I What is the role of chloride in the corrosion of reinforcement steel in concrete? (3 Marks) Figure 7-1 presents the total chloride profiles calculated for concrete exposed to seawater for different periods up to 50 years. The initial chloride content of the concrete is assumed nil (Co = 0). The total chloride surface concentration (at x = 0) is assumed to be equal to 4% of the cement mass (Cw = 4%). RILEM recommendation for total chloride threshold is adopted: total chloride threshold is assumed to equal 0.4% of the cement mass. The service life of the building is expected to be 20 years. Providing the chloride profiles presented in Figure 7-1, what is the minimum concrete cover required? (7 marks) C(x,t)/Cw 1 0,8 + 0,6 0,4 0,2 0 0 0,02 0,04 X(m) t=1 year - t = 5 years t = 10 years t = 20 years - t = 50 years 0,06 0,08 Figure 9-1: Total chloride profiles 0,1 C = 0