Deicing Salt Environment On Concrete Hollow Slab Hinge Joint Erosion And Damage Evolution

At present, small or middle span assemble hollow slab bridges are the main type in Western China highways. Looked from the use condition, hinged joint damage is the most prominent disease during the service life, especially under the aggression condition of deicing salt in winter, a mass of chloride come from sodium chloride and calcium chloride permeate into the hinged joint concrete, which lead to steel corrosion, concrete cracking. Furthermore, hinged joint damage weakens the transverse-connect performance and have bad effect on the working coordination performance and the ultimate performance of hollow slab bridges.In order to study the damage evolution of the hinged joint under the aggression condition of deicing salt, three different types hinged joint members was designed according to the demand of the West Region Communication Construction Technology Project of the Ministry of Communications (200631822302-04), and then carry out the experiment based on concrete structure durability and damage mechanics. The obtained achievements as follows:1. By analyzing the damage of the concrete structure, the damage process can be divided into three periods:incubation period, developed period and damage period of corrosion.2. A quantity about damage degree is defined to express the damage situation of concrete in incubation period of corrosion by use free chlorine density and critical chlorine density that near the surface of steel, and the corrosion situation of steel is checked by comparing the test value of free chlorine density with the value of critical chlorine density.3. Through analysis the process of concrete damage before the concrete-cover expansion, the damage degree is defined according to the surface tension of concrete-cover caused by expansion and tensile strength of concrete; meanwhile, the relation of damage degree, corrosion current density and corrosion time is obtained.4. According to the load-deflection curve that obtained from the static load test, it is known that the damage of hinged joint may reduce the working coordination performance and the ultimate state of hollow slab bridges.