چكيده به لاتين
The impact of using pre-rusted rebars, especially in aggressive environments with varying degrees of corrosion, on the corrosion of steel in reinforced concrete is a critical issue that has received limited attention in both international standards and research studies to date. This study aims to investigate the influence of three factors: rebar surface conditions, concrete performance, and environmental conditions on the corrosion of reinforced concrete when pre-corroded rebars are used. The investigation was carried out in real project environments in two coastal regions, the Persian Gulf and the Caspian Sea. To assess different surface conditions of stored rebars in the project environment and to evaluate concrete quality, different mix proportions of ordinary concrete and self-compacting concrete with and without supplementary cementitious materials were employed. Additionally, different water-to-cementitious materials ratios were used. Corrosion of reinforced concrete was evaluated in three different environmental conditions: laboratory, coastal region of the Persian Gulf, and Caspian Sea. Performance indicators for concrete included resistance and electrical resistivity, rapid chloride penetration, migration coefficient, chloride diffusion coefficient, and shape factor. For assessing steel corrosion in concrete, potential and current density were considered as corrosion indicators. The results showed that when pre-corroded rebars with increasing levels of surface corrosion were used for reinforcement, the corrosion current density increased by up to 95%. Improving concrete quality could reduce the potential and severity of rebar corrosion. However, the influence of concrete performance on corrosion reduction was affected by rebar surface conditions and decreased with increasing levels of pre-corrosion. When using S1 rebars, the effect of concrete quality on corrosion was calculated as 40.11, while with S13 rebars, this effect increased to 1.25. Furthermore, the presence of higher chloride levels in the coastal air increased the corrosion current density of pre-corroded rebars in reinforced concrete. However, the dominant factor in coastal environments when using pre-corroded rebars was the surface condition of the rebars. Changing the surface condition from S1 to S12 reduced the influence of environmental conditions on corrosion from 0.97 to 0.26. The surface condition of rebars before use in concrete was identified as a crucial factor in determining the corrosion of steel in reinforced concrete in coastal environments. Proper measures should be taken to store rebars in the project environment to reduce the negative effects of using rebars with inappropriate surface conditions in reinforced concrete. In summary, until the use of rebars with surface condition S5, the corrosion of steel in reinforced concrete is primarily influenced by concrete quality, rebar surface conditions, and environmental conditions in that order. Beyond this point, rebar surface conditions, concrete quality, and environmental conditions become the determining factors for steel corrosion in reinforced concrete.
