best glue for concrete

[have_blue]

I use Gorrilla Glue for attaching and sealing 2x4 plates to slabs.

No problem with moisture, gap filling, hardening, etc. It's an expanding polyurethane that sticks
to anything. If you get in on your clothes or shoes, I hope it's a good color match.

 

[herd]

I have used PL. Love the stuff. Different formulas based on what you want to use it for. I have glued wood to cement. Later tried to remove the wood. The wood will crack, splinter and still stay stuck to the cement. I still like to use a few Tapcons or something else, should the glue fail. Lots of construction guys just use the adhesive but maybe I am a little too conservative.

IMHO, I would not use tar, silicone or caulk. Does not have the strength or strong adhesion.

Lots of great tips and replies on this and I thank all y'all for your input. I experimented a little and I believe I am going with the PL Polyureathane adhesive. I glued a small block of 2x6 to my shop floor, put a 20# LP bottle on it to hold in place, waited two days and tested the bond. I kicked the block hard several times, did not budge. I finally used a prybar to get the block up and it removed a layer of concrete with it. I did sweep the area first but basically that was on a dirty, unsealed floor.

I am planning on acid-washing the floor, top with a good concrete sealer and once dried, use the PL Poly adhesive along with 3/8'' RedHead tapcons every 24''. I went ahead and put down a 4mil poly vapor barrier underneath the house. Will post final results.

Once again, thanks!