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 with the use of temporary or permanent casing or drilling mud. After that, the construction is finalized 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 master documents 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 requirements corelating with specification/contractual requirements.
- Frequency of tests and, the type of records for verification to ensure that the inspection and/or testing has been carried out are also part of ITPs 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 completed spanning across 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 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 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 joints of temporary casing and 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 normally be a checklist for this activity covers this section apart from frequency, type of inspection by authorized 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 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 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 bentonite gravity test and Check on Concrete mix comprises the next activity.
SECTION 7 – CONCRETE POURING
During concreting the major inspection points are
- Check on first charge of concrete
- Lifting of tremie
- Check on continuity of 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 is 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 inspections 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, pile integrity test takes much time. The different tests later to be carried out are as built eccentricity, cube result, pile load test as per the contract and details.
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