Chemical Interactions in Reinforced Concrete Exposed at a Tropical Marine Environment

J M Mendoza-Rangel ,Jesús Alejandro Cabrera-Madrid,M Balancán-Zapata ,Patricia Quintana‐Owen ,P Castro-Borges

doi:10.1155/2015/864872

Abstract

Prediction of concrete structure behavior is complicated by diverse factors, including interaction between elements and concrete compounds, chlorides diffusion through concrete, and compounds formed by corrosion of steel reinforcement. These factors were evaluated in concrete test cylinders exposed to a tropical marine environment since 1993 (during 126 months). Electrochemical, chlorides profile, scanning electron microscope, and energy-dispersive X-ray spectrophotometry analyses were done and results compared. This suite of analytical methods accurately characterized reinforced concrete condition and generated data useful in developing prediction models of corrosion in concrete structures.

Highlights

Beginning in the 1980s, service life in reinforced concrete has been classified into two stages: initiation and propagation [1]
Prediction of concrete structure behavior is complicated by diverse factors, including interaction between elements and concrete compounds, chlorides diffusion through concrete, and compounds formed by corrosion of steel reinforcement
Steel reinforcement in concrete is protected against corrosion by a passive film that forms on its surface in response to the concrete’s high alkalinity [4]

Summary

Introduction

Beginning in the 1980s, service life in reinforced concrete has been classified into two stages: initiation and propagation [1]. These, among other factors, have led to development of new systems dividing concrete service life into stages [2] that address the phenomena in each stage and adjust them to the changing circumstances affecting reinforced concrete. If concrete pH falls below 9, or if chlorides content exceeds a certain critical value (i.e., the chlorides threshold), the steel’s passive film is lost and with it any protection against corrosion. Under these conditions, corrosion products are formed with an approximate volume five times that of the reinforcing steel, producing internal tensions that cause the concrete covering to fracture and fail

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