Top 9 METHODS FOR TRANSPORTATION OF CONCRETE

Transporting Concrete defined as the process involve in carrying concrete mix from mixing place to place where the cast is described as transporting..

Transporting Concrete

Transporting Concrete defined as the process involve in carrying concrete mix from mixing place to place where the cast is described as transporting of concrete

Efforts have been made to minimise the time between the mixing of concrete and compaction of concrete within forms

The specification provides a maximum time of two hours between time from water added to the concrete mix ingredients and placing of concrete if the concrete mix is transported by use of vibrators or truck mixer if the agitator is absence then time reduce to one hour

In all of this, it is assumed that the concrete temperature during placing is not less than 5°C and not more than 32°C

However, it is now confirmed that the delay in placing the concrete, after the initial setting take place, is not harmful and may give strength, although the concrete retains sufficient efficiency to allow full compaction

Requirement during transporting of concrete

No matter which conveyance method is selected but it should be fulfilled below requirement during transportation of concrete which are:

  • Placing of concrete at the point of casting should be uniform and also proper consistency
  • Segregation of concrete should not happen
  • Excessive drying and stiffening of mix concrete is not allowed
  • The cost of transportation should be minimum
  • The time of the process of concrete mixing, transporting, placing of concrete, and compacting of the mix should not higher than 90 minutes in any case

Method of Transportation of concrete

  1. Mortar pan
  2. Wheelbarrow and hand carts
  3. Truck mixer and dampers
  4. Crane, bucket and ropeway
  5. Belt conveyors
  6. Chute
  7. Transit mixer
  8. Skip and Hoist
  9. Pump and pipeline

Mortar pan

  • Mortar span used for concrete transportation is one of the most general methods adopted
  • This method is adopted where concrete mix quantity is small and also point of placing of concrete is restricted to access
  • Normally iron span is used in transporting facilities and manually transport concrete in pans
  • This is a slow and costly method of transporting

Wheelbarrow and hand carts

  • Wheelbarrow of steel with pneumatic tyres are Used for medium distances
  • Wheelbarrow capacity varies between 70 litres to 80 litres
  • This method of transportation of concrete is mainly adopted when in road construction where concrete is deposited at or below concrete mixer level than steel wheelbarrow is the best mode of transportation of concrete

Truck mixer and dumpers

  • Truck, dumpers and any other open body vehicle lorries can be used in operation to transporting concrete economically for To carry of up to about 5 km
  • Dumpers capacity is normally 2 to 3 cubic metre whereas truck mixer capacity maybe 4 cubic metre
  • Inside the body of the vehicle should be wetted by water before loading concrete mix 
  • Tarpaulins or other covers should be used to cover the loaded wet concrete during transporting concrete to prevent evaporation and stiffening 
  • The agitators help a lot the mixing process at a slow rate

Crane, bucket and ropeway

  • Crane and bucket is mostly used when there is a need for transporting concrete above ground level
  • Cranes are extremely useful in high rise building construction project
  • Cranes are very fast and adaptable to transport concrete vertically as well as horizontally
  • Cranes carry buckets and skips containing green concrete mix and skip have the door at the bottom for discharge whereas buckets tilting operation needed for emptying
  • For medium job capacity of the bucket may be 0.5 cubic meter
  • Ropeway and bucket mostly used in transporting concrete for construction work like concrete dams, concrete bridge
  • In this process mixing of concrete is completed on the bank and then concrete brought in the bucket by pully or other operation to a place of discharge. steel towers are erected on the bank of the river to provide support to the rope for this operation

Belt conveyors

  • The belt conveyors method is used when there is a need to transport concrete continuously 
  • This method is highly preferable during summer days because there is a high rate of evaporating which decrease w/c ration to avoid this you should use belt conveyors for continuous transporting thorough work at a distance 250 to 500 meter from place of mixing
  • This method is also taken in work operation where it’s difficult for other types like lorries for transporting concrete
  • The belt which used in covering of rubber of 60 cm width and also the speed of belt should not more than 1 meter per second
  • The slump of concrete mix which transport by belt conveyors is not more than 6 cm
  • The angle is of the belt not higher than 15°
  • When concrete unload from the belt conveyer than should use a guild board so that segregation is eliminated. For short distance like 20 meter flat belts is suitable but for larger distance haul trough-shaped belts suitable

Chute

  • The chute is normally taken into operation when there is a need of transporting concrete from ground level to below leverslop is restricted by 1:2.5 (1 verticle:2.5 horizontal) because of point kept in mind to avoid segregation of concrete

Transit mixer

  • Transit mixer is most largely used equipment for concrete transportation through long distance 
  • It’s especially used in transporting RMC (ready mixed concrete) and in now day used of ready mixed concrete for construction on a large scale due to high quality and fast construction 
  • In transit mix, the concrete batched at a central plant is mixed materials during the time of transit to the site
  • The transit mixer mounted on a vehicle having the capacity of 4 to 7 cubic meter
  • The speed of mixer rotation is 2 to 6 revolutions per minute. Long haul offer by transit mixer
  • The time period of transit after adding water into an ingredient is normally limited from one hr to one and a half hr
  • The total number of mixture revolution is limited to 300

Skip and hoist

  • This method is taken into operation for transporting concrete vertically upward for the casting of multi-story building construction
  • Mixter directly feeds the skip at ground level
  • The skip vertically up over the rail up to the casting level
  • In the multi-story building where the time taken for transporting of skip and discharging of concrete mix is large skips with an individual which units are provided
  • When one skip travels the other one is filled with concrete thereby allowing greater efficiency of the whole operation

Pumps and pipeline

  • Pumping of concrete by use of steel pipe is one of the most successful methods of concrete transporting
  • In multi-storied building, tunnels and bridges mostly used pumped concrete
  • The concrete is fed from the hopper in to pump largely by gravity but is also assisted by the vacuum produced on the suction stroke of the piston and forces into the pipeline on the pressure stroke
  • The pipeline generally filled and concrete mix move uniformly cohesive and mix will feed more readily that a harsh and dry mix 
  • The concrete pump generally available in capacity varies from 15 to 150 cubic meter per hours 
  • Bends in the pipeline reduce the effective distance by 10 meters for each 90° bend, 5 meters for a 45° and 3 meters for a 22.5° bend

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