Distributing character of size of pits on steel strands corroded by chloride

Abstract：With the corroded steel strands from some prestressed concrete beams contaminated with salt,the configuration of the pits were studied.And then,4 samples of corroded steel strands with different corrosion rates were obtained,and the width,depth and length of the pits were measured and accounted,and the distributing character of pits size were studied.The results show that the configuration of the pits include 2 typical modes such as spheroidicity and saddle.With the developing of corrosion,the pits become denser and denser.The width of pits subjects to normal distribution approximatively and the length of pits subjects to logarithmic normal distribution preferably,but the depth of pits does not subject to the conventional distribution modes.So,on one corroded steel strand,the shallow and short and moderate wide pits are in the majority.The fractal characteristic does not show in the distribution of pits width but show in the distribution of pits depth and length,and both of the fractal dimensions increase with the corrosion development.So,with the increase of corrosion rate,the distribution of both pits depth and pits length are trend to approach.The compositive analyse indicates that the size of pits on steel strands is trend to approach with the increase of corrosion rate.The pits depth and pits length approach to the relative minor values,but the pits width approach to the relative moderate values.