor applications. Herein, the effects of internal structure and chemical compositions on the hygroscopic property of the BFRC was systematically investigated. The results showed that the Equilibrium Moisture Content (EMC) values and sorption rate of the BFRC with the density of 1.02 g/cm3 were much lower than those of the raw bamboo at the same Relative Humidity (RH) level. The decrease in the hygroscopic property for the BFRC was related to the changes in physical structure and chemical properties. Physically, the internal cellular structures with the large diameter and the thinner wall were broken and compressed together to enhance the bulk density and to decrease the porosity. This reduction in the internal voids inhibited the entrance of water molecules and decreased the hygroscopic capacity of the BFRC. Simultaneously, the Phenol Formaldehyde (PF) resin, which was impregnated into ground tissue lumens, intercellular gaps and pits, covered the cell wall surface and protected the raw bamboo substrate from water molecules. Meanwhile, both the thermal treatment and PF resin impregnation changed the chemical compositions, which caused the reduction of the hygroscopic groups in the BFRC contributing to the decrease of the moisture sorption.

Changes in the Chemical Properties of Phyllostachys iridescens Bamboo with Steam Treatment

This study explored the chemical properties of heat-treated bamboo. Oriented bamboo fiber mats (OBFMs) of Phyllostachys iridescens bamboo, as units of a bamboo fiber-reinforced composite (BFRC), were heat-treated in saturated steam at 0.40 MPa (150 °C) for 110, 140, or 170 min. After heat treatment, the color of oriented bamboo fiber mats changed noticeably. The chemical properties of the bamboo were examined. The results revealed that the contents of holocellulose and hemicelluloses decreased, while the contents of α-cellulose and water extractives and buffering capacity increased. The pH value decreased compared with control samples. The change in the chemical properties of the OBFMs would have an effect on the properties of the BFRC.

Effects of characteristic inhomogeneity of bamboo culm nodes on mechanical properties of bamboo fiber reinforced composite

Dendrocalamus farinosus and Phyllostachys heterocycla bamboo logs were subjected to a novel treatment process for the preparation of bamboo fiber mats (BFMs), and the obtained BFM were used to fabricate bamboo fiber reinforced composite (BFRC). We studied the mechanical properties of the BFRCs manufactured from the mats with and without bamboo nodes. The presence of nodes in BFM greatly reduced tensile strength, compressive strength, modulus of elasticity, and modulus of rupture of the BFRCs, while the BFRCs fabricated from BFMs with nodes possessed higher horizontal shear strength. Therefore, the nodes in bamboo culms were an important factor in the uniform distribution of mechanical properties, and BFMs should be homogeneously arranged to reduce the impact of nodes on the mechanical strengths of BFRCs.

Design Value of the Compressive Strength for Bamboo Fiber-Reinforced Composite Based on a Reliability Analysis

The objective of this study was to determine the design value for the compressive strength (CS) for bamboo fiber-reinforced composite (BFRC) based on a reliability analysis. A total of 180 specimens were subjected to static compressive testing. The CS of the BFRC was significantly higher than that of raw bamboo and other bamboo-based composites, and its cumulative probability distribution accorded with a normal distribution. Furthermore, a calculation program of the reliability index (β) was developed by adopting the first-order second-moment method. Results of the reliability analysis indicate that β increases nonlinearly not only with the enhancement of the partial coefficient but also with the live-to-dead load ratio in all the simulation load cases. The simulation load case of the maximum and minimum β is G+LO and G+LS, respectively. To meet the target reliability requirement, it is suggested that the design value of CS for BFRC be 43.247 MPa and the partial coefficient be 2.0.

A novel process to improve yield and mechanical performance of bamboo fiber reinforced composite via mechanical treatments

The aims of the present study are to produce bamboo fiber reinforced composite (BFRC) with high yield and to investigate the mechanical properties of BFRC comparing with those of commercial bamboo scrimber (BS) and laminated bamboo lumber (LBL). A novel process was developed for production of BFRC using oriented bamboo fiber mat (OBFM) made by a pilot machine. The yield and the mechanical properties of BFRC were investigated and analyzed in comparing with those of raw bamboo and other bamboo-based composites. The results show that the novel process produces 92.54% yield of OBFM due to without any chemical and special removing of inner and outer layer of bamboo during processing. In addition, all the mechanical properties and the variability of BFRC were significantly enhanced comparing with those of raw bamboo and other bamboo-based composites.