HAND BOOK OF THERMOPLASTIC ROAD MARKING & MATERIAL

Compiled by Arun Bakhshiram Chopra

For high efficiency in using thermoplastic road marking material, thermoplastic material can be applied to concrete cement and asphalt road surfaces and is suitable for heavy traffic. It is grease, oil and tire marking resistant, has faster drying time and harder film surface.

o thermoplastic material is best applied on asphalt road surface suitable for normal traffic. It is easy to melt and to apply with good flow ability for more convenience.

Using thermoplastic material on the concrete road surface must have proper guidelines from the manufacturer about the melting and application procedures.

Procedures in melting and applying thermoplastic materials. Clean and empty the preheater from the old materials. Check agitator system inside the preheater tank if mechanically functioning well. Start melting with a little amount of thermoplastic, after it is properly melted, add more

material step by step to obtain good melting results. One bag to start melting and one bag at a time for reloading until 80% of the preheater tank capacity is filled.

Use thermometer gauge to control the standard temperature in melting and applying the thermoplastic.

Note:

These melting and application temperatures are suitable for normal air and weather temperature (30°C ± 5°C). For cold areas or countries (10°C ± 5°C), adjust the melting and application temperatures higher to suit the air and weather temperature of the area.

For thermoplastic materials packed plastic bags, open the first bag of material and load to the preheater without the bag, after it is properly melted, load the next bag of material together the first bag, for proper mixing & melting.

Stir constantly while melting and before application. Use strainer or filter in transferring the melted materials from the preheater to the

applicator machine to make sure that no small solid particles will get in to the applicator machine and to avoid abnormalities on the film surface after application.

The hot melted thermoplastic material shall not be applied if the road surface temperature is below 10°C or if it is wet. The road surface shall be warmed carefully by a road heater equipment so that when the material is applied, the road surface temperature will be much higher than 10°C to avoid line defects.

Remove or erase any old road markings like traffic paint solvent and water based, thermoplastic or cold plastic before applying new thermoplastic.

In case it could not be avoided to apply the thermoplastic at the top of old thermoplastic line marking, adjust the screeding shoe opening plus 1 mm.

Ex. : If the old thermoplastic line thickness is 2 mm. adjust the screeding shoe opening plus 1 mm. It means 3 mm. Then notice the drop on glass beads if they are sticking evenly on the film surface if not, adjust screeding shoe opening wider

Note : Only old thermoplastic line can be applied with new thermoplastic materials.

1. Wrong melting and application of the Thermoplastic may cause following problems:

1.1 Low temperature in melting and application of Thermoplastic will cause: Rough irregularities on the line surface. Fast drying. (Material will not be flexible but brittle) Sides of the line are not straight. Glass beads are not even on the line film. The quantity of area in application is lesser. The adhesiveness will not be so durable.

1.2 High temperature in melting will cause

Appearance of bubbles on the line film surface. Appearance of pinholes on the line film surface. Color shade changing. Line edges are not straight because of too much flow ability of the melted

material. Glass beads are buried deeply and it could not be seen because the film is

too soft. Difficult to control the thickness of the line Reflective value is poor.

2. The recommended quantity of materials to load in the preheater is 80% of the tank capacity, do not melt the material in the preheater in full tank capacity, it will cause:

Thermoplastic material half done or not melted properly. Lots of small solid particles will appear on the melted thermoplastic. Wrong viscosity. Rough surface will occur on the applied materials.

3. Always check the heating system of the preheater. (Gas system or hot Oil system)

L P G cylinder for gas pressure. Heating surface for soot deposit. Soot formation in the burner flame. L P G cylinder gas hose for any leaks or damage.

4. Avoid preheating the material for too long because over preheating might cause the materials to become flammable and explosive. (Not more than 3 Hours)

APPLICATOR MACHINE

A) Check and clean the applicator machine specially the screeding shoe and agitator system to be ready for use.

1. Balance setting for the equal thickness of the left and right side of line, sharpen the blade of screeding shoe before using.

