Crack Seals

Crack seal products are used to fill individual pavement cracks to prevent entry of water or other non-compressible substances such as sand, dirt, rocks or weeds. Crack sealant is typically used on early stage longitudinal cracks, transverse cracks, reflection cracks and block cracks. Fatigue cracks are most often too extensive to warrant filling with crack sealer; they usually require an area treatment such as a patch or reconstruction. Crack filler material is typically some form of rubberized asphalt or sand slurry.

Figure 1: Crack sealing on I-37 near San Antonio, TX to repair top-down cracks.

Figure 2: Crack sealing on western Oregon road to repair transverse cracks.

Figure 3: Crack sealing on I-37 near San Antonio, TX to repair top-down cracks.

Purpose

Preventive maintenance. Crack filling to prevent entry of water or other non-compressible substances into the pavement.

Materials

Heated liquid asphalt (often some form of rubberized asphalt).

Mix Design

Various, including proprietary methods.

Other Info

• Before applying crack sealant, cracks need to be routed out and cleaned.
• Crack sealing is best done in moderate temperatures (spring or fall) and is most effective if performed immediately after cracks develop.
• Reported average performance life ranges from about 3 - 8 years.
• Cracks in portland cement concrete pavements are sealed with different practices, described in PCC Joint and Crack Sealing. In a concrete slab, sealing suits a single, narrow linear crack in an otherwise sound slab. A crack that works like a joint should receive dowel bars if a dowel bar retrofit is planned. Multiple linear cracks, corner breaks and punchouts extend through the slab and need a full-depth patch or slab replacement, and durability cracking continues to spread regardless of sealing or patching.

Matching the Treatment to the Crack

Crack sealing suits low-severity longitudinal, transverse and reflection cracks, generally those less than about 13 mm (0.5 inch) wide and not numerous. Sealing keeps moisture out of the underlying layers and slows raveling of the crack edges, and an asphalt pavement can give years of satisfactory service after small cracks develop if they are kept sealed. Where cracks are wider than about 13 mm (0.5 inch) and numerous, removing and replacing the cracked layer, or overlaying it, is usually more appropriate.

Each crack type points to a different cause:

• Longitudinal cracks run in the direction of travel and are often construction-related, for example a poorly built longitudinal joint or one located in the wheelpath. They can also indicate structural failure or the start of fatigue cracking.
• Transverse cracks run perpendicular to the direction of travel. They are usually thermal cracks, most common in cold climates, though some are reflection cracks.
• Reflection cracks form in an overlay above existing cracks or joints in an underlying asphalt, portland cement concrete or stabilized base layer.

Once fatigue (alligator) cracking has formed its interconnected pattern, sealing is no longer effective. Small, localized areas of fatigue cracking usually indicate a loss of subgrade support; the repair is to remove the cracked pavement, replace the poor subgrade, improve drainage if needed, and patch. Extensive fatigue cracking indicates general structural failure and calls for an overlay designed to carry the anticipated loads, since the cracked pavement beneath contributes little or no strength. A test pit or core can show whether moisture is contributing to the failure.

Calculator

Crack sealant quantity

Reservoir volume × length

Units

US customary SI (metric)

Length of crack to seal, ft

Reservoir width, in.

Reservoir depth, in.

Allowance for waste and overband, %

Sealant specific gravity

CalculateExample values. Use the sealant maker’s specific gravity.

@misc{pavint-crack-seals,
  author = {{Pavement Interactive}},
  title = {Crack Seals},
  year = {2026},
  publisher = {HeadLight},
  howpublished = {\url{https://pavementinteractive.org/reference-desk/maintenance-and-rehabilitation/maintenance/crack-seals/}},
  note = {Accessed [date]}
}