The compaction of longitudinal joints on roads by road rollers

Since the width of the road surface that a paver can spread at one time is limited, for wider roads, the paving and compaction need to be completed in several steps, and longitudinal ribbon-like joints are formed between each two steps. The rolling of longitudinal joints should vary according to the cold or hot conditions of the joints.

Rolling of the longitudinal joint between the hot material layer and the cold material layer

If static smooth wheel rollers or vibratory rollers with disengaged vibration mechanisms are used for the operation, at the beginning of the compaction, most of the weight of the roller should be supported on the cold material layer, and the compaction can only be carried out on the hot material with a wheel width of 10 to 20cm. When this method is used for compaction, the excess mixture will be squeezed out from the uncompacted material, reducing the amount of material at the bonding edge and thus resulting in a lower bonding density.

When using a vibratory roller for compaction at longitudinal joints, to achieve a smooth joint, the weight of the roller must be placed as much as possible on the hot asphalt, with only a 10 to 20cm wheel width pressing on the cold material layer, followed by vibratory compaction. In this way, on the one hand, the cold material layer will not be damaged due to vibration; on the other hand, the mixed material can be pressed from the hot side into the relatively cold bonding side, thereby generating a higher bonding density. However, if a tire-driven single-roller vibratory roller is used, it is necessary to consider placing 75% of the tire width on the cold material side of the joint for compaction.

The method of using vibratory rollers to compact longitudinal joints not only increases the compaction capacity per unit area, but also reduces the disturbance to traffic due to the smaller area occupied by the roller on the cold material side.

(2) Rolling of longitudinal joints between hot material layers

When using a vibratory roller for compaction, first compact the area about 20cm away from both sides of the central joint, and then compact the remaining mixed material band in the middle. In this way, the spread material will not be squeezed out from the side and a good bond can still be achieved.