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Consistent Retro Readings on Course Chip Seal and Seal Coats.
- 1. Presented by Eric Nelson, RoadVista www.roadvista.com | +1-858-279-8034 | © 2017 RoadVista
- 2. Today’s Agenda • Materials • Application • Inspection • retroreflectivity
- 3. Today’s Agenda • Materials • Application • Inspection • retroreflectivity
- 4. Material Basics of Traffic Paint • Most widely used material • Applied in liquid form • Spray system • Mechanical bond • Application vehicle evaporates • Solid components remain • Semi-durable marking
- 5. o Titanium Dioxide – White o Lead or Organic – Yellow o Alkyd o Acrylic o Calcium Carbonate o Clays o Water o Solvents Four Primary Components Pigment • Color • Opacity Binder (Resin) • Adhesive • Cohesive Filler • Adds Body Application Vehicle • Transports Solids • Evaporates
- 6. Paint Technical Specification Terms • Density – More Weight = More Solids • Water = 1 kg/liter – More Application Vehicle = Less Weight – Good quality paints will have higher density numbers • Viscosity – Also referred to as Thickness – Thicker ≠ more solids – Usually achieved with filler or special chemicals , which does nothing to improve the density of the paint • Total Solids % – What is left on pavement once dried (application vehicle fully evaporates) – High solids = longer lasting paint and better coverage • Dry Time – Time it takes to dry to no tracking • Pigment % – Amount of Coloring Component – Quality and Quantity Controls Tint, Brightness, Fade resistance, and Opacity • Opacity % – How much of the surface does not show through once dry – Primarily controlled by solids and pigment – High opacity = fewer coats needed
- 7. Waterborne vs. Oil-Based Paints Advantages of Waterborne • Environmentally Friendlier – Manufacturing, Application, Disposal – Low Volatile Organic Compounds – Most Lead Free • Easier Handling – Decreased Safety Hazards – Easier Equipment Cleanup – Minimal Transportation Restrictions • Better Overall Performance – Faster No Track Dry Time – Not as Affected by Humidity – More Durable Disadvantages of Waterborne • Equipment – Slightly More Wear – Larger Tip Size Required • Appearance – Flatter Appearance – Higher Track-ability – Holds Dirt & Debris • Reactions – Inferior Bond Strength to HCC – Known to Crack Asphalt at High Temperatures – Reacts to non-Stainless Steel Metals
- 8. Compatibility of Materials When Re-striping NEW→ ↓OLD Waterborne Paint Solvent Paint Epoxy MMA Thermo- plastic Waterborne Paint Solvent Paint Epoxy MMA Thermo- plastic
- 9. Today’s Agenda • Materials • Application • Inspection • retroreflectivity
- 10. Traffic Paint Equipment • Air pressurizes in sealed tank • Pressure forces paint out of tank • Additional air at gun tip atomizes paint for a smoother application • Durable and low- maintenance cost Conventional Air Striping Machine • Pump draws paint from tank • Paint forced into universal paint gun • Paint exits through RAC- type tip at high pressure • Sharper lines and easy operation Airless Striper Machine
- 11. Surface Preparation Ensure surface is free of dirt, dust and other contaminants. Remove poorly adhered existing markings or curing compound. Verify Pavement is Free of Moisture – Rain Forecast, Sprinklers Timer, Moisture Check, etc. Check that Ambient and Surface Temps are at 10⁰C & rising. Caution with Ambient Temps 32⁰C+
- 12. Paint Application • Thickness of 15-25 wet mils (0.380 – 0.635 mm) – Second application may be necessary on porous surfaces • Drop Glass Beads Immediately Behind Gun – Must have a 55-60% embedment • Protect the Line Until Dry to No Tracking • Caution - Parking Lots New Asphalt and Elevated Surface Temps: – Two Thin Applications • No Glass Beads
