advanced sealcoating

Advanced SealcoatingNPE, FEB 1, 2007, NASVILLE, TN

TOPIC HOW TO IMPROVE THE PERFORMANCE OF YOUR SEALER

Sealer CompositionMix DesignsCoverage Rates, Film ThicknessOptimum Cure & Film Formation

Presented by Girish Dubey President, STAR, Inc.

DESIGNED FORSEALCOATING PROFESSIONALSWHO WANT TOLEARN BEYOND THE BASICS OF SEALCOATINGS.

TO MAKE EVERY JOB LOOK & PERFORM THE VERY BEST.

PERFORMANCE IS THE CENTERPIECE

These facts are applicable to most water based coatings. All are very critical. GOOD QUALITY SEALER- Meets specifications, and has an established track record.RIGHT MIX DESIGN- Follow recommendations (manufacturer or job specs.). APPLY @ RECOMMENDED RATES- To deposit the right amount of sealer on the pavement. DRY & CURE UNDER RIGHT AMBIENT CONDITIONS- temperature, humidity, wind velocity.

PERFORMANCE THE CENTERPIECE

SEALCOATING BASICSSEALCOATINGS ARE ;

WATER-BASED COATINGS,A STABLE DISPERSIONS OF;a. BINDER (RT-12 or AC) is the backbone of the sealer and provides the protection to the pavement against the elements.- weather, salt, water, chemicals, etc.b. Clay and Fillers- Provide tensile strength, toughness, body and stability.c. Water- is the medium in which tar, clay fillers are dispersed. d. Emulsifiers, specialty chemicals- help dispersion, provide stability and special properties.

What Makes A Good SealerHow Can You Tell?1. Meets /or Exceeds Specifications: (ASTM, FEDERAL, FAA, etc.). 2. Proven Performance: Good Track Record.3. Dark, Chocolate Brown in Color- Indicating Fine Dispersion of Tar or AC.

4. pH - 7-8 - Below 7 slightly acidic- May be unstable,- Over 8- Alkaline- Prone to water sensitivity.

5. References, Comparative Evaluation

What Makes A Good SealerHow Can You Tell?4. pH of the sealer, 7-8: Lower Ph-slightly Acidic may induce instability.Higher pH-Alkaline- Prone to water sensitivity.5. References, Comparative Test Data.

TYPICAL SEALER COMPOSITION Undiluted (as manufactured)

Sheet1

SEALER COMPOSITION, %

BY WEIGHTBY VOLUME10.0733627251

BINDER3029.32.9126213592BINDER29.3

FILLER (CLAYS ETC.)198.90.8788159112FILLER (CLAYS ETC.)8.9

EMULSIFIER,ETC.11.30.1333333333EMULSIFIER,ETC.1.3

WATER5060.56.0024009604WATER60.5

TOTAL100100.09.9271715641

Sheet1

COMPONENTS BY WEIGHT, %

Sheet2

COMPONENTS BY VOLUME, %

Sheet3

MIX DESIGNSAN OVERVIEW.

SEALCOATING IS NEVER APPLIED IN ITS CONCENTRATED FORM GENERALLY MIXED WITH; 1. WATER- FOR FLUIDITY, WORKABILITY, 2. SILICA SAND- TEXTURING, - TRACTION, - FILLING VOIDS (profile, minor surface cracks),3. ADDITIVES (OPTIONAL)- PERFORMANCE BOOSTING (Flexibility, Toughness, Resistance to salt, water, chemicals..),- Drying Accelerator

MIX DESIGNSAN OVERVIEW.STANDARD SYSTEM: A 2-coat system Mix Design SEALCOATING (CONC) 100 GALWATER (30% BY VOL.) 30 GAL SILICA SAND /aggregate 200-300 lb TOTAL 145 GAL. Application Rates, Gal (conc.) Sealer/Sq. Yard: Ist. Coat- 0.10-0.12 IInd. Coat-0.08-0.10 TOTAL (2 COATS) : 0.18-0.20 GAL. /SQ. YARD.

MIX DESIGNS

Hazards in Altering the Mix DesignsFollow the recommended mix designsChanging the mix design may cause performance problems 1. WATER:A. EXCESSIVE- - Thinner Dry Film Thickness (D.F.T.) - Poor Durability, - Premature failure.Important ADJUST APPLICATION RATE TO MAINTAIN DRY FILM THICKNESS.B. NOT ENOUGH WATER- - Poor Flow, uneven appearance - The sealer may not wet out the surface properly for good adhesion.- Tracking is possible.

