A compliant trim for use between concrete slabs is disclosed, intended for the replacement of wood commonly used for formwork to divide concrete slabs. The compliant trim is easily inserted into the space cleared of wood, will not migrate deeper into the space, and is therefore independent of the depth of the cleared space beyond a minimum needed for installation. Additionally, the compliant trim lies flush or below the surface of slabs which have edge radii, making it relatively unaffected by foot traffic, vehicles, and the like. The trim may be extruded, may be manufactured from recycled materials, and remains compliant to allow for joint expansion and contraction.