Pile Repair Methods

Marine Pile Repair

The marine environment is hostile to infrastructure. Given enough time piled infrastructure will need to be repaired. Concrete piles, steel piles and wood piles will all be subjected to degradation from the marine environment. Each type of piling material will degrade differently. Concrete will crack and break apart, steel will corrode and wood will be subjected to biological attack.

Concrete piles, steel piles and wood piles can all be repaired permanently with the PileJax™ pile repair system. The mode of degradation may be different, but the solution is the same, the pile needs to be isolated from the environment.

Steel Pile Repair

Steel piles will need to be protected as soon as possible after parent metal loss starts to occur. Ultrasonic thickness measurement can be used to determine the extent of material loss. Steel piles are often protected by coatings or paint systems applied before the pile in put into service. Once the pile is in the water, retroactively applying coatings and paint systems is largely ineffective. This is due to the difficulty in applying coatings underwater and in the splash zone. Generally speaking underwater coatings stick to everything except the pile that is in need of protection, including the diver. In practical terms it’s almost impossible to achieve a uniform coating that is required for the system to work. Any exposed metal or insufficient coating thickness will allow the corrosion cell to remain active. Some coating systems are used in conjunction with wrapping the pile in an attempt to produce a uniform coverage. This belts and braces approach is labour intensive, and will often still allows for water ingress to take place and the corrosion cell to remain active.

Anodes are an effective means of protecting steel only while it is underwater. In the splash zone (area exposed at low tide, to the area affected by sea spray at high tide) however they provide no protection. This is because a corrosion cell is actually required for the anode to provide protection. Anodes in this type of cell are sacrificial, and corrode instead of the steel pile. For protection to be provided, an anode, a cathode (steel pile), and an electrolyte (water) are necessary. As soon as the pile is out of the water it is no longer protected and will corrode freely.

PileJax™ has a fully composite construction, no metallic components, and therefore can be used in conjunction with impressed current and sacrificial anode protection.

Encasing the steel pile in the PileJax™ pile repair system protects the steel pile by a chemical process called passivation. Once the PileJax™ jacket is correctly fitted it becomes water tight. It is then filled with a selection of proven grouts, epoxy resins or concrete. The PH of the filling mix chemically prevents the corrosion cell for forming (passivation). The water tight jacket prevents any water ingress into the annulus (space between the jacket and the pile to be remediated). Together they work to chemically and permanently protect the steel pile. Full encapsulation of a pile provides protection from below the sea bed to above the splash zone. The international patented PileJax™ locking system is super easy and fast for the dive team to use, no time consuming nuts and bolts, no wrapping of the pile, no underwater coatings to apply. These factors combine to deliver a system that is fast and easy to execute with permanent results. The expected service life is over 45 years.

Steel Pile Repair

Steel piles will need to be protected as soon as possible after parent metal loss starts to occur. Ultrasonic thickness measurement can be used to determine the extent of material loss. Steel piles are often protected by coatings or paint systems applied before the pile in put into service. Once the pile is in the water, retroactively applying coatings and paint systems is largely ineffective. This is due to the difficulty in applying coatings underwater and in the splash zone. Generally speaking underwater coatings stick to everything except the pile that is in need of protection, including the diver. In practical terms it’s almost impossible to achieve a uniform coating that is required for the system to work. Any exposed metal or insufficient coating thickness will allow the corrosion cell to remain active. Some coating systems are used in conjunction with wrapping the pile in an attempt to produce a uniform coverage. This belts and braces approach is labour intensive, and will often still allows for water ingress to take place and the corrosion cell to remain active.

Anodes are an effective means of protecting steel only while it is underwater. In the splash zone (area exposed at low tide, to the area affected by sea spray at high tide) however they provide no protection. This is because a corrosion cell is actually required for the anode to provide protection. Anodes in this type of cell are sacrificial, and corrode instead of the steel pile. For protection to be provided, an anode, a cathode (steel pile), and an electrolyte (water) are necessary. As soon as the pile is out of the water it is no longer protected and will corrode freely.

PileJax™ has a fully composite construction, no metallic components, and therefore can be used in conjunction with impressed current and sacrificial anode protection.

Encasing the steel pile in the PileJax™ pile repair system protects the steel pile by a chemical process called passivation. Once the PileJax™ jacket is correctly fitted it becomes water tight. It is then filled with a selection of proven grouts, epoxy resins or concrete. The PH of the filling mix chemically prevents the corrosion cell for forming (passivation). The water tight jacket prevents any water ingress into the annulus (space between the jacket and the pile to be remediated). Together they work to chemically and permanently protect the steel pile. Full encapsulation of a pile provides protection from below the sea bed to above the splash zone. The international patented PileJax™ locking system is super easy and fast for the dive team to use, no time consuming nuts and bolts, no wrapping of the pile, no underwater coatings to apply. These factors combine to deliver a system that is fast and easy to execute with permanent results. The expected service life is over 45 years.

