Mechanical Properties of Ply-Lam Cross-Laminated Timbers Fabricated with Lumber and Plywood

The mechanical properties of four ply-lam cross-laminated timbers (CLTs) containing a plywood layer were compared with those of glued laminated timber (GLT) and CLT. The bending, out-of-plane shear, compression strengths were highest in the GLT, which was followed by the ply-lam CLTs and CLT. The modulus of elasticity values for three studied ply-lam CLT samples were 1–2.5 GPa higher than GLT; however, the bending strength of all ply-lam CLTs was 7.3–18.8 MPa lower than GLT. The length of the plywood product is 2,440 mm, and longitudinal bonding is required to manufacture ply-lam CLTs of length > 3m. The prediction of bending capabilities by shear analogy was compared with the bending properties when joints were included. The performances of all the pilot-scale ply-lam CLT samples exceeded the predicted bending performance standards for MOE (10 GPa) and modulus of rupture (30 MPa) All samples exceeded 10 GPa and 30 MPa, based on projected and experimental data.