Initiation Time for Marine Structures

As mentioned above, the service life for chloride-induced corrosion is traditionally assumed equal to the initiation time and the period of propagation is not 

In the design process, the DuraCrete approach works as follows. The chloride surface content and the intended cover depth for the structure are identified. As a first step, concrete compositions are selected for appropriateness using input values for chloride-penetration resistance from a database. 

The next step is to test one or more of the selected concrete compositions using a compliance test that determines the chloride-penetration resistance. DuraCrete has adopted the rapid chloride migration (RCM) test for this purpose [21,25], which is a short-term test based on acceleration of chloride penetration by an electric field. 

The resistance of the selected concrete mix against chloride penetration is determined using this test and if necessary, the composition is modified until satisfactory values are obtained. At this stage, increasing the cover depth may also be possible. 

In the execution stage, quahty control is applied on site using simple methods with known correlation to the RCM test. For quality control with regard to chloride-penetration resistance, DuraCrete has adopted an electrical resistivity test, the two-electrode method (TEM), to be carried out on specimens kept in a fog room by a test described in Chapter 2. The correlation between the RCM and TEM values is based on theoretical and empirical work mentioned in Section 2.6 [26,27] and was documented for a wide range of concretes [28]. 

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