Concrete Pile Repair

Concrete piles will need to be repaired as soon as water ingress has reached the steel reinforcing. Water ingress can occur naturally in concrete given enough time, it can be accelerated by construction defects or by a reinforcing cage that is too close to the external surface of the pile.

Once the water has reached the reinforcing inside the concrete pile, a corrosion cell will form. This is because water ingress reduces the PH of the concrete. The reduction in the PH changes the level of corrosion protection. The level of protection will ultimately move from passivation to freely corroding. As the steel corrodes it will expand inside the concrete. This has a ‘runaway’ effect, cracking will occur and allow more water to reach the reinforcing. If left unchecked the concrete pile will break apart from the inside in a process known as spalling. Large sections of the pile will break away when spalling occurs, allowing further water ingress.

Encasing the concrete pile in the PileJax™ pile repair system protects the steel reinforcing by the same chemical process that protects a pile made entirely of steel, passivation. Once the PileJax™ jacket is correctly fitted it becomes water tight, it’s then filled with selection of proven grouts, epoxy resins or concrete. The PH of the mix chemically prevents the corrosion cell for forming. The water tight jacket prevents any water ingress into the remediated pile. Together they work to chemically protect the steel reinforcing cage. The remediation will fill any cracks, large areas of spalling, areas of abrasion, or construction defects like honeycombing or a reinforcing cage being too close to the piles external surface. If the original reinforcing cage is severely compromised, retro fitted reinforcing is an option.

The PileJax™ system is fully composite, no metallic components, and is therefore compatible with impressed current and sacrificial anode protection.

Spalling and or cracking can be a localised defects. And as such a full length pile encapsulation may not be required. PileJax™ is a modular system made to order, made for a specific pile. If spalling and or cracking is only occurring at a particular depth or localised area, then a midwater repair maybe the preferred option. PileJax™ jackets do not need to extend all the way to the sea/river bed. Reusable clamps can be deployed to hold the jacket in place for a midwater only repair. Once the repair has cured to a sufficient hardness, the clamps can be removed and used on the next repair location. For large jobs we recommend using several clamps in a leapfrog fashion.

Wood Pile Repair

Wood piles are subjected to biological attack form the marine environment. Worms, rot and other organisms will eventually degrade the load bearing capacity of infrastructure supported with wood piles. Even treated wood piles will eventually lose their integrity to marine organisms. The most important factor with the protection of wood plies is to intervene early. Once it has been determined that the wood pile is not protected and is subject to biological attack, the faster the intervention the better. Sadly this is generally not the case. Wood piles are often allowed to become seriously compromised before action is taken. The picture below illustrates the destructive capacity of a biological attack, a marine pile compromised by shipworms.

The PileJax™ pile repair system will isolate the wood pile from the environment. For preservation of wood piles a full pile encapsulation is required. Excavation of the seabed / riverbed around the pile is also required, the PileJax™ jacket must sit below the seabed / riverbed, incorporating as much of the pile as possible. By fully encapsulating the pile the PileJax™ pile repair system will deny the marine organisms the necessary conditions of life. All organisms inside the PileJax™ jacket will perish, the grout will fill wormholes, cracks and other voids. Once the grout has set the wood pile is shielded from any future biological attack.

Wood Pile Repair

Wood piles are subjected to biological attack form the marine environment. Worms, rot and other organisms will eventually degrade the load bearing capacity of infrastructure supported with wood piles. Even treated wood piles will eventually lose their integrity to marine organisms. The most important factor with the protection of wood plies is to intervene early. Once it has been determined that the wood pile is not protected and is subject to biological attack, the faster the intervention the better. Sadly this is generally not the case. Wood piles are often allowed to become seriously compromised before action is taken. The picture below illustrates the destructive capacity of a biological attack, a marine pile compromised by shipworms.

The PileJax™ pile repair system will isolate the wood pile from the environment. For preservation of wood piles a full pile encapsulation is required. Excavation of the seabed / riverbed around the pile is also required, the PileJax™ jacket must sit below the seabed / riverbed, incorporating as much of the pile as possible. By fully encapsulating the pile the PileJax™ pile repair system will deny the marine organisms the necessary conditions of life. All organisms inside the PileJax™ jacket will perish, the grout will fill wormholes, cracks and other voids. Once the grout has set the wood pile is shielded from any future biological attack.

Pile Repair Methods

Regardless of the type of pile to be repaired, concrete pile, steel pile or wood pile, the same basic methods are required for preparation and execution. The first step in any pile remediation is pile preparation.

