Rapid urbanization, particularly in developing countries, requires renewable building materials that reduce dependence on carbon-intensive concrete, steel, and increasingly scarce timber. Bamboo, an abundant, fast-growing and highly productive resource, offers strong potential for low-carbon construction; yet its uptake remains limited by gaps in processing technology, material consistency, and code approval. This review synthesizes current knowledge of bamboo biology and culm structure, and evaluates the material, environmental, and socio-economic attributes that shape its suitability for engineered products. We summarize recent advances and remaining challenges in manufacturing and structural applications, highlighting how culm variability and processing choices influence product performance. A roadmap is proposed to guide future progress, emphasizing reliable culm supply, improved manufacturing efficiency, enhanced durability, certification pathways, and circular end-of-life strategies. Properly processed engineered bamboo can outperform commodity softwoods in structural performance and renewability, positioning it as a viable and complementary material for sustainable construction.

With exterior cladding as the target application, this study developed an optimized refining and pressing strategy for converting Douglas-fir bark, which is rich in lignin and extractives, into high-performance binderless panels. Board structure development was first examined by comparing particle and fibre furnish at target densities of 800, 925, and 1050 kg/m3, followed by evaluation of coarse and fine fibre, press temperatures (200–260°C) and times (6–18 min). Internal bond, modulus of rupture, thickness swelling, and water absorption were tested, together with termite and soil-decay resistance to assess durability-related performance. Thermal and spectroscopic analyses were used to better understand the mechanisms contributing to bond development and durability. Board integrity was best with fine fibre pressed to 1050 kg/m3, and optimum properties achieved by pressing at 260°C for 14 min, meeting North American standard requirements for cladding. Bark boards had superior bonding and water resistance compared to representative wood-based panel benchmarks, and termite and soil-decay tests indicated promising biological durability. The successful fabrication of larger 600 × 600 mm panels for a prototype demonstration supports process scalability. This work demonstrates a durable bio-based cladding product from bark that could reduce reliance on petrochemical adhesives while creating higher-value uses for forestry residues.

A self-synthesized hyperbranched sulfuretted polyamidoamine-epichlorohydrin (PCDME) resin was developed to enhance high-temperature soybean meal (HSM) protein-based adhesives. In PCDME-modified HSM adhesives, a multi-crosslinked network is built based on ring-opening reactions, disulfide bond rearrangement, electrostatic interactions, and hydrogen bonding between the active groups in PCDME resins and HSM proteins. This results in the HSM-based adhesive with significantly enhanced internal cohesion, thermal stability, moisture resistance and bonding strength. HSM/PCDME-25 % had excellent dry and wet bond strengths of 2.23 MPa and 1.52 MPa, increasing by 46 % and 322 %, respectively, over the control and increasing toughness (work of adhesion) by 150 %. This PCDME-modified protein-based adhesives also have a satisfactory solid content and a good adhesion of various substrates.

To improve the fundamental understanding of the bamboo scrimber (BS) pressing process, this study examines the current lab and industrial pressing methods, mat compaction behavior and heat transfer compared to typical wood composites. Mat pressure and compaction ratio follow a polynomial relationship, which indicates only 10% of mat pressure required for hot pressing compared to traditional cold pressing. Typical hot pressing of BS consists of four stages: 1) fast closing to maximum pressure, 2) creep at maximum pressure, 3) stress relaxation at target thickness, and 4) degassing and press opening. Mat pressure and its holding time are critical for manipulating vertical density profile in bamboo scrimber through the mechanisms of thermal softening and viscoelastic creep. The core temperature and gas pressure in densely-packed BS are governed predominantly by heat conduction, similar to plywood rather than oriented strand board. This study provides the fundamental insights which can lead to optimization of the highly complex, energy intensive and lengthy pressing process of bamboo scrimber composites.

