Bond Strength in Case of Cathodic Protection

The impact of electric current on the bond strength between the steel rein­forcement and concrete is considered to be a very important subject and researchers have studied it for several years. From a practical point of view, there are no notes for any impact of the cathodic protection on the bond strength. There are some structures that have been studied for about 20 years, and there has been little impact on the bond strength, as most bond strength is carried out by the ribs that exist in the deformed steel reinforcement.

When using cathode protection, no other protection method, such as mem­branes, additives, or painting, is needed. This reduces the total cost of the project and eliminates the cost of a deteriorating concrete structure or some of its members. The cost of repairing the concrete member may actually be higher than the cost of constructing it.

Advantages and Disadvantages of Different Types of Protection

TABLE 9.3

Method

Advantages

Disadvantages

Compatibility

Increase concrete

No cost increase

Limited

Yes

cover

Obtained from good design

Increased cover will increase the shrinkage crack

Nonpermeable

Dependent on

Requires additives

Yes, but silica fume must

concrete

good design

for good curing

be <10% cement weight

Penetrating sealer

Relatively low cost

Complicated

Yes

Waterproof

Well-known

Can be damaged

Yes, but only cathodic

membrane

technology

Difficult to fix

without fault

protection under the membrane

Epoxy-coated

Known technology

Problems in quality

Yes, without continuous

steel bars

Little maintenance

control under certain weather conditions

electric current

Galvanized steel

Easy use on site

Easily damaged by contact with nongalvanized steels

Yes, with higher level of protection

Stainless steel

Excellent for corrosion prevention

High cost

Yes

Corrosion

Calcium nitrate

Must know chloride

Yes

inhibitor

effect for small

chloride

concentration

amount

Long-term effect not known

Cathodic

Known technology

Regular inspection

protection

Long life of titanium anode

of the rectifier

Source: K. Kendell, and F. S. Daily. 1999. Concrete International Magazine 21(6).

In some structures, because of the special nature of their construction, you will find it difficult to make necessary repairs, so cathode protection is the best and only solution. In Table 9.3, you will find a summary of the methods of protection prepared by Keven in 1999, which gives the advantages and disadvantages of each method and the appropriateness of use with the cath­ode protection at the same time.