Search Results (301)

The nominal maximum aggregate size (NMAS) plays a critical role in determining the mechanical performance of cement-stabilized macadam (CSM), yet its meso-mechanical influence mechanism remains insufficiently understood. In this study, three skeleton-dense CSM mixtures with different NMAS values were designed, and a combined experimental–numerical approach was adopted to investigate the macro- and meso-scale mechanical behavior. Uniaxial compression tests and aggregate crushing value tests were conducted to evaluate strength development and load-transfer characteristics, while a three-dimensional discrete element method (DEM) model incorporating realistic aggregate morphology was established to analyze the evolution of contact forces and crack propagation. The results show that increasing NMAS significantly improves the mechanical performance of CSM. Compared with CSM-30, the 7-day compressive strength of CSM-40 and CSM-50 increased by approximately 10.3% and 37.3%, respectively. The stress–strain response indicates that mixtures with larger NMAS exhibit higher stiffness and a higher strain. At the meso-scale, a larger NMAS promotes the formation of a more efficient force-chain network dominated by coarse aggregates. Strong contacts were predominantly carried by aggregates larger than 9.5 mm, and in CSM-50, the proportion of strong contacts in the 37.5–53 mm fraction exceeded 90%, indicating that the largest particles likely form the primary load-bearing skeleton. In addition, increasing NMAS delayed crack initiation, reduced crack propagation rate, and decreased the total number of cracks at failure. These findings demonstrate that macroscopic strength improvement is closely associated with meso-scale optimization of the aggregate skeleton and enhanced load-transfer efficiency. This study provides a mechanistic basis for NMAS selection and gradation optimization in semi-rigid base materials. Full article

Laminated bamboo (LB) has emerged as a promising sustainable structural material due to its rapid renewability, high strength-to-weight ratio, and favorable mechanical performance. Drawing on a comprehensive review of over 90 published experimental and analytical studies, this paper provides a critical synthesis of the structural behavior of LB, with emphasis on its compression, tension, flexure, shear, and creep responses. Reported mechanical properties exhibit variability, largely influenced by bamboo species, fiber orientation, processing methods, adhesives, lamination quality, and loading configuration. While LB demonstrates high tensile and flexural strengths comparable to or exceeding conventional timber products, pronounced anisotropy and brittle failure modes are consistently observed, particularly under shear and rolling shear loading. Recent studies on cross-laminated bamboo (CLB) highlight the significant role of interlaminar behavior and adhesive performance in controlling failure mechanisms, indicating that rolling shear capacities often govern the design of planar elements. Beyond mechanical behavior, this review synthesizes available research on thermal and fire performance. Emerging research on LB connections indicates that joint behavior often governs global structural performance, with strength and ductility strongly influenced by fastener type and embedment behavior. Key knowledge gaps are identified, underscoring the need for unified design frameworks to enable broader structural adoption of laminated bamboo systems. Full article

Bamboo materials usually exhibit creep behavior under external loading conditions. This study conducted the compressive creep property research on bamboo scrimber, a commonly seen natural fiber-reinforced composite material. Firstly, the compressive creep strain data under various stress amplitudes were recorded on the basis of a four-step compressive load. Secondly, different Zener models were adopted in analyzing the recorded compressive creep process. Finally, a creep strain prediction method was proposed with the help of the verified model and the stress level-related empirical equations. The following main conclusions were drawn: for bamboo scrimber, the modified Zener model based on various-order Caputo fractional derivatives can provide precise expression in analyzing the creep performance of the material under compressive load than the traditional Zener model, as well as predict the creep strain increase property under other stress levels with a relatively shorter experimental period. Therefore, this method is valuable for promotion in modern industry. Full article

