Zhaolingpu Bridge Reinforcement-New Advanced Material-Carbon Fiber Reinforcement

Zhaolingpu Bridge is a prefabricated hollow slab girder bridge with 6 holes and 20 m. After many years of operation, the pier column suffered from rust swelling, cracking, concrete peeling, and tendons. It was rated as a third-class bridge during the regular inspection in 2011. In order to repair the disease of the bridge pier column and ensure its safe use, the pier column adopts a double-layer carbon fiber cloth glued ring-oriented single double layer arrangement, the carbon fiber cloth width is 40 cm, and the outermost layer has a lap length of 30 cm.

The construction process is as follows: surface treatment of piers, painting of bottom resin, leveling repair, pasting of carbon fiber cloth, and surface protection.

Pier surface treatment

(1) Remove the spalling, looseness, honeycomb, corrosion and other inferior concrete on the surface of the pier and column, and apply polymer cement mortar to repair the large area of inferior layer after removal.

(2) Check whether the exposed steel bars are corroded, if there is corrosion, remove the rust

(3) For cracks, fill or seal the joints first.

(4) Use concrete angle grinders, grinding wheels and other tools to remove impurities such as scum and oil on the surface of the concrete until the fresh surface is completely exposed. The concrete of the base surface of the component should be smoothed, especially the protruding parts of the surface should be smoothed. The corner paste should be chamfered and polished into an arc shape with a radius of not less than 20 mm.

(5) Use a hair dryer to clean the surface of the concrete and keep it dry.

Apply primer

Configure the bottom resin HM-180 as required. Use a roller brush to evenly apply the glue on the surface of the concrete pier, the thickness is not more than 1 mm, and there should be no leakage, flow, or bubbles. After the glue is cured, proceed to the next process.

Leveling

After the resin is painted, the interval should be 30 -60 min. After the air bubbles in the base are cleared, the concave parts of the concrete surface should be repaired with leveling materials, and the parts with different heights such as formwork joints should be filled with leveling materials, and there should be no corners. At the corner, use leveling material to repair it into a smooth arc. The leveling material must be cured before proceeding to the next procedure.

Bonded carbon fiber on bridge

(1) Cut the carbon fiber cloth to the size required by the design.

(2) Configure the impregnating resin according to the mixing ratio requirements, then apply the impregnating resin evenly to the pasted parts with a roller brush, and apply more on the overlapping and corner parts.

(3) Paste the carbon fiber cloth on the surface of the resin-impregnated pillar, and then use a special roller to repeatedly roll the carbon fiber cloth in the same direction on the surface of the carbon fiber cloth.

(4) The above steps should be repeated for multi-layer pasting, and the next layer of carbon fiber cloth should be pasted immediately after the touch on the surface of the carbon fiber cloth is dry.

Surface protection

After the carbon fiber cloth is pasted, apply a layer of impregnating glue directly and evenly on the surface in time to dry naturally. After making sure that the surface of the patch has been fully air-dried and combined, apply a masking adhesive to the surface with a thickness of not less than 210 um. Then apply the atmospheric carbon topcoat, the dry film thickness is not less than 90 um, to ensure the durability of each layer of glue.

Conservation

After sticking the carbon fiber cloth, it should be cured naturally for 24 hours to achieve consolidation, and it should be ensured that it will not be interfered during curing. Before the resin hardens after each process, it should be covered with plastic film to prevent wind and sand or rain. When there is a possibility that the temperature drops below 50 during the curing of the resin, low-temperature curing resin or effective heating measures may be adopted.

Reinforcement effect

The pillars of Zhaolingpu Bridge are reinforced with Horse carbon fiber sheet to achieve a significant effect. After regular inspections in 2012, the bridge was classified as Class II. After reinforcement, there has been no phenomenon of rust swelling, spalling, or cracking, which has improved the quality level and seismic performance of the bridge.