ICP piles is another type of piling, it’s also known as Pretensioned Spun High Strength Concrete Piles (ICP PHC Piles) which offer an economical foundation system with consistent and superior quality compared to the ordinary concrete piles.

ICP Piles are circular in cross-section and are manufactured in sizes ranging from diameter 250mm to 1200mm with standard lengths varying from 6m to 46m in single pieces. ICP Piles can be easily joined to any combination of length as per design requirement. ICP piles are manufactured with steel end plates for splicing.

Today, with the state-of-the-art autoclave curing system, ICP Piles can be installed immediately after autoclaving. ICP piles have been used extensively as foundation piles for power stations, highrise buildings, civil engineering works, bridges, marine structures, harbours, schools and government project, etc.

Materials For ICP Piles

1) Aggregates
Coarse aggregates shall be 20mm granite. Fine aggregates shall be clean river sand or washed mining sand.

2) Cement
Ordinary Portland cement.

3) Prestressing Steel
High frequency induction heat treated bars.

4) Spiral wire
Hard drawn wire.

Joint

The joint is designed to have the same performance as the main body particularly in respect of bending strength. All ICP piles will be supplied with steel extension plates for splicing.

Lifting Points

Two lifting point will be marked on all piles exceeding 9m. No special lifting bolt or wire rope is cast into the piles. Lifting is by wrapping wire ropes round the piles at specified points.

Pile Shoes

All ICP Piles will be supplied either open ended, with a flat shoe or with an X-pointed shoe.

Curing

After casting, the piles are steam cured. When the concrete reaches the specified transfer strength, the piles are demoulded, marked and checked for quality. The piles can normally be transported and driven when the cube strength reaches 50 N/mm2. Today with the state-of-the-art autoclave curing system, the piles can be installed immediately after autoclaving.

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Micropile is another type of pile which is act as a supporting structure to transfer the load from the building to the ground. As the name implies, micropile is small diameter piles constructed by the drilling process and are often keyed into rock. There is various diameter of micropile can be found in the market ranging from 100mm to 250mm. Of late, technological advancement in machinery has made it possible for micropile of much greater diameters to be constructed.

Application of Micropile

In the past micropile was only used when the ground conditions warranted it because of considerations on cost and speed. Micropile is slow because of the drilling and flushing process, it might takes minutes or hours to complete.

But the trend is such, micropile is now gaining greater popularity and getting wider acceptance because of the requirement to comply with no noise and low vibration regulations, expecially in congested environments.

Geotechnically, micropile is most suitable in the following ground conditions :

1) Shallow Bedrock

2) Boulders and Cavities

3) Intermediate Hard Strata

4) Underpinning

How To Install Micropile

Micropile is widely used in the construction field because of the low vibration and no noise, micropile is widely used in housing area, school, hospital or any location which doesn’t allow to make noise while pile driving process. As you know, concrete pile like spun pile and reinforced concrete square pile produce high volume while driving pile. The installation procedure for micropile is almost similar to bored piling, it’s using drilling method.

1) Drilling and Flushing

2) Withdrawing Drilling String

3) Inserting Steel Reinforcement and Grouting

4) Completed Micropile

Construction Photos For Micropile

1) Micropile for underpinning an existing 4-storey office building which showed signs of settlement.

2) The workers are doing micropiling works.

3) Micropiling work in progress. A high pressure compressor is being used for flushing out the drilled materials.

4) A mini, but powerful hydraulic crawler drill which is useful for micropiling works in :
a) Congested locations with extreme headroom constraint.
b) Difficult hillside development where rock is encountered.

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There are several types of pile driving method in the piling construction, type of pile driving method used is depending on the condition of soil and location of the site. However, different piling machine will be used with different pile driving methods too. The specification for pile driving mentioned below is generally recommended for pile driving of prestressed spun concrete piles by using percussion method. Engineers may be required to modify some of the clauses to suit requirements of different site conditions.

How To Do Pile Driving With Percussion Method

1) Joints

The bending strength of a joint between two lengths of pile shall be equal or more than the bending strength of the concrete shaft. When two lengths of pile are jointed, the end plates must bear over their complete areas. The two end plates are then welded along their entire periphery with weld size as specified.

1.1 Welding of Joints
All welding shall be carried out in accordance with the requirements of B.S.5135:1974 - Metal-Arc Welding of carbon and carbon-manganese steel.

1.2 Tests for Approval of Welders
Welders shall be qualified in accordance with the requirementsof AWS Code D1.1. Only welders who pass the qualifying tests for the type of weld specified shall be employed on the Works.

1.3 Examination of Welds
Butt welds between the end plates of the joints shall be tested using magnetic particle or dye penetrant test methods. Copies of these test records and reports shall be furnished to the Engineer.

Where such examination reveals defects in the welds, the joints shall either be rejected or repaired. If repeat tests show the weld to be still defective, the joint shall be rejected. The defective weld shall be removed, replaced with a fresh weld and re-examined.

For the purpose of this Clause, cracks, leaks, laminations, lack of complete fusion, undercutting or reduction in wall thickness adjacent to the weld shall constitute a defect.

