Class III Dry and Wet (Rainy Night) Continuous Reflective Markings

1. Technical citation

Grade-3 wet-and-dry (rainy-night) continuous-reflective road markings—this solution addresses the drawbacks of using rainy-night glass beads (ceramic beads), which can only be applied by surface spreading and have a short reflective lifespan in rainy nights (with data showing a straight-line decay within 3 months). By adopting the large-sized D-HR glass beads ranging from 0.85 to 1.4 mm, as specified in the draft standard GB/T 24722 “Glass Beads for Road Markings,” these beads can be both internally mixed and surface-spread, effectively resolving the issue of persistent reflectivity in rainy nights and significantly reducing marking costs. (The market price of ceramic beads ranges from 130,000 to 180,000 yuan per ton, whereas the market price of 0.85–1.4 mm D-HR rainy-night reflective glass beads is only 6,000 yuan per ton.)

Note: For D-HR glass beads with a particle size range of 0.85–1.4 mm, the following rain-night retroreflective application methods are referenced from the U.S. Glass Bead Standard TYPE 3 and the Australian Glass Bead Standard D-HR Glass Beads—AS/NZS 2009:2006 (incorporating Amendment No. 1), Reconfirmed 2016, Glass Beads for Pavement-Marking Materials: When used in hot-melt pavement marking coatings, the inclusion rate shall be no less than 20%; when applied as a surface spread, the dosage shall be no less than 500 g/m².

2. Technical Requirements for Hot-Melt Road Marking Paints and Marking Techniques

1.1 Technical Requirements for Road Marking Paints

a. The total organic content in the coating shall be no less than 16%.

b. Brightness factor (white) ≥ 0.8, brightness factor (yellow) ≥ 0.5;

c. Compressive strength (MPa) ≥ 20;

d. Total content of internally mixed glass beads (by coating mass ratio) ≥ 30% (among which, glass beads with particle size of 0.85–1.4 mm D-HR shall account for no less than 20%, the roundness rate shall be no less than 90%, and those below 0.85 mm shall account for no less than 10%; other requirements shall comply with GB/T 24722 “Glass Beads for Road Marking”).

e. The roundness of the internal-mix glass bead assembly ≥ 85%.

f. Other performance indicators shall meet the requirements of JT/T280 “Road Marking Paint”;

g. Standard test conditions: ambient temperature 23 ± 2℃, relative humidity 50 ± 5% RH.

3. Technical Requirements for Retroreflective Brightness Coefficient

a. Initial testing (14 days after the opening of the traffic section; testing on non-open sections prior to completion and acceptance): The retroreflective brightness coefficient RL in dry conditions ≥ 350 mcd·m⁻²·lx⁻¹, and RL in wet conditions ≥ 175 mcd·m⁻²·lx⁻¹.

b. The retroreflective brightness coefficient measured at the end of the defect liability period shall meet the requirements specified in the “Standard for Quality Inspection and Evaluation of Highway Engineering” (JTG F80/1-2017): RL in dry condition ≥ 150 mcd·m⁻²·lx⁻¹, and RL in wet condition ≥ 50 mcd·m⁻²·lx⁻¹. (For detailed requirements, see Appendix Table 2.)

c. The retroreflective luminance coefficient tester shall use instruments that provide stable and reliable data. For the retroreflective luminance coefficient under wet conditions, instruments equipped with wet-condition functionality must be used, and the test light source must remain unobstructed.

4. Construction Process

a. The surface application of glass beads must employ a dual-spraying process, with a surface application rate of ≥0.7 kg/m². First, apply 0.85–1.4 mm D-HR glass beads, followed by the application of ※No. 3 glass beads. Each type of glass bead should account for 50%.

a. Melting temperature of reflective coating upon heating: ≥210℃.

c. The primer shall be clear and transparent (slightly yellowish) and have a solid content of ≥30%. For newly constructed asphalt pavements that are free from contamination, it is recommended not to use a primer. For other types of pavements, the primer application rate should be ≥0.15 kg/m². Line marking may be carried out only after the primer has dried.

5. Appearance Quality Requirements

a. The alignment of traffic markings shall not exhibit any bends or curves beyond those specified in the design requirements.

b. During the warranty period for quality defects, finished markings must remain firmly adhered, clearly visible, and uniformly colored, with excellent visibility both during the day and at night, as well as under wet conditions. c. During the warranty period for quality defects, thermoplastic reflective coatings applied to road surfaces shall show no noticeable fading or flaking.