I often talk about pavement seal coating with people who want me to manage their properties in New Jersey. One of their biggest complaints is that the seal coating they put on in this market doesn’t last as long as it does in other markets they manage. Their complaint has some truth to it. In fact, it is correct in every way.
“The Rock is everything.”
Before we can figure out why pavement sealers don’t last as long in this market as they do in other nearby markets, we need to look at the type of stone used in the asphalt. In the southern parts of New Jersey, there are no quarries with deposits of aggregates that are used to make hot mix asphalt. People know that the “pits” or “sand pits” in the southern parts of New Jersey are full of sand (as they are referred to). Sand is dredged out of these sand pits to get high-quality sands, like the sand used in septic tanks and the sand used as a mineral filler in hot mix asphalt. Because of this, the rocks that are used to make hot mix asphalt are usually trucked in from quarries in Eastern Pennsylvania.
Argillite aggregate is used to make asphalt at several plants in southern New Jersey. In New Jersey, large deposits of argillite stone are dug up, cleaned up, and then trucked to asphalt plants in the area.
I’m not a geologist, so I don’t know why, but it seems like the argillite aggregate oxidizes much faster than the granite stone that is usually used to make asphalt in other parts of New Jersey.
Once argillite starts to oxidize (turn gray), it’s almost impossible to get pavement sealer to stick to it.
I was able to get a big national account as a client in my first year of business. The first job they gave me was to fix up a house in Voorhees, New Jersey. When I went to the project to get an estimate for seal coating, I saw that the parking lot was only a few years old, but the asphalt was very gray and smooth. When I asked my supplier, Neyra Industries, how to move forward, they told me to use a penetrating primer before sealing.
I did what they said, and the seal coating lasted for almost 5 years.
When you sealcoat is very important.
If you use pavement sealer within 18 months of putting asphalt down, you probably won’t have any problems with it sticking. During the first 18 months, most of the aggregate is still covered with asphalt binder. But once the asphalt starts to “gray out,” it will be hard to get the pavement sealer to stick in areas with a lot of traffic.
What does “paving prime” mean?
For pavement priming, a penetrating primer like Neyra Poly Prime, Maintenance Inc.’s Oxi-Bond, or Southern Emulsions’ Tarloc MPC is applied. The primer goes deep into the asphalt and helps the pavement sealer stick to the asphalt by using the primer as the glue to make a strong bond.
What happens if you don’t use a primer before seal coating on oxidized asphalt?
Simply put, the pavement sealer will wear away in less than a year in places that get a lot of use. The pictures below show a project in South Jersey to seal coat the pavement. The pavement was not primed first, so the pavement sealer wore off in less than a year.
Does the pavement sealer need to be primed in every parking lot in this area for it to last 3 years?
No. Priming will help the pavement sealer stick better to the asphalt, but it is not necessary for all seal coating projects. Instead of argillite, some asphalt plants in the area use granite stone. Even though granite still breaks down, it does so much more slowly than argillite. In the pictures below, you can see that asphalt was put down with two different kinds of aggregate. For the pavement sealer to stick well to the white, oxidized asphalt, it would need to be primed.
Is the extra cost of priming oxidized asphalt before sealing it worth it?
Choose for yourself. The pictures below show a seal coating job that was done 5 years ago in an area with a lot of traffic.