Roads are built-in parts to allow other lanes for the public to use. After every section, you’ll notice an obvious joint in between, these are called longitudinal lanes. These are often seen as the weakest link in asphalt pavement. This part is prone to deterioration when subject to regular pressure, heat, and rain. As the least dense part of the pavement, it cracks and disintegrates easily. When this happens, air and water go down the cracks and further weakens the pavement.
The Asphalt Institute collaborated with the Federal Highway Administration (FHWA) to pioneer studies about longitudinal joints and how they can be strengthened. Permeability is a major concern that needs to be addressed to aid in the efficiency of the joint. The density in the joints is said to be 1-2% lower than that of the center. Permeability is also related to the quality of the mix and the construction method used. Depending on the density of the mix, air voids can be formed. The standard limit for air voids should only be within 8-10%.
In a recent article from The Asphalt Magazine they write, “Studies have shown that lower density is to be expected in the joint area than in the center of the paving lane; in the best cases, the joint density is only 1-2% lower.”