The concept borrows from a classic of aerospace engineering: the sandwich composite. Two stiff outer skins are bonded to a lightweight core, and under bending the skins carry most of the tensile and compressive stress while the core resists shear and crushing. By holding the skins apart, the core dramatically increases the panel’s moment of inertia, meaning it resists bending far better than its weight would suggest. Honeycomb and foam cores have long served aircraft and ships, but the Brazilian team wanted a core that grows in a few years, sequesters carbon as it grows, and would otherwise be thrown away.

Bamboo fits that brief almost perfectly. The researchers worked with Phyllostachys aurea, a species harvested at the University of São Paulo’s Pirassununga campus, using the lower portions of roughly three-year-old culms. The waste problem they aimed to address is striking: bamboo shoot processing discards about 70 percent of the harvested material, and conventional culm harvesting leaves behind branches, leaves, and upper sections that account for a significant share of aboveground biomass. Upcycling this residue into engineered structural components could turn a disposal burden into a carbon-storing asset, since bamboo construction materials have been shown to yield lower life-cycle emissions than steel, concrete, and even some novel low-carbon cements.

Preparing the rings involved a preservation step borrowed from established bamboo engineering practice. The culms were immersed for seven days in an 8 percent aqueous solution of disodium octaborate tetrahedrate, a borate treatment that protects the lignocellulosic material against biological attack, then air-dried for another week. The natural circular cross-section of the culm was retained, producing rings about 30.5 millimeters in outer diameter with a mean wall thickness of 4.4 millimeters. That diameter was not arbitrary: earlier studies found 30-millimeter rings outperform both smaller 20-millimeter rings and larger 45-millimeter rings in flexural strength and stiffness, making them the sweet spot for sandwich cores.

The facings were commercial fiber cement boards with a bulk density of 1.28 grams per cubic centimeter, a flexural strength of 6.80 megapascals, and an elastic modulus of 2.44 gigapascals. Spectroscopic and mineralogical analysis using Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction revealed a carbonated cementitious matrix containing portlandite, calcite, quartz, and residual alite. The bonding agent was a two-component polyurethane adhesive derived from castor oil, a bio-based resin with a 24-hour cure time that has become a favorite in sustainable composites research because it replaces petroleum-derived alternatives.

The experimental design was a rigorous full-factorial program. The team built 32 panels across eight configurations, varying three factors at two levels each: core height of 20 or 30 millimeters, compact versus gapped hexagonal ring arrangement, and adhesive bond-line thickness of 0.75 or 1.00 millimeters. Compact cores packed 23 rings tightly, leaving about 61 percent of the panel plan area as void, while gapped cores used 19 rings and pushed the void fraction to 73 percent. Panels were assembled under a gentle cold pressure of 2.3 kilopascals and tested in three-point bending according to the ASTM C393 standard, alongside measurements of density, thermal conductivity, and sound pressure levels.

The results delivered a genuinely counterintuitive lesson in structural mechanics. Making the core taller, from 20 to 30 millimeters, cut the equivalent density by 16.2 percent and boosted flexural rigidity by 86 percent in compact panels and 109 percent in gapped ones, exactly as sandwich theory predicts when skins move further from the neutral axis. Yet the taller panels were weaker in apparent flexural strength, dropping by 22 percent in compact and a dramatic 48 percent in gapped configurations. The gapped 30-millimeter panels also suffered a 33 percent reduction in nominal core shear stress, a consequence of fewer rings, smaller contact area between core and facing, reduced core continuity, and differences in specimen geometry. Lighter, it turns out, is not automatically better.

The standout performer was the 20-millimeter gapped panel with the thinner 0.75-millimeter adhesive line, which achieved the highest specific strength of 8.80 megapascal-centimeters-cubed per gram and the highest specific modulus among all configurations. Its low density more than compensated for a modest loss in absolute strength. Notably, thinning the adhesive line cut resin consumption by about 25 percent without significantly affecting flexural strength, and the adhesive content of 5.9 to 9.3 percent of panel mass compared favorably with bamboo boards that typically demand 10 to 20 percent resin. Failure analysis through microscopy showed that most panels failed by tensile cracking of the lower fiber cement facing, a sign that the adhesive bonds held firm, while the bamboo rings themselves never crushed under the loading nose, thanks to their impressive 64-megapascal compressive strength and 6-gigapascal modulus.

