Degradation effects in concrete bound ferrochrome slag under aggressive sulphuric acid and sulphate attack

Abstract

Ferrochrome slag (FS) having favourable mechanical properties) may be gainfully utilised as concrete aggregate. The concrete specimens with FS, natural stones (NS) and NS concrete mixed with 2% chromium nitrate salt (CR) as coarse aggregate were prepared. The samples were cured in aggressive curing solution like sulphuric acid solution at pH 2 and 10% magnesium sulphate in order to examine its degradation aspects in terms of possible loss of strength, reduction of mass and the surface damage. The deterioration effects are assessed after 28, 56, and 90 days of curing. The results indicate that FS concrete has the minimum reduction of strength, least reduction of mass and less surface deterioration in comparison to concrete with NS and CR. FS has appreciable amount of environmentally deleterious residual chromium but almost all of these chromium contents are inherently immobilized in the slag matrix as evidenced in microstructure study. The concrete specimens using FS as coarse aggregate with its immobile chromium acting as passivation agent may provide better corrosion resistance and along with the usage of slag-based cement as binder furnish some protection measures against the corrosion effect under aggressive acid and sulphate action. This is the principal research significance of this work and it will provide a suitable platform for global research to explore the further work on the corrosion resistance of concrete bound FS exposed to different aggressive curing environment.