To address the limitation of insufficient mechanical strength and short service life in biodegradable bamboo fiber mulch film (BFM) replacing plastic film in agriculture, this study applied a biochemical method to make bamboo fiber and used bacterial cellulose (BC) as a natural nanoscale reinforcing agent to fabricate high-performance bacterial cellulose bamboo fiber mulch film (BC-BFM). The physical and mechanical properties, chemical structure, seed germination and degradation behavior performance of BC-BFM were characterized. Results demonstrated the structural compactness and homogeneity of the BC-BFM were improved markedly with the increase in BC addition and BC formed a 3D nanofibrillar network that effectively bridged inter-fiber voids. The tensile, burst and tear indexes of BC-BFM all significantly rose with BC addition. Notably, compared to plastic film and BFM, BC-BFM exhibited a good effect on mung bean seed germination and the best growth speed was at 5% BC addition. Furthermore, the degradation test showed that the degradation rate of BC-BFM within 90 d was three times less than that of BFM and service life was similar to plastic film. This showed that it was a promising method to prepare biodegradable high-quality BFM through biochemical preparation of bamboo fiber and BC nanocellulose reinforcement. This method markedly enhanced the mechanical performance and durability of BC-BFM, providing a feasible technical path for the development of biodegradable high-performance green agricultural covering materials with long service life. Full article

Instance segmentation of moso bamboo cells is a critical step in quantitative structural analysis of bamboo materials and plant phenomics research. Moso bamboo tissues are mainly composed of vascular bundles and parenchyma cells. Within vascular bundles, fiber cells exhibit thick cell walls and extremely dense arrangements, whereas vessel cells are characterized by large diameters and complex internal structures. These features frequently lead to blurred boundaries, structural complexity, and local overexposure in microscopic images, making it difficult for traditional segmentation algorithms to achieve stable and accurate results. Although the U-Net has demonstrated outstanding performance in biological microscopic image analysis, its feature extraction capability and boundary recognition stability remain insufficient when dealing with the composite structure of moso bamboo. To address these challenges, this study proposes an improved model based on a multi-scale attention mechanism, termed MBMSA-UNet (Moso Bamboo Multi-Scale Attention U-Net). Building upon the encoder–decoder architecture of U-Net, the proposed model introduces a multi-scale channel-spatial attention block, aiming to handle the pronounced morphological and scale differences among vessels, fibers, and parenchyma cells. By adaptively reweighting features at different scales, the model enhances cross-layer feature fusion and strengthens responses to key regions, thereby effectively suppressing local overexposure interference and emphasizing boundary features between different cell types. Experimental results demonstrate that, compared with the U-Net and several of its improved variants, MBMSA-UNet achieves higher segmentation accuracy and greater robustness on microscopic images of moso bamboo, providing a solid foundation for fine-grained quantitative analysis of complex bamboo tissues. Full article

In recent years, there has been a notable increase in commercial demand for natural fibers. Consequently, numerous studies have concentrated on formulating innovative industrial production methodologies for natural fibers, with a particular emphasis on the environmental sustainability of production processes. Among natural fiber sources, bamboo has emerged as a leading candidate, attracting considerable interest due to its exceptional renewability, rapid growth, and low cultivation requirements. The contemporary industrial methodologies employed in the extraction of cellulose from bamboo frequently entail the utilization of concentrated solutions of strong acids and bases, often at elevated temperatures and with extended treatment durations. These processes generate highly polluting waste from mineral acids and bases, posing significant environmental challenges and ecosystem damage. In response to the prevailing concerns, there has been a marked increase in the focus on environmentally friendly techniques that combine enzymatic treatments, selective chemical reagents, and optimized mechanical processes. These processes facilitate the extraction of high-quality bamboo fibers, which are suitable for utilization in the textile industry and have the potential to replace synthetic fibers. This work demonstrates the efficacy of methodologies employing more diluted solutions than conventional approaches. Specifically, this study utilizes a weak base, such as NH₄OH, in conjunction with hydrothermal extraction. It is therefore possible for dilute weak base solutions to yield natural fibers after a relatively brief period of processing, typically just a few hours. Full article

