10 Most Common Types of Asphalt Concrete Maintenance Treatments and Terminology

Posted by Shell Zhang on

most common asphalt concrete maintenance treatments

Crack repair with sealing: A localized treatment method used to prevent water and debris from entering a crack, which might include routing to clean the entire crack and to create a reservoir to hold the sealant. It is only effective for a few years and must be repeated. However, this treatment is very effective at prolonging the pavement life. This method includes the following three crack repair methods :

  • Clean and seal: Used on all types of cracks, it involves using a hot air lance or compressed air to blow out the debris in the crack, then filling with a sealant.
  • Saw and seal: Involves using a pavement saw to create transverse joints at regular intervals along a newly placed pavement, then filling with a sealant.
  • Rout and seal: Used on transverse and longitudinal cracks. Involves using a pavement saw or router to create a reservoir centered over existing cracks, then filling with a sealant.

Crack filling: Differs from crack sealing mainly in the preparation given to the crack prior to treatment and the type of sealant used. Crack filling is most often reserved for more worn pavements with wider, more random cracking.

Full-depth crack repair: A localized treatment to repair cracks that are too deteriorated to benefit from sealing.

Fog seal: An application of diluted emulsion to enrich the pavement surface and delay raveling and oxidation. It is considered a temporary treatment.

Seal coat: Used to waterproof the surface, seal small cracks, reduce oxidation of the pavement surface, and improve friction.

Double chip seal: An application of two single seal coats. The second coat is placed immediately after the first. This treatment waterproofs the surface, seals small cracks, reduces oxidation of the pavement surface, and improves friction.

Slurry seal: A mixture of fine aggregate, asphalt emulsion, water, and mineral filler, used when the primary problem is excessive oxidation and hardening of the existing surface. Slurry seals are used to retard surface raveling, seal minor cracks, and improve surface friction

Microsurfacing: Commonly referred to as a polymer-modified slurry seal; however, the major difference is that the curing process for microsurfacing is a chemically controlled process, versus the thermal process used by slurry seals and chip seals. Also may be used to fill ruts.

Thin hot-mix overlays: Includes dense, open, and gap-graded mixes that improve; ride quality, reduce oxidation of the pavement surface, provide surface drainage and friction, and correct surface irregularities.

Pothole patching: Includes using cold and hot asphalt mixtures, spray injection methods, and slurry and microsurfacing materials, to repair distress and improve ride quality.

Terminology 

Backer Rod: A compressible material that is placed in joints or cracks before applying sealant to prevent bonding of the sealant on the bottom of the joint, control sealant depth, and prevent sagging of the sealant.

Band-Aid: An overband configuration where material is shaped/finished to desired Dimensions.

Blotting: The application of material to a freshly sealed crack to prevent the occurrence of tracking or pulling due to traffic loading.

Capped (crack capping): An overband configuration where material is not shaped or finished. The material is allowed to level over the crack channel itself.

Cleaning (crack cleaning): Removal of debris and loose material from an existing crack or crack channel using a hot air lance or compressed air to blow out the debris in the crack.

Crack channel: The crack cavity as defined by either the original (uncut) crack or cut Crack.

Crack Filling: The placement of materials into non-working cracks to substantially reduce the infiltration of water and to reinforce the adjacent pavement. Non-working crack refers to horizontal and/or vertical movements less than 0.1 inch (2.5 mm). Non-working cracks typically include mostly longitudinal, diagonal cracks and some block cracks. Such cracks do not move much due to the close spacing between the edges. Crack filling is therefore simply filling the cracks that do not show significant movement. Simple overbands are usually used with filling operations. Crack filling involves placing the filling material and spreading it out over and into the crack(s) with a squeegee. Squeegees are typically U or V shaped to push the material and concentrate it over the crack. Crack filling materials may be hot applied rubber or polymer asphalts, or cold applied emulsion-based products. The emulsion products assist with forming a good adhesive bond with the crack wall and additives such as Styrene Butadiene Rubber (SBR) latex ensure that the material can endure some degree of movement. In some cases, hot applied fiber modified asphalt binders may be used. For short-term crack-fill performance (1 to 3 years) in pavements with nonworking cracks (less than 0.1 inch (2.5 mm) of horizontal crack movement) and low to moderate traffic levels, asphalt cement should be placed in flush-fill configuration. For long-term crack-fill performance (between 5 and 8 years) under the above conditions, a hot asphalt rubber or hot rubberized asphalt may be placed in either a flush-fill or overband configuration, or a fiberized asphalt may be placed in an overband configuration.

