Surface preparation, repair

The final section in this volume deals with applications of adhesion science. The applications described include methods by which durable adhesive bonds can be manufactured by the use of appropriate surface preparation (Davis and Venables) to unique methods for composite repair (Lopata et al.) Adhesive applications find their way into the generation of wood products (Dunky and Pizzi) and also find their way into the construction of commercial and military aircraft (Pate). The chapter by Spotnitz et al. shows that adhesion science finds its way into the life sciences in their discussion of tissue adhesives. 

The outstanding virtue of zinc-rich paints is simplicity in application. No special equipment is required and the operation can, of course, be carried out on site, large or small structures being equally suitable for treatment. While there is some evidence that the zinc-rich paints will reduce iron oxides remaining on the steel surface, proper surface preparation is as important here as with traditional paints if the best results are to be achieved. The main use of zinc-rich paints is to protect structural steel-work, ships hulls, and vulnerable parts of car bodies, and to repair damage to other zinc coatings. 

A demand of 200,000 of these 750 square inch body panels was assumed for a model year. Costs for painting are assumed to be constant and are not considered 1n this study. Rather costs are calculated to produce the body panel ready for the painting operation, Including any surface preparation and repair that might be required. 

Bond to the substrate and dimensional stability. The repair materials should have a good bond to the concrete substrate. This bond depends on the surface preparation and the use of a bonding agent (Section 19.2.3) but is also influenced by the properties of the repair material and the compaction during its appfication. 

From 1975 to 2000, environmental regulations led to avoiding the use of lead, chromates, and VOC. Thus coatings comprised multipart epoxies and high-solid epoxies. The use of epoxies requires extensive surface preparation, which results in higher costs of application and repair. 

ICRI (2004). Guideline for the Preparation of Concrete Surfaces for Repair Using Hydrodemolition Methods Technical Guide G03737 International Concrete Repair Institute Des Plaines, Illinois, USA. 

Coatings do not have the durability of the coated titanium-based anodes. However, they are less expensive, easier to apply and can be repaired and maintained easily. They are not suitable for continuously wetted abraded or trafficked surfaces. They require excellent surface preparation to get good adhesion. 

Cryogenic and hydrodynamic abrasive-free blasting have also been used for surface treatment of substrates before coating or adhesive bonding. Both processes are ideal when the abrasive medium itself provides a contaminant or when the collection and reprocessing of the abrasive are prohibitive. These processes are often used in the field for surface preparation of structures in the need of repair. 

Because encapsulation is only effective on clean, stable, solid, dry, dust-free surfaces, proper preparation and application are critical. The manufacturer s instructions should be followed carefully, including any directions for cleaning or deglossing the surface. Depending on the condition of the surface, preparation might involve repairs that generate lead dust, which should be done with the necessary precautions and protective equipment, by trained certified contractors. 

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