Title: Role of Concrete Mix Design in the Corrosion of Steel in Reinforced Concrete

Author(s): M. L. Sennour, H. G. Wheat, and R. L. Carrasqillo

Publication: Symposium Paper

Volume: 151

Issue:

Appears on pages(s): 147-162

Keywords: admixtures; air entrainment; concretes; corrosion; fly ash; mix proportioning; reinforcing steels; slump; strength; superplasticizers; Materials Research

DOI: 10.14359/4014

Date: 7/1/1994

Abstract:
The role of concrete in the corrosion of steel in reinforced concrete has received a considerable amount of attention in recent years. This is due to the recognition of the strong relationship between the nature of the concrete and its ability to protect embedded steel. Therefore, in addition to some of the commonly used corrosion protection methods that focus on either coating the concrete, increasing the cover of the concrete, coating the reinforcing steel, or the use of inhibitors that change the nature of the surface of the reinforcing steel, other methods should be included that emphasize the role of the concrete mix design. Paper deals with the contribution of concrete to the corrosion of reinforcing steels in reinforced concrete. Twenty-six mix designs that represent concretes that could be used today were selected for study. Variables included cement content, water content, amount and type of fly ash, the addition of superplasticizers, and air entrainment. Strength and macrocell current were measured as a function of chloride exposure. The results of 1 year of cyclical exposure to 3.5 percent NaCl solution revealed that the concrete influences the corrosion process greatly. Furthermore, modification of concrete can become another method of corrosion protection through a better understanding of the relationship between the corrosion process and concrete mix design.