This paper studies the effect of the corrosion of hot-dip galvanized steel on the porosity development of cement paste at the interfacial transition zone (ITZ) between the two materials. The corrosion of hot-dip galvanized steel by hydrogen evolution was studied during the curing of cement paste samples stored above the water level (AW = 95% RH) and below the water level (BW). The changes in the corrosion process were recorded via the time – open circuit potential evolution (Ecorr/FeCr18Ni9) of stainless steel plate (recounted to Ecorr/SCE) in cement paste bodies. Total monitoring time for the development of both parameters were 6 days, 4 months and 1 year. Further, the bond strength between plain hot-dip galvanized steel and cement by modified pull-out test was verified. Total time of curing was in this case 6 days, 4 months and 1 year. The corrosion reaction between hot-dip galvanized steel and fresh cement produces hydrogen, which significantly increases the capillary porosity of the cement paste at the interfacial transition zone (ITZ). The resulting capillary pores are not effectively filled by the zinc corrosion products and the porous structure is maintained even after one year of curing. Porosity increase of cement consequently results in reduction of bond strength between plain hot-dip galvanized steel and concrete which remains low even for samples cured for very long exposure time.
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