Concrete, Timber & Steel Pile Repair with FRP

PileMedic® is the world's latest technology developed by Prof. Mo Ehsani for repair, restoration and strengthening of piles. We offers pile repair and strengthening services to steel piles, wood piles, concrete piles and H-Pile. These products have been developed following 25 years of research and development that started in 1992 with the financial support of the U.S. National Science Foundation. We thank you for your tax dollar support :) As you will learn below, these products are the only structural solution that offer strengthening of piles beyond the original strength of the pile. This means columns and piles can be repaired to resist larger loads; ports and piers can be strengthened to handle heavier loads; utility poles can be strengthened to support more and heavier cables, etc.

This presentation at the American Concrete Institute Convention summarizes some of the development and advantages of the PileMedic® system. The presentation entitled "FRP Laminates for Post-Earthquake Repair of Columns in 2 Hours" was a part of a session entitled "Post Earthquake Repairs" that was held in the ACI Spring Convention, in March 2012 in Dallas. Please click here to watch a video of this presentation.

Fiberglass or HDPE jackets have traditionally been used to repair deteriorated timber, concrete or steel piles. These jackets offer little in the way of strengthening and long term repair for piles. Traditional pile repair jackets are offered in standard sizes, which results in excessive enlargement of the pile, making the repair unattractive. In addition, the over-sized jackets require too much resin or grout to fill the annular space; this adds weight and cost to the repair of piles. These jackets are also bulky and expensive to ship and store. Contractors must order the right size jackets early to repair concrete, timber or steel piles and this delays the project.

To overcome the above shortcomings, Professor Ehsani has invented the PileMedic® system for repair of timber, concrete or steel piles. is a SuperLaminate carbon or glass FRP laminate that is manufactured in a special process. Fabrics of carbon and/or glass are saturated with resin and run through a special press that creates very thin cured FRP sheets with a thickness of only 0.02 inches (0.5 mm). The sheets are 48 inch wide x 150 feet long (1.2 m x 46 m). The sheets can be wrapped around the pile in the field to create a shell that provides tremendous confining pressure around the pile or column. The bottom of the shell can be sealed in a variety of ways and the annular space is filled with resin or grout. SuperLaminates are lightweight, fits to your specifications, and submerged piles can be repaired with very little to no use of divers. So it not only strengthens and reinforces piles, but it can save significant cost on timber pile repair projects as well.

Some owners reinforce their timber piles with concrete reinforcements; this is known as encasement. It will be only a matter of time before the concrete encasing the timber pile will suffers the same fate, namely begin to corrode and fall apart.

There are many reasons why piles or columns submerged in water may need repairs. General corrosion and deterioration with aging also causes decay in timber piles. Repairs of timber piles can be costly and time consuming.

Repair of Timber Piles

There is a large inventory of timber bridges worldwide. Many of these timber bridges are old and require repair and strengthening. The historic Powder Point Bridge in Duxbury, MA is the longest timber bridge in the U.S. with a length of approximately 2000 feet (610 m). Some 300 timber piles on this bridge were repaired with PileMedic® jackets in 2013-2014.

Thanks to EPA's success in cleaning the waterways, marine borers and ship worms are coming back and literally eating away timber piles. PileMedic® jackets can be wrapped around a deteriorated timber bridge pile to create an impervious layer of high confining pressure. Then the annular space is filled with our low viscosity resin. This resin will penetrate all voids and cracks in the timber pile. The result is a much stronger timber pile which is resistant to shop worms and marine borers.

In a recently completed research project funded by Nebraska Department of Roads, five timber bridge piles were repaired with PileMedic® jackets and tested. The results of this study entitled "Assessment and Evaluation of Timber Piles Used in Nebraska for Retrofit and Rating" were published in 2014 and are available in pdf format by clicking here.

