Breakdown rolling should start at which side of a hot bituminous mat?

Starting breakdown rolling on the low side of a hot bituminous mat is essential for several reasons. When asphalt is laid down, it usually has a slight slope to facilitate drainage, meaning one side will be higher than the other. By beginning the rolling process on the low side, the operator ensures that any excess material can be pushed toward the high side, promoting an even distribution of asphalt and preventing the mat from becoming uneven.

Initiating rolling on the low side also helps in maintaining compaction across the mat. As the roller traverses the low side, the weight and pressure exerted by the equipment can effectively compress the material toward the high side, resulting in a denser and more stable pavement. This method leads to better bonding between the layers of asphalt, ultimately enhancing the durability and lifespan of the road surface.

Rolling from the high side may exacerbate any existing discrepancies in the mat's elevation, leading to potential issues such as raveling, low spots, or inadequate density in certain areas. Moreover, starting in the middle or corner might not provide the same efficacy in ensuring a uniform compaction pattern throughout the entire surface, resulting in potential weaknesses that could lead to premature failure. Thus, by rolling from the low side, operators can achieve a smoother