Bored Cast

Installation of Bored Cast In Situ Piles
All piles are installed by hydraulic rotary piling rig.
The works comprises mainly of the following steps:
  • Drilling of bore holes of required diameter
  • Insert temporary casing
  • Lower Reinforcement Cage.
  • Flushing of bore.
  • Pouring of Concrete as per approved Design Mix.
  • Disposing of Muck / Bentonite etc.
 Equipment and Accessories required for Piling are detailed below:
  • Rotary piling rig with all accessories                                                   
  • Temporary casing pipe                                                                                   
  • Bentonite Mixing Set-up comprising of mixing tank and pumps                 
  • Tremie pipe of 200mm I. D. min along with Hopper                                                                  
  • Testing Apparatus                                                                               
    •             Measuring cylinder,
    •             Mud Balance Hydrometer                                           
    •             Marsh cone
    •             Weighing balance
    •             Hot plate                                             
    •             pH papers                   
                                      
Sodium based bentonite will be used with pH of Fluid between 9.5 and 11.5. Bentonite powder shall conform to requirements given in IS: 2911 (Part -1/Sec -2). All batches of bentonite powder delivered
& suspension fluid made there from shall be tested to satisfy requirements failing which they shall be rejected.
Bentonite powder shall be mixed with clean water to make a suspension of density as specified. The suspension shall be regularly tested to ensure its suitability for use as drilling mud.
 
Concrete as per approved mix design will be supplied from centralized batching plant for all piles. Slump test will be done to check the workability of Tremie Concrete & Concrete. The Concrete shall generally be poured with minimum interruption.
Grade, length, diameter etc. shall be as per design requirement shown on relevant drawings. Concrete cover blocks to ensure proper concrete covering shall be tied to rings of the cage.
 
Setting Out: This shall be provided by the Client.
 
Setting of Piling Rig: Rig will be centered on pile point. Drilling will be carried out using auger/bucket to a depth of approx. 2 to 3 meters. Then a temporary MS casing for about 4 to 6 m (approx) length from the ground level will be driven to protect loose soil from falling in the bore hole at locations where the soil is in loose state and there is a tendency of collapse of bore hole. After driving the casing its verticality will be checked by plumb bob.
 
Boring of Piles: The excavation is generally performed by rotation using a rotary drill, composed of a rotary table.
 
Borehole Stabilization: During the entire operation, the pile bore will be kept stable with bentonite solution.
Determination of Density: The bentonite sample from the bottom of borehole will be collected and its density will be measured by Hydrometer having a range of 1.001 to 1.300 gm/ml.
 
Determination of Marsh Cone Viscosity: The viscosity will be determined by using cone apparatus.
 
Reinforcement Fixing: Pile reinforcement cage shall be fabricated as per the details given in drawing and Bar Bending Schedule.
Flushing the Borehole: After cage lowering is completed the bore will be flushed with Bentonite Flushing shall be done continuously with bentonite till consistency of bottom slurry becomes less than 1.20.
 
Concreting:  Minimum time interval between the completion of boring and placing of concrete will be maintained.  The gap between the bottom of the bore to the end of tremie pipe will be min 300mm. The dia of the tremie pipe will be not less than 200mm. The Tremie pipe shall be removed in stages during pouring of concrete ensuring that the Tremie bottom is always inside the concrete.