Hazards in Altering the Mix Designs

The coverage rate will have to be adjusted to account for the higher amounts of water to maintain the same Dry Film Thickness (DFT)

COMPONENTS.%



BINDER3029.32.9126213592BINDER29.3



WATER5060.56.0024009604WATER60.5

TOTAL100100.09.9271715641

COMPONENTS.%


Sheet2


Sheet3

MIX DESIGNS

EFFECT OF WATER ADDITION ON DFT.

GALLONSWATERDILUTION RATE, %DFTWFT

SEALER10060.52512.840.43.15625

WATER2525.03012.8423.28125

ADDITIVE10.63512.843.63.40625

5012.845.23.53125

TOTAL12686.16012.851.64.03125

SEALER, % BY VOLUME79%

% WATER68.3%

SOLIDS, % VOLUME31.7%

APPLICATION RATE OF THE MIXTURE0.23GAL/SQ.YD

39.7SQ.FT/GALLON

WET FILM THICKNESS (WFT), MILS40.4

DRY FILM THICKNESS (DFT), MILS12.8

MIX DESIGNS


GALLONSWATER

SEALER10060.5

WATER3030.0DILUTION RATE, %DFTWFT

ADDITIVE10.62514.345

3013.745

TOTAL13191.13513.245

SEALER, % BY VOLUME76%5012.745

% WATER69.5%6011.245



38.2SQ.FT/GALLON



MIX DESIGNS


GALLONSWATER

SEALER10060.5

WATER3535.0

ADDITIVE10.6

TOTAL13696.1


% WATER70.7%



36.8SQ.FT/GALLON



MIX DESIGNS


GALLONSWATER

SEALER10060.5

WATER4040.0

ADDITIVE10.6

TOTAL141101.1


% WATER71.7%



35.5SQ.FT/GALLON



MIX DESIGNS


GALLONSWATER

SEALER10060.5

WATER5050.0

ADDITIVE10.6

TOTAL151111.1


% WATER73.6%



33.1SQ.FT/GALLON



MIX DESIGNS


GALLONSWATER

SEALER10060.5

WATER6060.0

ADDITIVE10.6

TOTAL161121.1


% WATER75.2%



31.1SQ.FT/GALLON



MIX DESIGNS


GALLONSWATER

SEALER10060.5

WATER8080.0

ADDITIVE10.6

TOTAL181141.1


% WATER78.0%



27.6SQ.FT/GALLON



Sheet3

DFT

WFT

% WATER OF DILUTION

MILS, DFT

MAINTAIN DFT-REDUCE COVERAGE

DFT

WFT

% WATER OF DILUTION

MILS, DFT

DFT WILL DECREASWE WITH DILUTION

Chart1

14.345

13.745

13.245

12.745

11.245

DFT

WFT

% WATER OF DILUTION

MILS, FILM THICKNESS

DECREASE IN DFT AT CONSTANT WFT

Sheet1

DILUTION RATE, %DFTWFT

2514.345

3013.745

3513.245

5012.745

6011.245

Sheet1

DFT

WFT

% WATER OF DILUTION

MILS, FILM THICKNESS

DECREASE IN DFT AT CONSTANT WFT

Sheet2

Sheet3

MBD0057DE41.xls

COMPONENTS.%



BINDER3029.32.9126213592BINDER29.3



WATER5060.56.0024009604WATER60.5

TOTAL100100.09.9271715641

COMPONENTS.%

0

0

0

0


Sheet2

0

0

0

0


Sheet3

MIX DESIGNS


GALLONSWATERDILUTION RATE, %DFTWFT

SEALER10060.52512.840.43.15625

WATER2525.03012.8423.28125

ADDITIVE10.63512.843.63.40625

5012.845.23.53125

TOTAL12686.16012.851.64.03125


% WATER68.3%



39.7SQ.FT/GALLON



MIX DESIGNS


GALLONSWATER

SEALER10060.5

WATER3030.0DILUTION RATE, %DFTWFT

ADDITIVE10.62514.345

3013.745

TOTAL13191.13513.245

SEALER, % BY VOLUME76%5012.745

% WATER69.5%6011.245



38.2SQ.FT/GALLON



MIX DESIGNS


GALLONSWATER

SEALER10060.5

WATER3535.0

ADDITIVE10.6

TOTAL13696.1


% WATER70.7%



36.8SQ.FT/GALLON



MIX DESIGNS


GALLONSWATER

SEALER10060.5

WATER4040.0

ADDITIVE10.6

TOTAL141101.1


% WATER71.7%



35.5SQ.FT/GALLON



