In most cases no. As long as the roadway is smooth and there is no upheavals along the cracks it can be scrub sealed as is.
Typically 3/8th or 5/16ths are the most commonly used aggregates. This ensures the cracks are properly filled while still leaving a friction surface texture.
PMRE – Polymer Modified Rejuvenated Emulsion is the most common emulsion used. It consists of an asphalt based material with rejuvenating oils, polymers and is a medium set type of emulsion. When you get enough rejuvenating oil in the material the polymer makes the material tough enough and elastic enough to stay in and properly bridge the cracks.
PMRE oils that are used in scrub seals are a medium setting emulsion developed and designed to be used in conjunction with the brooms to fill in the road surface alligatoring and cracking. CRS-2P and CRS-3P are faster setting emulsions and don’t consist of any rejuvenating oils. Being a higher rapid set material it also poses a higher difficulty dragging through the brooms and wetting out the surface filling the cracks.
Yes. The scrub seal can be left open as the wearing surface. You also can apply a MicroCoat™ or chip seal as a cover coat.