Pile Preparation for Repair

Piles to be remediated must be thoroughly cleaned using a high pressure water jet or appropriate mechanical tools. The exact pressure of the water jet will need to be determined, around 3500 psi to 4000 psi (240-275 bar). Some slight abrasion of the concrete surface is preferable, but only in areas to be covered by the PileJax™ repair. This will help the repair key into the existing concrete. Do not cut into or remove viable concrete, start at a lower pressure and increase the pressure if required. This is also true for wood piles, start at a low pressure and increase as needed. Steel piles can be cleaned at the safe maximum pressure of the given unit (HP water jet). Ensure all marine growth, oxidation, spalling, rot and any other loose material is removed. For a sea/river bed installation excavate around the pile about 300mm deep removing any rocks or debris. Once all surfaces are cleaned, line the excavation with Geo-textile. Qualified inspection of the pile should be carried out at this time. Suitable pile preparation must be confirmed before the installation of the PileJax™ pile repair system. The project engineer should co-sign approvals to proceed.

Once the project engineer has co-sign on pile preparation, it’s time to install the retrofitted reinforcing cage if one has been specified as part of the repair system. Also install anodes at this time if they are to be part of the remediation and ongoing protection protocol. Again the project engineer should co-sign approvals to move ahead. It is now time to install the PileJax™ pile repair system.

General Installation Steps

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All personnel must be suitably trained. They must hold the appropriate qualifications and certifications to be involved in diving operations. These requirements are determined by the government of the country in which the installation is going to take place. Topside only support crew should be familiar with the precautions required when working in proximity to an active dive operation.

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Ensure that all personnel involved in the handling and installation of the PileJax™ pile repair systems are fully aware of the procedures to be followed prior to any work commencing, as detailed in the project Safe Working Method Statement (SWMS). Work is to be conducted in accordance with International Risk Management and Safety Standards ISO 31000 and ISO 45001.

Firstly prepare the jacket for use. If annular spacers are called for, follow the pattern shown in the General Assembly (GA) Drawing. GA Drawings will be supplied in the PileJax™ system load-out. Annular spacers are epoxied (using epoxy gel) onto the inside surface of the jacket in a well ventilated area. Fit any pumping ports specified in the General Assembly Drawings. If specified in the GA drawings, ports will be included in the system load-out. These steps are best performed on land, prior to moving the jacket into position for deployment.

The most common method for deploying the jacket is from a barge or other stable work platform. Lay the jacket as flat as possible on the barge, jacket opening facing up and the bottom of the jacket pointed at the pile (the top of the jacket has the PileJax™ logo and jacket ident). This is the correct position to present the jacket to the pile.

Whenever possible deploy jackets at slack tide. When the current is running deploy the jacket on the upstream side of the pile. Water flow will help to close the jacket around the pile rather than push it away. The Dive Supervisor must make a judgment on environmental conditions and when to deploy the jacket. Small to medium jackets can be manoeuvred into position by hand, large jackets are best supported from above with lifting gear or an appropriate deployment rig. When the correct orientation is confirmed, and the jacket is sufficiently supported, the jacket can be slipped off the barge to the divers.

General Installation Steps

Z

All personnel must be suitably trained. They must hold the appropriate qualifications and certifications to be involved in diving operations. These requirements are determined by the government of the country in which the installation is going to take place. Topside only support crew should be familiar with the precautions required when working in proximity to an active dive operation.

Z

Ensure that all personnel involved in the handling and installation of the PileJax™ pile repair systems are fully aware of the procedures to be followed prior to any work commencing, as detailed in the project Safe Working Method Statement (SWMS). Work is to be conducted in accordance with International Risk Management and Safety Standards ISO 31000 and ISO 45001.

Firstly prepare the jacket for use. If annular spacers are called for, follow the pattern shown in the General Assembly (GA) Drawing. GA Drawings will be supplied in the PileJax™ system load-out. Annular spacers are epoxied (using epoxy gel) onto the inside surface of the jacket in a well ventilated area. Fit any pumping ports specified in the General Assembly Drawings. If specified in the GA drawings, ports will be included in the system load-out. These steps are best performed on land, prior to moving the jacket into position for deployment.

The most common method for deploying the jacket is from a barge or other stable work platform. Lay the jacket as flat as possible on the barge, jacket opening facing up and the bottom of the jacket pointed at the pile (the top of the jacket has the PileJax™ logo and jacket ident). This is the correct position to present the jacket to the pile.

Whenever possible deploy jackets at slack tide. When the current is running deploy the jacket on the upstream side of the pile. Water flow will help to close the jacket around the pile rather than push it away. The Dive Supervisor must make a judgment on environmental conditions and when to deploy the jacket. Small to medium jackets can be manoeuvred into position by hand, large jackets are best supported from above with lifting gear or an appropriate deployment rig. When the correct orientation is confirmed, and the jacket is sufficiently supported, the jacket can be slipped off the barge to the divers.