MIX DESIGNS


GALLONSWATER

SEALER10060.5

WATER5050.0

ADDITIVE10.6

TOTAL151111.1


% WATER73.6%



33.1SQ.FT/GALLON



MIX DESIGNS


GALLONSWATER

SEALER10060.5

WATER6060.0

ADDITIVE10.6

TOTAL161121.1


% WATER75.2%



31.1SQ.FT/GALLON



MIX DESIGNS


GALLONSWATER

SEALER10060.5

WATER8080.0

ADDITIVE10.6

TOTAL181141.1


% WATER78.0%



27.6SQ.FT/GALLON



Sheet3

00

00

00

00

00

DFT

WFT

% WATER OF DILUTION

MILS, DFT

MAINTAIN DFT-REDUCE COVERAGE

00

00

00

00

00

DFT

WFT

% WATER OF DILUTION

MILS, DFT

DFT WILL DECREASWE WITH DILUTION

Hazards in Altering the Mix Designs 2. SAND/ AGGREGATEEXCESSIVE (OVER 5,6 LB)-POOR FLEXIBILITY, BRITTLENSSPOOR ADHESION TO PAVEMENTPOOR ANCHORING,SAND ROLL OUTPREMATURE FAILURENONE OR VERY LITTLE (

Hazards in Altering the Mix Designs 3. ADDITIVES

- VERY SELECTIVE. - FOLLOW MANUFACTURERS RECOMMENDATIONS. - MAY NOT BE COMPATIBLE WTH THE SEALER.

EXCESSIVE (OVER 5 %):- WASTE OF MONEY- MAY ADVERSELY AFFECT PROPERTIES

NOT ENOUGH (LESS THAN 1 %):- INEFFECTIVE- MARGINAL PERFORMANCE IMPROVEMENT,- MOSTLY FOR NAMESAKE.

COVERAGE RATES AREA COVERED BY A GALLON OF (undiluted) SEALER

EXPRESSED IN 2 WAYS; 1. Gallons of sealer per square yard (gal./sq. yard) .Most commonly used. or2. Square feet area covered by one gallon of undiluted sealer.

A typical Coverage Rate for a two (2) coat application is- 0.18-0.20 gal (undiluted)sealer/sq. yard 1st Coat- 0.10-0.12 gal./sq. yd.2nd Coat-0.08-0.10 gal./sq. yd.

CRITICAL FACTORS FOR SEALER PERORMANCECOVERAGE RATE Sealer must be applied at the recommended coverage rate. It is assured by measuring:-WET FILM THICKNESS (W.F.T.) & -Calculating DRY FILM THICKNESS (D.F.T.)

2. CURE CONDITIONS: Must be right.TEMPERATURE (ground and surface) HUMIDITY OR RELATIVE HUMIDITY(R.H.)- Capacity of air to hold water @ ambient temperature.WIND VELOCITY

COVERAGE RATE CONFIRMATION-SEALER FILM THICKNESS STEP 1DETERMINE THE WET FILM THICKNESS (W.F.T.)Two methods: Calculate- Apply sealer on a known area (sq. feet) and divide gallons used, to get coverage in sq. ft./gallon. W.F.T. (IN MILS) = 1604/COVERAGE IN SQ.FT.GALLON.Discussed later.. Use a wet film thickness gauge

COVERAGE RATE CONFIRMATION-SEALER FILM THICKNESS

STEP-2

Determine the solids % by Volume

2. Calculate % solids by volumeWater (% by Vol.) = 101.2/155.9 = 65% Solids (% by Vol.) = 100% - 65% = 35%

Determine the wet film thickness Wet Film Thickness is expressed in mils 1 MIL= 1/1000 inch.

IF THE ;

a. COVERAGE IS KNOWN IN SQ. Ft./GAL. DIVIDE INTO 1604 (CONSTANT)

For example for 50 sq. ft/gal.,W.F.T. = 1604/50 = 32 MILS.

1604 = one gallon of coating covers 1604 sq. ft. in one (1) mil film thickness.

b. COVERAGE KNOWN IN GAL./SQ. YARD. MULTIPLY WITH 178.2 (CONSTANT)

For example 0.18 Gal./Sq. YardW.F.T. = 178.2 X 0.18 = 32 mils.COVERAGE RATE CONFIRMATION-SEALER FILM THICKNESS

Step-3

STEP 4

Calculate Dry Film Thickness (D.F.T.)

