Effect of Imperial Smelting Process Slag Addition in Self Compacting Concrete Concrete on the Efficiency of Electrochemical Chloride Extraction

Zofia Szweda; Janusz Mazurkiewicz; Petr Konečný; Tomasz Ponikiewski

doi:10.3390/ma16145159

Effect of Imperial Smelting Process Slag Addition in Self Compacting Concrete Concrete on the Efficiency of Electrochemical Chloride Extraction

Materials (Basel). 2023 Jul 21;16(14):5159. doi: 10.3390/ma16145159.

Authors

Zofia Szweda¹, Janusz Mazurkiewicz², Petr Konečný³, Tomasz Ponikiewski⁴

Affiliations

¹ Department of Building Structures, Faculty of Civil Engineering, Silesian University of Technology, 44-100 Gliwice, Poland.
² Department of Engineering Materials and Biomaterials, Faculty of Mechanical Engineering, Silesian University of Technology, 44-100 Gliwice, Poland.
³ Department of Structural Mechanics, Faculty of Civil Engineering, VSB-Technical University of Ostrava, 70800 Ostrava, Czech Republic.
⁴ Department of Building Processes and Building Physics, Faculty of Civil Engineering, Silesian University of Technology, 44-100 Gliwice, Poland.

Abstract

This paper presents the analysis of how ISP slag addition affects the effectiveness of chloride extraction from self-compacting concrete. Corrosion processes were initiated by chloride ions added to concrete by the method accelerated with an electric field. Corrosion of reinforcement was monitored using the method of linear polarization resistance (LPR). Polarization measurements of steel reinforcement and chloride profiles were analysed to evaluate the effectiveness of electrochemical extraction. Microstructural analysis was conducted on a specimen of concrete after migration and extraction of chlorides. The presence of chloride ions and the application of an electric field during migration were tested with respect to the changed microstructure of concrete evaluated on the basis of image analysis using a scanning electron microscope (SEM). The research contributes to a better understanding of the corrosion processes caused by the presence of chloride ions in concretes in which ISP slag was used as a substitute for sand in various amounts. Thanks to the treatments of concrete with already corroding reinforcement bars, it can be concluded that the moderate replacement of sand with ISP slag limited to 25% allows for the effective inhibition of corrosion processes taking place in these concretes. However, it is not possible to completely withdraw already started corrosion processes in steel. The observations of the microstructure of concrete in which sand was completely replaced with ISP slag indicate that after prolonged use of the chloride extraction process, we can expect a change in the microstructure and the formation of ettringite, which may cause the concrete structure to burst. The obtained information will contribute to the development of modelling methods for chloride ion extraction from a wide range of currently used concretes.

Keywords: ISP slag; chloride extraction; concrete microstructure; corrosion of reinforcement; diffusion process; linear polarization resistance; migration process; scanning electron microscope.

Grants and funding

The research was financed by Silesian University of Technology (Poland) 03/020/RGH_20/0096 and in part within the project BK-208/RB-2/2023(03/020/BK_23/0147) and in part within the project BK-209/RB-3/2023(03/030/BK_23/0156) and in part within the project BK-283/RMT1/2023 (10/010/BK_23/1143).