- 13. Tip Wear Spray Pattern Width 10” – 12” (25-30 cm) 8” (20 cm) 6” (15 cm) 4” (10 cm) Tip Size New 517 Worn to 419 Worn to 321 Worn to 223 Flow Rate .30 gpm (1.1 lpm) .40 gpm (1.5 lpm) .47 gpm (1.7 lpm) .57 gpm (2.1 lpm) Flow Rate Increase 33% 57% 90%
- 14. P A I N T A P P L I C A T I O N T R O U B L E S H O O T I N G WHAT YOU SEE POSSIBLE CAUSES WHAT YOU SEE POSSIBLE CAUSES Proper Application • Tip is clean and of proper size • Pressure / Power at proper setting • Paint proper thickness and complimentary to pump, power and tip settings Course Edges • Pressure / Power too low • Worn Tip • Paint too heavy or thick • Gun too close to surface Start/Finish Bulge or Splatter • Gun cable too loose • Worn tip • Pressure / Power too low • Paint too heavy or thick Edges Over Sprayed • Pressure / Power too high • Gun too far from surface • Too windy • Worn Tip • Tip too big • Paint too light or thin Pattern Surging • Pressure / Power too low • Suction leak • Filter clogged • Spray Hose too small • Worn tip • Paint too heavy or thick Too Narrow • Worn Tip • Tip too small • Gun angled, not perpendicular to surface • Pressure / Power too low • Paint too heavy or thick Spitting Gun • Tip is severely clogged • Filter clogged • Air system malfunction • Pressure / Power too low • Paint too heavy or thick; check for debris Too Wide • Gun too far from surface • Paint too light or thin • Tip too big • Pressure / Power too high Thin Edge, Thick Middle • Worn Tip • Paint too heavy or thick • Pressure / Power too low Too Thick • Application pace too slow • Tip too big • Pressure / Power too high • Paint too heavy or thick Thin Center, Thick Edge • Tip partially clogged • Pressure / Power too low Too Thin • Application pace too fast • Tip too small • Pressure / Power too low • Paint too light or thin Edge Lines Grooved • Tip Partially Clogged • Debris in Paint • Pressure / Power too low Gun does not Spray • Pressure / Power too low or off • Suction leak • Filter clogged • Pump not primed • Tip completely clogged • Paint too heavy or thick * Most likely causes are in bold redAll rights reserved © 2011 Professional Pavement Products, Inc.
- 15. T H E R M O A P P L I C A T I O N T R O U B L E S H O O T I N G WHAT YOU SEE POSSIBLE CAUSES WHAT YOU SEE POSSIBLE CAUSES Proper Application • Applied Straight • Has sharp edge • Correct Color, Width, Thickness, Bonding Line Cracks 1. Pavement is cracked (doesn’t affect durability) 2. Too cold 3. Temperature stress from overheating 4. Too thin No Adhesion, Bulges at Start 1. Material temperature too low 2. Road too gritty 3. Marking speed too fast 4. Road too cold Crumbly Edges 1. Material temperature too low 2. Moisture in Road 3. Overheated or scorched material Bubbles in Line 1. Moisture or solvent trapped in line 2. Material is overheated Jagged Endings, Drops within Gaps 1. Die not closing properly 2. Foreign objects caught in die Roughened, Pitted Line 1. Foreign objects in line 2. Foreign objects caught in die 3. Overheating forms crust Side Shadows 1. Heavily undulated surface 2. Die not riding evenly on substrate Crumbly Edges, Line Gaps 1. Material too cool 2. Material too thin 3. Application Speed too fast SPRAY APPL: Excessive Overspray 1. Too much atomizing pressure 2. Air leaking thru blow-back spray line Line Swollen; Skewed or Rounded Start 1. Material too hot SPRAY APPL: Hesitation at Start 1. Moisture or air in spray line 2. Material too hot 3. Material too cold Wavy Line 1. Strong road surface camber 2. Surface undulations 3. Poor operator direction SPRAY APPL: Lumps in Line 1. Material is to cool – comes out in globs All rights reserved © 2011 Professional Pavement Products, Inc.
