Tack coat is a spray application that is used to strengthen the bond between a new course of asphalt and an existing one. It also improves the pavement’s structural strength and reduces the possibility of shoving and pushing in the new surface as well as top-down cracking.
Tack Coat Improves Asphalt Paving Performance – When Should a Tack Coat Be Applied?
A tack coat is typically applied between an existing pavement and an overlay whether the existing pavement is concrete or asphalt. Sometimes, a tack coat may be applied between the layers of new hot-mix asphalt such as between a surface course and a leveling course. Tack coat is often needed if the pavement has been milled to help improve the bond between layers. Pavement with a steep grade, in areas where traffic is accelerating or braking, with relatively thin layers of asphalt or in hot climates may benefit from a tack coat.
Amount of Tack Coat Needed
Asphalt contractors must adjust the amount of tack coat applied to account for a variety of factors. For example, a new surface course needs minimal tack coat as the pavement will absorb little of the material. An oxidized, aged surface will need more tack coat to compensate for the increased absorption of material. A surface containing hairline cracks may also need additional tack coat.
The terrain is another factor that contractors must consider. If the terrain is mountainous or hilly, the contractor must ensure that an excessive amount of tack coat is used. In such terrain, excessive tack coat can cause slippage between the asphalt layers or between the existing pavement and the overlay. However, it is possible that shear stresses from traffic, especially heavy trucks, moving downhill or uphill can reduce the pavement’s performance.
The contractor must also evaluate the weather conditions during the paving process. If the ambient temperature or the humidity level is very high, the curing time will be affected. Setting and curing time can also be extended if the surface of the pavement is damp from a recent rain.
Tack Coat Performance
When cores are examined soon after pavement has been installed, it is often discovered that the bond between layers has not formed. The rate of bond development can be affected by a variety of factors, including the thickness of the individual layers, climatic factors and the volume of traffic. In many cases, it can take only days or weeks for a bond to develop between the old pavement and the new layer. At other times, it can take several weeks — possibly months — for bond development to occur. Warm weather and traffic can also influence the development of the bond.
Experience Counts
If tack coat is applied correctly and under the proper conditions, it can help ensure the pavement’s long-term durability. If too much or too little is used, the performance of the entire pavement can be compromised. Therefore, it is essential to hire an experienced asphalt contractor.
MH Greeson Paving is an experienced asphalt paving company serving Atlanta, Marietta, and most locations in North Georgia. Our services include asphalt paving, parking lot striping, seal coating, asphalt repair, pavement markings, bollards and traffic signs. We are committed to exceptional workmanship, outstanding customer service and competitive prices. To request a free quote, complete the online form or call us at (770) 335-2983.
