Question

Please name the RMS Specification of construction of cast-in-place reinforced concrete piles without permanent casing. (200-250 words)

Answer 1

   ROADS AND MARITIME SERVICES (RMS)

SPECIFICATIONS OF CONSTRUCTION OF CAST-IN-SITU REINFORCED CONCRETE PILES

WITHOUT PERMANENT CASING

1. Scope :- This specifications set out the requirements for thr construction of reinforced concrete piles which are formed and cast in place without the use of permanent casing.

2.Materials :- Temporary Casings (thickness,type and fabrications must be used as per intended work), concrete and reinforcements.

3. Pilling plant and equipments:- The equipments used for this work must provide adequate capacity for exacavating the pile shaft and the socket used in foundation material for achieving design pile resistance must be upto specified diameter and depth, including its capability to exacavate and additional 20% of the nominated pile depth.

setting out of the pile:- setting out the pile on the site requires adequate pegs and survey marks so that drilling/ pilling can be accurately set up on the allignmnet and its location.

coring:- take 50 mm cores in advance to excavate the pile hole, to confirm the adequacy of the pile base and its shift. Try to take the core samples at 1 meter above the top level of rocket shown in design drawings of the pile, to a depth of 3m or 3 pile dia's whichever is greater below the toe level of pile,

Excavation and cleaning up of the pile :- Submit the daily/weekly report of the pile excavation work, concrete placing and reinforcement cage. the supervisor and Geotechnical engg. must come to site for checking up the specifications as per the design.

pile tolerance limit should be as per code,for the vertical piles inclination tolerance is 1%

For the pile hole safety, keep the loose material at a distance of 1 m away from the pile hole and cover up the pile hole by the lid on the site when not under construction.

4. Excavation of pile hole:- To prevent the pile hole from collapsing use temporary casings if required and neccesary,Another alternative to temporary casings,one can use drilling fluids such as water, bentonite or polymer slurries to provide support to the sides of the excavated pile hole.

If we use the temporary casing then after its installation, excavate inside the casing past the toe of the casing and into the founding material to obtain the rock socket of the specified depth in rock as per the design drawings. If drilling fluids are used then maintain hydraulic head in the excavated pile hole that is at least two metres higher than the ground water level, allowing for artesian head where it exists. While withdrawing take care of the suction pressure below drill which can cause the collapse of socket.Do not leave slurry in a completed pile socket more than 2 hours.

5.Reinforcemnts Details:-

fix and place reinforcements as per the design drawing, provide spacers attached to cage and minimum cover the reinforcement.

6.Concreting

Keep the operation of concreting in one uniteruppted supply. Use self-compacting concrete mix, with a nominated slump not less than 180 mm and not more than 220 mm,

At the starting of concreteing operation the position of outlet tremie pipe must be at the base of the hole. Maintain a distance of 2 m below the concrete top of level of the outlet of treamie pipe throughout the operation.

Maintain the direction of pull on the temporary casing along the axis of the pile. Withdraw the casing slowly during concreting at a rate and in a manner such that no significant disturbance is caused to the surrounding material and that the pile hole is completely filled up with concrete to the exclusion of any voids

7.Testing

Test the nominated piles as per drawing specification test like Pile load test etc.