Impact of water-cement ratio and cement content on pore area percentage and chloride diffusion – A molecular dynamics study

K. S. Shahnaz; M. S. Islam

Abstract

The exposure of a reinforced structure to water-based settings leads to the occurrence of chloride-induced corrosion, resulting in a reduction in both the durability and performance of the structure. The entry of chloride ions into concrete and the pore area percentage is influenced by several elements, including the degree of humidity, the presence of fractures, environmental conditions, water-to-cement ratio (w/c ratio), and cement content. This research focuses on the utilization of the Molecular Dynamics (MD) simulation approach for determining the diffusion coefficient of chloride ions and the pore area percentage within concrete. The evaluation additionally considers the influence of water-to-cement ratio (w/c ratio) and cement concentration on the diffusivity of chloride ions. The diffusion coefficients were determined to be 2.16x10-12 m2/s, 3.62x10-12 m2/s respectively, for varying water-to-cement ratios of 0.40 and 0.50, while keeping the cement content constant. The diffusion coefficients were determined as 2.16x10-12 m2/s, 2.89x10-12m2/s with varying cement content of 350 kg, 300 kg while maintaining a constant water-to-cement ratio. The pore area percentage were calculated 18.7% and 24.5% for varying water-to-cement ratios of 0.40, 0.50 .The pore area percentage were calculated 15.6% and 18.7% with varying cement content of 300 kg/m3, 350 kg/m3 while maintaining a constant water-to-cement ratio .The findings from the simulation demonstrate a clear and significant impact of the water-to-cement ratio (w/c ratio) and cement concentration on the diffusion coefficient of chlorine and pore area percentage.