NOTE : Rough film surface will occur if screeding shoe blade is not sharpened.

2. The speed of applicator machine must not be delayed to avoid rough film surface and crooked line.

3. The thickness setting of the applicator machine screeding shoe is 2.5mm. or it depends to the customer requirement.

4. The thickness of the line film must be 2.50mm. or it depends to the customer requirement.

5. If the setting is less than the recommended ones, problems might occur like: 5.1:- Glass beads will not stick to the line film strongly.5.2:- Reflectance value becomes poor.

b) Checking the gas system of the applicator machine : The heating at the back gas system must be even. Notice the fire color is green. The heating at the front gas system must be even but must have lower temperature

than at the back gas system. Notice the fire color is orange.

NOTE :

After 10 meters of the initial application of the Thermoplastic, it is necessary for the technician to check the shape of the line, the thickness, the adhesiveness of the applied materials to the road surface, the Glass beads to the Thermoplastic line, the smoothness of the line film surface and correct the defects immediately to avoid further damages.

Striking an axe to the Thermoplastic line to test the adhesiveness. Notice the cracked and the peeled off areas still have residue of the applied materials.

SPRAYING THE PRIME COAT

Spray prime coat to the road surface where the melted thermoplastic will be applied.

1. Clean the surface from dust, moisture and oil stains (Broom sweeping, brushing machine for good cleaning result or other cleaning equipment).

2. Use powder marking to draw the guideline before spraying the prime coat. 3. The required thickness of the prime coat is 125 microns. Do not spray the prime coat

too thick, it will cause(Longer drying time)(Bubbles popping up on the line surface.)

4. The width of the prime coat must be wider than the width of the Thermoplastic line one cm. side by side to avoid cracking and peeling off.

5. The new concrete surface must be properly aged prior to the application of prime coat and Thermoplastic wait for 2 weeks before application.

6. For the new asphalt surface, wait after one week before applying the prime coat or Thermoplastic. Black spots will appear on the line surface if applied with prime coat or Thermoplastic less than one week.

7. The drying time of the prime coat depends on the weather and Air temperature & stick the finger tip to test the drying time of the prime coat, if it is almost dry but still sticks to the finger tip, then that’s the best time to apply the melted Thermoplastic. Notice the air temperature in the evening until morning 10 a.m. is not hot that means longer drying time for the prime coat but at noon and afternoon 4 p.m. the air temperature is hot that means shorter drying time for the prime coat.

1. Problems caused by too wet prime coat in the application of Thermoplastic. Flammable. Under part of the Thermoplastic line is not dry. After 2-3 days bubbles popping up the line film.

Craters appear on the film surface of the line.

2. Problems cause of too dried prime coat in applying Thermoplastic.

Cracking and peeling off of the line film because the prime coat becomes glossy. It could not stick and could not hold the Thermoplastic strongly.

REMARK: Prime coat is suitable to any type of road surfaces, new and old cement concrete road surfaces, new (1 Month) and old (Over 1 Month) asphalt road surfaces. It’s not necessary to apply prime coat on the new asphalt road surface (1 month) because it is sticky and adhesive enough to hold the Thermoplastic strongly. It saves cost, time and effort too.

STORING THE THERMOPLASTIC MATERIALS1. Store in a well ventilated area with the temperature not more than 40°C. 2. Do not store in lots of moisture and wet areas.

Storage life is 2 years, storing the Thermoplastic more than 2 years will slightly decrease its physical properties and color shades quality.

TROUBLE SHOOTING FOR PROBLEMS IN THERMOPLASTIC APPLICATION

PROBLEM CONTENT CAUSE SOLUTIONPoor ability of the workers to apply the Thermoplastic

Limited experience and knowledge of Thermoplastic application

Lack of information.

Lack of work experience.

No appropriate training.

Study recommendations and trouble shooting for Thermoplastic application.

Accuracy on the required standard temperature of the preheater and applicator equipment in melting and applying Thermoplastic using

thermometer gauge.