High-temperature soybean meal (HSM), a by-product of the soybean oil industry, is potentially a viable bioadhesive for its renewability and low cost. Strong water-resistant HSM-based adhesives remain a challenge to prepare due to protein denaturation and poor dispersion in water. Based polyelectrolyte complexation enhancement strategy, the bi-anionic waterborne polyurethane (WPUS) and sulfurized polyamidoamineepichlorohydrin (PADE) were self-prepared in this work, to synergistically reinforce and toughen HSM-based adhesives. The results indicated that the PADE/WPUS combined via the electrostatic complexation between the -COO- and -SO3- in WPUS and azetidinium groups in PADE, reinforcing adhesives through chemical interactions (ring-opening reactions, S-S reconstructions, etc.) and electrostatic bindings formed between PADE/ WPUS and amino acids; toughening adhesives by introducing the microphase separation structure to transfer stress and forming dynamic hydrogen bond to stretch protein chains. When the amount of WPUS added was 20 % of PADE, sample HSM/PADE/WPUS20 % showed the best comprehensive performance. Specifically, the dry shear strength and the adhesion work of this sample reached to 3.37 MPa and 14.42 J, respectively exceeding those of the blank sample by 11.95 % and 601.95 %, showing an excellent toughness and strength. Besides, the wet bonding strength of PADE/WPUS20 % modified adhesive can reach to 1.55 MPa and have been comparable to many frequently-used aldehyde adhesives in practice. The strategy presented in this work provide an efficient method for developing plant protein-based adhesives.

In this work, a dual resin application system using commercial phenol formaldehyde (PF) resins with different molecular weight (MW) was investigated to improve bonding performance of bamboo and wood composite laminates. Water droplet contact angle was deemed to be unreliable for assessing resin wettability on bamboo due to its unique tissue structure compared with wood. Microscopic observation of the resin penetration showed high MW PF largely remained in the glueline and only entered the lumens of cut or damaged bamboo cells near the bondline. Low MW PF appeared in cell corners of bamboo parenchyma but not lumens. Applying low MW PF to the bamboo and high MW PF to the wood surface separately significantly improved bond shear strength with reduced difference between dry and wet conditions. The dry and wet bond strengths using the new method were enhanced by 36.5% and 97.4%, respectively, compared to high MW PF alone. The results suggest that low MW PF can permeate bamboo cell walls and fortify them against swelling and stress on the bamboo-resin interface in wet conditions. Further modifications are required to produce a stronger adhesive than the bamboo tissue to improve wet shear fiber failure rates and develop a viable structural bond qualification test for bamboo and bamboo-wood composites.

Abstract Understanding the durability of emerging plantation hardwood resources is important for optimising their production and use. This study compared timber density, extractives content and decay resistance in 12–13-year-old plantation and native forest regrowth Gympie messmate (Eucalyptus cloeziana) trees. Density increased from pith to bark for both plantation and native forest trees. Inner heartwood density of the plantation timber was significantly lower than that of the native forest regrowth timber. While the total extractives content of the outer heartwood was comparable in the plantation and native forest regrowth trees, the inner heartwood of the latter contained significantly greater extractives levels. Laboratory decay tests showed that all heartwood zones of plantation and native forest regrowth Gympie messmate were resistant to decay by the white rot Pycnoporus coccineus. The inner heartwood of the plantation timber was, however, susceptible to decay by the brown rot Fomitopsis ostreiformis. The results illustrate the potential variations in wood quality parameters to be considered when moving from native forest to plantation resources that are harvested at a younger age and managed for more rapid wood production.

Bamboo is widely recognized as an engineering material with great potential. Conventional rectangular bamboo strip lumber has low utilization rate from milling arc-shaped strips flat and variable strength properties from natural bamboo’s hierarchical tissue structure. In this work an energy-efficient hydrothermal compression process to flatten and densify arc-shaped bamboo is presented. The green (70 % moisture content) bamboo strips were hot compressed in the radial direction at 3.0 MPa pressure, and at 170 °C or 190 °C heat for 20 min. After compression, arcs became rectangular with low (<10 %) moisture content and significant enhancement of mechanical properties. The bending strength, bending modulus, compressive strength, and shear strength of bamboo were improved by 128.1 %, 91.6 %, 58.2 %, and 74.5 %, respectively. Increased density and fiber bundle fraction, altered failure modes and chemical characteristics, increased cellulose crystallinity and crystalline size, and increased nanoscale mechanical properties were observed as contributing factors to tissue strength enhancement. The process could potentially eliminate the conventional strip milling and lengthy drying processes currently used to produce laminate bamboo lumber.

This paper investigates the hypothesis that bamboo and wood require different resin molecular weight (MW) for optimum bonding performance of structural bamboo-wood laminates. Phenol formaldehyde (PF) resins with two different MWs were used in high, low, mix and dual application for bamboo-wood bonding. The results showed that bamboo surfaces require application of lower molecular resins for adequate resin penetration. Applying low MW PF to the bamboo and high MW PF to the wood surface separately significantly improved the bonding performance. Further modifications are required to produce a stronger adhesive than the bamboo outer wall tissue to improve wet shear fiber failure rates.

