Chloride-induced corrosion of cracked cement-based composites

Abstract

Chloride-induced corrosion tests in cracked steel reinforced SHCC (R/SHCC) beams have recently been reported by the research group in Stellenbosch, South Africa. The influence of crack spacing has been investigated, including Coulostatic corrosion rate measurements and actual observation and recorded corrosion damage in the steel bars in terms of mass loss and pitting depths. To further investigate the influence of crack spacing on chloride-induced corrosion in cement-based composites, comparative tests are currently performed on cracked reinforced concrete (R/C), as well as lightweight foam concrete (R/LWFC) beams. Locally developed Coulostatic equipment, and a polarisation technique with Gecor 10 equipment are used for non-destructive measurement of corrosion rate. R/SHCC, R/C and R/LWFC beams are subjected to imposed strain in special load frames, combined with cyclic chloride ponding on the cracked face to induce corrosion in the reinforcing bars. The observed corrosion rates in the respective cement-based beams are compared, and the influence of cover depth, rebar reinforcement level and crack spacing is investigated and reported. The comparative study has the objective to identify mechanisms of chloride-induced corrosion in the respective cement-based materials, towards understanding of this deterioration mechanism, and towards development of rational prediction models for durability design.