Mold and mildew growth within Navy ships is a significant issue across the fleet. To investigate this issue the Environmental Security Technology Certification Program (ESTCP) and the Strategic Environmental
Research and Development Program (SERDP) funded an investigation into the prevalence of mold in the fleet, with the end goal of developing solutions to remediate and prevent future mold growth. Thus
far, mold and coating data was collected from 26 ships across 6 geographic locations. These mold samples have been analyzed to determine the most common species and highlight those that are toxigenic.
Construction companies will experience a crisis at some point during its existence.
This is especially true for construction companies, where it is not a matter of “if” one will happen but “when” it will happen. A crisis is the sudden occurrence of any unplanned or unexpected event that causes harm to the project /company, employees, or the public. The crisis could be a medical/safety emergency, a natural disaster, or personnel crisis dealing with unethical or illegal activities.
Construction companies must always operate with a “better safe than sorry” mindset. A proactive way to do so is to ensure that there is a crisis management plan in place.
The use of duplex coating systems (hot dip galvanizing or thermal spray coating with one or more liquid-applied coatings) for long term protection of structural steel is becoming more mainstream in many industries. This paper describes the advantages of employing duplex coating systems as well as some important considerations for designers prior to specifying their use. It also highlights an ongoing initiative to help agencies more efficiently and effectively use duplex coatings on steel bridges by developing guidelines, standards, and other materials.
Since the 1980s, fluoropolymer resin technologies have offered the possibility of a quantum improvement in topcoat decorative properties- gloss and color retention- compared to conventional acrylic and polyester resins. Specifiers of both protective and architectural restoration coatings systems have expressed a need for a new SSPC standard for field-applied fluoropolymer topcoats, particularly for bright and saturated colors.
Zinc-rich primers, with zinc dust loadings of 80-85% by weight in the dry film, are often the preferred primer during new construction of assets placed in environments with high atmospheric corrosivity. Coating standards such as SSPC-Paint 20 and ISO 12944 demand that zinc-rich primers contain at least 65% and 80% zinc dust by weight in the final dry film, respectively. Traditional zinc rich primers need this high zinc loading to achieve galvanic protection of steel. New technology allows us to develop zinc primers with a lower content of zinc and/or different zinc morphology than dust to provide similar or better corrosion protection to the steel.
A continuing problem with coatings applied to sharp edges of a structure is the corrosion that often develops at the apex of the edge. The conventional wisdom is that the reduction of film thickness, due to coating pulling away at the edge during the curing of the coating, is the primary cause for the onset of corrosion. This theory, however, is not necessarily correct, both from a mechanistic and practical point of view.
Zinc-rich coatings have long been known to provide excellent corrosion resistance in highly corrosive environments, in general,inorganic zincs for new construction and organic zincs for maintenance. A recent trend has been toward zinc-rich coatings with reduced levels of zinc dust. An SSPC committee formed to revise SSPC Paint 29, Zinc Dust Sacrificial Primer, Performance Based, to reference performance only, removing reference to minimum zinc dust level.
Zinc rich coatings have long been used in the protective coatings industry as one of the primary means of steel substrate protection against corrosion. The primary protection mechanism has historically been galvanic sacrificial loss of zinc metal and the simultaneous formation of protective zinc oxides and salts. Various standards and customer specifications exist to ensure that the coating will provide the necessary corrosion protection for the life of the asset.
We studied the corrosion resistance for topcoat systems made using a solvent-borne 2K fluoroethylene vinyl ether (FEVE) polyol blended with different acrylic resins. The topcoats were applied over primed steel substrates. The primers consisted of zinc-rich (for 2-coat) and zinc-rich/epoxy mid-coat (for 3-coat) systems. Standard, salt fog (ASTM B 117), cyclic Prohesion (ASTM G85 Annex A5) and EIS (electrochemical impedance spectroscopy) test methods were used to determine corrosion resistance. The blended system performance was compared against FEVE, acrylic, polyurethane, and polysiloxanes controls.
Cementitious repair mortars are commonly used to rehabilitate deteriorated wastewater concrete infrastructure prior to the application of high-performance lining systems. These repair mortars occasionally receive a broom finish creating a “profiled” surface prior to the application of a trowel- or spray-applied protective lining system. Other recommendations require that that the cementitious mortars receive a blasted surface to impart a mechanical profile prior to topcoating with a similar lining system. In the following paper the author summarize the results of an investigation to quantitatively assess adhesion of a protective lining when applied to a broom finish surface verses a blasted surface.
The author will present on the various generic coatings technologies available for lining concrete and discuss the advantages and disadvantages of each one. Discussion will include epoxy, polyurethane and polyurea technologies. The goal of the presentation will be to provide some guidance to the attendees on when is the right application to select each technology as part of a specification.
With coating and lining of concrete, while it may seem like a simple, novel task, there are always challenges. Even though concrete may be one of the largest construction materials used today, it is a complex structural matrix that can be ever changing even in a single placement. The need for coating concrete to either waterproof, or extend the life of the structure is not new to our industry.