This tool, which resembles a steel trowel with a lengthwise ridge on its underside, is used to make grooves or control joints in slabs of new concrete. These control joints allow the slab to expand and contract without cracking. Home Improvement Encyclopedia
1. A metal hand tool used to cut a joint partly through fresh concrete. 2. In masonry, a tool used by bricklayers to form the various types of mortar joints between the courses of masonry, as the V, the concave, and weather joints. 3. An electrically powered machine for making joints.