This study presents a machine learning framework for the reconstruction of fatigue life and fracture toughness in natural fiber-reinforced composites, evaluating the predictive accuracy of six regression algorithms—Random Forest, Gradient Boosting, Support Vector Machine, Neural Network, Ridge Regression, and Lasso Regression—using a controlled synthetic dataset of 600 samples generated from established Basquin fatigue and Rule of Mixtures fracture equations, incorporating stochastic noise calibrated to experimental scatter (CV = 15–50%), with log-normal noise standard deviation of 0.20 for fatigue life and Gaussian noise standard deviation of 0.15 for fracture toughness. The dataset encompasses eight natural fiber types (flax, jute, sisal, hemp, bamboo, coconut, banana, and pineapple) and five matrix systems (epoxy, polyester, PLA, vinyl ester, and polyurethane). Models were evaluated using a 70-15-15 train–validation–test split with 5-fold cross-validation and exhaustive grid search hyperparameter optimisation. Gradient Boosting achieved R² = 0.93 for fatigue life and Stacking Ensemble achieved R² = 0.87 for fracture toughness, representing 97% and 89% of their respective noise-ceiling values (theoretical maximum R² of 0.96 and 0.98 given the programmed noise levels). The ML models perform supervised function approximation—learning to reconstruct the programmed generation equations rather than discovering novel physical composite behaviour—and function as automated surrogates for the governing equations. Feature importance analysis identified engineered composite indicators, stress amplitude, and fiber length as the most influential parameters. The framework provides a reproducible ML evaluation pipeline as a methodological template for future experimental composite studies. Full article

This study investigates the durability performance of bamboo fiber recycled aggregate concrete (BFRAC) in a sulfate attack environment by simulating harsh conditions through dry–wet cyclic tests. It compares the sulfate attack resistance of steel fiber recycled aggregate concrete (SFRAC) and BFRAC, analyzing their durability performance. The experiments were designed with bamboo fiber admixtures (by volume) of 1%, 1.5%, and 2%, using a 5% Na₂SO₄ solution for dry–wet cycling. The tests evaluated the mass loss rate, microstructure evolution, compressive strength corrosion resistance coefficient, split tensile strength, and dynamic modulus at cycles 0, 30, 60, 90, and 120. A damage model was established to predict the concrete’s damage life. The results showed that as the number of wet and dry cycles increased, the specimens developed cracks, mortar detachment, and fiber rusting on the surface. The mass loss initially increased and then decreased, while the relative dynamic modulus of elasticity and compressive strength exhibited a trend of increasing followed by a decrease. Bamboo fiber concrete demonstrated better durability in terms of compressive strength and splitting tensile strength. Among the BFRAC specimens, those with a 1.5% bamboo fiber admixture had the longest predicted service life, as determined by the Weibull distribution model. Full article

To enhance the mechanical properties of bamboo-reinforced concrete slabs, 1%, 1.5%, and 2% of steel fibers (SF) were added to C30 bamboo-reinforced concrete slabs to produce two test groups, each containing 12 slabs. One group was tested under static loads, and the other under impact loads. In each group, the slab thickness was set to 50 mm, 65 mm, and 80 mm, and the steel fiber dosages were 0%, 1%, 1.5%, and 2%. While existing studies on bamboo-reinforced concrete slabs (BRCS) have primarily focused on static flexural behavior, and research on steel fiber-reinforced concrete (SFRC) has mainly addressed fiber network effects in plain or steel-reinforced matrices, the synergistic mechanism between bamboo and SF in steel fiber-reinforced bamboo-reinforced concrete slabs (SFRBCS) under dynamic impact loading remains unexplored. This study innovatively combines bamboo’s elastic energy absorption with SF’s plastic energy dissipation. Static load and drop hammer impact tests were carried out in each group to study the mechanical properties of SFRBCS under static and dynamic loads. The test results show that: under static load, adding SF transforms the failure mode of the slab from brittle shear failure to ductile bending failure, increases the ultimate load, and delays the development of the main crack. Under the action of impact loads, bamboo absorbs impact energy through elastic deformation, while SF dissipates energy through plastic deformation. The combined effect of the two significantly slows down the development speed of cracks. The slab with 80 mm thick and 2% SF dosage exhibits excellent impact ductility. Based on theoretical analysis and tests, the corresponding correction coefficients are introduced to establish the bearing capacity calculation model of SFRBCS under uniformly distributed loads, considering the synergistic effect of the mechanical properties of bamboo and the reinforcing effect of SF. The combination of 1.5% SF dosage and 80 mm slab thickness can effectively enhance the material utilization rate (defined as the ratio of the increment in ultimate bearing capacity to the increment in steel fiber dosage). Test and calculation models provide a theoretical basis for the design and application of SFRBCS, which is applicable to engineering fields such as low-rise buildings and temporary structures. Full article

