An exterior construction adhesive might work to a point but you cannot count on it for lateral stability if the lumber flexes against it for many seasons.
Are you trying to lay 2x4 lengthwise to the concrete directly? If so, I would shift thinking and put some nailers in place perpendicular first. A hammer drill, carbide tipped masonry bit, and some patience should get you into the concrete so you can get some expansion anchors and bolts in place. This would be the way I would approach the project.
A faster way would be to ramset or otherwise shoot the cross member suggested in place. Just warn the neighbors the gunshots they are hearing are not doing in the family, just anchoring for a bench. You can apply construction adhesive too if you want but I think it will be overkill.
Then screw your long 2 by to the cross members. This raises your bench height a bit but should work out better than construction adhesive alone.
You should be able to rent a ramset gun at a tool supply company and they will have the appropriate charges and fasteners. Just tell them what you are trying to accomplish.
http://www.hirequip.co.nz/images/product/gid_351A.jpg
If you have never used a ramset gun before? You will want ear and eye protection and gloves. You hold, or have a helper, hold the wood in place and press the face of the tool firmly on the lumber, pull the trigger and a cartridge---22 caliber---fires an anchor appropriate and matched to the charge through your wood and into the concrete.
Are you trying to lay 2x4 lengthwise to the concrete directly? If so, I would shift thinking and put some nailers in place perpendicular first. A hammer drill, carbide tipped masonry bit, and some patience should get you into the concrete so you can get some expansion anchors and bolts in place. This would be the way I would approach the project.
A faster way would be to ramset or otherwise shoot the cross member suggested in place. Just warn the neighbors the gunshots they are hearing are not doing in the family, just anchoring for a bench. You can apply construction adhesive too if you want but I think it will be overkill.
Then screw your long 2 by to the cross members. This raises your bench height a bit but should work out better than construction adhesive alone.
You should be able to rent a ramset gun at a tool supply company and they will have the appropriate charges and fasteners. Just tell them what you are trying to accomplish.
http://www.hirequip.co.nz/images/product/gid_351A.jpg
If you have never used a ramset gun before? You will want ear and eye protection and gloves. You hold, or have a helper, hold the wood in place and press the face of the tool firmly on the lumber, pull the trigger and a cartridge---22 caliber---fires an anchor appropriate and matched to the charge through your wood and into the concrete.
