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

Abstract

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.

Effectiveness of commercial anti-graffiti treatments in two granites of different texture and mineralogy

“…the estimated cost of cleaning graffiti in UK is over £1 billion a year [2]). Moreover, sometimes they may even be counter-productive, especially on porous materials such as concrete and natural stone [3][4][5][6][7]. On the one hand, chemicals can be retained in their pore systems (even after washing with pressure water) and this contamination can result in the precipitation of salts [3][4][5].…”

“…On the one hand, chemicals can be retained in their pore systems (even after washing with pressure water) and this contamination can result in the precipitation of salts [3][4][5]. On the other hand, mechanical procedures can open or create fissures or cracks which would favour water absorption and the adhesion of future graffiti paints [4][5][6][7]. For all those reasons and not only for aesthetic impact, graffiti is a major threat particularly on built heritage materials.…”

Evaluation of Accelerated Ageing Tests for Metallic and Non-Metallic Graffiti Paints Applied to Stone

“…However, although anti-graffiti protective coatings have been subjected to weathering tests in many studies (e.g., [2][3][4]); to our knowledge, the same has not yet been done for graffiti spray paint.…”

Microstructure Evolution of a Magnesium Phosphate Protective Layer on Concrete Structures in a Sulfate Environment

“…Magnesium phosphate cement (MPC)-based composites are favored with early strength and rapid solidification [4][5][6], small shrinkage [7,8], high adhesion to the old concrete [9][10][11], resistance to water [12][13][14][15][16][17], and strong chloride ion permeability [10,[18][19][20]. It can be coated over the new building structure or the old concrete structure for the purpose of protection.…”