Blog

Epoxy anchor tests: cold cure

  |   Materials

from Daizen News,  1 Nov 2011

Epoxy is a very reliable substance that bonds wood, steel, and stone. The epoxy itself must be precisely formulated for the specific materials it will bond. In our continued testing, we have found some epoxies that pass the test of a bond between wood and steel, and some that fail.

Here, at a Wood Works! BC conference in December, 2010, the steel rod broke (at 12) before the epoxy or the wood did.

Our testing apparatus.

Recently, we’ve been testing and using an epoxy fastening system from Japan that bonds wood, steel, and stone together. The other benefit of this system is its epoxy delivery method: it allows us to place all structural members and inject the epoxy afterwards. It injects from the middle of the rod, flows out from the end, and fills out from all the injection holes so we know the entire space is filled with epoxy, ensuring that the connection is properly done.

Above, square hole in the very bottom of the post, with the injection gun in place. The nose is within the wood, not visible.

Once the epoxy is applied, the only visible sign is a small square hole in the post bottom. We can leave as is or we can plug it with wood.

The Japanese diagram below explains how the epoxy is filled inside the timber by using red colored epoxy and two different types of rod. The rod comes in various lengths, and application is not limited just to a post connection.

If you’re interested in wood, there are some upcoming Wood Works! BC luncheon conferences in November and December.