Microbiologically Influenced Deterioration

Why deterioration and not corrosion In fact, the definition of corrosion is based on anodic and cathodic reactions. These reactions make sense only when applied to metals. Therefore, corrosion is a terminology that is normally used for metals. 

The annual global production of concrete has been reported to be second to water consumption by mankind. It is estimated that current consumption of concrete in the world is of the order of 11 billion metric tons every year. Also, about 10% of global production of steel goes to reinforced concrete applications.  

In the following section, microbial deterioration of concrete will be studied in more detail. 

FIGURE 4.30 Schematic presentation of orange bloom on a steel pile (not to scale). (With kind permission from Springer Science+Business Media Microbiologically Influenced Corrosion—An Engineering Insight, 2008, Javaherdashti R.) 

The possible impact of nonbacterial species such as algae on the biological deterioration of concrete has been explained in a previous section (see Section 4.5.1.2.1.1) and the related references given there, and it will not be repeated here. However, the impact of microorganisms on MID will be briefly described. 

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FIGURE 4.44 Stability of some polymers to microbial attack. (From Z. Filip and E.-H. Pommer, Microbiologically Influenced Deterioration of Materials, in Microbiological Degradation of Materials and Methods of Protection, European Federation of Corrosion Publications, Number 9, The Institute of Materials. Tabled. , 1992.)... 

Filip Z, Fornrncr E-H (contributors) (1992) Microbiologically influenced deterioration of materials. In Microbiological degradation of materials and methods of protection. European Eedeialion of Conosion Publications, Ninnber 9, The Institute of Materials... 

Gu J-D, Mitchell R (1995) Microbiological influenced corrosion of metal, degradation and deterioration of materials of space applications. Chin J Mater Res 9 (suppl.) 473-489... 

The review of inhibited paint coatings would be incomplete without mentioning coatings with Cl that inhibit biological corrosion. Microbiologically influenced corrosion is the deterioration of a metal by a corrosion process that occurs either directly or indirectly as a result of the activity of living organisms [85]. 

Resin is applied usually to the long chain of repeated units in the polymeric materials. This may be linear, branched, or cross-linked. Other constituents that contribute along with plastics as additives are plasticizers which improve the flexibility of the plastic, colored pigments, antioxidants, UV stabilizers, lubricants, mold-release agents, and sometimes biocides to inhibit microbiological deterioration. Additives influence the physical properties and resistance to deterioration in plastics. 

These microbial deterioration mechanisms represent the main categories of action. Several mechanisms are usually active jointly, and because these mechanisms may also influence other types of physical or chemical attack, the microbial share of the total attack can rarely be determined. Much too often, studies of deterioration mechanisms suffer from inadequate microbiological analysis (if it is done at all). If corrosion occurs in the range where life is possible, a microbial contribution needs to be taken into account and, hence, a microbiologist should be consulted [54,84]. 

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