The scrub seal is a process by which a unique polymer modified asphalt emulsion is applied to a pavement surface by an asphalt distributor. The emulsion is scrubbed into the cracks and voids with a broom before a layer of aggregate is applied over the asphalt. The scrub seal is then rolled with a pneumatic tire roller and is usually ready for controlled traffic in 1 hour or less. The scrub seal process is intended to rejuvenate dry, oxidized, and cracked asphalt pavements in lieu of a microsurfacing, chip seal or asphalt overlay.
Equipment variations can be seen usually with the equipment utilized after the emulsion is placed which can included the following:
Material variations for scrub seals will usually come from either different types or sized aggregates.
SCRUB CAPE SEAL (SCRUB SEAL + MICROSURFACING): Utilizing a scrub seal broom behind the asphalt distributor during the chip seal phase of a cape seal project helps to force more of the chip seal emulsion into the existing cracks further delaying reflective cracking.
Note: Some agencies also opt for a cape seal in lieu of a stand-alone scrub seal in more heavily populated areas to provide a smoother texture finish wearing surface than the scrub seal alone can provide.
SCRUB SEAL + THIN LIFT HMA & SCRUB SEAL + HMA OVERLAY (SAMI): The combination treatment is utilized to retard the rate of reflection cracking in new asphalt overlays. The combination treatment with a HMA Overlay is known as a SAMI or a stress absorbing membrane interlayer.
SCRUB SEAL + FOG SEAL: This combination treatment is used to lock down any loose aggregate and to give the scrub seal a nice asthetic appearance.
SCRUB SEAL + CHIP SEAL: This combination treatment is a version of a double chip seal except that the first layer of emulsion is applied through the scrub seal process instead of the chip seal process. The second layer is applied as a regular chip seal.