Experimental study on isolation protection system durability of anchor rod for suspension bridge main cable anchorage system

Objective The study investigated the isolation protection system durability of anchor rod for suspension bridge main cable anchorage system in corrosion enviroments. The combination protection specimens composed of concrete-sealant-steel plate were prepared. Their synergistic mechanisms were investigated in both seawater submerged zone and seawater level variation zone. Method The long-term immersion and dry-wet alternating accelerated aging test were carried out. The aging degree of combination specimens, in different corrosion environment, corrosion age and stress state, were explored. The variation rule of bonding load between sulphurized sealant and concrete was revealed through concrete pull-out test. Result The contact surface of concrete and sealant was relatively smooth in different aging conditions, and there is no obvious pull-out crack and sealant residue. The sealant did not react with concrete to form corrosive products. With the increase of aging, the concrete and sealant bonding load was gradually reduced and less than 1.0 kN, indicating that the sealant-concrete interface had a good non-bonding effect. There was no trace of corrosion on steel plate surface inside the sealant after the pull-out test, verifying the effective protective effect of anchor rod sealant. The influence of long-term immersion on bonding load of interface between concrete and sealant was greater than that of wet-dry alternation with a maximum difference of 23%. The eccentric force mode affected the damage pattern of specimens, and also caused an increase in interface bond strength with a maximum increase of 18.5%. Conclusion The proposed anchor rod isolation protection system in corrosion environments could meet the design requirements for long service life. The study result would provide a theoretical basis for the design of isolation protection for main cable anchorage system of suspension bridges.