The state of the art requires a closed waiting time of about one hour for the beech glulam production. This has a negative influence on the production costs. Micro structured surfaces showed good performance in combination with coatings. The authors have performed tension-shear and delaminating test in order to investigate the influence of micro structured surfaces on the bond quality of hardwoods. The results are very promising and show clearly improved delaminating resistance for all tested adhesive. No closed waiting time was needed to achieve satisfying results using MUF in combination with beech.
Delamination resistance and tensile shear strength (TSS) are essential for structural adhesives used in timber industry. Thus these two factors were investigated on bonded ash (Fraxinus excelsior L.) to check the suitability of adhesively bonded ash as building material. For determination of the delamination resistance industrially bonded ash glulam was used. The specimens for the tensile shear tests where produced in the laboratory. Four different adhesives types and different pre-treatment were investigated. The samples for TSS were tested in dry and wet condition. 80% of the tested series met the requirements of the standards at dry, and only 30% passed at wet condition. None of the adhesives tested was able to pass the delamination test. No distinct influence of the different parameters studied is notable for most of the adhesive systems, only extended closed assembly time and lower mixing ratios seem to improve the bond quality of MUF. Additional chemical analyses, conducted to find evidence for the poor bonding performance, showed that fatty acid content, pH and acidic extractives are in between the range of beech (Fagus sylvatica L.) and Spruce (Picea abies Karst.). However the formic acid is an exception with a four times higher amount as the other two species investigated.
In Australia CLT has a big potential but has to be imported from overseas to date for quite high prices. Milling of Pinus Radiata using optimised sawing patterns for yield and consecutive mechanical grading lead to a substantial amount of boards, which cannot be used for structural purposes directly. Therefore it should be economically interesting to produce CLT using this resource. The authors performed a considerable amount of mechanical tests using various setups and optimised layups in order to investigate the mechanical properties of Pinus Radiata CLT using non-structural boards. The results showed that depending on the layup of the CLT the used resource leads to a product that performs similarly to the ones on the market in Europe