Bamboo shoots are a valuable source of dietary fiber and antioxidants; however, their high levels of soluble oxalates and uric acid require reduction prior to consumption. This study evaluated the effects of washing, soaking, and boiling on soluble oxalate content, uric acid content, antioxidant activity, and the phenolic and flavonoid profiles of bamboo shoots. Washing resulted in only slight reductions in soluble oxalates and uric acid. Prolonged soaking (7–10 h) produced more pronounced decreases, while extended boiling (60 min) was the most effective treatment, reducing uric acid and soluble oxalate levels by 86% and 89%, respectively. Processing also led to significant reductions in total phenolic content, antioxidant activity, and individual phenolic and flavonoid compounds, primarily due to leaching and thermal degradation. FTIR analysis indicated that processing mainly affected soluble components, whereas the core polysaccharide structure remained relatively stable. After selecting the optimal pretreatment, the resulting dried powders exhibited markedly reduced antinutritional factors while maintaining desirable nutritional, physicochemical, and functional properties. These findings demonstrate that processed bamboo shoot powder can be safely incorporated into food products and has strong potential as a functional ingredient for health-oriented applications. Full article

This study evaluates bamboo–coir hybrid composite panels developed for formwork applications using an 80:20 fiber–matrix ratio and a 50:50 bamboo-to-coir distribution. The novelty of this study lies in the combined assessment of formwork-relevant mechanical performance, Mode I and Mode II fracture behavior, finite element validation and post-fracture microstructural correlation for a high fiber volume fraction natural fiber hybrid panel. Mechanical, durability, fracture, numerical and microstructural investigations were performed and benchmarked against 10 mm thick construction-grade plywood. The hybrid panels exhibited a density of 805 ± 10.84 kg/m³, which is within 0.7% of plywood, a tensile strength of 50.20 ± 2.85 MPa, representing an increase of 41.8% over plywood, and a flexural strength of 38.60 ± 2.10 MPa, corresponding to an increase of 12.9% as compared to plywood. The impact energy absorption of hybrid panels was 7.85 ± 0.62 J, which is 26.6% greater than plywood. Mode I fracture testing yielded a fracture toughness of 456.65 ± 15.42 J/m², corresponding to an increase of 9.3% over plywood, while Mode II fracture toughness yielded a value of 792.42 ± 30.18 J/m², representing an increase of 13.7% over plywood. Finite element predictions deviated from experimental load–displacement responses by 5–13%. SEM observations identified fiber bridging, fiber pullout and interfacial sliding in the hybrid panels, consistent with the measured fracture energy values. The results indicate that bamboo–coir hybrid panels satisfy the mechanical and fracture performance requirements for reusable formwork systems. Full article

The impact of pretreatment methods on the fermentation quality and nutritional profile of bamboo silage was assessed to determine the optimal ensiling strategy. Tender bamboo underwent microwave, ultrasound, alkali, and irradiation pretreatments. Subsequently, a four-factor, three-level L9 (3⁴) orthogonal experiment was employed, utilizing pretreated bamboo as the substrate. The experiment evaluated the effects of silage time (30, 45, 60 days), moisture content (55%, 60%, 65%), cellulase addition [2, 4, and 6 mg/g FM (Fresh weight)], and silage inoculant addition (0.5, 5, 50 mg/g FM). Results indicated that γ-ray irradiation pretreatment effectively reduced lignin and cellulose content while increasing reducing sugars levels approximately fourfold compared to the control group. Six out of the nine treatment groups exhibited superior comprehensive fermentation quality scores, with silage time demonstrating the most significant influence on the fermentation quality of tender bamboo silage. The order of influence was silage time > silage inoculant level > moisture content > cellulase, with a silage time of 30 days, a silage inoculant level of 0.5 mg/g FM, a moisture content of 65%, and a cellulase level of 2 mg/g FM, all contributing to enhanced fermentation quality. Regarding nutritional composition, silage time significantly impacted crude protein and soluble sugar levels, with optimal levels observed at 30 and 60 days, respectively. Moisture content primarily affected soluble sugar levels, followed by neutral detergent fiber, with an optimal level of 55%. Other factors showed minimal effects. Based on fermentation quality and nutritional component analysis, and prioritizing fermentation quality while considering cost-effectiveness, the optimal ensiling conditions for bamboo were determined to be a silage time of 30 days, a moisture content of 65%, an addition of 2 mg/g FM of cellulase, and an addition of 0.5 mg/g FM of silage inoculant. Full article

