Efficiency of accelerated techniques for assessing corrosion protection of blended cements

Abstract

The efficiency of different accelerated corrosion techniques was compared to evaluate the role of some blended cements in corrosion protection for reinforced-concrete elements exposed to chloride. Specifically, a quick impressed voltage accelerated corrosion technique was implemented and compared with slower macrocell techniques, such as southern exposure and cracked beam. For the same purpose, corrosion protection performance was also evaluated for reinforced-concrete slabs made with identical cement blends and exposed to severe freely corroding conditions for 140 weeks. Corrosion results for the impressed voltage technique were remarkably comparable to those obtained for the other, slower, corrosion techniques investigated. Therefore, instead of using more complicated techniques, the impressed voltage technique can prove reliable for assessing the chloride-induced corrosion activity of cementitious materials with noticeable differences in durability characteristics. However, further research is currently underway to verify the repeatability of the latter conclusion. Based on the impressed voltage technique, an empirical equation is proposed to predict the delay in steel corrosion initiation obtained by replacing Portland cement with blended cements. The proposed equation depends on some easily measured durability characteristics of concrete surrounding steel. Further research results and data published in the literature can be used to refine the proposed equation.