This document provides an introduction to sealcoating asphalt surfaces. It discusses how asphalt pavements are constructed but deteriorate when exposed to elements like UV rays and chemicals. Sealcoating forms a protective barrier over asphalt to prevent breakdown. Refined coal tar sealcoatings are most effective as they are very stable and resist deterioration from external factors. Regular sealcoating maintenance can extend the life of asphalt surfaces by 300% and prove more cost effective over time than repeated overlays without protection.
2. OBJECTIVES
1. To understand Asphalt Pavements , their;
Basic construction and make up,
Strengths and weaknesses,
2. Why they have to be protected ?
3. Which types of pavements can be
protected?
4. How can they be protected ?
5. Overall Savings and value to the property
owner.
Concept Of
SEALCOATINGS
3. ASPHALT PAVEMENT DEFINITION
PAVEMENT
The solid floor of any construction that carries traffic;
VEHICULAR :
High Traffic :Highways, Roads, Streets,
Low traffic : Airport runways, aprons, parking lots,
driveways, service stations..
PEDESTRIAN: Walkways.
CONSTRUCTION
The earth is removed and
- Filled with large aggregates (gravel, rocks, limestone- Base course
- Filled with smaller aggregates- Sub-base course
- Covered with hot molten asphalt (5-10% By weight) mixed with finer
aggregates- top course.
THIS TOP LAYER, SO TO SPEAK , IS THE " ROOF OF THE PAVEMENT".
TOP COURSE
(ASPHALT MIX)
SUB-BASE COURSE
BASE COURSE
THE CONSTRUCTION VARIES WITH THE TRAFFIC LOAD REQUIREMENTS.
4. A. PRIOR HISTORY OF ROAD
CONSTRUCTION:
Constructed with Clay, Limestone, Rocks
Functional but severely damaged by rain:
The aggregates absorbed water, became soft
and lost their strength to carry loads.
Roads were destroyed in no time.
B. ASPHALT AS A PAVING MATERIAL- Used since 18th.
century
A by-product of petroleum refining process was plentiful
and had excellent;
Adhesive (Gluing) properties,
Water repellency- will not let water penetrate the
pavement and damage it.
Flexibility- Pavement surface will flex under
traffic without cracking.
ASPHALT KEPT WATER OUT OF THE PAVEMENTS,
KEEPING THE BASE DRY AND FUNCTIONAL
Roads were destroyed in no time
5. WHAT IS ASPHALT
IT IS A BY-PRODUCT OF PETROLEUM REFINING PROCESS.
CRUDE PETROLEUM- ORIGINATED FROM THE DECAY OF
MARINE LIFE OVER MILLIONS OF YEARS.
CRUDE PETROLEUM
REFINING PROCESS (REMOVES
LIGHTER FRACTIONS
SOLVENTS, GASOLINE, OILS,
GREASE..)
RESIDUE : ASPHALT -CHEAP, PLENTIFUL
IT IS A VERY COMPLEX MIXTURE OF OVER 5000 COMPOUNDS.
ASPHALT AS A PAVING MATERIAL
SHORTCOMINGS
1. DETERIORATES UNDER SUN'S ULTRAVIOLET
RAYS
2. DISSOLVED BY PETROCHEMICALS
(GASOLINE, OILS, FATS, GREASE ETC.)
3. ATTACKED BY CHEMICALS, DEICING SALTS
ETC.
6. WHY ???
ATTACKED BY THE ULTRAVIOLET RAYS AND CHEMICALS
BECAUSE A MAJORITY OF THE COMPOUNDS
PRESENT IN ASPHALT ARE NOT STABLE. THEY
HAVE ;
• OPEN CHAIN STRUCTURE (ALIPHATIC) WITH
• SITES OF UNSATURATION (DOUBLE AND TRIPLE
BONDS)
O H H O H H H H H H H H H H H
HO C C C C C C C C C C C C C C C H
H H H H H H H H H
ATTACK
ASPHALTIC COMPOUNDS ARE:
ATTACKED AT THE SITES OF UNSATURATION
THE RESULTING PRODUCTS:
DO NOT POSSESS ANY OF THE PROPERTIES
OF THE ORIGINAL ASPHALT MOLECULES.
DISSOLVED BY PETROCHEMICALS
(GASOLINE, OILS, FATS, GREASE ETC..)
- SAME ORIGIN, SIMILAR MOLECULAR STRUCTURE.
- NATURAL AFFINITY, THEY COEXISTED IN NATURE
OVER MILLION OF YEARS.
LIKE DISSOLVES THE LIKE.
7. ASPHALT PAVEMENTS BREAKDOWN
THE TOP LAYER
(UNDER THE ELEMENTS OF WEATHER,
PETROCHEMICALS ETC. )
ASPHALT BINDER BREAKS DOWN
(GLUING PROPERTIES ARE LOST)
AGGREGATES COME UNGLUED, START RAVELING
SURFACE CRACKS DEVELOP
(WATER SEEPS IN, STARTS DAMAGING THE BASE)
CRACKS WIDEN
(FURTHER DAMAGE BY WATER)
BASE AND SUBBASE COURSES ARE DAMAGED
(LOAD CARRYING CAPACITY IS LOST)
END OF THE PAVEMENT
FRESH OVERLAY NEEDED IN 5-6 Year
8. HOW TO PROTECT ASPHALT PAVEMENTS
SEALCOAT !!!!
