CASE STUDY

49 Corroded Steel H-Piles Restored Under Four Interstate Bridges

At the I-70 and I-270 interchange in St. Louis, the Missouri Department of Transportation repaired 49 corroded steel H-piles with PileMedic® laminate shells and grout. The work took two weeks and brought all four bridges from a poor to a satisfactory substructure rating.

PRODUCT: PILEMEDIC®
APPLICATION: STEEL H-PILES
INDUSTRY: TRANSPORTATION

GET A PILE REPAIR CONSULTATION ALL PROJECTS

Interstate bridge over a sloped embankment with steel H-pile bents, and a close-up inset of a corroded H-pile base with section loss

49 corroded steel H-piles repaired

steel H-piles repaired: 49
section loss: 20 to 80%
for all four bridges: 2 weeks
substructure rating, poor to satisfactory: NBI 4 to 6

Project Details

OWNER: Missouri Department of Transportation (MoDOT), St. Louis District
LOCATION: I-70 and I-270 interchange, St. Louis, Missouri
STRUCTURE: Four five-span bridges carrying I-270; two intermediate bents per bridge on exposed steel H-piles (26 to 32 10 x 42 piles per bent, 30 to 46 ft long)
DAMAGE: Corrosion at the pile base from deck drainage carrying anti-icing chlorides
QUAKEWRAP® SYSTEM: PileMedic® carbon laminate, formed into two-ply 16 in. shells and filled with high-strength non-shrink cementitious grout
DOCUMENTED: QuakeWrap video (2010); Government Engineering and Modern Contractor Solutions articles (2011), co-authored with MoDOT's St. Louis District Bridge Engineer

PROJECT VIDEO

Steel Bridge Pile Repair in St. Louis

Plays from YouTube

01 · THE CHALLENGE

Structurally Deficient After Years of Chloride Runoff

Drainage from the deck ran onto the concrete slope protection and carried anti-icing chlorides to the base of some piles. The damage was concentrated over a 1 ft high section at the pile base, and 49 piles near the edges of the bridges had lost 20 to 80 percent of their section.

Two months before the repairs, routine inspections lowered the substructure condition rating to poor (NBI 4 on a 9-point scale), so the bridges were considered structurally deficient. The piles sit behind a barrier wall on a 3:1 concrete slope with limited overhead space, so all work had to be done by hand.

Crew lowering a black PileMedic laminate shell around a steel pile through a square opening cut in a concrete slab under a bridge

02 · THE SOLUTION

A Two-Ply Shell Formed by Hand Around Each Pile

MoDOT determined that repairing a 2 ft high length of each pile would be sufficient. A section of slab about 2.5 ft by 2.5 ft was cut out to expose the pile, the corroded steel was sandblasted, and a corrosion-inhibiting paint was applied.

Each pile took a 2 ft by 9 ft piece of PileMedic® laminate. Epoxy paste was troweled on 30 to 40 mil thick, and the laminate was wrapped twice around the pile to form a 16 in. diameter shell with 8 in. of overlap, held round with ratchet straps. The soil below the slab sealed the bottom of the shell.

High-strength non-shrink cementitious grout, mixed in a 5-gal pail with a hand-held mixer
Grout consolidated with a small vibrator; its pressure pressed the two plies together
Straps removed after several hours, then the shell painted
About 2 hours per pile, excluding painting, with no heavy equipment

Three photos: epoxy troweled onto PileMedic laminate, the laminate wrapped around a steel H-pile, and the two-ply shell positioned in the slab opening

03 · THE RESULT

Four Bridges Back to Satisfactory in Two Weeks

The repairs were completed in two weeks and raised all four bridges to a satisfactory condition rating (NBI 6). The work was affordable enough to be funded from the region's operations budget, and it was done on one of the busiest highways in Missouri without delays to the traveling public.

In this application the shell provided a confining pressure of 650 psi, and the authors report that the grout's 6,700 psi compressive strength rose to more than 9,000 psi under that confinement. It was the first installation of PileMedic® on a highway project.

piles: 49
bridges: 4
per pile: ~2 hr
confining pressure: 650 psi