2) Pile Driving by Using Percussion Method

2.1 Pile Hammers
Shall be of size and type able to deliver consistently an effective dynamic energy suitable to the piles to be driven and the material into which they are to be driven. Hammers shall be provided with proper driving helmets suited for the piles. Any indication of collapse of hoses, tripping of hose lining or any erratic action of the hammer shall be cause for immediate shutdown until the problem has been corrected.

Pile hammers shall be operated at the full rated efficiency and capacity and in the manner specified by the manufacturer, except as directed otherwise by the Engineer, or noted herein below under Reductiono of Hammer Energy.

When a steam or air hammer is used for driving any type of piles, both the volume and pressure of steam or air recommended by the manufacturer of the hammer shall be maintained at all times to ensure full energy of the driving blows. Before pile driving is started, the Piling Contractors shall provide written certification to the Engineer that the pile hammer, compressors and valves have been inspected and found to be in good working condition.

2.2 Reductiono of Hammer Energy
When the pile is set in a pre-jetted or pre-drilled hole or when the point of a prestressed concrete pile is passing through soft soil so that there is little or no resistance to penetration of the pile, there is a possibility that longitudinal tensile stresses may be set up in the pile shaft by the elastic shock waves travelling up and down the pile. For such driving conditions, the length of stroke of the hammer shall be reduced. Failure of the piles due to longitudinal tensile stresses caused by excessive driving shall be the Contractor’s responsibility.

2.3 Pile Cushion Block
The heads of all prestressed concrete cylinder piles shall be protected with a soft wood cushion block at least 15 cm thick to effectively and uniformly distribute hammer blog energy. The block shall be composed of layers of 20mm hi-grade marine plywood or approved equal, and of such dimensions as to completely cover the concrete cross-section of the pile. The cushion block shall be inspected periodically during driving and no driving shall be done with a block that has been unduly worn and compressed with use. Cushion blocks must be replaced when compressed to 1/2 their original thickness, when badly worn or when burning.

2.4 Driving
The piles shall be driven to the driving resistance or tip elevation as determined by the Engineer from pile load tests. The maximum allowable variation at the butt end of the pile shall be 150mm in any direction from the location shown on the Drawings or as directed by the Engineer. Any variation beyond these limits shall be allowed or rejected at the sole discretion of the Engineer.

3) Cutting Off and Capping Piles

Tops of foundation piles shall be embedded in the concrete footing or pile cap for a minimum depth of 75mm (measured at center line of pile). When the top elevation of a pile is below the elevation of the bottom of the cap, the pile shall, if approved by the Engineer be built up from the butt of the pile to the elevatioon of the bottom of the cap by an approved method. The cuts shall be made accurately in clean, straight lines; care shall be exercised to avoid damaging the remaining pile and to ensure full bearing between the footings (or pilecaps) and piles.

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Usually bored pile is used for those tall buildings or massive industrial complexes, which require foundations which can bear the load of thousands of tons, most probably in unstable or difficult soil conditions. The method of drilling bored pile is different from RC Square pile or spun pile which are using driving method, the piling machine to be used will be different too. Bored piling works required specialist bored piling contractor to follow up instead of hiring general piling contractor. There is a simple step-by-step method on how to drill the bored pile in construction site.

How To Drill Bored Pile

1) Adjust the piling machine on the pile axis and haul with the auger to the drilling place.

2) Start drilling until the auger is filled.

3) Return from the drilling level to the top of the pile hole.

4) Swing to the uploading area.

5) Unload the dirt in the unloading area.

6) Swing back to the top of the hole.

7) Repeat steps 2 to 7 until the pile is completely drilled. Relocated the machine and start steps 1 to 8.

8 ) Start erecting rebar cage using a crane.

9) Use funnel for dry method and tremie for wet method. Start pouring the concrete and finish the pile.

Video On How To Drill Bored Pile

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Bored pile is another type of reinforced concrete pile which is used to support high building which has heavy vertical load. Bored pile is a cast-in-place concrete pile where the bored piles have to be cast on construction site, while other concrete piles like Spun Pile and Reinforced Concrete Square Pile are precast concrete pile which they’re cast in the factory.

Normally bored piling has be to carried on those tall buildings or massive industrial complexes, which require foundations which can bear the load of thousands of tons, most probably in unstable or difficult soil conditions. Bored piling is cast by using bored piling machine which has specially designed drilling tools, buckets and grabs, it’s used to remove the soil and rock. Normally it can be drilling into 50metres depth of soil. The advantage of bored piling is its’ drilling method, little vibration and lower noise level.

The drilling method is depending on the condition of soil, piling contractor has to do soil investigation and decide which drilling technology has to be carried on. Piling contractor decide the correct drilling technology and minimize disturbance of the surrounding soil. For cohesionless soils such as sands, gravels, silts etc, whether it’s under the water table or not, the pile bore hole must be supported using steel casing or stabilizing muds such as bentonite suspension. After these, reinforcement bar will be put into the bore hole and concrete will be poured into the bore hole.

Bored piling is popular to be used in construction as a foundation especially for bridge work and tall building as well. Bored piling work has to be done by specialist bored piling contractor, normal piling contractor can’t be done without experience and knowledge about bored piles.

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