I haven't used Triple Strike, but I regularly use Roundup (glyphosate)
and it is very effective against all weeds and grass in my experience.
It's the most widely used herbicide. I have a long crushed stone
driveway and use it there. It kills everything, but it does take some
time. About 2 weeks for all plants to totally die. What concentration
are you using? Also, it is temp dependent as you want the plant to be
actively growing for it to be most effective.