California Department of Transportation
Coronado Bridge Carquinez Bridge San Francisco/Oakland Bay Bridge Richmond San Rafael Bridge

Materials Engineering and Testing Services

Office of Roadway Materials Testing
Chemical Testing Branch

Frequently Asked Questions
(Or questions you should ask)

 

  1. The Thermoplastic State Specification numbers are so confusing, how can I understand them?
  1. There are four different State Specifications for lead-free thermoplastic.

 

State Specification

 

Application thickness

Material application temperature

Specification location

Supercedes

PTH-02SPRAY

Sprayable thermoplastic, can be alkyd or hydrocarbon binder

0.76 mm (0.030 inches) minimum.

177-205 ° C (375 ° F)

SSP 10-1.4X

PTH 392B and PTH 392A

PTH-02HYDRO

Hydrocarbon binder, low viscosity or extrude grade viscosity.

Stripes- 1.5 mm (0.060 inches) minimum.

Pavement markings- 2.5 to 3.8 mm (0.100-0.150 inches)

200-220 ° C (400-425 °F)

Section 84-2 SSP 10-1.4X

8010-01B,8010-21C-21, 8010-01 and 8010-01A

PTH-02ALKYD

Alkyd binder low viscosity or extrude grade viscosity.

Stripes- 1.5 mm (0.060 inches) minimum.

Pavement markings- 2.5 to 3.8 mm (0.100-0.150 inches)

200-220° C (400-425 °F)

Section 84-2 SSP 10-1.4X

8010-19A, 8010-21C-19 and 8010-19

PTH-02PROFILE

Profilable

thermoplastic

To match plans

 

SSP 10-1.X

PTH 499A

Variations in pavement surface texture will impact the amount of material required to achieve the minimum specified thickness above the plane of the pavement surface. To measure the thickness of the thermoplastic in the field you may use the following commonly found implements. Due to pavement surface texture, variations may require more material to reach the minimum film thickness.

 

Credit card- minus the embossed letters

0.76 mm

Quarter

1.5 mm

Two dimes

2.5 mm

Two quarters

3.2 mm

 

  1. The newly installed pavement striping is not very bright at night when illuminated by my headlights.
  1. Nighttime retro-reflectivity is dependent on the amount and location of the glass spheres and the quality of the paint or thermoplastic. If there are not enough glass spheres embedded in the thermoplastic then the line will not appear bright. Beads should be close enough to each other to appear to be touching. If the glass beads are shoulder to shoulder but they are sunk up to the tops of the beads, no light is reflected back from oncoming headlights. Ideally, the bead should be embedded 60 % for optimal retro-reflection and retention. The optimal striping truck speed is 10 mph; any faster than this will affect the finished product. Less than 60 % embedment and the bead will likely pop out very quickly. With 75-100 % embedment the light cannot enter the bead or return. Very commonly the contractor will apply the incorrect material at the improper thickness. If the molten thermoplastic has a very low viscosity (such as PTH02-SPRAY) and is applied too thickly (e.g. 1.3 mm (0.050 inches)) then the beads will sink too far before the thermoplastic cools. The good news is that the thermoplastic cools rapidly so you can inspect the line right away. Establishing a quality product very early on in the project will save you grief down the road.
  1. The contractor has just given me a Certificate of Compliance containing testing performed by the curing compound manufacturer.  Is it the proper curing compound specified for the job?
  1. Concrete curing compounds are listed in Section 90-7.01B of the Standard Specifications. The drums should be labeled as to the contents; which system and batch number at the very least. According to Directive CPD 01-13 the manufacturer of the curing compound is required to perform testing and document it on the COC.  The containers of cure should have the same batch number as on the COC.  The State is no longer tagging and releasing cure.  Bridge decks and approaches usually require a poly-alpha-methyl styrene resin type-curing compound. PCC paving is typically C309, 2B and lean concrete base is C309, 2A. Some projects require a non pigmented cure with fugitive dye, Type 1-D, Class A.  The pink fugitive dye will fade to clear when exposed to direct sunlight.  If the area is in the shade it may remain pink.  If you wish to send in the material to confirm that it still meets specified requirements, please ensure that it is well mixed before sampling. Improperly mixed material will be rejected as non-compliant and you will probably not get the results until the job is finished. If the material is applied at the proper rate, taking into account wind velocity and surface and air temperature, then the curing compound will minimize cracking due to rapid surface drying. Under extreme conditions (such as high wind and temperature) curing compound will not replace the water method of curing.
  1. Do I have to take a sample and send in for testing a cartridge epoxy if it is on the Qualified Products list?

A. Yes, send in one cartridge system with a mixing nozzle per 100 used on the project. Mail to the Transportation Laboratory, 5900 Folsom Blvd., Sacramento, CA 95819, Attn. Lisa Dobeck.