Atmospheric chloride-induced corrosion of steel-reinforced concrete beam exposed to real marine-environment for 7 years

Steel-reinforced concrete structure easily suffers from chloride corrosion when exposed to a marine atmosphere environment. In this work, OPC/slag concrete beams combined with loading were naturally exposed to My Island (Qingdao, China) for 7-years and their chloride distributions were investigated as well as carbonation and corrosion-products. The results show that a concentration (Cs,%)-time (t,month) relationship was obtained as Cs=0.022t for concrete surface-chloride. With the increasing corrosion-depth, twice chloride accumulations occurred and were located near the carbonation depth and frontier, respectively. Slag increased the depth and height of the first accumulation peak-value while exacerbating its faster decrease of chloride concentration compared to the control. The chloride increment in the tensile zone was greater than its reduction in the compressive zone. The chloride corrosion mainly occurred in the stirrup bends, where the inner corrosion products mainly contained α-FeOOH and γ-FeOOH while further transforming into Fe3O4 in its outer layer.