I have used many approved compounds to fill in the cracks in my patio.  Finally, I just gave up and grabbed my gorilla tape a couple of years ago.  I cleaned the area around the crack really well with a simple spray from my Windex bottle, let it dry, then applied my Gorilla tape, pressing it well to adhere.  The tape has been on the floor of my patio for over two years now keeping rain out of the cracks with no sign of failing or weathering, even where the tape goes out from beneath the cover and into the sun.