- 16. G L A S S B E A D A P P L I C A T I O N T R O U B L E S H O O T I N G WHAT YOU SEE POSSIBLE CAUSES WHAT YOU SEE POSSIBLE CAUSES Proper Application • Evenly dispersed • Adequate coverage Proper Embedment Properly embedded at 55-60% Heavy Side 1. Defective bead dispenser 2. Insufficient amount of beads in applicator 3. Low bead gun pressure 4. Hand applied Too Deep Material too hot Bubbles in Line 1. Defective bead dispenser 2. Insufficient amount of beads in applicator 3. Low bead gun pressure 4. Hand applied Not Deep Enough Material too cold Roughened, Pitted Line 1. Defective bead dispenser 2. Insufficient amount of beads in applicator 3. Low bead gun pressure 4. Hand applied Excessive Beads Too many beads Crumbly Edges, Line Gaps 1. Defective bead dispenser 2. Insufficient amount of beads in applicator 3. Low bead gun pressure 4. Hand applied All rights reserved © 2011 Professional Pavement Products, Inc. 10%.................. 20%.................... 30%...................40%.................... 50%....................60%................ 70%................. 80%................... 90%
- 17. Today’s Agenda • Materials • Application • Inspection • retroreflectivity
- 18. Paint Inspection Components Appearance Within Specified Color Box Thickness within Specs Width within Specs Beads Embedment of 55-60% Retroreflectivity within Specs Adhesion & Cohesion
- 19. DEFECT: Premature Wear High traffic volume Thin initial application Rough pavement surfaces
- 20. DEFECT: Delamination Pavement improperly cleaned Ambient or surface temp too low during application Pavement too smooth Initial material applied too thick
- 21. DEFECT: Bead Loss Material applied too thin Beads applied too late
- 22. DEFECT: White Dull Finish Paint Defect Not Enough Titanium Dioxide Low Quality Titanium Dioxide
- 23. DEFECT: Appears Transparent Application Defect Material applied too thin Paint Defect Low Opacity / Pigment
- 24. DEFECT: Dirty Dust or Debris on material post application Poor surface preparation
- 25. Today’s Agenda • Materials • Application • Inspection • retroreflectivity
- 26. Retroreflectivity Must have a 55-60% embedment Anything less means the beads will pop out and be lost Anything more means you are decreasing the amount of light that can be reflected
- 27. Retroreflectivity What’s the deal with coarse chip seal, anyway? • Smooth surfaces make it easy to apply road lines • With rough surfaces, all sorts of things happen…
- 28. Retroreflectivity What’s the deal with coarse chip seal, anyway? Shadowing Aggregate Loss Bead Loss on Top Beads Falling Between Aggregates Poor Coverage of Backside - Centerlines
- 29. Retroreflectivity What’s the deal with coarse chip seal, anyway? • According to a recent study published by the Minnesota Department of Transportation – After 8 months, retroreflectivity of a line on chip seal decreased 36%-55% whereas the same line on hot mix asphalt concrete (HMAC) only decreased 0% to 7% • So why do drivers report the line looks good but the retroreflectometer gives poor readings?
- 30. Retroreflectivity Geometry 30-meter illumination 15-meter illumination Shadowing!!
