The causes of bridge crash pier damage may be as follows:
De-icing salt - chloride ion destruction: In cold areas, the use of de-icing salt for bridge concrete diseases is a common problem, which is more harmful, and there is no effective solution at present. The snow melting agent solution penetrates into the concrete from the cracks or pores on the concrete surface, which is difficult to be discharged and continuously enriched, causing chemical erosion to the concrete, which will quickly corrode the steel bar and affect the structural safety. Because de-icing salt is cheap, snow and de-icing effect is good, and there is no effective substitute in the short term, it is necessary to consider the resistance method from the structure itself.
2.Snow plough and de-icing vehicle sweeping brush physical destruction.
The brush head of the snow and ice removal equipment will polish the root of the anti-collision pier within 20cm, and the plain concrete surface without painting will have a matte surface, and if the paint or silane paint coating is painted, there will be a large area of paint film damage, which will seriously affect the appearance of the bridge.
3.The thickness of the original anti-collision pier protective layer is small.
In the "Detailed Rules for the Design of Highway Traffic Safety Facilities" promulgated in 2017, the thickness of the protective layer of the anti-collision guardrail stipulates that the thickness of the reinforcement protective layer of the concrete on the collision surface of the guardrail shall not be less than 45cm。
The problem of insufficient thickness of the protective layer of the reinforcement is manifested in the fact that the concrete surface is prone to local damage and cracks due to external force, and soon develops to the surface of the reinforcement, and the reinforcement is easy to be corroded, and the cracking development of the concrete will be further accelerated after the steel rust rises.
4.Corrosion of internal steel bars.
The existing anti-collision pier is corroded because of the crack on the surface, and the steel bar of the facing face is corroded, because the structural stress bar is the whole, so the corrosion will gradually develop to the internal steel bar, but the local repair can only remove the rust of the steel bar exposed by water milling on the facing face, and the steel bar rust removal can not be carried out thoroughly.
Because the corrosion of the steel bar is non-reversible, it is recommended to replace the anti-collision pier with serious steel corrosion to ensure its structural safety performance.
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