Concrete idea

A method that is expected to double the service life of concrete is being patented by engineers at the US National Institute of Standards and Technology (NIST).

The key to the idea is a nano-sized additive that slows down penetration of chloride and sulphate ions from road salt, sea water and soils into the concrete. These cause internal structural damage over time that leads to cracks and weakens the concrete. A reduction in ion transport translates to reductions in maintenance costs and the catastrophic failure of concrete structures.

Past attempts to improve the lifetime of concrete have focused on producing denser, less porous concretes, but unfortunately these formulations have a greater tendency to crack.

NIST engineers took a different approach, setting out to double the material’s lifetime with a project called viscosity enhancers reducing diffusion in concrete technology (VERDICT).

Rather than change the size and density of the pores in concrete, they reasoned, it would be better to change the viscosity of the solution in the concrete at the microscale to reduce the speed at which chlorides and sulphates enter the concrete.