CASE STUDY

Timber Bridge Pile Repair on the Araz Road Bridge

A timber bridge pile repair for the County of Imperial, California: 20 deteriorated timber piles in four bents were jacketed with glass FRP laminate and epoxy grout, and the four timber cap beams were wrapped with biaxial glass fabric, all in place under the bridge.

PRODUCT: GLASS FRP LAMINATE AND FABRIC
APPLICATION: TIMBER BRIDGE PILES
INDUSTRY: TRANSPORTATION

GET A PILE REPAIR CONSULTATION ALL PROJECTS

Crew filling the annular space of glass FRP pile jackets with epoxy grout under the Araz Road timber bridge in Imperial County, California

20 timber piles jacketed in four bridge bents

timber piles jacketed: 20
bents: 4
cap beams wrapped: 4
glass FRP laminate per jacket: 2 plies

Project Details

OWNER: Imperial County Public Works (County of Imperial)
PROJECT: Emergency Repair of Araz Road and Bridges
LOCATION: Araz Road over Araz Wash, Imperial County, California
STRUCTURE: Timber bridge on 20 timber piles in four bents, with four timber cap beams
PILE REPAIR: Two-ply glass FRP laminate shell on 1 in. spacers, filled with epoxy grout
CAP BEAM REPAIR: Biaxial glass fabric saturated with high-strength epoxy
REPAIR DETAILS AND TECHNICAL REVIEW: QuakeWrap, Inc.
FRP INSTALLER: Composite Pros
GENERAL CONTRACTOR: Pyramid Construction & Aggregates
CONSTRUCTION OVERSIGHT: The Holt Group
FIELD WORK: April 13 to 24, 2026

01 · THE CHALLENGE

Deteriorated Piles and Cap Beams Under a County Bridge

The Araz Road Bridge carries Araz Road over Araz Wash in Imperial County, California. As part of the County of Imperial's Emergency Repair of Araz Road and Bridges project, the timber piles and cap beams that support the bridge needed rehabilitation.

The work covered 20 existing timber piles arranged in four bents. Decades of exposure, checking and localized deterioration had reduced the capacity of the piles and of the horizontal cap beams that carry the bridge above them. Some piles and caps were severely deteriorated.

Replacing these members would have been disruptive and expensive. The project team instead chose fiber-reinforced polymer (FRP) materials to strengthen and protect the existing timber.

Severely deteriorated top of a timber pile below a checked timber cap beam on the Araz Road Bridge before repair

02 · THE SOLUTION

Timber Bridge Pile Repair With a Glass FRP Shell and Epoxy Grout

Each timber pile jacket started with 1 in. spacers placed around the pile. Crews then wrapped high-strength glass FRP laminate around the pile, creating a permanent shell about 1 in. away from the original wood. Two layers of laminate were used, with the overlaps bonded with epoxy paste. Depending on field conditions, the jacket extended about 5 ft 6 in. to 6 ft 6 in. in height.

The space between the pile and the new shell was filled from the top with a specially formulated epoxy grout. Workers used a handheld concrete vibrator and hand tamping to consolidate the grout and eliminate voids. The result is a tightly fitted composite-and-grout system that works with the remaining timber and shields the repaired region from further exposure.

Glass FRP laminate2 plies, overlaps bonded with epoxy paste
Epoxy groutAbout 1 in. annulus, filled from the top
Spacers1 in., set around the pile
Existing timber pileHost

Two workers wrapping glass FRP laminate around a timber bridge pile fitted with spacers, with finished laminate shells on nearby piles

03 · THE RESULT

Cap Beams Wrapped and the Existing Timber Kept

After the piles were jacketed and grouted, crews turned to the timber cap beams. Damaged or irregular areas were filled with epoxy, and beam ends were rebuilt where needed. A noncorrosive biaxial glass fabric, saturated with high-strength epoxy, was then wrapped around each cap beam, with hand squeegees pressing the fabric against the timber to remove trapped air.

Construction logs show the pile and cap-beam rehabilitation ran from April 13 through April 24, 2026. Composite Pros performed the field work under general contractor Pyramid Construction & Aggregates, The Holt Group provided construction oversight, and QuakeWrap® provided the timber pile and cap-beam repair details and technical review.

When enough sound material remains, a deteriorated timber member does not always have to be removed and replaced. This repair preserved much of the existing structure, reduced the heavy construction needed beneath the bridge, and gave the piles and caps a corrosion-resistant exterior.