ITEM 644  THERMOPLASTIC PAVEMENT MARKING

644.01   Description
644.02   Materials
644.03   Equipment
644.04   Application
644.05   Layout and Premarking
644.06   Basis of Payment

644.01  Description.  This work consists of furnishing and applying screed extruded thermoplastic pavement markings according to Items 641, 740.04, 740.09, and the additional requirements specified below.

644.02  Materials.  Furnish materials from the Department’s Prequalified List conforming to:

644.03  Equipment.  Use application equipment that includes a kettle for melting the thermoplastic and maintaining it at the proper temperature.  Equip the kettle with a thermostat to control the temperature of the melted thermoplastic and to prevent overheating.  Use equipment that continuously mixes and agitates the molten thermoplastic.  Ensure that the parts of the equipment that convey the thermoplastic from the kettle to the application point maintains it at the required temperature.

Furnish thermometers to measure the thermoplastic temperature in the kettle and at the point of application.

Ensure that the application equipment applies lines with a square end and can apply dashed lines.

If applying surface-applied glass beads, attach an automatic bead dispenser to the equipment so that the beads are immediately and uniformly dispensed over the marking surface.  Equip the bead dispenser with an automatic cut-off control synchronized with the cut-off of the thermoplastic material.

Ensure that the applicator portion of the equipment has a shoe that rides on the pavement and extrudes the thermoplastic.  Furnish application equipment for applying screed extruded markings that consists of dies of varying widths to produce different widths of lines.  Do not use pans, aprons, or similar devices that the die overruns.

Use equipment that ensures uniformity in the thickness and width of lines.  Use equipment that forms lines 12 inches (300 mm) wide or less by one application pass, and lines wider than 12 inches (300 mm) by no more than two passes.  Do not allow individual passes to overlap or to be separated by a gap greater than 1/4 inch (6 mm).

644.04  Application.  If applying thermoplastic to pavements that are less than a year old, ensure that both the pavement surface and the ambient air temperature at the time of application are not less than 50 °F (10 °C) and rising.  However, if applying thermoplastic to pavements that are older than a year, ensure that both the pavement surface and the ambient air temperature at the time of application are not less than 70 °F (21 °C) and rising.  Ensure that the temperature of thermoplastic at the point of application is at least 400 °F (204 °C) and not more than 440 °F (227 °C).  Apply thermoplastic at a thickness of 0.125 to 0.188 inches (3 to 5 mm).

Apply thermoplastic at the following rates:

Mechanically dispense glass beads uniformly at a rate of 8 pounds (4 kg) of beads for each 100 square feet (10 m²) of thermoplastic surface area.  Do not place beads by hand, except to arrows and letters, and to complete the end of a line.  uniformly dispense hand-applied beads over arrows, letters, and ends of lines at a rate of not less than 8 pounds (4 kg) of beads for each 100 square feet (10 m²) of thermoplastic surface area.  The Contractor may leave small gaps in arrows or letters resulting from template use unfilled.

If required, furnish primer, and apply it according to the manufacturer’s recommendations.  Use primer except on new asphalt pavement.

Do not apply thermoplastic by spraying.

Remove according to 641.10 any thermoplastic pavement markings that are more than 20 percent deficient in thermoplastic or beads and reapply the markings at the rates stated in 644.04.

644.05  Layout and Premarking.

A.     Initial Thermoplastic Installation.  In addition to the requirements specified in 641.06, only place auxiliary markings on new pavement.  The Contractor may place initial thermoplastic markings over work zone traffic paint markings.

B.     Subsequent Thermoplastic Installation (Repair or Refurbishing).  In addition to the requirements specified in 641.06, place markings over existing thermoplastic markings or portions thereof.  Before installing new thermoplastic, remove the existing thermoplastic markings by grinding so that the final combined thickness of the old and new thermoplastic is 0.125 to 0.188 inches (3 to 5 mm) and a clean, intact substrate is present.  Removal of existing thermoplastic markings shall be at the contract unit price for 644 Removal of Pavement Marking.

644.06  Basis of Payment.  The Department will pay for accepted quantities at the contract prices, or prices adjusted according to 641.11, measured according to 641.12, with the provisions specified in 641.13, and as follows: