Investigations on atmospheric carbonation corrosion of concrete structure beam exposed to real marine-environment for 7 years

Concrete structure beam exposed to marine atmosphere environment easily suffers from car-bonization corrosion and their true characterization is significant for their durability designs. In this work, concrete structure beam was exposed naturally for 7-years in a marine atmosphere en-vironment of My Island (Qingdao, China) and their carbonization degree was characterized using the phenolphthalein (pH-value) and hydrochloric acid (HCl) titrations respectively to obtain their carbonation depth (Xd) and frontier (Xf). The results showed that the OPC concrete beam is only carbonized in its surface layer with a 3 mm carbonization depth while 6 mm Xf, both of which are smaller than the Xd (9 mm) and Xf (16 mm) of the concrete mixed with 50% slag replacement. The recommended carbonation amplification coefficients (Xf/Xd) of the OPC/slag-cement con-cretes are 2.1 and 1.8, respectively. The increased carbonization of the load-bearing concrete beam in the tension zone is greater than the reduction carbonization in the compression zone.