Corrosion Science and Corrosion Engineering

Since corrosion involves chemical change, the student must be familiar with principles of chemistry in order to understand corrosion reactions. Because corrosion processes are mostly electrochemical, an understanding of electrochemistry is also important. Furthermore, since structure and composition of a metal often determine corrosion behavior, the student should be familiar with the fundamentals of physical metallurgy as well.

Metal Cladding

The corrosion resistance of a substrate can be improved by metallurgically bonding to the susceptible core alloy a surface layer of a metal or an alloy with good corrosion resistance. The cladding is selected not only to have good corrosion resistance but also to be anodic to the core alloy by about 80 to 100 mV. Thus if the cladding becomes damaged by scratches, or if the core alloy is exposed at drilled fastener holes, the cladding will provide cathodic protection by corroding sacrificially.

Reinforced Concrete: CP

The pH of environment in concrete usually is greater than 12.5, which causes a passive film on the surface of embedded steel reinforcement. However, this protective film breaks down when concrete reacts with atmospheric carbon dioxide or chloride ions (present in aggressive environments such as seawater or de-icing salt) penetrate into the hardened concrete and reach the surface of reinforcing steel.

The chloride threshold

The chloride threshold for the initiation of pitting corrosion for a given structure depends on numerous factors. Major factors have been identified in the pH of concrete, i. e. the concentration of hydroxyl ions in the pore solution, the potential of the steel and the presence of voids at the steel/concrete interface.

Corrosion of Steel in Concrete: Prevention, Diagnosis, Repair

by: Pietro Pedeferri Rob B. Polder
Link:
http://rapidshare.com/files/17988933/Corrosion_of_Steel_in_Concrete.rar.html
or
http://ifile.it/mrsf2x

Chloride Attack

By Dr. J. P. Broomfield

Chlorides can be present in concrete for a number of reasons:

1. Contamination

-Deliberate addition of calcium chloride set accelerators
-Deliberate use of sea water in the mix
-Accidental use of inadequately washed marine sourced aggregates

Cathodic Protection of Steel in Concrete

by: Paul M. Chess
Link:
http://ifile.it/2blduc7
or
http://www.filefactory.com/file/d8607e/n/0419230106_zip
or
http://rapidshare.com/files/148336319/0419230106.zip

ASTM C867 Criteria for Corrosion of Steel in Concrete

Corrosion of Steel In Concrete 2nd Edition

by: Broomfield
Link:
http://ifile.it/g90yjkz

Degradation of Concrete

Degradation processes of concrete can be classified (Figure below) as: physical (caused by natural thermal variations such as freeze-thaw cycles, or artificial ones, such as those produced by fires), mechanical (abrasion, erosion, impact, explosion), chemical (attack by acids, sulfates, ammonium and magnesium ions, pure water, or alkali aggregate reactions), biological (fouling, biogenic attack) and structural (overloading, settlement, cyclic loading). In practice these processes may occur simultaneously, frequently giving rise to synergistic action.