Accuracy in timing and speed of applying prime coat and Thermoplastic, see problem III solution b.) Road test.

Color changing Yellow becomes yellow green.

White becomes dirty white

Over preheating of Thermoplastic. Scorching, resulting in thermoplastic becoming brittle and less durable, caused by over heating or too many reheats. Mixture of old and new materials.

Control heating temperature. Don’t melt the Thermoplastic inside the preheater very long (not more than 3 Hours) Empty the preheater content and put new materials if color change occurs.

Peel off Cracking then peeling off

Moisture, grease and oil stuck on the surface. Too dry prime coat.

Clean road surface from dust, moisture, grease and oil properly. Wait for the right timing between the wetness and the dryness of prime coat before applying the Thermoplastic.

Stick finger tip to the prime coat surface, if it’s almost dry but still sticks to finger tip, then that’s the best time to apply the melted Thermoplastic

Poor reflectance at night and wet road condition

Poor and uneven reflectance on some areas.

uneven dispersion of glass beads and

insufficient drop on glass beads.

Weak adhesion of glass beads on the marking.

Beads may be wet.

Adjust the dispersing rate of the glass beads dispenser. The sufficiency of the glass beads in the glass beads box. Try to install the  chain driven glass bead dispenser for uniform & sufficient dispensing of glass beads. Adjust the beads dispenser use only dry beads

TROUBLE SHOOTING FOR PROBLEMS IN THERMOPLASTIC APPLICATION

PROBLEM CONTENT CAUSE SOLUTIONCratering Hollow craters on the

line surface.Wet prime coat upon application of melted Thermoplastic.

Wrong viscosity of the molten Thermoplastic causing uneven amount.

Road surface Temperature is lower than 10°C

Melt the Thermoplastic to the required temperature Adjust screeding shoe opening to suit viscosity.

Cracks Cracks reaching the Cracks on some portion of Adjust the viscosity of the

road surface. the road surface.

Thermoplastic is too hard and can not cope with the softer asphalt road surface.

Uneven thickness causing some portion to crack on heavy traffic.

Ambient temperature exceeds 40℃ and the bituminous pavement exceeds 60℃ under the sun shine. The bituminous pavement becomes soft. The paint is harder than the road surface. It sometimes cracks when the wheels pass it.

Thermoplastic to increase its flexibility by controlling the temperature using Thermoplastic gauge.

Apply uniformly and evenly.

Apply drop on Glass beads to cover small cracks on the line film of Thermoplastic.

Select paint with a softening point compatible with the ambient conditions.

Pinholes Tiny holes on the Thermoplastic line marking.

High melting & application temperature

Expanded air inside open void of the road break through the wet Thermoplastic.

Road surface temperature is below 10°C.

Lower the temperature of the Thermoplastic

Apply drop on Glass beads to cover pin holes and other line defects.

Road heater equipment to warm the road surface before applying the melted Thermoplastic if the road surface temperature is below 10°C.

Bleeding Scattering of excess Thermoplastic at the sides of the line marking.

Over melting temperature than the required standard temperature.

Reach the required standard melting temperature and maintain this temperature then apply the melted Thermoplastic

Grooves and scratches

Open, deep and long stripes or grooves on top of the line marking.

Screeding shoe discharge point is choked with hardened Thermoplastic solids and foreign solid particles

Check the filter sieve.

Get rid of the foreign matters like small solid particles.

Clean and sharpen the screeding shoe blade.

TROUBLE SHOOTING FOR PROBLEMS IN THERMOPLASTIC APPLICATION

PROBLEM CONTENT CAUSE SOLUTIONBubbles Tiny bubbles

popping up on the line marking surface.

Insolated moisture evaporates and expands inside wet concrete.

Evaporation and expansion of moisture under road surface.

Solvent evaporates from

Apply Thermoplastic if the concrete is properly aged (wait for 2 weeks or more).

Millipore and blistering

Moisture remaining in the Millipore on the road surface

wet prime coat.

