Frequently Asked Questions:
What are Pavement Sealers and why are they used?
Pavement sealers are emulsion coatings designed to extend the life of asphalt from damage caused by UV degradation, gas/oil, road salt and prevent water from entering into the pavement which causes freeze/thaw damage. Pavement sealers protect the natural characteristics of pavement, and help retain it’s integrity longer. Re-paving is expensive and uses a lot of our natural resources and energy, preventing this capital outlay is one of the benefits of sealing.
What are pavement sealers made out of?
Currently the majority of pavement sealers are an emulsion, a mixture consisting typically of water, clay, sand, polymers and usually less than 20% of either asphalt or refined coal tar.
How long have pavement sealers been in existence?
The products have been applied for over six decades and is a tried and true way to protect & beautify a pavement, ie. prolonging it from having to be repaved which consumes A LOT of energy (fuel to manufacture, deliver and install) and natural resources.
Are pavement sealers hazardous?
No, air sampling studies showed refined coal tar based sealers pose no inhalation risk to applicators, manufacturers or the general public. Research with insurance carriers (both in liability and workers comp) have supported the FACTS of no claim history.
What is the difference between refined coal tar based sealers and asphalt based sealers?
Asphalt emulsions have many of the same beneficial properties as refined coal tar based sealers except they lack the superior strength and resistance to petroleum, UV bleaching and road salts.
What are PAHs?
PAHs stand for Polycyclic Aromatic Hyrdocarbons (which are found in asphalt, vehicle exhaust and refined coal tar) and there is a very small percentage of PAHs in ready-to-use pavement sealers. PAHs are a group of chemicals that are formed during the incomplete burning of coal, oil, gas, wood, garbage, or other organic substances, such as tobacco and charbroiled meat. There are more than 100 different PAHs and they are ubiquitous in the environment. Among the oldest known carcinogens in humans, PAHs are released into ecosystems from atmospheric emissions/auto exhaust. Other sources of PAHs come from when you grill on the barbeque, car/truck tires, asphalt/pavement, power generation, etc. The typical person is exposed to PAHs daily. PAHs typically occur as complex mixtures and not found as individual compounds.
Coal tar sealants are not to be confused with coal tar pitch. Coal tar sealants use a refined coal tar known as Refined Tar 12 and is usually less than 20% of a finished/ready–to-use sealer. The Refined Tar on it’s own has not been shown to cause cancer in humans. Furthermore, any claim that “all” PAHs cause cancer is simply not accurate. With the exception of BAP (usually .002% of finished product), no other PAH has been characterized as a “known” human carcinogen by IARC, and most are not even “probable” human carcinogens.”
How are people exposed to PAHs?
Smoking cigarettes and eating smoked and charcoal broiled meats and fish are significant sources of PAHs. Humans also inhale contaminated air from car exhaust, incinerators, automotive tire decomposition and asphalt processing and use. PAHs are present in pavement sealants but are are not soluble and are bound in the coating (ie. they do not enter our water supply). Research conducted indicates refined tar sealants are NOT a significant source of PAHs found in urban environments.
Do the PAHs in refined coal tar based sealants separate from the pavement and contaminate sediment or water?
Research shows that PAHs do not actively migrate to subsurface soils or groundwater. The chemical nature of PAHs cause them to bind to asphaltic material and they do not leach out of these substances into ground or water. PAHs in raw water will tend to adsorb to any particulate matter and be removed by any filtration before reaching the tap. (Refined coal tar based sealers do not solubilize or selectively release individual components into the air or water).
While research on PAHs in pavement sealants is continuing, the best information currently shows that the level of PAHs found in pavement sealants is too small to be considered a significant source of PAHs found in the urban environment. Testing (Toxicity Characteristic Leaching Procedure) sometimes referred to as TCLP have shown sealer components do not leach into the environment.
A scientific review of the Austin study, commissioned by the Pavement Coatings Technology Council (PCTC) concluded that, in general, elevated PAHs were found only on the land (or parking lot) surface in samples with observable roadway material. Samples of soil and roadway runoff materials contained PAHs concentrations consistent with typical urban background soil levels. The PCTC review also concluded that it was not possible to directly link the PAHs concentrations that were found to pavement sealers, because of the many other sources of PAHs in the urban environment.