The incorporation of abundant natural bamboo fiber (BF) into biodegradable polymers has emerged as a promising strategy to develop environmentally friendly materials. However, the poor interfacial compatibility between BF and biodegradable polymers has led to reduced performance, especially deteriorated toughness, and has limited the practical applications of bamboo–plastic composites. In this study, a compatible modifier, polydopamine (PDA), was employed to modify the surface of natural BF, and poly(lactic acid)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) bamboo–plastic composites were fabricated via melt blending. And then, a commercial multifunctional compatibilizer (AX8900) was introduced to further enhance the interfacial compatibility and physical properties of the composite. After adding 20 wt% modified BF and 2 wt% compatibilizer, the composite exhibited a better notch impact strength (9.7 kJ/m²) than that filled with unmodified BF (3.2 kJ/m²), indicating a substantial enhancement. This work provides a novel approach to produce friendly biodegradable composites utilizing natural cellulose resources. Full article

The increasing need for lightweight, personalized, and sustainable orthopedic braces has motivated the development of bamboo fiber (BF)-reinforced polylactic acid (PLA) composites. In this study, BF/PLA composites were prepared by melt blending. The effects of polybutylene adipate terephthalate (PBAT) toughener, BF content, and a silane coupling agent on the mechanical properties were evaluated, along with their suitability for 3D printing foot braces. The results showed that at a PLA/PBAT mass ratio of 85/15 and a bamboo fiber content of 10 wt.%, the impact strength of the composite reached 7.7 kJ/m². Silane treatment of BF further improved the impact strength, with a maximum value of 11.3 kJ/m² achieved at a silane/BF mass ratio of 2/98. The optimized composite exhibited good printability across nozzle temperatures of 190–210 °C. Printing speed significantly influenced the process; a speed of 35 mm/s enabled successful fabrication of the foot brace, whereas higher or lower speeds led to model collapse due to overheating or cracking caused by insufficient interlayer adhesion. This study successfully developed a bamboo fiber-reinforced PLA composite suitable for 3D printing of orthopedic braces and identified the optimal 3D printing process parameters. Full article

The influence of forest type on soil aggregates distribution, stability, and the contribution of aggregate-associated carbon (C) to bulk soil organic carbon (SOC) remains poorly understood. This may be crucial for the accumulation and persistence of SOC in subtropical ecosystems. In this study, we examined soil aggregate distribution and stability at two depths (0–15 and 15–30 cm) in 10-, 20-, and 30-year-old Cryptomeria japonica (Japanese cedar) and Chimonobambusa quadrangularis (square bamboo) plantations. We further assessed the contribution of carbon (C) associated with distinct aggregate fractions to bulk SOC. Across all stand ages and soil depths, macroaggregates accounted for 19%–56% of total soil aggregates in Japanese cedar plantations, whereas their proportion was 30%–337% higher in square bamboo plantations. In contrast, fine aggregates constituted 3%–67% of total aggregates in Japanese cedar plantations, but were 29%–94% lower in square bamboo plantations than in Japanese cedar plantations. Compared with Japanese cedar plantations, aggregate mean weight diameter (MWD) and geometric mean diameter (GMD) increased by 17%–88% and 35%–152%, respectively, in square bamboo plantations. In Japanese cedar soils, C and nitrogen (N) were primarily concentrated in coarse macroaggregates and fine macroaggregates, whereas in square bamboo plantations, C and N were mainly associated with coarse macroaggregates only. Both aggregate-associated soil C and N varied significantly with aggregate size and forest type, and Japanese cedar soils exhibited higher aggregate C/N ratios, particularly in older stands. Bulk SOC was positively correlated with macroaggregate-associated C in both forest types and with the silt and clay fractions in Japanese cedar plantations. MWD increased with higher macroaggregate C content and declined as the proportion of C in smaller aggregate fractions increased. These findings indicate that forest type plays a critical role in regulating soil aggregation and SOC stabilization pathways, with square bamboo plantations enhancing C sequestration by promoting macroaggregate formation and stability. Full article