Influence of Supplementary Cementitious Material on Estimated Service Life of Structure in Chloride Environment

Chloride ingress in concrete leads to deterioration of reinforcement and subsequent distress in concrete. The focus of the present study was to determine the amount of chloride ingress in concrete with and without supplementary cementitious materials (SCM) using Rapid Chloride Penetration Test (RCPT) and Rapid Chloride Migration Test (RCMT). A comparison of chloride ingress was made of Control concrete with six other mixtures having varying percentages of fly ash (20% & 30%), ground granulated blast furnace slag (GGBFS) (30% & 40%), silica fume (5%) as replacement of cement. Compressive strength, RCPT and RCMT tests were evaluated for all the mixtures after 28 and 90 days respectively. A correlation between RCPT and RCMT tests was established. Mixtures containing fly ash as SCM had lesser initial compressive strength compared to mixtures with GGBFS and silica fume. Chloride permeability of concrete mixture with silica fume as SCM has a significant decrease in chloride permeability in both RCPT and RCMT tests at both ages compared to concrete without SCM. Estimation of service life was carried out using Life-365TM software. It was observed that the service life of concrete without SCM was estimated to be 14.8 years while in the concrete with 5% silica fume expected service life was 24.9 years. Thus, the incorporation of supplementary cementitious material in concrete enhances the service life and is a boon to the construction industry.