How would you go about attaching baseboard to a concrete wall. Would you use a constructive adhesive and then what type of fastener?
Slow setting hot glue every other dot with PL Premium as the alternate glue. The Hot glue will hold the baseboard on until the PL Premium sets. Use heavy weights to keep the baseboards against the walls if walls are wavy.
why would you be attaching, i assume, non PT wood to concrete. sounds like mold and wet wood in your future.
How much thickness do you have to work with?
If you're planning to install a baseboard along the base of this concrete wall, then I presume you have plans to finish the wall somehow (with drywall fastened to wood strapping perhaps). If you could outline your plans for this concrete wall, we could better assist you in deciding how best to attach a baseboard.
LePage's now has a new version of PL Premium on the market called "PL Premium Advanced". The "Advanced" version is still a moisture cure polyurethane (correctly pronounced "polyurea"), but it has 4 times the initial "grab" that the original version does. That might allow the original poster to avoid the use of the hot melt glue.
If it wuz me, I'd prefer to see you use a construction adhesive to fasten some kind of wood to that concrete, and then use brads or nails to fasten the baseboard to the wood. But, that gameplan depends on how much thickness you have to work with.