CASE STUDY OF COMMON DEFECTS AT SITE- Part 2

1. Bubbles

Problem: Bubbles formed under the surface of thermoplastic road marking lines.

Causes: Evaporation and expansion of moisture trapped in the surface of concrete.

Preventive Measures:

• Allow time for the road surface to dry completely.
• Ensure proper curing of the concrete surface.
• Do not apply thermoplastic immediately after rain or under dew conditions.
• Apply marking only after a minimum of 75 days of the finish coat of bitumen/concrete surface.
• Let primer dry completely before application.
• Ensure the surface temperature is above 9°C.

2. Colour Changes

Problem: White color changes to yellow or dirty white.

Causes:

• Overheating during preheating of thermoplastic.
• Mixing of old and new material.

Preventive Measures:

• Follow the manufacturer’s recommendations regarding temperature.
• Gradually increase and constantly monitor temperature to check viscosity and color.
• Clean the boiler after every batch.

3. Peel Off

Problem: Thermoplastic road marking lines peel off.

Causes:

• Improper adhesion to the road surface.
• Moisture, grease, or oil remaining on the road surface.
• Low road surface and ambient temperature.

Preventive Measures:

• Ensure proper curing of concrete or asphalt surfaces before marking.
• Remove existing road markings before applying new ones.
• Apply primer for better adhesion, especially on older surfaces.
• Ensure the road surface is thoroughly cleaned.

4. Grooves and Scratch Marks

Problem: Marks and striations seen on the surface of markings.

Causes: Clogged discharge point of the screed shoe with stones, dust, or other foreign particles.

Preventive Measures: Clean the shoe filter and adjust the angle of the applicator shoe.

5. Tyre Marks

Problem: Marks of vehicle tires appearing on road markings.

Causes:

• Insufficient curing time for thermoplastic.
• Traffic released too early.
• Bleeding of asphalt transferred from tires to road markings.

Preventive Measures:

• Allow a minimum of 75 days curing time for asphalt surfaces.
• Allow thermoplastic to cure for at least 2 hours before allowing vehicles.
• Wash the surface with water to remove temporary blackening.