The thermal and acoustic results add practical appeal. Estimated thermal conductivity came in at 0.276 watts per meter-kelvin for compact panels and 0.260 for gapped ones, an order of magnitude below the 1.6 to 3.2 range typical of normal-weight concrete, thanks to the insulating air cavities threaded through the core. Acoustic testing at 125, 500, 1000, and 2000 hertz showed frequency-dependent sound pressure reductions, with significant differences between compact and gapped panels at 125 and 1000 hertz, likely reflecting internal scattering and viscous dissipation within the bamboo’s porous cellular architecture. The authors caution that these were comparative laboratory estimates rather than standardized absorption or transmission-loss measurements.

The researchers are candid about the road ahead before bamboo-ring panels reach real buildings. Future work must address concentrated-load resistance, screw-holding capacity, impact behavior, long-term durability under moisture and weathering, fire response, and full-scale wall-system testing. Still, the study demonstrates that a material once destined for the compost heap can be engineered into a panel that is lighter than conventional cementitious alternatives, thermally insulating, acoustically functional, and mechanically competitive, all while locking away biogenic carbon. As the construction industry scrambles to decarbonize, the answer may lie in a field of bamboo, sliced into rings and glued together with castor oil.

Subject of Research: Lightweight bamboo-ring core sandwich panels with fiber cement facings for sustainable construction

Article Title: Lightweight sandwich panels with bamboo-ring cores and fiber cement facings

Article References: Emadifard, A., Azevedo, A., Fioroni, C., Gholizadeh, P., Batista, F., Panzera, T., & Savastano, H., Jr. (2026). Lightweight sandwich panels with bamboo-ring cores and fiber cement facings. Results in Engineering, 32, Article 113327. https://doi.org/10.1016/j.rineng.2026.113327

Image Credits: AI Generated

DOI: 10.1016/j.rineng.2026.113327

Keywords: bamboo, sandwich panels, fiber cement, polyurethane adhesive, flexural strength, thermal conductivity, acoustics, sustainable construction, Phyllostachys aurea, core geometry, carbon emissions, building materials

The work builds on an earlier innovation from the same laboratory: a vermicompost made from finely ground bamboo and kudzu, a nitrogen-fixing but notoriously invasive vine. That original blend, known as VFBK, had already demonstrated an impressive capacity to suppress soilborne pathogens and plant-parasitic nematodes. Yet its path to commercial use was blocked by two stubborn problems. Grinding bamboo down to fine particles between 0.2 and 1.0 millimeters proved expensive, and harvesting enough wild kudzu added further labor costs. Worse, the finished compost carried relatively little nitrogen, and seedlings grown in it often developed visibly pale leaves—a sign that the plants were starved for this essential nutrient.

To overcome these limitations, the researchers reengineered the entire production system. They replaced kudzu with rapeseed oilcake, a widely available by-product of oil pressing that carries a much higher and more stable nitrogen content, with a carbon-to-nitrogen ratio of roughly 8 compared with about 16 for kudzu. More importantly, they abandoned fine grinding altogether, using bamboo particles between 0.3 and 6.5 millimeters with a mean of 1.6 millimeters—roughly two and a half times coarser than before. The resulting product, dubbed VCBR, was compared against both the original kudzu-based VFBK and a finely ground bamboo–rapeseed oilcake blend called VFBR, allowing the team to separate the effects of particle size from those of the nitrogen source.

The production process itself followed classic vermicomposting principles. Bamboo culms were ground, soaked in water for at least 24 hours to remove compounds repellent to earthworms, and mixed with either kudzu or rapeseed oilcake in plastic containers. After four weeks of precomposting at 25 degrees Celsius, roughly 70 grams of red wiggler earthworms (Eisenia fetida) were added to each container. Over three months, with moisture maintained at 70 to 80 percent, the worms and their associated microbes transformed the fibrous bamboo into a dark, biologically active amendment. Three replicate containers were prepared for each recipe, and equal amounts from each were pooled into composite samples for analysis.

The cost savings were dramatic. Estimated at a practical production scale of one metric ton per month, VCBR came in at 267,200 yen—about 1,670 US dollars—per ton. Simply switching back to finely ground bamboo added 32,960 yen, roughly 206 dollars, per ton. The original kudzu-based VFBK was the most expensive of all, at 349,600 yen, or about 2,185 dollars per ton, burdened by both fine grinding and the labor of harvesting and processing kudzu. For small- to medium-scale producers hoping to use locally available bamboo biomass, the coarser recipe removes a major economic barrier to adopting organic disease-suppressive amendments.