Crack Sealing: The placement of specialized materials either above or into working cracks using unique configurations to prevent the intrusion of water and other incompressibles into the pavement cracks. Working cracks refers to horizontal and/or vertical crack movements greater than 0.1 inch (2.5 mm). Transverse cracks are a good example of working cracks; however, some longitudinal cracks may also meet the movement criterion. Crack sealing involves thorough crack preparation followed by the placement of a high-quality material in a specific configuration. Crack sealant materials are rubberized products that have the ability to seal the crack and flex with the pavement’s movement. They are used for active cracks that continue to extend both in size and severity with time and the ravages of the traffic and weather. Crack sealants have excellent adhesive and cohesive properties. In other words they firmly adhere to the walls of the cracks and do not tear or split when the cracks widen. Reservoirs are generally associated with sealing operations. In a sealing operation, sealant is placed either flush with the surface or slightly recessed within a cut reservoir. The purpose of the reservoir is to create room for enough material to be applied, create a desirable sealant shape, and provide a uniform surface for the sealant to adhere to. The sealant also may be recessed to prevent plow and traffic damage. For sealing working cracks, the preferred sealant is usually elastomeric. This means the sealant has a low modulus of elasticity and will stretch easily and to high elongations (usually around 10 times its non-strained dimensions) without fracture. Such sealants also recover over time to close to their original dimensions. For short-term crack-seal performance (between 1 and 3 years) in pavements with ordinary working cracks 0.1- 0.2 inch (2.5-5 mm) of horizontal crack movement) and moderate traffic levels, a standard rubberized asphalt should be placed in a simple Band-Aid configuration. For medium-term crack-seal performance (between 3 and 5 years) under the above conditions, either a standard hot rubberized asphalt may be placed in a recessed Band-Aid configuration or a modified hot rubberized asphalt may be placed in a simple Band-Aid configuration. For long-term crack-seal performance (between 5 and 8 years) under the above conditions, a modified rubberized asphalt sealant should be installed in either a standard or shallow recessed Band-Aid configuration.

Crack reservoir: A uniform crack channel resulting from cutting operations. Generally rectangular in shape.

Flush Fill: Crack filling method where fill material is forced into a crack and is struck flush with the pavement surface.

Hot air lance: A preparation device that uses heated compressed air to clean, dry, and warm cracks prior to sealing.

Incompressible: Material, such as sand, stone, and dirt, that resists the compression of a closing crack channel.

Melting Kettle: A device used to heat sealing materials to working temperatures in the field.

Non-working Cracks: cracks that experience relatively little horizontal and/or vertical movement as a result of temperature change or traffic loading. As a general rule, movement less than 0.1 inch (2.5 mm).

Overband: A type of finish in which material is allowed to completely cover crack channel by extending onto the pavement surface. Overbands consist of Band-Aid and capped configurations.

Routing: Crack preparation method involving the use of pavement router to create a reservoir centered over existing cracks.

Sawing: Crack preparation method involving the use of a pavement saw to create transverse joints at regular intervals along a newly placed pavement.

Squeegee: A device used to apply sealant in an overbanding configuration or remove excess sealing material from the sealed crack.

Working Cracks: Cracks that experience considerable horizontal and/or vertical movement as a result of temperature change or traffic loading. In general, movement greater than or equal to 0.1 inch (2.5 mm).