PRESERVATION OF WOODEN MARINE PILES USING A PVC SNAPJACKET

A technical evaluation of the efficacy of Shoreline Plastics “SnapJacket” used as a “remain in place” form to repair, preserve and strengthen marine pilings by encapsulation in concrete.

Shoreline’s patented SnapJacket is a substantial PVC shell that can be opened sufficiently to be placed around a timber (or concrete) piling that is either freestanding or supporting an existing structure.  The SnapJacket can then be snapped shut engaging a unique, irreversible locking system. The void between the piling and jacket can then be filled with a concrete grout. Under-cut fixtures on the inner wall of the Snapjacket further prevent the shell from being deliberately or accidently removed from the piling.

The SnapJacket was developed to provide a relatively inexpensive means of preventing further decay or marine damage and afford structural improvement to the marine piling.

The use of concrete encapsulation of damaged marine pilings has been a standard practice for well over 50 years (ref), the method of retaining the concrete around the piling has taken many forms. The SnapJacket is the most recent and we believe the most effective.

Numerous studies have been conducted that have established the additional strength that concrete grout imparts to a wooden piling. This evaluation includes test data and conclusions from several published studies that we deemed relevant to timber repairs with concrete grout confinement using the PVC SnapJacket.

A study conducted by Florida International University, department of Civil and Environmental Engineering titled “assessment and Evaluation of Timber Piles Used in Nebraskafor Retrofit and Rating” established in their testing that:

“…..further, the failure load of the repaired pile specimens was at least five times greater than the design load capacity of the timber pile.”

The purpose of their study was to evaluate the structural performance of wooden piles retrofitted using different methodologies. We looked at their study to best compare our SnapJacket repair technique with the performances of their test subjects.

The tests subjected the full size pilings, jacketed with various fills, to both axial and bending loads. The samples were tested to failure. The jacketed test pilings that were filled with cement grout, as used with the Snapjacket, failed away from the repaired area, and as previously stated, the failure load exceeded the design load capacity by greater than  five fold.

Photo depicts piling failing at 6.8 times rated capacity, note that the failure did not occur at the repair site.

The purpose of their study was to evaluate the structural performance of wooden piles retrofitted using different methodologies. We looked at their study to best compare our SnapJacket repair technique with the performances of their test subjects.

The tests subjected the full size pilings, jacketed with various fills, to both axial and bending loads. The samples were tested to failure. The jacketed test pilings that were filled with cement grout, as used with the Snapjacket, failed away from the repaired area, and as previously stated, the failure load exceeded the design load capacity by greater than  five fold.

Due to inherent imperfections in material and geometry of timber piles, it was not feasible to compare the ultimate load capacity of the timber pile specimen with each other or with a control test specimen. Therefore, the ultimate load capacity obtained from the test result is compared to design load capacity of the timber piles. The test results indicate that the repaired pile specimens were able to carry at least five times of the design load capacity used in structural design of timber pile bridges.”

It should be noted that the jackets employed in the test were GRP

A study entitled: “Durability-Based Ranking of Typical Structural Repairs

for Corrosion-Damaged Marine Piles”   published in  “PRACTICE PERIODICAL ON STRUCTURAL DESIGN AND CONSTRUCTION “   November 2013   concluded that a concrete grout filled thermoplastic jacket on a damaged pile provided the most effective long term corrosion protection, and was also the most cost effective.

A 1985 study by the US army determined:

8-4. Concrete encasement.

Effective protection can be provided by encasing timber piles in concrete, usually by grouting the annular space between the pile                           and a section of pipe. Precast concrete jackets have been designed and used for permanent installations. Concrete jackets have also been formed by shooting concrete (guniting) on timber piles, either before or after driving.

The protective coating is generally from 1½ to 2-inches thick and reinforced with wire mesh. Protection provided to the pile is excellent.

© Copyright 2017 SnapJacket by Shoreline Plastics