The accelerated method for estimating corrosion of reinforced concrete structure in seawater

The corrosion of concrete for offshore structures is generally caused by the penetration of chloride ion deriving from the salts in seawater. Up to now, lots of researches have been done concerning the corrosion of concrete by seawater and durability of concrete. However, the investigation for corrosion of reinforced concrete structure by seawater are relatively rare, because of the needs for long term tests (at least 3 to 5 years usually). The structures sited in the intertidal zone always accompany severer deterioration by seawater. Under such environmental conditions, frequent wetting and drying will aggravate the effect of sulfate attack, while the crystallization of sea salts in the concrete on evaporation may also contribute to expansive forces. For these reasons above, the purpose of this paper is to study the corrosion of reinforced concrete structure in the intertidal zone by a accelerated method presented. The critical variables considered in this research include the temperature and concentration of seawater. During the experimental period (1 year), the specimens were cured in wetting and drying situation (for each circle, submerged by seawater for 24 hours and then drying at 70? for the following 24 hours), and this repeatedly cyclic procedures is to accelerate the corrosion of reinforced concrete structure by seawater. According to the experimental results, the increased concentration and temperature of seawater would accelerate deterioration of concrete obviously. The duration of testing could be shortened about 75% by using the sweater with 10 times the concentration. As the curing temperature increased, the corresponding strength concrete at earlier age would increase, and which could reduce the corrosion of reinforced concrete.