Modeling the service life of slag concrete exposed to chlorides

Abstract

This paper focuses on the service life of slag concrete, where the time to corrosion initiation for a given chloride threshold value of 0.3% by mass of cement and different surface chloride concentrations (Cs), (1%, 3%, and 5%) was calculated using the error function solution to Fick’s second law of diffusion as a service life model, where the chloride diffusion coefficients of different OPC/slag mixes were collected from literature.To gain improved understanding of the above-mentioned aspect, this research presents an experimental investigation to elucidate the impacts of local by-product water cooled slag (WCS) on the microstructure of OPC cement paste mixes using thermo-gravimetric analysis and de-sorption approaches.A partial replacement of OPC with 50% WCS in OPC paste mixes resulted in an increase in the amount of calcium silicate hydrate (CSH) by 57%, a decrease in the amount of calcium hydroxide (CH) by 66%, and a decrease in the amount of capillary pores by 57%, compared to those in the pure OPC matrix. In addition, the research results demonstrate that increasing Cs from 1% to 5% resulted in dramatically decreasing the service life of OPC/slag concrete, where the amount of decreasing reaches about 71%. Also, the service life of concrete increases with increasing slag content.