Assessment of corrosion-induced damage and its effect on the structural behavior of RC beams containing supplementary cementitious materials Shaikh Faiz Uddin Ahmed 1 , Mohamed Maalej 2 , P. Paramasivam 2 and Hirozo Mihashi 1 1 Tohoku University, Aoba-Ku, Japan 2 National University of Singapore, Singapore Summary This paper reports the results of an experimental program on the effect of steel loss and corrosion induced-damage (cracking, delamination, spalling, etc.) on the post-corrosion flexural response of reinforced concrete beams incorporating supplementary cementing materials (fly ash, slag and silica fume) used as partial replacement of ordinary Portland cement. Eight reinforced concrete beams measuring 2.5 m in length and 210  300 mm in cross-section were cast, four of which were subjected to accelerated corrosion. Among all specimens incorporating supplementary cementing materials (SCM), the specimen containing fly ash showed the best performance in terms of the highest residual load carrying capacity at failure. Its best performance was also evident from the lowest measured steel loss, the least corrosion-induced cracking and the lowest tendency for the concrete cover to delaminate as measured by a concrete- embeddable fiber optic strain sensor (FOSS). Correlation between the amount of steel loss and the reductions in load carrying at failure was also established. Key words: supplementary cementing materials; durability; corrosion damage; fiber optic sensing; mechanical properties; high-performance concrete Prog. Struct. Engng Mater. (in press) Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/pse.214 1 Introduction The deterioration of reinforced concrete structures due to reinforcement corrosion has been recognized as a major problem worldwide. Reinforcement corrosion not only reduces the cross-sectional area of the reinforcing steel in the structure but may also induce cracking, delamination and/or spalling of the concrete cover and loss of bond with surrounding concrete. This corrosion-induced damage may also adversely affect the load carrying behavior of the structure during its service life. In recent years, supplementary cementing materials (SCM) like fly ash (FA), slag (SG) and silica fume (SF) have been proposed as an effective means of addressing reinforcement corrosion[1,2]. Apart from enhancing the durability of RC structures, the use of these materials recycles waste products and reduces the production of cement, which releases large amount of CO 2 into the atmosphere[3]. In the literature, there are numerous articles reporting on the corrosion durability of various types of reinforced concrete members incorporating SCM[4–20]. In these studies, the half-cell potential[5,6,8–13], the linear polarization[4,7,9,10] and the AC impedance[9,10,13] techniques have been used to monitor the corrosion of steel in SCM-modified concrete. The corrosion resistance of SCM-modified concrete has also been evaluated by measuring the concrete’s electrical resistivity[14], the rapid chloride permeability[9,10,16], the ionic concentration of the pore solution[15–19] and the oxygen and chloride ion diffusion[19,20]. The reported studies have shown that the SCM-modified concrete offers a greater resistance Concrete Construction Copyright & 2006 John Wiley & Sons, Ltd. Prog. Struct. Engng Mater. (in press)