Road surface temperature is lower than 10°C.

High melting and application temperature.

Road not fully dry after rain, Wet primer,

Allow moisture to dry completely (new asphalt wait for 1 week or more).

Allow road / Primer to dry before thermoplastic application

Black Spots Big and small black spots on the line surface of the new asphalt road surface

New Asphalt road surface not aged properly. ( Min. 48 Hrs. After final asphalting)

Wait for one week before applying the prime coat and thermoplastic to the new asphalt road surface

Small solid particles

Small solid particles found in the melted Thermoplastic material and on the line surface after application.

Over loading the preheater tank more than 80% of the tank capacity and not constant agitation of the melted materials while melting and before application.

Wrong melting temperature.

No strainer used in transferring the melted materials to the applicator machine.

Load materials 80% of the preheater tank capacity and stir constantly while melting and before application. Use strainer to transfer melted materials to the applicator machine.

Edge concerns Rough around edges

Wavy, with irregular edges

Inconsistent bond, resulting in less durability, caused by material being applied too cold and/or too thin

Flow-out of material. Edge is not well defined, caused by material being too hot or too liquid, application pressure being too high, extrusion gate open too wide, and/or surface being too uneven

Make sure thickness is as specified check temperature of thermoplastic, it should be 180 to 200°C

Make sure temperature is 180 to 200°C adjust application equipment slow application rate on rough surface

TROUBLE SHOOTING FOR PROBLEMS IN THERMOPLASTIC APPLICATION

PROBLEM CONTENT CAUSE SOLUTIONDrop-on bead concerns Smooth, shiny

glossy

No beads, resulting in no retro-reflectivity caused by malfunctioning gun or beads sinking too deep.

Repair bead applicator increase bead application rate move point of bead application

Smooth with slight dimples

Glazed with iceOr Silver effect reflection

Drop-on beads sunk too low, resulting in lower retro-reflectivity, caused by material being too hotBeads sit too high, not adhered well, will wear off quickly, caused by material being too cold or bead gun being positioned too far from application point.

Increase bead application rate cool material, staying above 180°C

Make sure thermoplastic is between 180 to 200°C move point of bead application.

Reflective crack

Thermoplastic road marking requirements

Properties : The properties of thermoplastic material, when tested in accordance with ASTM D36/BS−3262−(Part I), shall be as below :

Luminance : White  : Daylight luminance at 45 degrees−65 per cent min.Yellow : Daylight luminance at 45 degrees−45 per cent min.

Drying Time : When applied at a temperature specified by the manufacturer & to the required thickness, the material shall set to bear traffic in not more than 15 minutes.

Skid Resistance : Not less than 45.

Cracking Resistance at Low Temperature : The material shall show no cracks on application to concrete blocks.

Softening Point : 102.5 ± 9.5°C

Flow Resistance : Not more than 25%

Yellowness Index (for white Colour) : Not more than 0.11

Storage Life: The material shall meet the requirements of these Specifications for a period of one year. The thermoplastic material must also melt uniformly with no evidence of skins or unmelted particles for the one year storage period. Any material not meeting the above requirements shall be replaced by the manufacturer/supplier.

Reflectorisation : Shall be achieved by incorporation of ballotini (reflective glass spheres), the grading & other properties of ballotini shall be as specified in Clause 803.4.3.

Marking : Each container of the thermoplastic material shall be clearly and indelibly marked with following information :

1. The name, trade mark or other means of identification of manufacturer. 2. Batch number. 3. Date of manufacture. 4. Colour (White or Yellow).

Maximum application temperature & maximum safe heating temperature.

Sampling & Testing:

The thermoplastic material shall be sampled & tested in accordance with the appropriate ASTM/BS method. The Contractor shall furnish to the Employer a copy of certified test reports from the manufacturers of the thermoplastic material showing results of all tests specified herein & shall certify that the material meets all requirements of this Specification.

