Crackfilling and Sealing in Pavement Maintenance

[MikePhua]

Why Cracks Form and Why They Matter
Cracks in asphalt and concrete pavements are inevitable. They result from thermal expansion and contraction, traffic loads, subgrade movement, and aging of the binder. Left untreated, these cracks allow water infiltration, which accelerates base erosion, freeze-thaw damage, and pothole formation.
Terminology clarification:

• Crackfilling: The process of placing filler material into non-working cracks (minimal movement) to reduce water entry and debris accumulation.
  
• Cracksealing: A more robust method involving the placement of sealant in working cracks (subject to horizontal movement), often with routed edges and backer rods.
  
• Working Crack: A crack that experiences significant movement due to temperature or load changes, typically >3 mm annually.
  
• Non-working Crack: A crack with minimal movement, often longitudinal or block-type.
  

According to a 2022 FHWA report, untreated cracks can reduce pavement lifespan by up to 40%, while timely sealing can extend service life by 5–7 years.
Choosing Between Crackfilling and Cracksealing
The decision depends on crack type, climate, traffic volume, and budget. Cracksealing is preferred for transverse and reflective cracks in high-traffic areas, while crackfilling suits longitudinal and fatigue cracks in low-volume roads.
Comparison:

• Crackfilling
  • Cost: $0.35–$0.75 per linear foot
    
  • Lifespan: 2–4 years
    
  • Material: Asphalt emulsion, fiberized asphalt
    
• Cracksealing
  

• Cost: $0.75–$1.50 per linear foot
  
• Lifespan: 5–8 years
  
• Material: Rubberized asphalt, silicone, polymer-modified sealants
  

In Minnesota, a county road department reported that switching from crackfilling to cracksealing on key routes reduced annual patching costs by 30% over a five-year period.
Best Practices for Application
Successful crack treatment depends on preparation, timing, and material compatibility.
Steps:

1. Crack Identification
   Map and classify cracks by type, width, and movement.
   
2. Cleaning
   Use compressed air, wire brushes, or heat lances to remove debris and moisture.
   
3. Routing (for sealing)
   Enlarge cracks to uniform width and depth to improve sealant adhesion.
   
4. Backer Rod Placement
   Insert foam rods to control sealant depth and prevent three-sided adhesion.
   
5. Sealant Application
   Use calibrated melters with temperature control (typically 350–400°F for rubberized asphalt).
   
6. Tooling and Shaping
   Ensure proper crown and feathering to prevent water ponding.
   
7. Curing and Traffic Control
   Allow adequate cooling time before reopening to traffic, typically 30–60 minutes.
   

Recommendations:

• Avoid crack treatment during wet or freezing conditions
  
• Maintain sealant temperature within manufacturer specs
  
• Use low-modulus sealants in cold climates to accommodate movement
  
• Apply sand or blotting agents to reduce tracking in high-traffic zones
  

In Colorado, a contractor used a heat lance and polymer-modified sealant on a mountain highway. Despite sub-zero temperatures, the treated cracks remained sealed for over six years, outperforming traditional methods.
Equipment and Material Innovations
Modern crack maintenance equipment has evolved to improve efficiency and safety.
Key technologies:

• Oil-jacketed Melters
  Maintain consistent sealant temperature and reduce overheating risk.
  
• Auto-routing Machines
  Combine routing and cleaning in one pass, reducing labor.
  
• GPS Mapping Systems
  Track crack locations and treatment history for asset management.
  
• Eco-friendly Sealants
  Low-VOC formulations reduce environmental impact and meet EPA standards.
  

Manufacturers like Crafco, Cimline, and Marathon have led the industry in developing integrated cracksealing rigs. In 2023, Crafco reported a 12% increase in sales of their SuperShot melters, reflecting growing demand for preventive pavement maintenance.
Economic and Strategic Considerations
Crack maintenance is one of the most cost-effective pavement preservation strategies. According to the National Center for Pavement Preservation, every dollar spent on cracksealing saves $4–$6 in future rehabilitation costs.
Strategic tips:

• Prioritize high-value roads with early-stage cracking
  
• Combine cracksealing with surface treatments like chip seal or microsurfacing
  
• Schedule treatments during shoulder seasons (spring/fall) for optimal adhesion
  
• Monitor performance annually and reapply as needed
  

In Tennessee, a DOT pilot program integrating cracksealing with pavement preservation extended the average pavement life from 12 to 17 years, reducing lifecycle costs by 22%.
Conclusion
Crackfilling and sealing are more than patchwork—they are proactive investments in pavement longevity. By understanding crack behavior, selecting appropriate materials, and applying proven techniques, agencies and contractors can protect infrastructure, reduce costs, and improve safety. In the world of pavement maintenance, the smallest cracks often carry the biggest consequences—and the greatest opportunities for smart intervention.