Search Results (3)

With increasing global concern over carbon emissions in the construction industry, cross-laminated-thick veneer (CLTV) has emerged as an innovative green building material with significant potential to promote the achievement of “dual-carbon” goals. This study developed a groove and tenon splicing technique for thick veneers, enabling infinite splicing of the length direction and the preparation of a large-size CLTV measuring 12 m (length) × 3.25 m (width) × 105 mm (thickness). The mechanical properties of CLTV were studied in relation to splice position, assembly pattern of grain directions, and layer combinations. The results showed that increasing the number of // layers (// or ⊥ indicates grain direction of layer parallel or perpendicular to the length direction of CLTV) and using high-level layers significantly improved the compressive strength and reduced the coefficient of variation of CLTV. In terms of bending properties, reasonable splice distribution, placing // layers away from the neutral axis, and elevating layer level dramatically enhanced CLTV performance. Furthermore, the study revealed the synergistic effect among these design elements. The effects of layer level and the number of // layers on mechanical properties varied depending on splice arrangement and assembly pattern of grain directions, highlighting the importance of efficient structural design and raw material selection. This study addresses the limitations of traditional cross-laminated timber in raw material selection and production efficiency. Through structural innovation, it offers a solution for physical design and performance regulation, enabling the application of larger CLTV in wood structures and presenting new ideas for using fast-growing wood to reduce construction emissions. Full article

Optimization of structural elements via composition of different components is a significant scientific and practical point-of-view problem aimed at obtaining more economical and environmentally friendly solutions. This paper presents the results of a static work analysis of small-size laminated veneer lumber (LVL) beams reinforced by a Carbon Fiber Reinforced Polymer (CFRP) sheet. The nominal dimensions of LVL beams were 45 × 45 × 850 mm, and 0.333- and 0.666-mm thick reinforcement layers were used. The reinforcement was applied on opposite sides of the cross section obtaining a sandwich-type structure. An epoxy resin was used as a bonding layer. The bending tests were conducted in the so-called four-point bending static scheme in edgewise and flatwise conditions. The results of experimental tests confirmed the validity of this combination of materials. The highest load-bearing capacity was obtained for configuration, where CFRP sheets with a thickness of 0.666 mm were placed on the sides of the core, parallel to the direction of loading and the veneer’s grain in the core. The increase in this case was up to a maximum of 57% compared to the core alone. The highest bending stiffness increase, 182% compared to the core alone, involves placing two layers of sheets perpendicular to the direction of loading, i.e., on the upper and lower surfaces. The presented novel sandwich structure can be competitive against traditional steel and reinforced concrete elements in civil engineering and can be utilized as beams or slabs. Full article

Compared with wood, bamboo has a special fiber gradient structure. Bamboo fibers have attracted attention as reinforced polymer composites. This study investigated the effects of lamination and fiber volume on the physical and mechanical properties of bamboo laminated composites (BLCs). Six types of BLC were derived by parallel and cross laminating bamboo veneers with high, middle, and low fiber volumes. The results indicated that the laminated structure and fiber volume significantly influenced the BLC properties. Microstructural analysis showed that parallel lamination and low fiber volume were more conducive to resin penetration and enhanced the bonding strength. Both the bending and tensile strengths of the cross lamination were lower than those of the parallel lamination. BLCs made of veneers with high and middle fiber volumes and parallel lamination had the maximum bending and tensile strengths (145.1 and 101.53 MPa, respectively). When tested for water resistance, parallel and cross lamination inhibited expansion in the thickness (TSR, 0.56–2.14%) and width (WSR, 0.07–1.61%) directions, respectively. Laminated structures and veneers with varying fiber volume contents should be chosen according to the specific application scenarios. This study provides a reference for selecting an appropriate BLC structure and fiber volume based on application. Full article