Common Failure Problems of Roadmarkings
Problem on Asphalt: Paint appears to fade, turn brown or wear away very quickly.
Paint applied too soon after asphalt has been laid. The volatiles in the bitumen need to “crack – off” to atmosphere – a process, which usually takes +- 14 days. If the paint film is applied before this process has happened, the volatiles are trapped under the paint layer and have a chemical effect on the fresh paint and its bond to the substrate, causing the paint to become brittle, crack and fail.
On slurry, curing term is much longer – usually 3 months is required to allow full curing of the surface. Any markings applied before this period will cause the paint to peel, actually lifting the top surface of the slurry with it.
Paint is not of good quality.
Check on source of paint, ask manufacturers to send the batch to SABS for testing, ask for proof of purchase from suppliers to ensure product used is correct.
Problem on Asphalt: Paint is of good quality, correctly applied onto cured surface, yet appears to “fade” or wear our quickly.
Check location of problem. The worst areas are where the traffic flow is having a turning and/or stopping action i.e. Stop lettering, stop bars, lettering/arrows at entrances or intersections. The problem is the shear – force being placed on the surface by the tyres of passing traffic causing greatly increased wear on the paint. Since the paint is applied at uniform spread rates across the entire job, the areas with this wear pattern will show up first.
None – regular repainting on high – wear areas.
Dirty surfaces. Dust or sand on the roadway surface gets between the vehicle tyres and the painted surface. This acts as “grinding – paste” between the tyre and paint and will cause a rapid wear rate on the painted markings.
Regular cleaning of surfaces by “Tenant” type cleaning machines, or hosing down and brooming to keep the surface clean. This problem also applies to concrete surfaces.
Problem on Concrete: Paint wears off to quickly or flakes off.
Preparations not correct. Was curing compound used/removed from surface? Was surface acid etched or sandblasted to provide a roughened surface for paint to adhere to? If not, why not?
Budget or ignorance? Client’s problem.
Remove all paint, etch or sandblast then re-paint.
Poor Paint – see as per asphalt above.
Dirty surfaces – see as per asphalt above.