Role of cement type on performance change of reinforcing steel due to chloride extraction

Electrochemical chloride extraction ECE has been used for reinforced concrete structures to protect steel from chloride-induced corrosion. ECE may change the performance of steel interface as represented by polarization resistance, corrosion rate and pull out bond strength. Thus, there is a need to evaluate these effects before and after ECE treatment for reinforced concrete made with different types of cements. This paper presents the evaluation of the performance changes of concrete specimens containing steel rebar with different times of (ECE) treatments. In this study; plain and blended cement which are commonly used in marine environment are investigated; two types of ordinary Portland cement CEM I 42.5N with different alkalis and percentages of C(3)A and two types of blended cement; SLAG cement CEMII/B-S-42.5N and CEM I 42.5N with 10% silica fume. Concrete mixes are subjected to either internal or external sources of chlorides. Other protective methods have been evaluated for comparison; corrosion inhibitor admixtures and cementitious surface coating. Corrosion initiation and corrosion rate were estimated by non-destructive techniques (Half-cell potential and polarization resistance), while the pull out bond strength was evaluated for all mixes before and after chloride extraction. The results indicated that applied ECE is an effective method of chloride removal, but it adversely affects the pull out bond strength irrespective of cements type. However, the use of silica fume blended cement has been proved to be effective. (C) 2019 Elsevier Ltd. All rights reserved.