Principles of Corrosion Engineering and Corrosion Control
Highly illustrated, with worked examples and definitions, this one-stop guide covers basic corrosion principles, and more advanced information for postgraduate students and professionals.
TABLE OF CONTENTS Principles of Corrosion Engineering and Corrosion Control
Chapter 12: Concrete Corrosion
12.1 INTRODUCTION
Concrete is the most widely used constructional material in the world. In spite of the impressive performance of concrete in several structures, the deterioration of concrete has assumed alarming proportion in harsh climatic conditions, such as the sea-coastal areas in Gulf countries. Concrete can be defined as the artificial stone produced when cement (usually Portland cement) is mixed with fine aggregate (sand), a coarse aggregate (gravel or crushed stones) and water.
12.1.1 APPLICATIONS
The intended application of concrete dictates the proportioning of major concrete ingredients, cement type, as well as particle size gradations of the fine coarse aggregates. Concrete generally provides to embedded steel a high degree of protection against corrosion by providing a highly alkaline environment which passivates the steel against corrosion. Corrosion of reinforcing steel can, however, proceed in some environments, suchasamarineenvironment, duetothepresence of chloride.
12.2 TECHNICAL TERMS
Definitions and a brief explanation of important terms related to concrete are given below to familiarize engineers with the applications of concrete.
12.2.1 AGGREGATES
Aggregates used in normal construction comprise granular materials, like limestone, dolomite, gravel, silica, etc. Table 12.1 shows the effect of properties and characteristics of aggregates which affect the characteristics of concrete. The salts in the aggregates, such as sulfates, chlorides and carbonates of calcium, magnesium and sodium, contribute to the corrosion of concrete.
| Concrete property | Relevant aggregate property |
|---|---|
| Durability: | |
| Resistance to freezing and thawing | Pore structure |
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