Ultratect WR was applied to the Shin-Akashishi Bridge in Aomori Prefecture to mitigate salt damage and extend the service life of the structure.

Bridge Longevity Strategy and the Severe Impact of Salt Damage on the Shin-Akashishi Bridge

Aomori Prefecture faces accelerated deterioration of roads and bridges due to salt damage from sea air and cold-related deterioration caused by harsh winters. Since 2008, the prefectural government has implemented a long-term repair plan to prolong the lifespan of its infrastructure.

Inspections of the Shin-Akaishi Bridge, a prestressed concrete (PC) bridge, revealed serious deterioration caused by salt contamination. In particular, the main girders were severely affected by chloride ions carried by sea breezes and by the deicing agents used during winter, leading to corrosion of reinforcing steel beyond critical thresholds.

Although a jacketing repair had been performed on the piers in fiscal 1997, salt damage on the sea-facing side remained pronounced, confirming the need for urgent preventive maintenance.

Adoption and Application of Ultratect WR

To extend the lifespan of the bridge and reduce maintenance costs, the decision was made at the outset to incorporate salt damage prevention measures. Ultratect WR, a silane?siloxane-based surface impregnation material with high penetration performance, was selected to suppress chloride ion infiltration.

Ultratect WR was chosen for its superior performance in the following areas:

• High Salt Resistance
  Suppresses the ingress of chloride ions and prevents rebar corrosion.
• Excellent Cold Weather Durability
  Prevents moisture from penetrating fine cracks in concrete even in sub-zero conditions, helping to reduce temperature-induced deterioration.
• Stain and Mold Resistance
  Minimizes the adhesion of dirt and mold on bridge surfaces, helping maintain aesthetic appearance.
• Long-Term Durability
  Offers longer-lasting concrete protection compared to conventional impregnation materials.

Following application, the durability of the Shin-Akaishi Bridge is expected to be maintained over the long term. Whereas previous maintenance approaches required periodic repairs, the use of Ultratect WR is anticipated to reduce repair frequency and lower long-term maintenance costs.

This case study illustrates that Ultratect WR is well suited not only for coastal and cold-climate bridges, but also for a wide range of concrete structures, including tunnels, dams, and port facilities.

Ultratect WR for Cold-Climate Applications

Ultratect WR can be applied at temperatures as low as -20°C, making it suitable for winter construction in cold climates. In particular, it is highly effective in regions where deicing agents are used, significantly reducing deterioration caused by chloride ions. This makes it an optimal solution for maintaining infrastructure such as bridges, expressways, and tunnels.

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