Placing and Finishing Tools and Equipment

Chapter 6

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

End of Chapter 6