Review of state of the art of dowel laminated timber members and densified wood materials as sustainable engineered wood products for construction and building applications

Copyright © 2019 The Authors. Engineered Wood Products (EWPs) are increasingly being used as construction and building materials. However, the predominant use of petroleum-based adhesives in EWPs contributes to the release of toxic gases (e.g. Volatile Organic Compounds (VOCs) and formaldehyde) which are harmful to the environment. Also, the use of adhesives in EWPs affects their end-of-life disposal, reusability and recyclability. This paper focusses on dowel laminated timber members and densified wood materials, which are adhesive free and sustainable alternatives to commonly used EWPs (e.g. glulam and CLT). The improved mechanical properties and tight fitting due to spring-back of densified wood support their use as sustainable alternatives to hardwood fasteners to overcome their disadvantages such as loss of stiffness over time and dimensional instability. This approach would also contribute to the uptake of dowel laminated timber members and densified wood materials for more diverse and advanced structural applications and subsequently yield both environmental and economic benefits.Interreg North-West Europe (NWE) funded by the European Regional Development Fund (ERDF) supporting the project (Towards Adhesive Free Timber Buildings (AFTB) - 348)

Experimental investigations on adhesive free laminated oak timber beams and timber-to-timber joints assembled using thermo-mechanically compressed wood dowels

© 2019 Elsevier Ltd This paper presents an experimental investigation on a novel adhesive free engineered Wood Products (AFEWPs) as an alternative to the conventional glued EWPs which have a high degree of petrochemicals. The research outcomes demonstrate the feasibility of using compressed wood dowels (CWD) as a joint element, to connect timber laminates and members as well as to substitute for adhesives and metallic fasteners. The paper describes the production of thermo-mechanically compressed wood dowels as well as the manufacturing of the dowelled timber specimens. The strength and stiffness properties of CWD are characterized based on three-point bending tests and compared to the values obtained from uncompressed wood specimens. After that, the paper discusses the relative mechanical performances of three-layer dowelled oak beams subjected to four-point bending, in comparison to their conventional glued counterparts. Finally, the paper shows results obtained from double shear push-out tests under both monotonic and cyclic loadings, using two wood species, namely spruce and oak. The obtained results show clearly the potential of thermo-mechanically compressed wood dowel, as a joint fastener, for load bearing capacity

Coupled nonlinear-damage finite element analysis and design of novel engineered wood products made of oak hardwood

This paper presents a comprehensive experimental and numerical investigation to design novel engineered wood products (EWPs), namely adhesive-free laminated beams (AFLB) and adhesive-free cross-laminated timber (AFCLT) panels, for the first time. Thermo-mechanically compressed wood (CW) dowels were used as a joint element as an alternative to the traditional glue and metallic fasteners. The following structural elements were studied: (1) solid timber beams, (2) middle-scale and large-scale three-layer AFLB, (3) timber-to-timber connections and (4) AFCLT panels. In addition, a predictive coupled nonlinear-damage model was proposed as a predictive and powerful tool design to reduce expensive experimental tests. The main mechanical characteristics and performance of the designed EWPs are assessed experimentally and addressed in the paper. Furthermore, the accuracy and the performance of the developed FE model were verified against experimental results from the studied example showing a fairly good prediction of the non-linear behavior as well as the modes of failure and its growth. Finally, the validated FE model was used to carry out a parametric study of the influential design parameters and some design recommendations are made