Chemical analysis revealed that particle size had surprisingly little effect on the raw bamboo itself: coarsely and finely ground material showed no significant differences in water-soluble nutrients or pH. The real differences emerged after vermicomposting. Both rapeseed-based blends outperformed the kudzu version on nitrogen: VFBK had much lower ammonium content and a markedly higher carbon-to-nitrogen ratio, confirming that swapping kudzu for oilcake improved nitrogen availability. Interestingly, although identical amounts of rapeseed oilcake were added to VCBR and VFBR, the finely ground version ended up with higher total nitrogen. The authors suggest that the coarser particles may have improved aeration during composting—larger particles create more free air space and better oxygen flow—and such conditions are known to influence nitrogen losses, though aeration was not directly measured.

The disease-suppression trials formed the heart of the study. The team tested two economically important pathosystems: shiso, a popular Japanese culinary herb, challenged with Pythium myriotylum under warm conditions, and cucumber challenged with Globisporangium ultimum at moderate temperatures. Each vermicompost was mixed into commercial nursery soil at 20 percent by volume, with unamended soil serving as the control. Disease was triggered by pouring inoculum grown on bentgrass-seed agar around the base of seedlings, and incidence was scored four days later across multiple independent experimental runs. Because statistical analysis revealed significant treatment-by-run interactions, the researchers compared each treatment against the control within every individual run using Dunnett’s test.

The results were striking. VCBR proved the most consistent performer of the three, significantly reducing damping-off in all three runs of the shiso–Pythium assay and in three of four runs of the cucumber–Globisporangium assay. VFBR suppressed disease in two runs of each assay, while the original VFBK managed only two runs against Pythium and a single run against Globisporangium. Notably, these differences could not be explained by the general microbial indicators the team measured—culturable fungal and bacterial counts, fungal-to-bacterial ratios, and total adenylate levels via bioluminescence assay all came back statistically indistinguishable among treatments. The authors point out that disease suppressiveness in organic amendments is generally tied to biological properties such as microbial community composition and specific antagonistic organisms, which their plate-count methods could not capture, leaving the precise mechanism an open question for future work.

There was, however, a significant catch. Seedlings grown in VCBR-amended media showed reduced SPAD values—a chlorophyll meter reading that serves as a proxy for leaf greenness and nitrogen status—in both shiso and cucumber compared with plants in unamended commercial soil. The finely ground VFBR was gentler: it lowered SPAD in shiso but not significantly in cucumber. This pattern suggests a genuine trade-off between production cost and seedling chlorophyll status, likely rooted in nitrogen dynamics. The authors emphasize that extractable ammonium and total carbon-to-nitrogen ratios do not fully predict nitrogen availability to seedlings; the balance between mineralization and immobilization after the compost enters the nursery substrate, along with the physical and microbial properties of the medium, all play a role. Encouragingly, they note that nitrogen status could potentially be improved simply by adjusting the amount of rapeseed oilcake added during production, since the oilcake carries more total nitrogen than kudzu—a hypothesis that now awaits experimental testing.

Beyond the greenhouse, the study carries a broader environmental message. Unmanaged moso bamboo forests now cover approximately 167,000 hectares of Japan, expanding relentlessly into farmland and native forests, reducing understory diversity, destabilizing soils, and worsening wildlife damage. Converting this troublesome biomass into a disease-suppressive nursery medium offers a rare win-win: a use for an invasive resource and a step toward pesticide-free seedling production. The authors caution that their cost estimates rest on specific assumptions and that the mechanisms underlying suppression remain unelucidated, but the direction is clear. With its combination of simple processing, accessible feedstocks, and consistent protection against two major seedling pathogens, the coarse bamboo–rapeseed oilcake vermicompost stands as a promising foundation—provided its nitrogen supply can be tuned to keep seedlings as green as they are healthy.

