The durability of ground granulated blast furnace slag (GGBS) concretes and the corrosion behavior of reinforced concrete beams under various loading ratios were investigated. Prismatic beam specimens with a size of 150 mm x 150 mm x 900 mm were subjected to various sustained loadings (37 and 75% of the ultimate load) and exposed to 3.5% NaCl solution. A direct current (1 mA cm(-2)) was applied to accelerate the corrosion process. Open circuit potential (OCP) and direct current polarization resistance were obtained to evaluate the rebar corrosion. Deflection and residual loading rigidity of the beam were measured at the end of the experiment. In addition, rapid chloride penetration test (RCPT) and permeability test were conducted on GGBS concretes. Test results indicate that partial replacement of cement by GGBS has inhibiting effects on both total charge-pass and permeability. Slag addition and sustained loading have significant effect on corrosion rate and flexural rigidity of reinforced concrete beams. (c) 2005 Elsevier B.V. All rights reserved.