The nation's infrastructure uses concrete for millions of miles of roadways and 600,000 bridges, many of which are in disrepair. With a project called viscosity enhancers reducing diffusion in concrete technology (VERDICT), Engineers at the National Institute of Standards and Technology (NIST) set out to double concrete's lifetime. The key is a nano-sized additive that changes the viscosity of the solution in the concrete at the microscale to slow down penetration of chloride and sulfate ions from road salt, sea water, and soils into the concrete. Infiltrating chloride and sulfate ions cause internal structural damage over time that leads to cracks and weakens the concrete.
The NIST researchers demonstrated that the additives can be blended directly into the concrete with current chemical admixtures, but that even better performance is achieved when the additives are mixed into the concrete by saturating absorbent, lightweight sand. Research continues on other materials as engineers seek to improve this finding by reducing the concentration and cost of the additive necessary to double the concrete's service life. The new technology could save billions of dollars and many lives.
