Development and structural behaviour of adhesive free laminated timber beams and cross laminated panels

Abstract Glued-laminated timber (glulam) beams and cross-laminated timber (CLT) panels are increasingly being used as structural members for buildings, because of their excellent mechanical properties, ability to be processed into larger structural sections and environmental benefits. Nevertheless, the inclusion of adhesives during their production raises environmental concerns due to the release of Volatile Organic Compounds (VOCs) and formaldehyde, which also causes difficulties in recycling. This environmental burden has led to the development of adhesive free laminated timber (AFLT) beams and cross-laminated (AFCLT) panels, which are intended to be used as alternatives to glulam beams and CLT panels in structural applications. In this paper, details of the materials and manufacturing processes for the AFLT beams and AFCLT panels are described, followed by the structural tests and the observed failure modes. Furthermore, parametric studies are carried out to investigate the effects of the following factors on the structural response, i.e. lamella species, dowel species, dowel insertion angles, dowel diameters and configurations, number of dowels (or dowel spacing), section sizes and number of interfaces. It is found that the flexural modulus and flexural strength of the 26 AFLT beams and 26 AFCLT panels are in the range of 1.1–5.3 GPa and 19.3–38.2 MPa, respectively. The experimental results are compared with commonly used glulam beams and CLT panels. The results are useful in understanding the mechanical properties of AFLT beams and AFCLT panels fastened with compressed wood dowels, and constitutes useful structural design information for future construction and structural applications, as well as providing data to validate the finite element modelling. In addition, the study has demonstrated a practical and sustainable approach in timber construction, which may lead to a substantial reduction in the use of structural adhesives and environmental benefits.