Confluence of chloride diffusivity influence functions in unsaturated concrete

Chloride induced corrosion is one of the most cited cause of durability loss and strength degradation of reinforced concrete structures under service conditions. The durability capacity of the concrete structure to resist chloride exposure loads in the field is significantly limited to the corrosion initiation time that is very much dependent on the chloride diffusivity property of the concrete. Characteristic behaviour of the chloride diffusivity has been investigated across a number of studies to be controlled by concrete material quality factors for which water-cement ratio, cement content, and maturity time are crucial. However the challenge posed by concrete operating under concomitant field conditions remains complex with regard to addressing the combined effect of these factors in relation to the interaction effects of moisture ambience on the chloride transport. In this paper aspects of finite element methodology have therefore been applied to formulate a coupled moisture diffusion and chloride ingress model centred on a notional multivariate diffusivity function for chlorides in concrete. Results of the analysis show that confluence of material quality based influence functions has significant effect to proper understanding of durability performance of concrete structures against chloride ingress and hence associated initiation time of corrosion problems in the field.