- 31. HMAC Road
- 32. Chip Seal Road
- 33. Retroreflectivity What’s the deal with coarse chip seal, anyway? • In the previous 2 slides, you see the same edge line showing how it would appear on HMAC and then on coarse chip seal • It is visually obvious that the retroreflectivity of the line is very good at short distances from the vehicle, but it drops off much faster the farther away you go on the chip seal road
- 34. Retroreflectivity Geometry • So wouldn’t it be easier to measure at a 15-meter geometry? – Maybe, but not necessarily • There is no correlation with 15-meter and 30-meter measurements – Drivers, and autonomous vehicles, need as much long distance visibility as possible to have adequate reaction time to road deviations
- 35. Retroreflectivity How to achieve good 30 meter retroreflectivity on coarse chip seal • Use higher build materials, like thermoplastic, to fill in the valleys – Studies have shown lines with >90 mil (2.3mm) thickness have better long-term performance • On new surfaces, wait 2 weeks before applying new lines – Allows time for loose aggregate to wear off – Some agencies apply a thin stripe within a week (10- 15 mil, 0.25-0.38mm), then come back 3-4 weeks later to apply a proper stripe
- 36. Retroreflectivity How to achieve good 30 meter retroreflectivity on coarse chip seal State of Louisiana Thermoplastic evaluation
- 37. Retroreflectivity How to achieve good 30 meter retroreflectivity on coarse chip seal • Consistent retro readings on coarse chip seal and other rough aggregates is an ongoing problem worldwide • The best solutions for long term performance have been high-build lines that fill in the valleys and give the line a smooth surface • Research and evaluation is ongoing to improve performance
- 38. Acknowledgements • A special thanks to… – Greg Driskell, Professional Pavement Products – Adam Pike, Texas A&M Transportation Institute – Paul Carlson, Texas A&M Transportation Institute – Neal Hawkins, Center for Transportation Research and Education, Iowa State University – Omar Smadi, Center for Transportation Research and Education, Iowa State University – Texas Department of Transportation – Minnesota Department of Transportation – Louisiana Department of Transportation & Development • … for contributions made to this presentation
Editor's Notes
- Density –The weight of paint is mostly dependent upon solids. (see Total Solids %). Generally the more solids in paint, the higher the density and the more water the lighter the paint. Good quality paints will have higher density numbers Viscosity – The thickness of the paint. This is one that fools us most. We think that just because a paint is thick and hard to spray, it must be good. The paints thickness is adjusted with thickeners more so than solids. So thicker doesn’t always mean better! Total Solids % - The solids are basically what will be left on the pavement after the paint dries. For example if a paint has 46% solids that means that 54% of what you applied will evaporate during the drying period. Paint with a high % of total solids will be longer lasting paint that yields better coverage. Dry Time – The time that it takes the paint to dry with no tracking – This is very critical in the striping business. The faster the stripes dry, the faster you can open to traffic and less chance for problems created by weather or careless traffic. Pigment % - How much pigment (the coloring component) is in the paint. Quality and quantity of pigment controls the tint or brightness, fade resistance and opacity (see Opacity %) of the paint. If the pigment percentage is low the paint will look duller and results in a dry paint that is somewhat transparent. Poor quality pigment will cause the same in addition the stripe to be more susceptible to fading. Pigment is oftentimes the most expensive part of the paint, thus the primary corner that is cut to reduce costs. Opacity % - What percentage does the paint hide the surface once dried. Based on a scale of 1-100 (1 being completely transparent and 100 being opaque (covered)). This is controlled primarily by the solids and pigment. Large variances are rare between paints but even 2% is noticeable by the naked eye. The opacity of yellow tends to be consistently lower than white. Reducing the need of multiple coats.
- When beginning a project, choosing the right tip size and fan width is one of the most important decisions to make. If the tip size being used is wrong – by either choice or through wear – mil thicknesses will be too heavy and the finish will be unprofessional. The spray pattern chart demonstrates what happens as a tip wears. As wear occurs, the pattern size decreases and the orifice size increases. You will find that you have to make more passes to cover the same area. There is no standard rate of tip wear due to the variation of the abrasiveness of all coatings. Replace your tips after 100 gallons and minimize the opportunity for lost or substandard rentals.
- Optimum embedment of reflective beads is 55-60% assuring optimum retroreflectivity. Embedment of less than 50% may affect the longevity of the beads. Increasing embedment beyond 60% significantly decreases the amount of light that can be directed back to the driver. Not all beads will be embedded 55-60%. Some beads will be completely buried and others will be embedded less than 55%. A new line will generally have 70% of all the beads completely buried in the paint or other marking material.