Lec 17 Concrete Equipment
Lec 17 Concrete Equipment
Lec 17 Concrete Equipment
Construction Methods
Concrete Equipment
Review
• Ingredients
• Aggregate (fine to coarse)
• Cement
• Water
• General Operations
• Batching
• Mixing
• Transporting
• Placing
• Consolidating
• Finishing
• Curing
http://www.youtube.com/watch?v=0Aqq3a0GTjY&feature=related
https://www.youtube.com/watch?v=zhgh1buqUFM
http://www.youtube.com/watch?v=tjPsvSmlLtQ&NR=1&feature=fvwp
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Batching
• The process of proportioning the ingredients of the
concrete mix
• Batching Plants
• Manual ‐ small jobs (< 500 cy or approx. 20 cy/hr)
• Semiautomatic ‐ automated termination of
charging/discharging of batchers
• Fully Automatic ‐ preprogrammed quantities are run
automatically
2
Mobile
batch
plant
Example at http://www.youtube.com/watch?v=coZODyW6dS8&feature=related
Batching
3
Mixing
• Mixing Operations
• Job‐batched
• Central‐batched
Transporting
• Ready‐Mixed Concrete: proportioned in a remote
central location and transported to the purchaser
after mixing either at the plant or en route
• Central‐mixed
• Shrink‐mixed
• Truck‐mixed (or transit‐mixed)
4
Transporting
• Mixer Trucks
• 6 to 15 cu yd capacities
• Mixing accomplished in 70‐100
revolutions
• ASTM C94 allows 1.5 hours from
addition of water to placement
or 300 drum revolutions,
whichever comes first.
• Additional water (with
limitations) or plasticizer added
at site to lessen stiffness
Placing Concrete
• Placing Equipment
• Buckets or hoppers (0.5 –4 cu yd)
• Buggies (10‐30 cu ft capacities; up to 15 mph travel
speeds)
• Chutes and drop pipes
• Belt conveyors
• Pumps (up to 200 cy/hr; up to 170 ft vertical or 150
horizontal for truck mounted)
• piston pumps
• pneumatic pumps
• squeeze pressure pumps
5
Placing Concrete
Placing Concrete
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Placing Concrete
Placing Concrete
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Consolidation
• Mechanical action to
remove trapped air
voids
• Vibrating Methods
• Internal vibrators
• Surface vibrators
• Form vibrators
Finishing
• Shaping the surface to the desired elevation and
texture
• screeding: striking off at desired elevation
• floating: smoothing and compacting the surface while
embedding the coarse aggregate
• troweling: imparting a smooth surface
• brooming: dragging a broom across the surface to
provide skid‐resistant textured surface
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Finishing
Finishing
Laser screed
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Finishing
Finishing
10
Finishing
Finishing
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Finishing
Finishing
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Curing
• Maintaining moisture to support completion of
hydration
• Curing Methods
• Wet burlap covering
• Ponding water on the surface
• Spray application of curing compound
Curin
g
Blanket for
Ponding
cold
on
weather
house
concrete
slab
curing
Wettin Application
g of curing
burlap agent
bags
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Curing
Curing and
Texturing
Machine
Productivity
• Regardless of the placement method, try to order
enough trucks to maintain a smooth placement
rate.
14
Productivity
Bucket productivity:
Productivity
Buggy productivity:
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Productivity
Productivity
• Solution:
• Cycle Time = 1.5 min + 90 ft / [(1 mph)(88 ft/min per mph)]
= 90 ft / [(2 mph)(88 ft/min per mph)]
= 1.5 + 1.0 +0.5 = 3.0 min.
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