Transcript Planning for slab-on

Placing and Finishing Tools
and Equipment
Chapter 6
Chapter Topics
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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:
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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