Nano-Additives Increase the Service Life of Concrete

摘要

A new method increases the service life of concrete structures by reducing the infiltration rates of deleterious ions. The key is a nano-sized additive that slows down penetration of chloride and sulfate ions from road salt, seawater, and soils into the concrete. Conventional approaches have focused on producing a more impermeable matrix by reductions in water-to-cementitious materials ratio, and the addition of fine particles such as silica fume. In the new approach, focus is shifted to changing the properties of the viscosity of the solution in the concrete at the microscale to reduce the speed at which chlorides and sulfates enter the concrete. Viscosity modifiers are used to substantially increase the viscosity of the concrete pore solution, and proportionally decrease the rate of diffusive transport. Thus, a doubling of the service life of structural concrete can be achieved by increasing the pore solution viscosity by a factor of two.