Utilizing Colloidal Nano-Silica as Treatment for Concrete in Salt Water Ports: Laboratory Chloride Diffusion, Life Cycle Modeling, and the Port of Marseille Test Case

摘要

Colloidal nano-silica treatment for concrete was initially developed in the oil and gas industry to reduce the permeability of undersea well caps in the 1970s, acting as a capillary and pore-filling agent to reduce oil loss into seawater. Portland cement concrete with a high chloride diffusion rate leads to premature corrosion of reinforcing steel. Recently, colloidal nano-silica has been shown to reduce the chloride diffusion rate in conventional concrete and to reduce drying shrinkage. Laboratory testing utilizing chloride ponding and non-steady state chloride migration confirm previous work. Lifecycle corrosion modeling demonstrates the utility of colloidal nano-silica for extending the expected lifespan of concrete in saltwater ports. In addition, a test case is presented at The Port of Marseille, France, where a 70 m long boat dock was placed in 2014 with the goal of testing low shrinkage, less permeable concrete treated with colloidal nano-silica as a preamble to renovation of the 6 km sea wall that protects the harbor.