Techniques Electrical Corrosion Of Reinforced Concrete Structures Acceleration

Various accelerated corrosion techniques have been adopted in the research ofcorroding reinforced concrete structures, which are different with natural corrosion.Three representative acceleration methods were employed in this work to corrode sixconcrete slabs, including full-immersion, half-immersion and wet-dry cycling. Based onthe specimens, the developing of expansive cracks was investigated comparatively alongwith surface characteristic of corroded rebars.After the specimens had been corroded to the designed degree, expansive crackswere measured and recorded, then corroded bars were retrieved and cleaned from rusts. Athree-dimensional laser scanning technique was used to build virtual models of thoserebars through reverse engineering approach. Samples of corroded rebar segments withdifferent lengths were taken from the models and their coefficients of nonuniformcorrosion distribution, which is defined as the maximum cross-sectional area loss ratiodivided by the average one over a segment, were calculated and denoted as R value. Inaddition, average corrosion area at the position of each measured expansive crack wasdetermined to set up their correlation models.Shown by the results, R values obey generalized extreme value (GEV) distribution,and they are independent of corrosion degree for all the three accelerated corrosions. Rvalue increases with sample length but is indistinctly influenced by rebar diameter,despite of the large scatter in case of small diameter. Half-immersion leads to maximal Rvalues in general as well as relatively bigger scatters, which indicates higher nonuniformdistribution of corrosion. Wet-dry cycling takes second place and full-immersion is thelowest.Expansive crack width increases linearly with the increasing of average corrosionarea of corroded bars. A minimal degree of corrosion is required for half-immersionspecimens to create an expansive crack of same width, which means more corrosionproducts would be oxidated to generate expansion pressure instead of leaking out.Wet-dry cycling takes second place and full-immersion is the highest. Therefore, it canbe concluded that half immersion is more close to the natural corrosion, wt-dry cyclingtakes second place and full-immersion is the worst.