Screw bonding in glulam beams

The project has followed a common thread to achieve the best possible end result. First, the flow of the glue was examined, this was carried out on small test beams, about 600x600 mm. To eventually move on to gluing larger beams.

The combinations investigated in this screw bonding project are:

1. Glulam beam to glulam beam (flat side to flat side)
2. Knob against glulam beam
3. 3 Glulam beam (edge side) against CLT.

• Examination of the adhesive flow was carried out on option 1 as above. A plexiglass sheet was placed on the glue joint on the glued beam before the two beams were pressed together with a screw in the middle or self-weight. This is to see how the adhesive flow has occurred at different use and waiting times (use time is the time from when the adhesive is mixed until it is extruded / waiting time is the time from extrusion to full pressure).
• The dimensional accuracy of the panels was measured to investigate how much the thickness of the panels varied along and across the beams.
• The clamping force in screws was examined to see its differences.

After investigating the three points mentioned above, screw bonding experiments were carried out on larger beams to see the final results by taking delamination samples.

The project has been so successful that the results have started to be implemented at Holmen Wood Products AB's manufacturing today to control the screw bonding process with its own developed instructions for screw bonding "Internal manual screw bonding" and "Quality manual screw bonded glulam".

Area: Industrial wood construction
Budget: SEK 200,000
September 2020 - December 2021
Project manager: Jon Martinson, Martinsons Byggsystem
Funding: This project was funded by TCN.