With bamboo’s rapid renewability, short rotation period, versatility, and good mechanical properties, engineered bamboo composites have undergone significant evolution. This paper examines the recent changes in bamboo product manufacturing, starting with a wholistic classification of culm breakdown to the plethora of different constituent elements: full culm, flattened bamboo, bamboo bundles, splits/strips, mats/curtains, and strands. Highly cracked flattened strips used in bamboo scrimber are 4–5 times greater in specific surface area than crack-free strips, requiring an estimated 6–10 times higher resin consumption than laminated bamboo. Based on their structure, bamboo composites can be classified into three categories: 1) lamination of minimally modified culms, 2) laminated mat structures with controlled or semi-random placement of constituent elements and 3) random mat structures composed of thin bamboo strands. Composite formation is transitioning from random placement of large, thick strips to more controlled layup with secondary elements of stitched strip curtains, helping minimize edge-to-edge strip overlaps and improve bonding efficiency with less mat compaction. Density-structure-strength property relationships are also compared between various engineered bamboo and common engineered wood products. Other technical advancements include crack-free flattened bamboo and hybrid bamboo-wood products.

Transverse compression of bamboo occurs during manufacturing of engineered bamboo products and densified bamboo, as well as in service under compressive-loading in structures. This study investigates the transverse compression behavior of Moso bamboo and the relationship of its compression modulus with density, and provides microscopic observations of the changing cellular structure during transverse loading. When compared to softwood of same density, bamboo shows higher compression modulus and yield strength. Bamboo’s matrix (parenchyma cells, vessels and sieve tubes) resembles a closed cell foam in transverse compression, presenting high density variation among specimens and plays an important role in its overall density, behavior and compression modulus. Bamboo’s behavior and compression moduli are also influenced by tissue density and its natural fiber reinforced composite structure. A refined model is required and presented which captures the non-linear stress-strain behavior of bamboo considering these characteristics. The model works in a range of densities in Moso bamboo and provides accurate prediction of its transverse compression behavior and magnitude.

Controlling the variability in mat structure and properties in bamboo scrimber (BS) is key to producing the product for structural applications, and wide strip scrimber (WBS) is an effective approach. In this study, the effects of scrimmed bamboo bundle morphology and product density on the properties of WBS were investigated. WBS panels were manufactured and tested using wide (200 to 250 mm) bamboo strips with different fiberization intensity. Maximum strength properties (flexural, compressive, and shear strength), and lowest thickness swelling and water absorption were achieved with three or four passes due to the higher resin absorption by strips. For balanced product cost and performance, we recommend 1–2 fiberization passes and a panel density of 0.9–1.0 g/cm3. Panel mechanical properties were compared with other common bamboo composites. Bamboo scrimber products were highly variable in properties due to differing manufacturing processes, element treatments, and suboptimal mat structure. Products including laminated bamboo lumber and flattened bamboo made from nonfiberized elements show markedly different relationships between strength and elastic properties mostly due to inadequate bonding between the laminae, which causes premature bond-line failure. This study helped improve the understanding of the structure–property relationship of engineered bamboo products while providing insights into process optimization.

Bamboo winding composite pipe (BWCP) is a commercialized, bio-based product suitable for below-ground infrastructure tunnels and low-pressure water and sewage reticulation. Being manufactured from fast-growing and sustainable but moisture-sensitive bamboos, plus winding resin and fillers, the long-term bond durability of this bio-pipe requires evaluation. Existing standards for assessing the moisture and chemical durability of traditional mortar, plastic, and metal pipes are not suitable for evaluating the bond durability of wound bio-based pipes. Furthermore, standards for testing bond durability of flat resin-bonded structural wood composites are not suitable for continuous cylindrical composites. This paper reports an adapted protocol for rapid assessment of the bond durability of bio-pipes based on existing ASTM standards for bond aging in structural composite lumber and strength testing procedures for pipes. Standard pipe ring compression tests induce adequate interlaminar shear on curved bond lines, and after accelerated aging, although the winding resin was severely moisture degraded, a helically wound bio-pipe like BWCP can retain good residual compression strength. The accelerated aging regime had little effect on the pipe wall tensile strength, assessed using apparent hoop tensile tests, suggesting BWCP may still be able to maintain its internal pressure holding capacity even if water enters the wall substrate provided the bamboo does not decay. The wall structure retains its integrity if it remains sealed from water but once water infiltrates the wall substrate it is difficult to dry out. The proposed protocol is expected to be transferrable to the rapid assessment of moisture-induced durability of other bio-based pipe products.

