Several ways of preventing--or stopping--rebar corrosion are explored in this article.

WATERTIGHT CONCRETE AND PROPER COVER

The first defense against rebar corrosion should be a thick covering of dense, highly impermeable concrete. To produce this, minimize the water-cement ratio and consolidate and cure the concrete well.

NONCHLORIDE ACCELERATORS

The American Concrete Institute (ACI) claims that calcium chloride can contribute to corrosion. Because of this, ACI 318 now recommends limits on chloride ion content.

CATHODIC PROTECTION

Cathodic protection stops corrosion by reversing the electrochemical process that causes corrosion.

SEALERS

There are several products available: epoxy coatings; acrylic sealers; silane sprays; and linseed oil emulsions.

SPECIALTY CONCRETE OVERLAYS

Polymer concrete overlays are very impermeable to water and chlorides. Latex modified concrete (LMC) has higher bond, tensile, and flexural strengths than conventional concrete. LMC creates a barrier to water, oxygen, and corrosive chemicals. Adding silica fume to concrete slows carbonation and helps keep chlorides out, both of which reduce rebar corrosion. Iowa low-slump concrete--a high-cement, high-density, low-slump, air-entrained concrete--resists chloride penetration.

SPECIAL REBAR TYPES

Rebars completely coated with epoxy don't rust. Stainless steel rebars are very corrosion resistant, but very expensive. Some sources say galvanized rebar won't protect against corrosion long enough to justify their use. Others disagree. Because they don't corrode, glass-fiber-reinforced-plastic (GFRP) rebars have been used to control cracks in concrete structures exposed to highly corrosive environments.