Common diseases of Concrete Bridges：Spalling, exposed tendons, honeycomb, concrete corrosion, mesh cracks.

Spalling, exposed tendons

• By construction

Cause analysis: the quality of construction is not good, such as the displacement of the reinforced protective layer block when pouring, the steel bar close to the template, because the protective layer is too thin, the chloride ion in the air is impregnated and the steel corrosion and the concrete are spalling.

Disposal suggestion: in order to avoid the vicious cycle of corrosion and expansion of steel bars and concrete flaking, it is suggested that the exfoliation and ribs are isolated from the air, and it is suggested that epoxy mortar or epoxy resin can be used to repair the surface. The surface dirt is removed first and the depth of 30mm is cut by the plumb. Then the epoxy mortar is applied to the chisel.

• Vehicle action

Cause analysis: due to the lack of concrete binding force under the repeated action of the vehicle, it is exfoliated with the chemical substances in the air, which can easily cause the large area peeling of the beam to cause the vicious cycle of corrosion of steel bar and the peeling of the bottom of the beam.

Disposal suggestions: fresh concrete can generally be used to repair, the concrete used for repair, good grading, and special attention to ensure good and easy to reduce the difficulties of tamping work. Repair of concrete can be done by direct pouring, spraying and grouting.

• External force collision

Cause analysis: Vehicle scraping or external impact caused concrete spalling reinforcement.

Disposal suggestion: it is recommended to set up the super high limit card and the super high limit rack. At the same time, the concrete is repaired with fresh concrete. The concrete used for repair should be well graded and special attention should be paid to ensure good and easy nature to reduce the difficulty of tamping work. Repair of concrete can be done by direct pouring, spraying and grouting.

Honeycomb

• Honeycomb

Reason analysis: improper construction. Lack of proper tamping, improper formwork slit, loss of cement slurry and so on.

Disposal methods: fresh concrete can generally be used to repair, the concrete used for repair, good gradation, and special attention to ensure good and easy to reduce the difficulties of tamping work.

• Pitting surface

Cause analysis: the surface of the formwork is not smooth, and the wetting of the formwork is not enough, so that the water in the concrete of the surface of the component is absorbed.

Disposal methods: fresh concrete can generally be used to repair, the concrete used for repair, good gradation, and special attention to ensure good and easy to reduce the difficulties of tamping work.

Concrete corrosion

(chloride penetration, alkali silica reaction, sulphate, acid corrosion, freeze-thaw)

• Corrosion of construction reasons

The reason is that the amount of asphalt is not controlled enough during construction, which makes the surface roughness not enough, and it is difficult to remove the water. The drainage of the seams leads to the flow of water flowing to the table.

Disposal suggestion: in order to avoid the vicious circle of corrosion and expansion and concrete flaking, it is suggested that the corrosion and exfoliation places be isolated from the air, and it is suggested that epoxy mortar or epoxy resin can be used to repair the surface. The surface dirt is removed first and the depth of 30mm is cut by the plumb. Then the epoxy mortar is applied to the chisel.

• Poor drainage

Cause analysis: because the drainage of the bridge deck is not smooth, the location of the drain hole is not proper, so that the structure is washed by rainwater.

Disposal suggestion: first, the bridge deck waterproofing is treated, then the epoxy mortar is artificially applied to the corroded component.

Reticulate fissure

The cause analysis is mainly caused by the internal water heat of concrete and the temperature difference of the external temperature, the change of daily temperature and the influence of sunshine.

Disposal suggestion: surface repair method and artificial cement mortar can be used.