The contribution is dedicated to the durability of geotechnical stabilization applications. The long-term corrosion behavior of unprotected and galvanized thread-bars for micro-piles and nails in different soils is described. The bars in the ground are embedded in an up to 20 mm thick cement mortar, which may be cracked and locally destructed. First, the corrosion-affecting parameters of the steel corrosion in the ground are described and soil classes are defined. Furthermore, an estimation of the long-term (up to 50 years) corrosion behavior was assessed on the base of information from the literature. Here the corrosion of the thread-bar in direct contact with the soil was in the center of interest. The corrosion protection of the cement mortar cover was not taken into consideration, in order to be on the safe side. On the other hand, a macrocell-corrosion of the thread-bars cannot be completely excluded, if the cement mortar casing exhibits defects and constructional and environmental corrosive conditions in the ground are fulfilled. Two cases are discussed:
• element formation between sections along the thread-bar,
• element formation between the thread-bar and other reinforced concrete parts.