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KAS-2012 1
TRANSPORTATION OF CONCRETE
K A Shah
B.Sc.(Civil Engg.) MSc.(Environment Engg.)
Ex-GM-MNC
Guest Faculty- CTE
KAS-2012 2
TRANSPORTATION OF CONCRETE
Precaution in concrete transportation: Homogeneity of conc. Mass is maintained Movement of hand trolly or truck on rough
road surface makes vibrations This results in deposition of heavy
aggregates at bottom of truck Water & cement slurry comes on top.
KAS-2012 3
METHODS OF TRANSPORTATION
1. Mortar Pan2. Wheel barrow3. Truck Mixer & dumpers4. Crane, Bucket & rope way5. Belt conveyors6. Chutes7. Skip & hoist8. Transit Mixer9. Pump & pipeline10. Helicopter
KAS-2012 4
MORTAR PAN
Common method in India More labour required Segregation of concrete is less Greater surface area of concrete is
exposed to sun, concrete dries.
KAS-2012 5
WHEEL BARROW
When transportation of concrete is at
ground level. Movement of wheel on rough road
surface, segregates concrete. Some wheel barrows have pneumatic
wheel to reduce vibration
KAS-2012 6
CRANE
Used for transporting concrete above ground level.
For high rise buildings. Cranes are fast Can move horizontally & vertically Concrete in skip discharge from bottom In bucket concrete is discharged by tilting.
KAS-2012 7
CONCRETE TRANSPORT BY CRANE-VIDEO
Pouring Concrete-Cement Truck-Crane-Construction Excavation Site.flv
KAS-2012 8
BUCKET & ROPEWAY
Use for construction in: Valley Bridge pier in river Dam
Advantage:
Concrete is not exposed to sun or air & no loss of water.
KAS-2012 9
ROPEWAY-VIDEO
Package
KAS-2012 10
Truck Mixer & dumpers
Used for large concrete works. Can travel any part of site. Dumpers - 2-3 M3 Capacity Trucks – 4 M3 Capacity Bottom surface of truck is kept wet Top of truck is covered to prevent
evaporation
KAS-2012 11
BELT CONVEYOR-VIDEO
Package
KAS-2012 12
BELT CONVEYORS
Limited use in construction
Advantages:
Can transport large volume Very quick Can go where access is limited
Disadvantages :
On steep slope concrete segregates. Exposed to sun for long time.
KAS-2012 13
CHUTE
For transporting from ground level to lower level. (basement etc).
Used where labour can not reach due to less space in trench etc.
Made of metal Slope should not be < 1 vertical : 2.5
horizontal.
KAS-2012 14
SKIP & HOIST -VIDEO
Package
KAS-2012 15
SKIP & HOIST
Labour can go upto 3rd or 4th floors. So skip is used for transport vertically up
(in multistory building). Skip travels on vertical rail. Skip can discharge manually or
automatically.
KAS-2012 16
TRANSIT MIXER
KAS-2012 17
TRANSIT MIXER
Used for long distance travel in RMC plant. Concrete is continuously agitated in truck drum
(2 – 6 rpm). Also transported mix in dry condition and water
is added on reaching the destination. Wet Mix in truck must reach site in 1- 1.5 hours. Pumps are also fitted on truck mixer to
discharge concrete.
KAS-2012 18
PUMPS & PIPELINE
Most popular method Reliable & good quality pumps are used. Mostly operated by diesel. Concrete is placed in collecting hopper. Rotating blades in hopper pushes concrete
towards pipe. Vacume in hose pipe (600 mm Hg) Rotating rollers in pump chambers squeeze the
concrete in pipe and flow of concrete is started. Concrete is discharged from other end of hose
pipe. Concrete can be pumped upto 400 m height and
2000 m distance.
KAS-2012 19
SECTION OF PUMP
KAS-2012 20
PIPELINE
Pipeline should : Have correct diameter as per pump
pressure. (generally 125 mm) Have sufficient thickness Good couplings Poor pipeline can cause blockage.
KAS-2012 21
PIPELINE
Thumb rule : For 30 M3 /hr concrete and 200 m length, dia should be 100 mm.
Length > 500 m then dia = 150 mm. Dia = 3 to 4 times the size of aggregate Leaky pipe & coupling result in escape of
water /air & finally block the concrete. Vertical pipe should good otherwise
difficult to change at height. Pump is kept at distance from building
about 15 % of vertical length.
KAS-2012 22
CONCRETE FLOW IN PIPE
KAS-2012 23
PUMPABLE CONCRETE
Concrete which can be pushed through a pipeline is called pumpable concrete.
Friction between pipe wall and concrete is less. Concrete flows in the form of plug which is separated
from pipe wall by a thin layer of lubricating cement paste. Flow resistant must be < pump pressure. If the concrete is more wet then water comes out of mix
which makes more resistance to flow. Stiff and also very wet concrete is not pumpable.
KAS-2012 24
Design of pumpable concrete
Concrete Mix is so designed that all material remain together.
Mix must make redial movement of grout to maintain lubricating paste.
Mix should be deformed at bends Cement & fine particles (0.25 mm size) are important for
good flow. 350 to 400 Kg/ M3 of fine particles are necessary for flow. Slump of pumpable concrete is above 75 mm.
KAS-2012 25
PROBLEMS IN PUMPING
Blockage in pipe Pipe should be cleaned after each day
operation Blockage can be cleaned by forward-backward
pumping. Tapping pipe with hammer Clean pipe with rod or sponge ball pushed by
compressed air.
KAS-2012 26
THANKS