What is the purpose of applying a tack coat (such as SS-1h asphalt emulsion) to vertical saw-cut edges during asphalt patch repairs?

1. To provide a strong adhesive bond between existing pavement and new HMA patch material.
2. To color the surrounding pavement red so inspectors can locate patch boundaries.
3. To prevent the new hot mix asphalt from compacting during steel rolling.
4. To act as a lubricant that allows the patch material to slide out of the hole during compaction.