Bridge Over Brown's Creek

The Problem

The bridge over Brown’s Creek is located north of Jacksonville, Florida. The bridge consists of fifteen 39-ft simply supported spans. Each span consists of eight 18? x 48?voided pre-stressed concrete slab units. These slab units are joined together by a minimum amount of transverse post-tensioning to form the bridge deck. The bridge was built in 1962 and was designed to carry two lanes of AASHTO HS-15 loading.

The voided slab units exhibited severe deterioration due to corrosion of the pre-stressing strands. The high moisture level and exposure to chloride attacks resulted in corrosion of the pre-stressing strands and spalling of the concrete cover. At various locations, several pre-stressing strands were completely severed. The estimated strength loss approached 25% in some of the damaged slabs.

Conventional repair methods were determined to be unsuitable due to the type and level of deterioration. Upon initial evaluation, it was determined that complete replacement of the damaged members was the only viable option. However, further analysis indicated that this option was costly and required to detour the traffic for more than 40 miles. Therefore, other options of rehabilitation were sought.


View of Damage

The use of advanced composite materials was considered to be a feasible solution as well as innovative, economical and fast. The MAS2000 Fiber Wrap System provided the high resistance to the severe environment and the high strength required to restore the members to their original design strength. Part of the rehabilitation program involved treating the remaining pre-stressing strands, restoring the concrete section by using a high strength cementitious material, then applying the carbon composite wrapping.

The Solution

The composite laminate, MAS2000 Fiber Wrap System, was designed such that the loss of strength due to severed pre-stressing strands could be accommodated. The rehabilitation program involved the application of carbon laminate over the cracked area to restore the slabs to original design strength and provide an effective moisture barrier.

A full structural evaluation of the entire bridge was made after rehabilitation with a load test to determine the actual strength of the bridge. The structure easily passed all evaluations and, despite the continuous exposure to such a harsh environment, has been performing perfectly since 1993.

The corroded strands were cleaned and chemically treated to prevent further corrosion. The concrete sections were then restored to their original shape using high quality concrete capable of achieving full strength within 24 hours. The section restoration was followed by surface preparation and the MAS2000 Fiber Wrap System was then applied to the bottom of the concrete slabs, resulting in complete restoration of the slabs.


Application of MAS2000

Application of the system took less than 8 hours with no shutdown of the bridge. The repair crew performed the work from a small barge. One week after completion of repair, a specially designed coating was applied to the structure to achieve ultraviolet (UV) resistance and a pleasing aesthetic appearance.