This post details the inspection test plan of Concrete Bored Piles. Bored cast-in-situ pile is constructed by digging a hole in the ground by suitable means such as percussive or rotary method,s with the use of temporary or permanent casing or drilling mud. After that, the construction is finalised by filling the hole with reinforced concrete.
What is an ITP
Inspection and Test plans and checklists are an integral part of quality management systems, not only in construction but in almost every industry where Quality Management systems are in place. It is considered to be a master document through which different parameters and actions of a process or activity would be monitored and recorded, which play a vital part during the verification later, or in simple terms, during auditing.
- It is a comprehensive document that identifies the quality targets to be achieved with respect to specifications, standards based on the contract for the projects.
- It provides details of specific personnel assigned for the inspections.
- It also explains the acceptance criteria for each specific testing/inspection requirement correlating with specification/contractual requirements.
- Frequency of tests and the type of records for verification to ensure that the inspection and/or testing have been carried out are also part of ITP’s common structure.
- Reference to the type of inspections to be carried out by different parties involved with activities also part of ITP’s structure.
In the construction industry, where there are a lot of activities, for a variety of trades such as structural, Finishes, Façade, Electrical, Mechanical, Plumbing, etc., are to be complete,d spanning from excavation for the foundation to handing over stage, thereby Preparation and implementation of different inspection test plans form the most crucial part of the project management system.
ITP For Concrete Bored Piles
SECTION 1 – DOCUMENTATION REVIEW
The first part of the ITP for Bored Pile construction activity is Documentation Review. Shop drawings, Detailed section drawings etc, Details of Ready Mix Concrete (RMC) Supplier or Batching plant details if it is from contractor’s own plant, Concrete mix Design, Trial mix details, steel, Bentonite suppliers details, and Method statement generally comprises of documents for this lTP. Normally, the method for ensuring compliance with the respective acceptance criteria is a Review of this document. Normally, the frequency of the same is limited to once before 2-4 weeks before starting of scheduled start of work on site.
These documents are reviewed for compliance with contract specification/design requirement, and in most cases, it would be through the approval of shop drawings / Good for construction stamped drawings, and as per the approved details for each document specified above.
SECTION 2 – INSPECTION OF INCOMING MATERIALS
Consist of details of inspections on incoming materials required to complete this Bored Pile construction. These are reinforcement steel bars, bentonite, cement, sand Ready Mixed concrete. Acceptance criteria, Methods, Frequency, Verifications documents, concerned inspection authority with the type of inspection are detailed in this section.
SECTION 3 – PRE-BORING INSPECTION
Different inspections for this section are
- Check on pile location (peg positioning) and pile diameter
- Rig positioning
- Rig verticality (1)
- Temporary casing installation
- Check on the joints of the temporary casing and the tremie pipes
- Chisel diameter and clean bentonite ports
- Rig verticality (2)
- Slurry pump readiness
- Check for the level of bentonite
- Bentonite specific gravity test
Acceptance criteria for the above inspections based on the relevant standard, like IS code, verification records that are normally a checklist for this activity, covers this section apart from frequency, type of inspection by authorised personnel related to this activity.
SECTION 4 – BORING IN-PROGRESS
During this phase, Bored Pile construction bentonite specific gravity and verticality will be checked. Refer to ITP for further details.
SECTION 5 – POST-BORING
- Bottom flushing
- Borehole depth
- Spillage of Bentonite
The above three points are to be inspected against the approved details and standards to ensure the work meets the criteria.
SECTION 6 – RE-BAR CAGE & TREMIE PIPE INSTALLATION
Rebar cage and tremie pipe installations are two points that need to be inspected with the corresponding details for Bored Pile construction in this section.
SECTION 6 – PRE-POUR (NOT LATER THAN 12 HOURS AFTER LAST BOTTOM FLUSHING)
Checking of the bentonite gravity test and checking on Concrete mix comprises the next activity.
SECTION 7 – CONCRETE POURING
During concreting, the major inspection points are
- Check onthe first charge of concrete
- Lifting of the tremie
- Check on the continuity of the pour
- Cut-off level
These works are the final phase of the bored pile construction activity. The acceptance criteria and other relevant details pertaining to this ITP are mentioned in this section for compliance.
SECTION 8 – POST POUR
To confirm that the installed pile is cast as per the approved details, specification, and contractual requirements remaining part of the inspections is to be carried out. This may normally have some relaxation in the time frame since the compressive strength of cubes will be available only after 28 days. Also, the pile integrity test takes much time. The different tests to be carried out later are as built eccentricity, the cube result, pile load test as per the contract and details.
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