SIMPLEMULTIPLY WET FILM THICKNESS (W.F.T.) WITH SOLIDS % BYVOLUME)D.F.T = W.F.T. x % solids by vol.

EXAMPLED.F.T. = 32 mils x 0.35 = 11.2 mils.

COVERAGE RATE CONFIRMATION-SEALER FILM THICKNESS

DRYING & CURING of SEALCOATINGSDRYING- EARLY STAGES CURING-FINAL FILM SET UP SEALCOATINGS CURE THROUGH:

RELEASE OF WATER , THROUGH EVAPORATION

FILM SHRINKS IN VOLUME

PARTICLES OF THE BINDER AND FILLER ARE FORCED TO COALESCE

BINDER PARTICLES SOFTEN, FUSE AND ENVELOPE CLAY/FILLER PARTICLES.

CONTINUOUS SEALER FILM IS FORMED.

DRYING & CURING OF SEALCOATINGS

WE WILL DISCUSS

1. CURE MECHANISM

2. FACTORS AFFECTING CURE

TEMPERATURE- (SURAFCE & AMBIENT) RELATIVE HUMIDITY (% R.H.)

WIND VELOCITY

DRYING & CURING OF SEALCOATINGS1. Cure Mechanism:

Sealcoatings are water-based Water represents the largest portion of mix design (65%) They dry/ cure by releasing water. As water evaporates, the film shrinks in volume (to 35% remaining as dry film)

Binder (tar/asphalt) and clay/filler particles are forced in closer proximity

Binder particles touch each other and start fusing, thus enveloping clay/filler particles and bonding to the pavement

Continuous film results-Free of voids

DRYING & CURING OF SEALCOATINGSCURE MECHANISM:Volume Shrinkage in Film

Sealer Solids onlyWATER

DRYING & CURING OF SEALCOATINGS

CURE MECHANISM:Sealer wet film: Is multi-layered (composite) layer of many thin films

Each layer dries individually from top to bottom,

The release of water becomes more difficult as each layer dries Bottom layer takes longer to cure

The sealer may appear fully dry on the surface but the bottom layers may still be soft.

Allow sufficient drying.

DRYING & CURING OF SEALCOATINGS CURE MECHANISM:

2. CURE CONDITIONSFactors Affecting Drying

TEMPERATURE (ambient & surface)

Min. 500 F and rising is preferredA. Lower temperatures :

POOR FILM FORMATION. BINDER PARTICLES DO NOT SOFTEN PROPERLY TO FUSE AND FORM A CONTINOUS FILMIt may result in: POOR PERFORMANCE. SEALER PROPERTIES ARE LOST, SELDOM RECOVER.GRAY COLOR ON INITIAL DRYING.

Factors Affecting Drying (cont..)

B. Higher Temperatures: Over 90o F

WATER FLASHES OFF- IMMOBILIZING THE BINDER PARTICLES IN THE FILM. IT MAY RESULT INTO:

TRACKINGPINHOLINGSAND BALLINGDRYING IN THE WINDROWPOOR & STREAKY APPEARANCE

HumidityCapacity of the surrounding air to hold water Low Humidity: Very favorable for drying and cure. Will speed up drying.

High Humidity- Slow cure. Need more drying time.

WIND VELOCITY Will carry volatiles away.

HumidityWater Vapor in the Air Additional Notes

Relative Humidity (R.H.) : Capacity (%) of air to hold water vapor at a particular temperature.- Low R.H.- MEANS THE AIR HAS ROOM TO ABSORB MORE WATER VAPOR. 30% MEANS 30% of the capacity used up- 70% remaining.Good for sealer drying.- High R.H.- MEANS THE AIR HAS VERY LITTLE ROOM ABSORB MORE WATER VAPOR. 80% MEANS 80% of the capacity used up- 20% remaining.Poor for sealer drying.Air is like a blotting paper.- It will keep absorbing water as long as it is not saturated. The capacity of the Air to hold water vapor will change with temperature.Higher temperature Higher the capacity . Air will expand.

CAPACITY OF AIR TO HOLD WATER VAPOR @ SATURATION VS. TEMPERATURE

EVAPORATION RATE @ VARIOUS R.H. and TEMPERATURE

DRYING & CURING of SEALCOATINGSFavorable Conditions: Moderate Temperatures Low humidity Moderate wind velocity

Unfavorable Conditions: Low Temperatures High humidity Stagnant wind

GENERAL

Allow each coat to dry sufficiently, prior to applying the subsequent coating.

