DIAgnostics and Mechanical tests Of aged adhesive layers used in joiNts of wooDen structureS (DIAMONDS)

PROJECT CODE: N2-0280
PROJECT TITLE: DIAgnostics and Mechanical tests Of aged adhesive layers used in joiNts of wooDen structureS (DIAMONDS)
PROJECT TEAM: Matthew Schwarzkopf, PhD (leader), Jaka Gašper Pečnik, Rok Prislan
PERIOD: 1. 1. 2023 – 31. 12. 2026
BUDGET: 806.765,00 (150.000€ for InnoRenew CoE)
FINANCING: ARRS
COORDINATOR: InnoRenew CoE (Slovenia)
PARTNERS: Slovenian National Building and Civil Engineerig Institute (Slovenia); Tadeusz Kościuszko Cracow University of Technology (Poland)

In the last decades, civil engineering sector in Central Europe has been experiencing an increase in utilizing natural materials for construction. Among these materials, wood plays the most significant role due to its advantageous mechanical and environmental-impact properties. However, to utilize wood in a structure, one is obliged to use connections to provide needed structural dimensions and spans. Adhesive bond is the most frequent connection to form wood-based composites (WBC’s), such as cross-laminated timber or glued laminated timber and it also plays significant role in performance of the material, especially from a long-term perspective. WBC’s undergo cyclic hygro-thermo-mechanical loads and, at the same time, aging or weathering of the material and adhesive bond in their service life, influencing structural resistance to wind, earthquake and dead loads. These mechanical deterioration, weathering and aging effects have not yet been fully described in the literature, although they strongly influence the performance of the adhesive bond and, eventually, the integrity of the whole structure.

The project will focus on diagnostics and assessment of mechanical performance of aged adhesive bond made of beech, and rigid and flexible polyurethane adhesives. The aim of the project is to answer the question to what degree the ageing of the adhesive bondline can be predicted and diagnosed prior to its functional failure. Within the project, all the adhesive bonds will be examined from many various perspectives such as weathering regime, short-term loading, long-term loading, static and dynamic loads, fracture characteristics, fatigue, acoustic, thermal, visual; and at three scales – macro, micro and nano using techniques such as X-ray CT and SEM. Examining the adhesive bond from such wide range of perspectives will provide significant fundamental answers on anticipated researched goals that will lead to provide ultimate answers about beech connected with rigid and flexible polyurethane adhesives.

InnoRenew CoE project activities

In this project we will study the properties of beech glueboards with rigid and elastic polyurethane adhesives, focusing on how adhesive joints are affected by natural and accelerated artificial ageing processes.
To this end, we will study in detail the characteristics of the individual materials, the formation of the adhesive joint, the influence of changes in wood humidity, elevated temperature, etc. Using different approaches, we will evaluate the static, dynamic mechanical properties of adhesive joints, assess the parameters for achieving quality adhesive joints and verify the use of acoustic methods for assessing damage in adhesive joints.