The divers then guide the jacket into position around the pile. Continue to support the jacket from above as the locking system is closed. All jackets must be clear of the sea/river bed when closed. This prevents debris being scooped up by the bottom of the jacket. If the jacket is resting on the sea/river bed, debris may make it difficult to close the jacket and prevent the keys from being tapped into place. When the jacket is supported from above and closed clear of the sea/river bed, the jacket and locking system will self-align. The keys can now be tapped in with the correct application of force.

The divers, working from the bottom of jacket to the top, can start to lock the PileJax™ system together. The bottom key is unique, and must be tapped into place in the bottom position first. Once the bottom key is tapped home correctly all other keys will index from it. Fit the bottom locking key first by inserting it laterally into the key passage one pitch height above the bottom of the jacket. Use a lump hammer to strike the PileJax™ key insertion tool, rather than the key itself. Tap the key down until the stops are reached. At this point the jacket can be lowered into its final position. Fit all other keys the same way, tapping them down until they touch the key below. The locking sequence is finalized by inserting the small yellow locking pin into the top key. Apply epoxy gel to the yellow locking pin before tapping it in. The PileJax™ jacket is now ready to be filled.

For a mid-pile / mid water only installation, a PileJax™ bottom seal is required to fill the jacket. There are two types. A single use profiled foam seal that wraps around the pile, and a reusable seal that is comprised of a metal clamp, that bolts to the pile, and a foam sealing gasket.

The single use seal is held in place with a strap. The jacket is then closed around this seal. The sealing face compresses as the jacket is closed, producing a water tight interface. This type of seal does not support the jacket on the pile. With the single use seal the jacket must be supported from above.

For large jobs with multiple piles, the reusable type is recommended. The reusable seal is comprised of a metal clamp that bolts to the pile, and a flat foam sealing gasket. The jacket is made water tight by the interface with the seal and supported by the clamp. Straps are used to pull the jacket down onto the clamp. The clamp provides temporary support for the jacket during the filling operation. Once the repair has cured to a sufficient hardness, the clamps can be removed and used on the next repair location. For large jobs we recommend using several clamps in a leapfrog fashion.

When the jacket is fully locked together and in its final position (on the sea/river bed or supported mid water) the jacket is ready to be filled. Start by using the bottom pumping port to pour a 500mm plug. In the rare occasion that the GA Drawings do not specify pumping ports, tremie the 500mm plug from the top of the jacket. Allow this plug to cure. When the plug has cured, the remediation pour can be continued all the way to the top of the jacket.

PileJax™ recommends a grout pumping rate that fills the jacket at approximately 1m per hour. Various methods can be used to achieve this fill rate. Pumping ports, bottom up, or tremie hose inserted from the top of the jacket down. Regardless of the selected method, the grout must not be allowed to ”fall through the water” at any point. Always fill from the bottom up.

Depending on the pour height above the waterline it may be necessary to apply 2500kg ratchet straps as temporary support for the jacket. As each installation is different you will be supplied with a temporary strapping regime in the PileJax™ load-out if it is required.

Finish the installation using epoxy grout to seal the jacket to the soffit or batter to existing pile at a 45 degree angle to allow water runoff and prevent bird nesting. Finally clean any excess grout off the outside of the jacket for best presentation.

For large jobs with multiple piles, the reusable type is recommended. The reusable seal is comprised of a metal clamp that bolts to the pile, and a flat foam sealing gasket. The jacket is made water tight by the interface with the seal and supported by the clamp. Straps are used to pull the jacket down onto the clamp. The clamp provides temporary support for the jacket during the filling operation. Once the repair has cured to a sufficient hardness, the clamps can be removed and used on the next repair location. For large jobs we recommend using several clamps in a leapfrog fashion.

When the jacket is fully locked together and in its final position (on the sea/river bed or supported mid water) the jacket is ready to be filled. Start by using the bottom pumping port to pour a 500mm plug. In the rare occasion that the GA Drawings do not specify pumping ports, tremie the 500mm plug from the top of the jacket. Allow this plug to cure. When the plug has cured, the remediation pour can be continued all the way to the top of the jacket.

PileJax™ recommends a grout pumping rate that fills the jacket at approximately 1m per hour. Various methods can be used to achieve this fill rate. Pumping ports, bottom up, or tremie hose inserted from the top of the jacket down. Regardless of the selected method, the grout must not be allowed to ”fall through the water” at any point. Always fill from the bottom up.

Depending on the pour height above the waterline it may be necessary to apply 2500kg ratchet straps as temporary support for the jacket. As each installation is different you will be supplied with a temporary strapping regime in the PileJax™ load-out if it is required.

Finish the installation using epoxy grout to seal the jacket to the soffit or batter to existing pile at a 45 degree angle to allow water runoff and prevent bird nesting. Finally clean any excess grout off the outside of the jacket for best presentation.