AASHTO TP 130-18 pdf free download

AASHTO TP 130-18 pdf free download.Producing Draw Down Panels and Measuring the Coefficient of Retroreflected Luminance (RL) of Pavement Markings in a Laboratory Panel.
3. TERMINOLOGY 3.1. cofficient of retroreflected luminance, Rc- -the ratio of the luminance, L, of a projected surface to the normal illuminance, E, at the surface on a plane normal to the incident light, expressed in candelas per square meter per lux [(cd’m- )/x]. Because of the low luminance of pavement markings, the units commonly used are millicandelas per square meter per lux [(mcd’m ?)/lx]. 3.2. portable retroreflectometer- -an instrument that can be used in the field or laboratory for measuring the coefficient of retroreflected luminance, Rr. 4. SUMMARY OF TEST METHOD 4.1. This test procedure is used to predict the retroreflectivity of M 247, Type I glass beads in waterborne paint using a laboratory simulation of a field striping operation. Measured quantities of glass beads are dropped on top of a repeatable, uniform thickness of paint on top of a glass panel. When the paint is dry (after 24 hours), the retroreflectivity is measured using a 30 m geometry portable retroreflectometer. 5. SIGNIFICANCE AND USE 5.1. One of the characteristics of a pavement marking is the coefficient of retro reflected luminance, RL. Under identical conditions of headlight illumination and driver viewing, larger values of RL correspond to higher levels of visual performance at corresponding geometry.6.9 Reflectometer, 30 m geometry based on retroreflective measurements made with portable hand- operated instruments in compliance with ASTM E1710; . 6.10. Paint film thickness gauge, 5-30 mil (125-750 microns); and 6.11. Magnifying glass to check glass bead embedment. SAMPLING 7.1. A representative sample of glass beads meeting the requirements of M 247, Type 1, should be taken following T 346 procedures. The sampling shall be random in the following ratios: 100 lb (45 kg) of sample (in full bags) per 10,000 lb (4,535 kg) shipped. Upon arrival, material shall be reduced in a sample splitter to a size of approximately 2.2 lb(1 kg). CALIBRATION 8.1. The draw down procedure must be calibrated to ensure the correct thickness of paint is applied. The retroreflectometer must be calibrated in accordance with the manufacturer’s instructions. The retroreflectivity is very dependent on the paint formula in addition to the glass bead quality. Use a control paint to compare glass bead retroreflectivity (Sherwin Williams TM2 152 White). Note 1- Use of this specific control product was chosen by NCHRP research team to minimize the test variables and compare testing and final retroreflection performance. Users could consider alternate control traffic paints to suit their specific needs.9. PROCEDURE . 9.1. Obtain a sufficient quantity of glass beads meeting the requirements of M 247, Type 1 and sampled in accordance with sampling procedures in T 346. Use a large splitter to reduce the glass beads to a 2.2 lb (1 kg) sample size and then a small splitter to a sample size required for the test (Figure 3). Split sample to approximate weight for area of paint coverage on the substrate. For example, witha4 in. by 18 in. stripe at 15 mil with an application rate of 8 lb of beads per gal of paint, the bead sample size would be 17 g. This rate is equivalent to 0.236 g of beads per 1 in.2 of paint. 9.2. Pour beads from weighing dish evenly onto the bead support bar on top of the drop box (see Figure 4).AASHTO TP 130-18 pdf download.