Subject of Research: Development of a low-cost, disease-suppressive bamboo-based vermicompost for seedling production

Article Title: Coarsely ground bamboo and rapeseed oilcake produce a lower-cost vermicompost with damping-off suppressiveness

Article References: Kawasumi, R., & Tojo, M. (2026). Coarsely ground bamboo and rapeseed oilcake produce a lower-cost vermicompost with damping-off suppressiveness. Discover Soil, 3(1), Article 172. https://doi.org/10.1007/s44378-026-00335-5

Image Credits: AI Generated

DOI: 10.1007/s44378-026-00335-5

Keywords: vermicompost, bamboo, rapeseed oilcake, damping-off, Pythium myriotylum, Globisporangium ultimum, Eisenia fetida, nursery medium, soilborne disease, organic amendment, invasive species, sustainable agriculture

The significance of the work lies in the mounting pressure on the global dissolving pulp supply chain. The market for dissolving-grade pulp was valued at approximately 5,540 million US dollars in 2023 and is projected to grow at a compound annual rate of 3.3 percent through 2032, driven largely by rising demand for man-made cellulosic fibres in emerging economies such as China and India. Traditionally, the industry has relied on wood pulp and cotton linters, but rising pulpwood prices and growing deforestation concerns have intensified the search for fast-growing, renewable alternatives. Bamboo, a woody grass in the subfamily Bambusoideae encompassing roughly 1,250 species in 75 genera, offers abundant fibre, rapid regeneration, high carbon sequestration potential and the ability to thrive on degraded land — yet systematic, side-by-side comparisons of species and harvest ages have been largely missing from the literature.

Dissolving pulp is not ordinary paper pulp. It is a chemically refined, low-yield product with an overall fibre-line yield of only 30 to 35 percent, engineered to contain 90 to 99 percent pure cellulose, less than 4 percent hemicelluloses, and only trace amounts of lignin, resins and inorganic impurities. Grades are classified by cellulose content: low grades at about 90 percent serve textiles and cellophane, medium grades at roughly 94 to 95 percent, and high grades above 96 percent are reserved for cellulose acetate and specialty derivatives. Because the pulp is ultimately dissolved and regenerated or chemically modified, its reactivity — the accessibility of hydroxyl groups on the cellulose chain — is a critical quality parameter, demanding a narrow molecular weight distribution, an open porous structure and minimal microfibril aggregation.

The research team, led by Vikas Rana, Gyanesh Joshi and Ajay Thakur, obtained one- and two-year-old culms of Dendrocalamus asper, Bambusa tulda, Bambusa nutans, Melocanna baccifera and Bambusa bambos from the institute’s bambusetum in Dehradun, all cultivated under National Bamboo Mission guidelines. Culms were split and chipped into uniform pieces, and proximate chemical analysis was carried out using TAPPI standard methods. The analysis revealed that all five species carried high cellulose and comparatively low lignin, ash and silica contents — a favourable starting profile for pulping. Notably, Klason lignin ranged from 19.68 to 25.40 percent, with the lowest value recorded in one-year-old B. nutans and the highest in two-year-old B. bambos, confirming that younger bamboo is chemically predisposed toward easier delignification because secondary cell-wall lignification accumulates with age.

Before pulping, the chips underwent a simple hot-water pretreatment at 150 degrees Celsius for either 60 or 90 minutes, with a solid-to-liquor ratio of 1:5. This autohydrolysis step exploits the self-dissociation of water at elevated temperature: protonated water liberates acetyl groups from hemicellulose, creating a mildly acidic environment that hydrolyses the branched, low-degree-of-polymerization hemicellulosic sugars and washes them out of the biomass. The treatment extracted between 5.88 and 15.21 percent of hemicelluloses across samples, with longer reaction times consistently improving extraction. Crucially, the pretreatment also stripped out significant quantities of inorganic contaminants: ash fell from a range of 1.67 to 5.70 percent in untreated material to 0.44 to 1.79 percent after treatment, while silica dropped from 0.08 to 1.51 percent down to 0.03 to 0.44 percent. Because silica is notorious for causing scaling in digesters and evaporators and for inflating chemical consumption in recovery cycles, its removal markedly improves bamboo’s industrial credentials.

