I want to put down some pavers as an edging around a garden spot in my lawn. They are going to be level with the grass for the sake of lawn-mowing. I need a filler to put between the bricks to keep bugs/weeds out. I have weed control tarping underneath the bricks already. I don't want the pavers to be cemented in, so I don't want to use the polymeric sand stuff. I've heard there is a grit/sand that slices bugs/plants to shreds if they try and crawl through it. Does this ring a bell to anyone? Can anyone tell me what this stuff is called or if it even exists?