Destructive repair methods

The chosen method depends on the geometry and properties of the article. Table 2.2 lists many of the available non-destructive test methods for composites for initial quality control and for assessing damage and repair [8]. The following discussion highlights just a few of the more important techniques. 

Additional protection will be afforded by improved methods of non-destructive in-service inspection to demonstrate the integrity of sodium vessels and pipework and to detect incipient defects so that they can be repaired before they grow to cause leaks. Ultrasonic methods for inspecting welds in austenitic steels, and transition welds between steels of different composition, have been improved and further improvement can be expected. Components will increasingly be designed to facilitate in-service inspection. 

The key to the successful clinical application for hard tissue repair using the ECM-derived tissues is the preservation of bioactive factors and the elimination of any immunogenic substance remained in the source tissue during the decellularization or demineralized procedures. However, the current acellular methods normally cause loss of bioactive factors and/or the destruction of the ultrastructure due to the extreme conditions experienced during the process (Zimmermann and Moghaddam, 2011 Badylak et al., 2011). Therefore, further optimization of the ECM scaffolds is required in the following studies so as to ensure the safety and effectiveness of these promising scaffolds. 

The reasons described above lead to a conclusion that the interface may be the weakest element in the repair work, and as such, a source of future destruction. That is why there are many practical methods available to reinforce the interface and to ensure its high quality. Among the various known measures, special interface layers of the Portland cement paste, neat or reinforced with thin grids of steel or textile wires may be mentioned. Careful preparation of the surface of old concrete is always needed by cleaning and moistening. Intermediary layers may be prepared with increased Portland cement content, admixtures of polymeric materials or silica fume, or composed with epoxy resins. 

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