Transportation Equipment

Once the concrete has been batched and mixed  the next obvious step is to transport it to the site of work, ensuring that the homogeneity obtained at the time of mixing is maintained at the final place of deposition. The choice of selection of a particular equipment of transportation will depend upon the amount of concrete involved, the size and type of construction, the typography  of job site, the location of the central plant  and relative costs. 

The different equipment for transportation of concrete are: 

• Mortar pan 
• Wheel barrow, hand cart 
• Bucket  and rope way 
• Truck  mixers  and dumpers 
• Belt conveyors 
• Chute 
• Skip  and hoist 
• Concrete pumps 

Let us study these in more details 

Mortar Pan 

For short distances, this is one of the most common method  used in India. Small quantities of concrete are carried more number of times. Mortar pan method of conveyance of concrete is usually adopted for concreting at ground level, below or above ground level without much difficulty. 

Wheel Barrow 

Wheel barrows are employed for transporting concrete for comparatively longer distance on level ground as  in the case of concrete road construction. 

Bucket and Ropeway 

Buckets or skips are a versatile means of moving concrete about the job site by the use of ropeway. This method is adopted in case of concreting work in a valley or construction of a pier in the river for a bridge or for dam construction. The  mixing of concrete is done on the  bank or  abutment at a convenient place. The  bucket is brought by the ropeway, filled and then taken back to the desired point.  The horizontal and vertical movement of the bucket is controlled by a set of pullies. For  discharging the concrete, the bucket may be titled of sometimes the concrete is discharged by providing a hinged bottom  in the bucket. The discharge of concrete can also be achieved by a gate system operated by compressed air. However, you must ensure that concrete is not  made  to fall  freely from great height. An advantage is that large quantity of concrete can be transported  with no exposure to  sun  and wind  and  without much change in workability. 

Truck Mixers and Dumpers 

Trucks and dumpers are used for transporting concrete works.  They  have  a distinct advantage  over wagons  which  need rail  tracks.  Dumpers  are generally of 2 to 3 cubic metre  capacity where as the capacity  of truck trimesters may be 4 cubic metre  or more. The inside of the body of the truck mixer  should be wetted before  loading it with concrete. Insulated sheets, tarpaulins  or their covers may be provided to render protection  against evaporation of moisture from concrete during  transit. When concrete is to be  hauled  over  long distance, it will be prudent  to use trucks with  agitators  which  prevent segregation and stiffening. The agitators carry  out the mixture process continuously at show speed. 

Belt Conveyors 

Belt conveyors can also be  used to transport concrete both  horizontally  and vertically.  However  special care is required  to be taken with this mode of transportation. The principal  drawback is the tendency of the concrete to segregate an steep inclines, at transfer  points,  at changes of direction, at places where the belt  passes  over the rollers and at discharge point. Since the concrete is spread out rather  thinly, it is susceptible to loss of moisture or increase of temperature during hot weather,  which  will increase slump loss. Care is also required  to be taken to prevent  mortar from adhering to  the belt. The use of belt  conveyors is therefore  not recommended in very  hot conditions.

Chute 

Chutes are generally  used for transporting concrete form ground to a  lower level, The chute should  be  lined  with  metal and shall have  slope not flatter than 1 vertical to 2.5 horizontal. The layout of chute should be such that concrete slides evenly  in  a compact mass  without  any  separation  or segregation. Chute is not considered  a god method  of  transporting  concrete. However, it is adopted  when movement of labour is not  possible due to lack of space or fear of disturbance to reinforcement and  other accessories. 

Skip and Hoist 

It is one of the most widely  used methyl for  transporting concrete upwards for multistcreyed building construction, specially more than 4 storeys. In this  arrangement, the concrete mixer  directly feeds the skip at ground level. The skip travels up on the rails up to the required  storey where the concrete is discharged  automatically or by manual operation. The quality  of concrete i.e. freedom from segregation  depends upon the height  traveled  and the rolling over the rails. For greater  heights, the concrete must he turned yore before  being  placed in position. 

Concrete Pumps 

Pumping of concrete through  rigid  or flexible pipeline,  directly into the desired location is one of the most  satisfactory  method of transportation. This is a  very  versatile  method and is  specially useful where working space is limited like in tunnels.  Depending on the power of engines, the effective pumping range varies from 90 to 300 metres horizontally and 30 to 90 metres  vertically. The pumping  rate could vary from 8 to 75 cubic metres per hour.