APPLY A COATING THAT WILL:
-NOT BE ATTACKED BY THE SAME ELEMENTS THAT DESTROY
ASPHALT
- FORM A BARRIER COAT IN BETWEEN ASPHALT SURFACE
AND THE ELEMENTS.
- KEEP THE EXCELLENT PROPERTIES OF ASPHALT " SEALED
IN " THE
PAVEMENT AND "SEAL OUT" THE DESTRUCTIVE ELEMENTS.
DESTRUCTIVE ELEMENTS "SEALED OUT"
ULTRAVOILT (UV) RADIATIONS
SOLVENTS
WATER
FUEL
SEALCOATING
ASPHALT PROPERTIES
"SEALED IN"
SUCH COATINGS ARE ALSO, RIGHTFULLY CALLED
"SEALCOATINGS”
9. REFINED COAL TAR
(MATERIAL OF CHOICE)
BECAUSE:
REFINED COAL TAR HAS EXCELLENT resistance to:
Ultraviolet Radiation
PETROCHEMICALS, GASOLINE, OILS, FAT
DEICING SALTS & CHEMICALS
REFINED COAL TAR IS A VERY COMPLEX
MIXTURE OF (>5000) VERY STABLE
CLOSED RING, AROMATIC COMPOUNDS
ORIGIN- ENTIRELY DIFFERENT THAN ASPHALT.
ASPHALT- DECAY OF MARINE LIFE
COAL TAR IS DERIVED FROM COAL
COAL- ORIGINATES FROM THE DECAY OF PLANT LIFE
(FORESTS, BOGS, VEGETATION..)
COAL COKE (FUEL FOR STEEL MILLS)
DISTILLATES, COAL TAR
FURTHER DISTILLATION
REFINED COAL TAR
CHEMISTRIES OF PLANTS ARE QUITE DIFFERENT TO
THOSE OF MARINE LIFE, THEREFORE , THE
DIFFERENCES IN THE PROPERTIES OF THEIR
DERIVATIVES.
10. SEALCOATINGS COMPOSITION
SEALCOATINGS ARE ALSO CALLED COAL TAR
PITCH EMULSIONS (C.T.P.E.), THEY ARE;
- EASY TO APPLY (BRUSH, SQUEEGEE,
SPRAY)
- EASY TO HANDLE AND STORE,
- EASE OF WATER CLEAN UP OF TOOLS,
- NO SOLVENT FUMES OR HAZARDS OF
SOLVENT BASED COATINGS
APPROVED BY
U.S. - FEDERAL AVIATION ADMINISTRATION:
P-625, 627,628
U.S. GOVERNMENTAL SERVICES ADMIN.
LOCAL AND STATE GOVERNMENTS
11. APPLICATION
PAVEMENT PREPARATION:
GENERAL GUIDELINES
PRIOR TO SEALCOATING:
1. A. NEW PAVEMENTS:
ALLOW TO CURE (OXIDIZE) TO RID OF SURFACE OILS,
PERFORM WATER BREAK TEST- NO SURFACE
BEADING
B. OLD PAVEMENTS:
REPAIR THE DAMAGED AREAS;
SEAL ALL CRACKS,
REMOVE DAMAGED AREAS- REPATCH WITH
FRESH ASPHALT MIX,
2. CLEAN THE PAVEMENT:
REMOVE DIRT AND DEBRIS,
SCRAPE OIL SPOTS AND PRIME WITH
OIL SPOT PRIMER.
3. APPLY SEALCOATING MIX:
FOG THE SURFACE WITH A MIST OF WATER
IF SURFACE TEMPERATURES ARE ABOVE
FORTY (40) DEGREES CELSIUS.
APPLY THE FIRST COAT WITH A RUBBER
SQUEEGEE, FOLLOWED BY A BRUSH FOR
THE 2ND. COAT.
SPRAY APPLICATION ACCEPTABLE IF APPLIED BY AN
EXPERIENCED APPLICATOR.
4. FOLLOW SAFE HANDLING PROCEDURES
DO NOT APPLY
BELOW 50° F
RAIN IN THE FORECAST
12. MIX DESIGNS
SEALCOATING IS NEVER APPLIED IN ITS CONCENTRATED
FORM GENERALLY MIXED WITH;
WATER,
SILICA SAND
WORKABLE CONSISTENCY
DESIRED PROPERTIES
STANDARD SYSTEM
(A 2-COAT APPLICATION SYSTEM)
Two coat application @ 0.18-0.20 gal/sq. yard.
IST COAT : 0.1-0.12 GAL OF SEALER/ SQ. YARD
IIND. COAT : 0.1-0.12 GAL OF SEALER/ SQ. YARD
MIX DESIGN
SEALCOATING (CONC) 100 GAL
WATER (30% BY VOL. OF THE SEALER) 30 GAL
SILICA SAND (AVG. 50-70 MESH), LB 200-300
TOTAL 145 GAL.
13. BENEFITS OF SEALCOATING
THROUGH REGULAR MAINTENANCE PROGRAMS:
1. SAVES MONEY FOR THE OWNER:
PAVEMENT LIFE CAN BE EXTENDED BY APPROX. 300%
2. PROTECTS AND PRESERVES THE
ASPHALT PAVEMENT
3. ENHANCES BUSINESS IMAGE
THE BLACK/ DARK SLATE COLOR OF THE
SEALCOATING WILL NOT FADE .
ASPHALT TURNS GRAY IN NO TIME.
4. CLEANING BECOMES EASIER.
DIRT AND DEBRIS ARE EASILY WASHED OFF BY RAIN.
5. TRAFFIC MARKINGS LAST LONGER.