Sustainable development and applications of bamboo and bamboo-wood composites require better understanding and optimization of bamboo bonding. This paper provides a critical review of bamboo composite bonding in relation to wood bonding characteristics and processes. A polylamellate cell wall structure, low tissue porosity and permeability, and poor surface wettability hamper bamboo bonding with most wood adhesives. Bamboo element preparation, treatment and adhesive modification must be optimized in conjunction with more efficient material utilization and processes. Development of bond qualification standards similar to engineered wood products but tailored to stronger bamboo tissues are essential for structural bamboo composites. While phenolics are still commonly used for structural bamboo composite bonding, the industry is shifting away from formaldehyde systems. Isocyanate-based resins offer viable solutions, especially for bamboo strand composites. Changes in bamboo surface pH and wettability after industrial treatments like bleaching and pressure-steaming likely explain the variations in bonding performance with common wood adhesives. Hybrid bamboo-wood composites are promising cost-effective approaches for the engineered bamboo industry leading to viable building products. Future research subjects related to bamboo composite bonding are also discussed.

A cooperative flame-retardant system based on natural intumescent-grafted bamboo charcoal (BC) and chitosan (CS) was developed for polylactic acid (PLA) with improved flame retardancy and minimal decline in strength properties. Chitosan (CS) as an adhesion promoter improved the interfacial compatibility between graft-modified bamboo charcoal (BC-m) and PLA leading to enhanced tensile properties by 11.11% and 8.42%, respectively for tensile strength and modulus. At 3 wt.% CS and 30 wt.% BC-m, the crystallinity of the composite increased to 38.92%, or 43 times that of pure PLA (0.9%). CS promotes the reorganization of the internal crystal structure. Thermogravimetric analysis showed significantly improved material retention of PLA composites in nitrogen and air atmosphere. Residue rate for 5 wt.% CS and 30 wt.% BC-m was 29.42% which is 55.1% higher than the theoretical value of 18.97%. Flammability tests (limiting oxygen index-LOI and UL-94) indicated significantly improved flame retardancy and evidence of cooperation between CS and BC-m, with calculated cooperative effectiveness index(Ce) >1. From CONE tests, the peak heat release rate (pHRR) and total heat release (THR) were reduced by 26.9% and 30.5%, respectively, for 3% CS + 20% BC-m in PLA compared with adding 20% BC-m alone. Analysis of carbon residue morphology, chemical elements and structure suggest CS and BC-m form a more stable char containing pyrophosphate. This char provides heat insulation to inhibit complete polymer pyrolysis, resulting in improved flame retardancy of PLA composites. Optimal mix may be recommended at 20% BC-m + 3% CS to balance compatibility, composite strength properties and flame retardance.

Bamboo scrimber, including 'bamboo fibre composite' (BFC), is an engineered bamboo composite made by forming and consolidating resin-coated parallel bamboo bundles. The composite panel density is above 1000 kg/m(3), and exhibits variability arising from variations in culm bundle geometry and manual mat formation process. Based on object collision physics, this paper presents a novel computer simulation model for BFC mat formation in terms of bamboo bundle spatial arrangement and horizontal density distribution. The model was calibrated and validated using experimental data of commercial panels. While animating bundle deposition and 3D density distribution, the model also predicts the density variability (standard deviation, sigma(p)) in BFC panels. Parametric analyses using the model showed that bundle and panel thickness, bundle width and width taper have significant effects on sigma(p) and hence the composite uniformity. This model provides a simulation platform for further analyses of mat consolidation and element orientation for bamboo and wood composites.

