Get rid of tree stumps by drilling holes in the stump and filling them with 100% Epsom salt. Follow with water, and wait. Live stumps may take as long as a month to day, and start to decompose all by themselves.
Concrete gap filler. Never weed again!! I did this on my patio and driveway. Love it! This is what parks and public places use. Available at Lowes and Home Depot in different colors in the concrete dept.