Weathering of Two Anti-Graffiti Protective Coatings on Concrete Paving Slabs

Paula Carmona-Quiroga,Heather Viles,Robert Jacobs

doi:10.3390/coatings7010001

Abstract

The durability of anti-graffiti coatings is of special relevance since, unlike other protective treatments, they are not only affected by environmental factors, but also by often aggressive cleaning procedures. However, little is known about the long-term performance of either permanent or sacrificial coatings. This study explores the durability of two commercial coatings on concrete paving slabs under both natural and artificial ageing tests. The results of this research show that a fluorinated polyurethane and a crystalline micro wax weathered in less than 2000 h in a chamber with UVB radiation and after one year of outdoor exposure in the south of England. The former weathered by getting yellow and dark, and eventually, only under the accelerated ageing test, by losing its adhesion to the concrete slabs, and the latter weathered by getting dark, cracked and by reducing its water repellency under natural conditions. Cleaning efficiency of the protected surfaces from graffiti paints was therefore diminished, particularly when pressurized water spray was used on the polyurethane coated surfaces, since the treatment was partially removed and the concrete surface eroded.

Highlights

The development of anti-graffiti coatings is a growing challenge, since the problem of graffiti, which has social and economic impacts, needs to be counteracted
In New York where this phenomenon started in the 1960s, despite anti-graffiti initiatives graffiti has not yet been got rid of [1]
Anti-graffiti coatings can help to attenuate this problem by minimizing cleaning efforts and discouraging graffiti writers, through hindering the adhesion of paints to the surface of the materials and so making graffiti easier to remove, but their durability can be an issue

Summary

Introduction

The development of anti-graffiti coatings is a growing challenge, since the problem of graffiti, which has social and economic impacts, needs to be counteracted. In New York where this phenomenon started in the 1960s, despite anti-graffiti initiatives (including the application of these coatings) graffiti has not yet been got rid of [1]. Anti-graffiti coatings can help to attenuate this problem by minimizing cleaning efforts and discouraging graffiti writers, through hindering the adhesion of paints to the surface of the materials and so making graffiti easier to remove, but their durability can be an issue. Several different factors affect their integrity (thickness, gloss, adhesion) and their protective ability: including cleaning procedures (solvents, pressure water, etc.) and environmental conditions (temperature, UV radiation, etc.). On concrete—the building material par excellence in civil engineering works and a target for graffiti writers—a new factor can affect both the effectiveness and durability of the protective treatments and substrates. As a hydraulic binder of concrete, can chemically interact with anti-graffiti products, giving rise to modified hydration products [2]

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