Bamboo is a short-rotation crop yet with high stem strength, possessing evolved pore network with considerable potential in porous functional material fields. While limited understanding and complex anatomical properties of this pore network require reliable and effective methods to systematically characterize the overall architecture, to further promote its industrial applications. Here an improved microcasting approach is proposed, in which maleic anhydride pre-treatment ensures a close fit between the cell wall and casting resin and toughens the final casts. The bamboo tissue was then dissolved and removed by digestion, leaving only accurate resin replicas of the entire pore network. Precise microcasting allows simultaneous measurements of various structures to explore their correlations, which is hard by previous methods. The smallest replicated conduits 40-100 nm in diameter exposed diverse pit membrane microstructures ("connecting valves" in the network). The hitherto undocumented compensatory system, xylem polymorphism, high abundance of parenchyma, pit distribution rules, and network connecting patterns are revealed, aiding improved understanding of the biomechanics and fluid transport effi-ciency/safety coordination. Simplicity, reliability, and quantifiability make this method an effective technique to study complex pore systems in biomaterials, and enlighten studies on structure-function relationships and bio-inspired designs.

Bamboo Winding Composite Pipe (BWCP) is a novel product that reintroduces and modernizes the use of biobased pipes in below ground water reticulation infrastructure, and can replace PVC and concrete pipe in many low to medium pressure water service and sewerage applications. Pipes are built to accommodate service pressures of up to 1.6 MPa, with a long-term hydrostatic pressure projection of 50 years. Maximum burst pressures are up to 3.75 MPa. The new technology overcomes the structure and performance limitations of earlier wood veneer-based hollow tubes by encasing helically wound layers of thin but strong bamboo sliver curtains in a protective matrix of gauze wrap, thermosetting resin and powdered bio-filler. Bamboo has unique and very high tensile strength fiber and aligning this around the pipe circumference produces a high strength, ductile and pressure resistant pipe. This fabrication technology is extremely versatile, producing pipes ranging from 150 mm to 5000 mm in diameter with a wall thickness of 9 mm-38 mm for a wider range of applications including non-round shells for train cars and modular housing construction. An integrated supply chain model of satellite fabrication sites for curtain winding elements at the source and centralized manufacturing of pipes close to market locations can provide employment and income for remote villages and increase transportation efficiency. BWCP is energy efficient, requiring less than a quarter of the energy of steel pipes per meter. It presents a significant potential for carbon storage over time, holding an estimated 0.5 t of sequestered atmospheric CO2 per t of pipe manufactured.

Bamboo fiber composite (BFC) is a unidirectional and continuous bamboo fiber composite manufactured by consolidation and gluing of flattened, partially separated bamboo culm strips into thick and dense panels. The composite mechanical properties are primarily influenced by panel density, its variation and uniformity. This paper characterized the horizontal density distribution (HDD) within BFC panels and its controlling factors. It revealed that HDD follows a normal distribution, with its standard deviation (SD) strongly affected by sampling specimen size, panel thickness and panel locations. SD was lowest in the thickest (40 mm) panel and largest-size (150 × 150-mm2) specimens. There was also a systematic variation along the length of the BFC due to the tapering effect of bamboo culm thickness. Density was higher along panel edges due to restraint from the mold edges during hot pressing. The manual BFC mat forming process is presented and found to effectively minimize the density variation compared to machine-formed wood composites. This study provides a basic understanding of and a quality control guide to the formation uniformity of BFC products.

In this work, an alternative flame-retardant filler based on phosphate- and urea-grafted bamboo charcoal (BC-m) at 10-30 wt % addition was aimed at improving the flame retardancy of polylactic acid (PLA) composites. The filler caused only a small reduction in strength properties but a slight increase in the modulus of elasticity of PLA composites. BC-m significantly improved the flame-retardant performance compared with pure BC. The limiting oxygen index (LOI) was 28.0 vol % when 10 wt % of BC-m was added, and 32.1 vol % for 30 wt % addition, which was much greater than the value of 22.5 vol % for 30 wt % pure BC. Unlike pure BC, adding BC-m at 20 wt % or more gave a UL-94 vertical flame test rating of V-0 with significantly reduced melt dripping. The peak heat release rate (pHRR) and total heat release (THR) of BC-m/PLA composites decreased by more than 50% compared with pure PLA, and the values for 20% BC-m were significantly less than that for 25% BC addition. The grafted biochar-based system provides an effective flame retardancy effect by a condensed-phase protective barrier through the rapid formation of a dense, honeycomb-like cross-linked carbonized char layer. The results suggest a promising route to enhancing the flame-retardant properties of biodegradable polymer composites using nontoxic, more environmentally friendly grafted biochar.