Superior Resistance to Rebar Corrosion

Rebar in concrete is normally protected from corrosion by the high alkalinity (pH ~12.5–13.5) of the surrounding concrete, which forms a thin, stable passive oxide film on the steel surface. This film prevents rust as long as it remains intact. Corrosion occurs when this protection is lost, initiating an electrochemical process in the presence of moisture and oxygen.

One primary cause of this film loss and subsequent rebar corrosion is 'Chloride Attack'. Chloride ions (Cl⁻) from external sources—such as de-icing salts, seawater in marine/coastal environments, or contaminated aggregates / mixing water — penetrate the concrete and reach a critical threshold concentration at the rebar (~0.4–1% by cement weight). Chlorides locally disrupt the passive film and trigger pitting corrosion. This reaction is autocatalytic; it feeds itself, and the pits deepen rapidly with high local corrosion rates.

Rebar Corrosion Is Destructive and Expensive

Once initiated, corrosion products (rust) occupy 2 – 6.5 times the volume of the original steel, generating expansive pressure that cracks, spalls, and delaminates the concrete cover. This creates a vicious cycle: more cracks allow faster entry of destructive agents, accelerating deterioration, reducing bond strength, and compromising structural integrity. Rebar corrosion remains the leading cause of failure in reinforced concrete structures worldwide.

Aeternum Inherently Protects Rebar from Corrosion

Because its core chemistry offers vastly superior chloride binding capacity, part of its self-healing characteristics, Aeternum slows chloride diffusion into the concrete matrix. Here’s an example from a durability test (ASTM C876), contrasting concrete made with Aeternum and concrete made with OPC, at the same strength level.