What Is Sealcoating
Protection & Preservation of Asphalt Surfaces - An Introduction to Seal Coating
PAVEMENT
The solid floor of any construction that carries traffic;
1. Vehicular:
High Traffic: Highways, Roads, Streets
Low traffic: Airport runways, aprons, parking lots, driveways, service stations
2. Pedestrian: Walkways
3. 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".
The Construction Varies with the traffic load requirements.
HISTORY OF ROAD CONSTUCTION:
Roads were constructed with Clay, Limestone and 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.
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 which kept the base dry and functional.
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.
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.
Why is it 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)
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 millions of years.
Like dissolves the like.
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 Sub-base Courses are Damaged
(load carrying capacity is lost)
↓
End of the Pavement
↓
Fresh Overlay or Replacement Needed in 6-7 Years or Sooner
WHY PROTECT???
- Save your major investment
- Enhance the value of your property
These pavements DO NOT need protection:
traffic bearing- highways, roads, streets
The advantage:
the rolling traffic brings up the fresh layers of asphalt continuously. Deterioration is not localized to the top surfaces.
These pavements DO need protection:
Low traffic, non-traffic bearing pavements: airport runways aprons, parking lots, service stations, driveways, walkways
The disadvantage:
Do not have the advantage of the life giving rolling traffic.
Top layers are under continuous attack by ultraviolet, gasoline, oils, chemicals etc.
REFINED TAR (MATERIAL OF CHOICE)
Refined tar has excellent resistance to:
- Ultraviolet Radiation
- petrochemicals, gasoline, oils, fat
- deicing salts & chemicals
- refined tar is a very complex mixture of (>5000) very stable
- closed ring, aromatic compounds
- Origin- entirely different than asphalt
Asphalt- decay of marine life
Refined tar is derived from coal
Coal- originates from the decay of plant life
(forests, bogs, vegetation...)
SEALCOATINGS COMPOSITION
Sealcoatings are water- based coatings
Formulated by dispersing:
- refined tar
- water
- clays and fillers
- surfactants/ emulsifiers
also called refined tar pitch emulsions (c.t.p.e.), they are;
- easy to apply (brush, squeegee, spray)
- easy to handle and store
- ease of water cleanup of tools
- no solvent fumes or hazards of solvent based coatings
Approved by
U.P. - federal aviation administration:
p-625, 627,628
U.S. governmental services admin.
R-P-355e (superseding r-p355d)
Local and state governments
APPLICATION
Pavement preparation: general guidelines
Prior to sealcoating:
1. A. New pavements:
allow to curing (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 with a brush.
Spray application acceptable if applied by an experienced applicator in a commercial setting.
MIX DESIGNS
Sealcoating is never applied in its concentrated form generally mixed with;
- water
- silica sand
- additives to enhance & extend performance
Workable consistency desired properties
We never exceed manufacturer’s recommended mix design! That’s why beckage sealcoating has maintained reputation and quality since 1994.
Beckage sealcoating meets or exceeds federal specification r-p-355e
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 residential 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