I don't know but it sounds a bit extreme and surely can't be a good idea if there are young ones or animals about?

salt is good and bio friendly.just cut the weeds down or strim them then be liberal with the salt.you can buy special weed killer in a spray form for just this job but i dont know how good it is . its called round up.

I always use Pathclear, works pretty well.

I am sure that caustic soda will kill anything, including the skin on your hands if you are not careful. Are you thinking of Sodium chlorate which is more readily available as a total weedkiller.