Pretreated chips were then kraft-cooked with an 18 percent active alkali charge expressed as sodium oxide and 20 percent sulphidity. Screened pulp yields ranged from 38.73 percent for two-year-old D. asper pretreated for 60 minutes to a standout 52.57 percent for one-year-old B. nutans under the same conditions — and every two-year-old species yielded less pulp than its one-year-old counterpart, a pattern the authors attribute to lower lignin and higher cellulose content in juvenile culms. Counterintuitively, pretreatment sometimes increased yield relative to untreated controls: two-year-old D. asper pretreated for 60 minutes delivered roughly 48.45 percent yield versus about 40.07 percent untreated, because removing water-soluble extractives and minerals beforehand improved chemical penetration and made delignification more selective, sparing cellulose from degradation. Kappa numbers, a proxy for residual lignin, fell across the board after pretreatment, with the lowest value of 9.14 achieved by one-year-old B. nutans pretreated for 60 minutes — the same sample that combined the highest yield with the easiest bleaching response.

That champion pulp was carried forward into an elemental chlorine-free D0EpD1 bleaching sequence, the industry’s preferred environmentally acceptable route. In the D0 stage, a 2 percent chlorine dioxide charge at 70 degrees Celsius and pH 4.5 oxidized and fractured residual lignin; the subsequent alkaline extraction stage, boosted with 1 percent sodium hydroxide and 0.5 percent hydrogen peroxide at pH 11, solubilized the oxidized fragments and accounted for the largest yield loss at 95.88 percent; a final 1 percent chlorine dioxide stage polished brightness. Kappa number declined stepwise from 5.30 to 4.50 to 3.80 across the sequence, and the finished pulp reached 92.3 percent brightness — comfortably above the 88 percent minimum typical of commercial dissolving grades.

X-ray diffraction analysis of the extracted alpha cellulose added a structural dimension to the story. Crystallinity indices for one-year-old samples ranged from 55.17 percent for B. tulda to 60.4 percent for B. nutans, and dipped slightly for all species in the second year, suggesting that maturation redistributes lignin and hemicelluloses within the cell-wall matrix and expands amorphous regions. Higher crystallinity in juvenile bamboo reflects tightly packed cellulose microfibrils, which the authors note could benefit strength-critical applications, while the more open structure of older material may suit chemically intensive processing. B. bambos and B. tulda held their crystallinity most stable over the two-year window, hinting at more uniform cellulose organization over time.

The final characterization of the B. nutans dissolving pulp read like a specification sheet: 93.70 percent alpha cellulose, 1.70 percent hemicellulose measured as pentosan, 0.81 percent lignin, 0.23 percent ash and 467 millilitres per gram intrinsic viscosity in cupriethylenediamine — squarely within the 400 to 600 millilitres per gram window considered desirable for downstream conversion. Ash was marginally above the roughly 0.15 percent typical of commercial pulps, but the overall profile matched or exceeded benchmarks reported for dissolving pulps from other bamboo species and from conventional wood sources.

Beyond the laboratory, the implications are economic and environmental. Bamboo attains most of its height within four months of sprouting and most of its biomass within eleven, meaning a harvest cycle dramatically shorter than the decades required for pulpwood plantations. Its regeneration after cutting can relieve pressure on natural forests, its tolerance of marginal soils opens degraded land to productive use, and the hemicellulose-rich liquors recovered during pretreatment could feed a biorefinery stream rather than a waste stream. For India — home to roughly 125 indigenous bamboo species yet still an importer of dissolving-grade pulp — the study offers a practical recipe: choose one-year-old B. nutans, pretreat with hot water at 150 degrees for an hour, kraft-cook, and bleach chlorine-free. The result is a renewable, domestically grown feedstock capable of anchoring the viscose, lyocell and cellulose-derivative industries of a circular material economy.

Subject of Research: Species- and age-dependent evaluation of bamboo feedstocks for sustainable dissolving-grade pulp production

Article Title: Evaluating bamboo species and age effects on dissolving grade pulp production for sustainable materials

Article References: Rana, V., Joshi, G., Thakur, A., Malik, S., Chauhan, J., & Chaudhary, U. (2026). Evaluating bamboo species and age effects on dissolving grade pulp production for sustainable materials. Discover Industrial Chemistry and Materials, 1(1), Article 6. https://doi.org/10.1007/s44508-026-00006-x

Image Credits: AI Generated

DOI: 10.1007/s44508-026-00006-x

Keywords: bamboo, dissolving pulp, Bambusa nutans, kraft pulping, hot water pretreatment, alpha cellulose, elemental chlorine-free bleaching, viscose rayon, crystallinity index, silica removal, sustainable materials, Forest Research Institute Dehradun