Reflectorising Glass Beads :

The glass spheres shall be transparent, colourless & free from milkiness, dark particles & excessive air inclusions.

Roundness: The glass spheres shall have a minimum of 70 per cent true spheres.

Refractive Index: The glass spheres shall have a minimum refractive index of 1.50.

Free Flowing Properties: The glass spheres shall be free of hard lumps & clusters & shall dispense readily under any conditions suitable for paint striping. They shall pass the free flow test.

Test Methods : The specific requirements shall be tested with the following methods :

Free Flow Test : Spread 100 grams of spheres evenly in a 100 mm diameter glass dish. Place the dish in a 250 mm inside diameter desiccator which is filled within 25 mm of the top of a desiccator plate with Sulphuric acid water solution (specific gravity 1.10). Cover the desiccator & let it stand for 4 hours at 20 to 29 degree C. Remove sample from desiccator, transfer beads to a pan & inspect for lumps or clusters. Then pour beads into a clean, dry glass funnel having a 100 mm stem & 6 mm orifice. If necessary, initiate flow by lightly tapping the funnel. The glass spheres shall be essentially free of lumps & clusters and shall flow freely through the funnel.

The Contractor shall furnish to the Employer a copy of certified test reports from the manufacturer of glass beads obtained from a reputed laboratory showing results of all tests specified herein & shall certify that the material meets all requirements of this Specification. However, if so required, these tests may be carried out as directed by the Engineer.

Application Properties of Thermoplastic Material

The thermoplastic material shall readily get screeded/extruded at temperatures specified by the manufacturers for respective method of application to produce a line of specified thickness which shall be continuous & uniform in shape having clear & sharp dimensions.

The material upon heating to application temperatures, shall not exude fumes, which are toxic, obnoxious or injurious to persons or property.

Properties of Finished Road Marking :

The stripe shall not be slippery when wet. The marking shall not lift from the pavement in freezing weather. After application & proper drying, the stripe shall show no appreciable deformation

or discolouration under traffic & under road temperatures upto 60°C. The marking shall not deteriorate by contact with sodium chloride, calcium

chloride or oil drippings from traffic. The stripe or marking shall maintain its original dimensions & position. Cold

ductility of the material shall be such as to permit normal movement with the road surface without chopping or cracking.

The Colour of yellow marking shall conform to IS Colour No. 356 as given in IS :164 − 1981.

Application :

Marking shall be done by machine. For locations where painting cannot be done by machine, approved manual methods shall be used with prior approval of the Engineer. The contractor shall maintain control over traffic while painting operations are in progress so as to cause minimum inconvenience to traffic compatible with protecting the workmen.

The thermoplastic material shall be applied hot either by screeding or extrusion process. After transfer to the laying apparatus, the material shall be laid at a temperature within the range specified by the manufacturer for the particular method of laying being used. The paint shall be applied using a screed or extrusion machine.

The pavement temperature shall not be less than 10°C during application. All surfaces to be marked shall be thoroughly cleaned of all dust, dirt, grease, oil and all other foreign matter before application of the paint.

The material, when formed into traffic stripes, must be readily renewable by placing an overlay of new material directly over an old line of compatible material. Such new material shall so bond itself to the old line that no splitting or separation takes place.Thermoplastic paint shall be applied in intermittent or continuous lines of uniform thickness of at least 2.5 mm unless specified otherwise. Where arrows or letters are to be provided, thermoplastic compound may be hand sprayed. In addition to the ballotini included in the material, a further quantity of glass spheres, conforming to the above noted Specification shall be sprayed on the hot paint line in quick succession of the paint spraying operation. The glass spheres shall be applied at the rate of 250 grams per square meter area.

The finished lines shall be free from reggedness on sides & ends & be parallel to the general alignment of the carriageway. The upper surface of the lines shall be level, uniform & free from streaks.

Measurements for Payment

The painted markings shall be measured in Sq. meters of actual area marked (excluding the gaps, if any).

In respect of markings like directional arrows & lettering etc., the measurement shall be by numbers.