Effect of w/c ratio and cement content on diffusivity of chloride ion in concrete: A molecular dynamics study

Abstract

When a reinforced structure is exposed to marine environments, chloride-induced corrosion occurs and it decreases the durability and performance of the structure. The degree of humidity, the presence of cracks, environmental conditions, w/c ratio, and cement content are the influencing factors for chloride ion ingress into concrete. All of them, w/c ratio and cement content are treated as the most crucial factors on diffusion. This paper focus on Molecular Dynamics (MD) simulation method to determine the diffusion coefficient of chloride ion in concrete. The effect of w/c ratio and cement content on the diffusivity of chloride ion is also evaluated. The diffusion coefficients are obtained 2.88x10-12 m2/s, 3.13x10-12 m2/s, and 3.61x10-12 m2/s respectively for different w/c ratio of 0.40, 0.45 and 0.50 with constant cement content. Again the diffusion coefficient are calculated 4.6x10-12 m2/s, 3.13x10-12 m2/s, 2.78x10-12 m2/s respectively for different cement content of 300 kg/m3, 350 kg/m3 and 400 kg/m3 with constant w/c ratio. The simulation results clearly indicate that the diffusion coefficient of chlorine was affected by w/c ratio and cement content significantly.