placing and finishing tools and equipment
Post on 01-Jan-2016
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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
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