It is worth remembering the following when mechanically spreading a layer of SMA mixture:
• Manually scattering mixture over the mechanically placed mixture is not permitted.
• Allowing any vehicles other than rollers on the hot mixture, before it is finally compacted and its temperature drops below the expected level, is not permitted.
• The end of a working lot (the transverse joint) should be finished by cutting; suitable joint bonding ought to be secured prior to laying the next lot—for example, by applying a PMB tape or a special compound (Figures 10.8 and 10.9).
• When executing the SMA layer in separate lanes (i. e., each traffic lane separately), the edge of the first layer should not be cut vertically but with a falling gradient, e. g., of 3:1 (height: width).
• Longitudinal edges should be cut while the mixture is hot. A special cutting wheel installed on a roller is user friendly; it is even more convenient with a metal pusher for the cut mixture located next to the cutting wheel, which eliminates manual removal operations.
• The utmost attention should be paid to the execution of an appropriate and tight longitudinal joint between two SMA layers; it is difficult due to the high content of chippings in mixtures; experiences have proved that the PMB compounds, laid down mechanically, are very effective.