Take light vehicular traffic (application equipment - e.g. spray rig) scuffing and tearing.

ADDITIVES1. WHAT ARE ADDITIVES? DEFINITION TYPES

2. WHAT THEY DO & HOW THEY IMPROVE THE SEALER PERFORMANCE? FAA QUALIFYING TESTS

3. WHAT THEY DO NOT DO?COMPENSATE FOR POOR PERFORMANCE, IF EXCESSIVE WATER OR SAND IS USED.

DEFINITIONSADDTIVES ARE THE

Materials Added to Sealcoatings to ACCOMPLISH SPECIFICOBJECTIVESADDITIVES

ADDITIVESOBJECTIVESIMPROVED PROPERTIES:Flexibility and elongationToughnessWater resistanceResistance to chemicals, de-icing salts, oils, fats, grease etc..FAST DRYING:Even under not-so-ideal weather conditions. UNIFORM DRY COLOR:Under shade or shine.THICKENING:To accommodate large amounts of water.SAND OR AGGREGATE SUSPENSION: No streaking, NO SAND BALLING.

ADDITIVESfor PERFORMANCE BOOSTING

Have been used for the last 30-35 years.

Extensively used since mid-70s FAA specified

A/B (Acrylonitrile/butadiene) rubber latex for coal tar based sealers.

PERFORMANCE BOOSTING RUBBERIZING ADDITIVES FOR SEALCOATINGS

1. REDUCE TEMPERATURE SUSCEPTIBILITY; Reduce Tack and flow in summer & brittleness in winter months.

2. INCREASE TOUGHNESS;Greater resistance to abrasion, scour and wear. Better retention of aggregates.

3. INCREASE FLEXIBILITY AND ADHESION;Better anchoring of aggregates.

OTHER BENEFITS

THICKENING Due to pH alteration of the coating system.FAST DRYING Even under not-so-ideal weather conditions.

UNIFORM DRIED COLOR

RUBBERIZING ADDITIVESHOW DO THEY WORKRubberizing additives are water emulsion of polymer molecules.

Polymers (selected) have;Large chain length, heavily branched, Excellent resistance to chemicals, salts, water, weathering, etc.

When mixed with the sealer:Polymer chains in sealcoating materials, 1. Form a flexible and tough network of polymer molecules,2. Hold binder (tar, asphalt), fillers and aggregate uniformly.

AS THE SEALCOATING DRIES

Polymer network tightens within the film, it forces water out at a uniform rate, producing uniform dry color. Polymer fuses onto the tar (asphalt) particles thus improving;

ELXIBILITY, TOUGHNESSFUEL & CHEMICAL RESISTANCESAND SUSPESION AND ANCHORINGFAST DRYING.

THE POLYMER FOR THE ADDITIVEMUST BE RESISTANT TO:

WEATHERINGGASOLINE, OILS, FATSSALTSPETROCHEMICALSOTHER CHEMICALS..

WEAKNESS IN THE POLYMER (ADDITIVE) WILL INTRODUCE WEAK LINKS IN THE SEALER AND MAY CAUSE PREMATURE FAILURE.

Majority of the POLYMERIC ADDITIVES:

Produce Thickening, Speed up Drying Time, Produce Uniform Dry Color, Help to Suspend aggregates.

But they differ in their abilities to;

Reinforce the properties like, Flexibility, Toughness, Temperature Susceptibility etc.

Improve resistance to Chemicals, oils, fats, grease, de-icing salts, aromatic fuels etc.

ADDITIVESThe Right Additive Used in Right Proportion will;Reinforce the properties,Improve the overall performance

BUT WILL NOTMix design deficiencies caused by the excessive amounts of ;

Water- thinner dry films Sand/Aggregate- May not supply enough binder to satisfy the demand of the excessive amounts of aggregates used in the mix.

ADDITIVES: CONCLUSIONS

1.Acrylonitrile/Butadiene polymers (NBR TYPE) have the best overall properties. - They reinforce and boost the properties of asphalt and coal-tar based sealers.- better resistance to oils and other petrochemicals than Styrene/Butadiene polymers. Rest of the properties are similar.

2.Polyvinyl Acetate/acrylic co-polymers (PVAs) are not recommended due to poor water and alkali resistance. Introduce weak spots in the film when attacked by water. Useful only as thickeners and for speeding up drying.

advanced sealcoating

Documents

water sensitivity

waterbased coatings

right mix design

mix designsfollow

proven performance

performance problems

good quality sealer

mix designs hazards