How to fix broken tree slabs?

Wood glue and very large furniture clamps. They will need to be stored in a more climate controlled area, so they don’t crack further.

I would suggest wood glue and clamps as well. However, depending on how large the cracks are, you could also use a woodfil epoxy: https://www.google.com/search?q=how+to+repair+cracked+wood+slab&rlz=1C5CHFA_enUS744US744&oq=how+to+repair+cracked+wood+slab&aqs=chrome..69i57j0l2j69i64.17196j1j4&sourceid=chrome&ie=UTF-8#kpvalbx=1

Thank you, will give it a try!!!😊

You could create some very nice woodfill epoxy effects with a hi-lighted color.

Good suggestion from Cheryl about the climate controlled area.

Around here in Oregon they use contrasting wood butterfly or Dutchment to joint splits.... https://www.youtube.com/watch?v=Q6IZkr2zI_Y

You could use wood glue and a clamp for 24 hours

Thanks, good 👍 idea.

I saw on you tube a man who made a butterfly clamp.