Scrub Seal Process

Equipment variations can be seen usually with the equipment utilized after the emulsion is placed which can included the following:

• Rollers - pneumatic rollers and steel static wheel rollers can be used for scrub seal projects, however, caution should be used when using steel static wheel rollers due to crushing and degrading the aggregate.  Some agencies only have access to steel wheel rollers but pneumatic rollers are a best practice.
• Sweepers - the rotary broom is the common sweeper on scrub seal projects, however, vacuum sweepers can be seen where dust has to be minimized and loose aggregate cannot be seen off the road.  Urban roadway that have gutters would classify as an area where loose aggregate would be undesirable.
• Broom sleds - broom sleds can be made in different widths and with different materials such as wood or metal.

Material variations for scrub seals will usually come from either different types or sized aggregates.

• Aggregates
  • Types - granite, slag, limestone, or lightweight aggregates are some of the types that are usually utilized in scrub seals.  Which type that is utilized is usually dependent on local availability and the local specification.
  • Sizes - scrub seal aggregates can range from 1/4" to 3/8" in size.

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.