Chloride binding and diffusion of slag blended concrete mixtures.

Ground granulated blast furnace slags (GGBFS/slag) can have a range of chemical compositions, especially in alumina content that could potentially affect several concrete properties including chloride binding capacity and chloride penetration. Chloride binding capacity and diffusivity of several cement-slag combinations were assessed using two slags of 8% and 17% alumina contents and four cements, ASTM C150 Type I, ASTM C150 Type I (high alkali), ASTM C150 Type II(MH) and ASTM C595 Type IL(14) at a cement replacement level of 60%. The findings indicate slag addition improved chloride binding and lowered chloride diffusivity. Between the two slags, chloride binding capacity was higher in high alumina slag. Type I cement mixtures had the highest binding capacity while it was the lowest in Type IL cement mixtures due to lower C 3 A, C 3 S and clinker factor. Chloride diffusivity experiments showed that plain Type IL mixture had the highest chloride ion penetration while it was the lowest when blended with high alumina slag due to carboaluminate formation. Therefore, chemical, mineralogical, and physical characteristics of cement-slag combination should be considered in service life analysis of slag blended concrete mixtures. [ABSTRACT FROM AUTHOR]