Fill concrete cracks and joints without using a pro grade melter with the 1/4 in. Small Gray Crack-Stix Permanent Concrete Joint and Crack Filler. Originally used for federally specified highway jobs, this filler is an easy permanent solution for keeping concrete smooth. Crack-Stix is applied with heat (a simple hand held torch) and bonds to the sidewalls of the crack. Unlike some fillers, Crack-Stix expands and contracts along with the weather to keep joints and cracks sealed. Designed for joints and cracks from 1/4 in. to 1/2 inch in Dia.