A recent industry study published in Construction and Building Materials (September 2025) took a close look at how tack coat affects the long-term performance of asphalt pavement. Tack coat is the thin layer of asphalt emulsion applied between old pavement and a new asphalt layer. Its job is simple but critical: bond the layers together so the pavement behaves like one solid structure instead of two separate layers that can slip, crack, or fail prematurely.
In this full-scale field study, researchers built real roadway test sections using two different methods:
- the traditional process, where tack coat is sprayed, allowed to set, and then covered with asphalt, and
- a newer method using specialized equipment that sprays the tack coat and lays the new asphalt at the same time.
After construction, the pavement was cored and lab-tested for strength and bonding performance between layers. The results showed that when tack coat is properly applied, both methods provided strong bonding between layers. In fact, the test sections showed similar resistance to shearing and bending forces, two key measures of how well pavement holds together under traffic. In simple terms, the layers stayed bonded and worked together, which helps prevent slippage, cracking, and early failure.
The study also confirmed something experienced contractors already know: the type of tack coat used and the quality of application matter. Polymer-modified tack coats generally performed better than basic emulsions, and consistent, well controlled application produced more uniform bonding across the pavement.
Why does this matter to property owners and facility managers?
Because most pavement failures don’t start on the surface, you can’t see them until the damage is already done. Poor bonding between layers leads to premature cracking, shifting, and delamination, which means repairs and resurfacing happen much sooner than they should. The study reinforces that tack coat isn’t just a “step in the process”, it’s a structural component of the pavement system.
The takeaway is simple: customers should work with contractors who understand the importance of tack coat and apply it correctly, with the right materials, proper coverage rates, and the right equipment. At American Paving, we follow industry-backed best practices for tack coat application because we know that what’s between the layers is just as important as what you see on the surface. Choosing the right contractor today can add years to the life of your pavement and reduce long-term maintenance costs.
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Did you know there’s a “glue” that helps your asphalt last longer?
It’s called tack coat, the thin bonding layer between old pavement and new asphalt. Most people never see it, but it plays a huge role in how long your parking lot or roadway holds up.
A recent industry study published in the journal Construction and Building Materials found that when tack coat is applied correctly, asphalt layers bond together and perform as one solid structure. The researchers tested real pavement sections and confirmed that proper tack coat application helps reduce early cracking, shifting, and layer separation; all common causes of premature pavement failure.
The study also showed that the type of tack coat used and how evenly it’s applied can make a measurable difference in performance. In short, skipping steps or cutting corners during this phase can shorten the life of your pavement and lead to higher repair costs down the road.
Takeaway for property owners:
Not all paving jobs are created equal. The details you don’t see can make the biggest difference in how long your pavement lasts.
At American Paving, we follow proven, industry-backed best practices from the ground up, because what’s between the layers matters just as much as what you see on the surface.
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Why Tack Coat Matters in Pavement Performance
Tack coat is a thin bonding layer placed between existing pavement and new asphalt. Although it isn’t visible after paving, it plays an important role in how well pavement holds together over time.
A study published in the journal Construction and Building Materials examined how tack coat affects bonding between asphalt layers. Researchers built and tested full-scale pavement sections and found that when tack coat is applied properly, the asphalt layers work together as one structure instead of acting as separate layers. This bonded behavior helps reduce early cracking, shifting, and layer separation, which are common causes of premature pavement deterioration.
The research also showed that the type of tack coat material and the consistency of application can influence performance. More uniform application resulted in more consistent bonding across the pavement surface.
Why does this matter?
Many pavement problems begin below the surface and are not immediately visible. Weak bonding between layers can lead to premature distress that shortens pavement life and increases long-term maintenance needs. Studies like this help explain why some pavements perform well for years while others show signs of failure much sooner, even when they look similar on the surface.
