Chapter Topics • Spreading tools • Consolidation or vibrating tools • Laser-guided screeds • Hand screeding tools • Tools for smoothing after screeding • Jointing and edging tools • Hand floats and trowels • Power floats and trowels • Power saws
Spreading Tools • Amount of hand work needed depends on: • Concrete being placed close to the desired location • Tools for hand spreading include: • Short-handled, square-end shovels • Come-alongs • Concrete rakes
Consolidating or Vibrating Tools • Consolidation removes the entrapped air, producing concrete with the properties normally expected and desired for concrete slabs. • Equipment for consolidation of slabs: • Internal vibrators • Surface vibrators • Vibrating screeds • Vibratory roller screeds • Laser-guided screeds
Hand Screeding Tools • Screeding or strikeoff is sometimes done manually with a straightedge consisting of a rigid, straight piece of wood or metal. • Several types of manually operated straightedges including hollow magnesium straightedges made especially for screeding. • Short straightedges are usually made of either wood or magnesium, whereas longer ones are made of steel angles or channels. • Some straightedges are built in such a way that they can be adjusted to provide a crown (or camber) to the surface.
Tools for Smoothing After Screeding • Bullfloats • used for FF 20 or less • handle with large piece of wood or metal attached • Highway straightedges • used for FF greater than 20 • 6 to 12 ft long rectangular metal straightedge • Darbies • long, hand-held floats used in congested areas
Jointing and Edging Tools • Edgers • Make neat round edges less likely to chip or spall. • Various hand-held sizes and shapes; walk-behind. • Jointers (Groovers) • A cutting edge that makes a narrow groove. • The groove (contraction joint) produces a weakened section that helps cracks appear below the neat, straight joints. • Groove depth should be ¼ slab thickness.
Hand Floats • Used to remove small imperfections and produce a level, plane surface and prepare surface for troweling • Type of hand floats • Wood • Magnesium • Composition • Wood used for non-air-entrained and high-slump concrete. • Magnesium used for air-entrained and lightweight concrete.
Hand Trowels • Used in final stages of finishing, after floating, to create hard and dense surface. • As surface hardens, subsequent trowelings are done with smaller trowels to increase pressure on surface. • Fresnos are large, long-handled trowels used to smooth the slab quickly but does not provide a hard, dense surface.
Power Floats and Trowels • Machines • Walk-behind (3 ft to 4 ft ring diameter) • Riders (6 ft to 10 ft wide) • Blades/attachments • Float blades or shoes: wider than trowel blades • Trowel blades: narrowest blades • Combination blades: for floating and troweling • Pans: circular disks attached blades
Power Saws • Dry-cut and wet-cut saws with an abrasive or diamond blade to cut contraction joints in large concrete surfaces. • Dry-cut saws • Lighter than wet-cut saws • Permit joint sawing within 1 to 4 hours after finishing • Wet-cut saws • Can cut deeper joints • Joints sawed later than 4 hours after finishing