Repair of Timber Utility Poles

Timber utility poles often break during storms or when they are hit with a vehicle traveling at a high speed. There are also many cases where additional loads induced by newly installed power lines call for strengthening of timber utility poles. In collaboration with Tucson Electric Power (TEP) we are developing and testing a new FRP system to strengthen timber utility poles. These tests have shown how we can strengthen a broken timber pole to become stronger than a new steel pole! The short video here shows some of our early tests on strengthening of timber utility poles using PileMedic® FRP jackets. Please click here to watch the video. You can also read a brief description of tests of timber utility poles repaired with PileMedic® by clicking on this link.

Repair of Concrete Columns & Piles

Concrete piles and columns often get damaged by corrosion of steel. Both prestressed concrete piles and reinforced concrete piles are subject to similar corrosion damage. When steel corrodes, the iron oxide that is formed occupies a larger volume than the steel from which it was formed. This results in expansion of the surrounding concrete that causes the concrete to crack in tension. This in turn accelerates the corrosion process and the concrete pile will deteriorate rapidly.

As shown here, PileMedic® laminates can be cut in the field to desired length, and wrapped around the concrete pile to create a jacket or shell of desired size. The jacket is then filled with grout, leaving a beautifully finished pile. The confining pressure offered by PileMedic® jackets adds tremendous strength to the pile. For example, a typical 4000 psi (30 MPa) concrete pile will become as strong as a 6000 psi (45 MPa) concrete due to the confinement provided by PileMedic® carbon or glass jackets.

Many concrete piles and columns get damaged during earthquakes. In a unique study funded by the U.S. National Science Foundation and California Department of Transportation (Caltrans), a large concrete column was subjected to simulated earthquake motion, causing fracture of the longitudinal bars. Researchers from three major universities in the U.S. participated in this study. The objective of the study was to see if PileMedic® laminates could repair and restore the strength of the damaged column quickly. The column was repaired in 20 hours and the repaired column was as strong as the original concrete column. Please click here to watch a video of this test.

Repair of Steel Columns & Piles

Corroded steel H-Piles or pipes that may be filled with concrete can be repaired with PileMedic® laminates. In one of the first applications of PileMedic, some 50 steel bridge piling were retrofitted. This project involved 4 overpasses in a busy interchange (at the intersection of I-70 & I-270) in St. Louis, MO. Click here to watch a video of this project.

There are a couple of published papers that describe this project in full detail. Viewers are invited to click on the links below for these papers:

A Novel Solution for Restoration of Deteriorated Piles By Mo Ehsani, and Mark Croarkin, Modern Contractor Solutions, A two-part article published in June and July 2011 issues.

A Novel Solution for Restoration of Deteriorated Piles By Mo Ehsani, and Mark Croarkin, Government Engineering Magazine, March-April 2011

PileMedic® laminates can also be used to repair steel poles in power electric substations. In one application for Tucson Electric Power (TEP) some 70 such steel poles were repaired. You can read a paper on this project that was published:
Repair of Steel Columns with FRP Laminates , by M. Ehsani, M. Farahani, and E. Raatz, Structure Magazine, January 2012, pp. 35-37.

Texas Department of Transportation has funded a research study to evaluate the effectiveness of PileMedic® laminates in repair of steel H-Piles. Large- and small-scale steel H-Piles are being tested at the University of Houston under this grant. A companion study also funded by Texas DOT is underway at Texas Tech University to examine the durability of PileMedic® jackets.

Government Approvals

Perhaps the best testimony to the outstanding features and capabilities of PileMedic™ is that the US Army Corps of Engineers and FEMA’s Urban Search and Rescue Program have singled out PileMedic™ as the only system for fast repair of columns and piles that are damaged in a disaster such as hurricane, earthquake, terrorism, etc. The detailed instructions for how to install PileMedic™ carbon laminates are shown on pages 4-4 and 4-5 of the 7th edition of the Field Operations Guide (FOG) shown below. Please click here to see the document.

Additional Links

Please click on the following links for information about each specific repair:
Repair of Timber Piles and Utility Poles with FRP Laminates
Repair of Concrete Piles and Columns with FRP
Repair of Steel Columns and Piles with FRP